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頁巖氣

2015-10-31 03:21MississippianBarnettShaleFortWorthbasinnorthcentraltexasGasshaleplaywithmultitrillioncubicfootpotential
中國學術期刊文摘 2015年10期
關鍵詞:頁巖氣

Mississippian Barnett Shale,Fort Worth basin,north-central texas: Gas-shale play with multi-trillion cubic foot potential

Scott L. Montgomery; Daniel M. Jarvie; Kent A. Bowker; et al.

Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment

Daniel M. Jarvie; Ronald J. Hill; Tim E. Ruble; et al.

Shale gas potential of the Lower Jurassic Gordondale Member,northeastern British Columbia,Canada

Ross,DJK; Bustin,RM

Characterizing the shale gas resource potential of Devonian-Mississippian strata in the Western Canada sedimentary basin: Application of an integrated formation evaluation

Ross DJK,Bustin RM

中國頁巖氣勘探開發進展與發展前景*

董大忠1,鄒才能1,楊樺1,王玉滿1,李新景1,陳更生2,王世謙2,呂宗剛2,黃勇斌2

(1. 中國石油勘探開發研究院,北京100083;2. 中國石油西南油氣田公司,四川成都650001)

中國頁巖氣形成機理、地質特征及資源潛力*

鄒才能1,2,董大忠1,2,王社教1,2,李建忠1,2,李新景1,2,王玉滿1,2,李登華1,2,程克明1,2

(1. 中國石油勘探開發研究院;2. 提高石油采收率國家重點實驗室)

頁巖氣成藏機理和分布

張金川,金之鈞,袁明生

頁巖氣

·編者按·

“頁巖氣(shale gas)”是最重要的非常規天然氣資源,資源潛力超過致密氣和煤層氣之和,美國“頁巖氣革命”對全球能源格局已產生深刻影響.科羅拉多礦業學院Curtis教授系統闡述了頁巖氣的概念,頁巖氣是連續生成的生物化學成因、熱成因或兩者混合的天然氣聚集,具有普遍含氣、大面積分布、多種巖性封閉、短距離運移等特點,以游離形式存在于天然裂縫和孔隙中,以吸附狀態存在于干酪根和粘土顆粒表面,以溶解狀態存在于干酪根和瀝青質中.近年來,“頁巖氣”概念被廣泛引入國內,普遍認為,頁巖氣是賦存于富有機質泥頁巖層段中,以吸附態和游離態為主要賦存方式、大面積連續分布的非常規天然氣,為典型“自生自儲、原地滯留”聚集模式,成分以甲烷為主.

相比常規天然氣,頁巖氣開發較為困難,但具有開發壽命長和生產周期長的優點.大部分產氣頁巖分布范圍廣、厚度大、普遍含氣,這使得頁巖氣井能夠長期產氣,但是頁巖氣儲集層滲透率低,開采難度較大.頁巖氣為完全的、獨立的、自生自儲的含油氣系統,富有機質黑色頁巖本身就是源巖、儲層和封蓋層,為源儲一體、原位持續聚集、早成藏的典型源巖氣藏,它既不同于常規天然氣,也有別于致密砂巖氣、煤層氣等非常規天然氣,具有五個重要的地質與開發特征:(1)頁巖氣可形成于有機質演化的各個階段,包括生物氣、干酪根熱降解氣和原油熱裂解氣.研究表明,頁巖產氣能力與熱成熟度、TOC等密切相關,一般生物成因頁巖氣產量低,熱成因頁巖氣產量高.(2)頁巖氣儲層致密,以納米級孔隙為主,具有極低的孔隙度和超低滲透率.(3)頁巖氣在成藏、開采機理上與其它類型天然氣有明顯的不同.頁巖氣氣體主要以吸附、游離2種狀態賦存.吸附氣含量一般為20%~85%,并隨深度不同有較大的變化,這一賦存形式類似于煤層吸附氣,但其吸附氣量小于煤層吸附氣(85%以上).游離氣含量一般為80%~20%,和常規天然氣相似,儲層物性愈好,游離氣含量愈高.(4)頁巖氣大面積連續分布,資源規模大,源儲一體,含氣范圍與有效氣源巖相當,沒有明顯的圈閉界線,分布不受構造的控制.(5)單井產量低,生產周期長,采收率變化較大.隨著水平井、多級水力體積壓裂等鉆完井、儲層增產改造等技術的進步,頁巖氣采收率正在逐步提高.

頁巖氣發現較早,1821年美國在東部泥盆系鉆探第一口頁巖氣井,1914年美國發現第一個頁巖氣大氣田—Big Sandy氣田,1981年頁巖氣之父喬治·米歇爾對Barnett頁巖實施大規模壓裂,實現了頁巖氣開采真正意義上的大突破.頁巖氣由南部地區的Barnett頁巖,到Haynesville頁巖,再到東部地區的Marcellus頁巖,持續獲得重大發展,至2014年,北美地區在約50個富有機質頁巖區帶中證實存在頁巖氣資源,在其中9個區帶實現了頁巖氣的規模開發,2014年美國頁巖氣產量為3637×108m3,占美國天然氣總產量的50%,依靠頁巖氣,美國實現了天然氣自給.全球正在進行一場“頁巖氣革命”,北美以外地區已有20多個國家正在進行頁巖氣資源的前期評價和勘探開發先導試驗,中國、阿根廷、英國、印度、新西蘭等國已發現了頁巖氣,全球頁巖氣資源量約為456×1012m3,勘探開發前景廣闊.中國頁巖氣資源豐富,發育海相、海陸過渡相—湖沼煤系和湖相3類富含有機質頁巖,均具備頁巖氣形成條件.近年來,頁巖氣已得到國家和企業的高度重視,已在地質基礎研究、資源評價和核心區優選、水平井壓裂等技術創新、工業化試驗區建設等攻關取得重大進展.2004—2007年,引入頁巖氣概念;2008年,鉆探第一口頁巖氣地質井長芯1井;2009年,首次在中國頁巖氣儲集層中發現豐富的納米級孔隙;2010年,成立國家能源頁巖氣研發(實驗)中心;2010年,四川盆地威201井在志留系龍馬溪組獲日產大于1×104m3頁巖氣;2011年,國家第一個頁巖氣重大專項《頁巖氣勘探開發關鍵技術》立項;2012年四川盆地焦石壩構造焦頁1HF在志留系龍馬溪組獲日產氣20.3×104m3工業氣流,發現了中國首個大型頁巖氣田—涪陵氣田,并已啟動一期50×108m3產能建設,中國頁巖氣勘探取得戰略突破.目前,中國已在重慶焦石壩、巫溪,四川長寧-威遠、富順-永川,云南昭通、陜西延安等地區開展頁巖氣工業開采或先導試驗.截至2014年底,中國累計投資200億元,完鉆頁巖氣井400口,壓裂獲氣160口井,2013年頁巖氣產量2×108m3,2014年產量13×108m3,中國頁巖氣開發利用已順利實現工業起步.

中國頁巖氣開發利用面臨保存較差、埋藏較深、地表復雜、水源短缺、環境保護等一系列問題,大規模經濟有效開發難度較大.中國頁巖氣規?;l展,需要突破理論關、技術關、成本關、環境關“四道關”,需注意優先解決四川盆地龍馬溪組構造型“甜點”和連續型“甜點區”頁巖氣遞減規律、四川盆地筇竹寺組優質資源落實、3500 m以深頁巖氣效益開發技術與裝備研發、海陸過渡相/陸相頁巖氣資源潛力評價等關鍵問題.初步估算,中國頁巖氣技術可采資源量大約為(10~25)×1012m3.預計未來5~10年,將是中國頁巖氣技術攻關與先導試驗的關鍵期,需要制定“加快‘核心區’評選、加大‘試驗區’建設、加強‘生產區’規劃”等戰略發展路線圖,力爭2020年前后實現頁巖氣工業化全面突破和規模發展.

本專題得到了鄒才能教授(中國石油勘探開發研究院)、郝梓國教授(中國地質學會)的大力支持.

·熱點數據排行·

截至2015年4月20日,中國知網(CNKI)和Web of Science(WOS)的數據報告顯示,以頁巖氣(shale gas)為詞條可以檢索到的期刊文獻分別為1726與1020條,本專題將相關數據按照:研究機構發文數、作者發文數、期刊發文數、被引用頻次進行排行,結果如下.

研究機構發文數量排名(CNKI)

研究機構發文數量排名(WOS)

作者發文數量排名(CNKI)

作者發文數量排名(WOS)

期刊發文數量排名(CNKI)

期刊發文數量排名(WOS)

根據中國知網(CNKI)數據報告,以頁巖氣(shale gas)為詞條可以檢索到的高被引論文排行結果如下.

國內數據庫高被引論文排行

(數據來源:中國知網,檢索時間:2015-4-20)

根據Web of Science統計數據,以頁巖氣(shale gas)為詞條可以檢索到的高被引論文排行結果如下.

國外數據庫高被引論文排行

·經典文獻推薦·

基于Web of Science檢索結果,利用Histcite軟件選取LCS(Local Citation Score,本地引用次數)TOP 30文獻作為節點進行分析,得到本領域推薦的經典文獻如下.

來源出版物:AAPG Bulletin,2002,86(11): 1921-1938

Mississippian Barnett Shale,Fort Worth basin,north-central texas: Gas-shale play with multi-trillion cubic foot potential

Scott L. Montgomery; Daniel M. Jarvie; Kent A. Bowker; et al.

Abstract: The Mississippian Barnett Shale serves as source,seal,and reservoir to a world-class unconventional natural-gas accumulation in the Fort Worth basin of north-central Texas. The formation is a lithologically complex interval of low permeability that requires artificial stimulation to produce. At present,production is mainly confined to a limited portion of the northern basin where the Barnett Shale is relatively thick(>300 ft; >92 m),organic rich(present-day total organic carbon >3.0%),thermally mature(vitrinite reflectance >1.1%),and enclosed by dense limestone units able to contain induced fractures. The most actively drilled area is Newark East field,currently the largest gas field in Texas. Newark East is 400 mi2(1036 km2)in extent,with more than 2340 producing wells and about 2.7 tcf of bookedgas reserves. Cumulative gas production from Barnett Shale wells through 2003 was about 0.8 tcf. Wells in Newark East field typically produce from depths of 7500 ft(2285 m)at rates ranging from 0.5 to more than 4 mmcf/day. Estimated ultimate re coveries per well range from 0.75 to as high as 7.0 bcf. Efforts to extend the current Barnett play beyond the field limits have encountered several challenges,including westward and northward increases in oil saturation and the absence of lithologic barriers to induced fracture growth. Patterns of oil and gas occurrence in the Barnett,in conjunction with maturation and burial-history data,indicate a complex,multiphased thermal evolution,with episodic expulsion of hydrocarbons and secondary cracking of primary oils to gas in portions of the basin where paleotemperatures were especially elevated. These and other data imply a large-potential Barnett resource for the basin as a whole(possibly >200 tcf gas in place). Recent assessment by the U.S. Geological Survey suggests a mean volume of 26.2 tcf of undiscovered,technically recoverable gas in the central Fort Worth basin. Recovery of a significant portion of this undiscovered resource will require continued improvements in geoscientific characterization and approaches to stimulation of the Barnett reservoirs.

Keywords: interdisciplinary approach; Pennsylvanian; marattialean pecopterids; functional groups; FTIR

來源出版物:AAPG Bulletin,2005,89(2): 155-175

Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment

Daniel M. Jarvie; Ronald J. Hill; Tim E. Ruble; et al.

Abstract: Shale-gas resource plays can be distinguished by gas type and system characteristics. The Newark East gas field,located in the Fort Worth Basin,Texas,is defined by thermogenic gas production from low-porosity and low-permeability Barnett Shale. The Barnett Shale gas system,a self-contained source-reservoir system,has generated large amounts of gas in the key productive areas because of various characteristics and processes,including(1)excellent original organic richness and generation potential;(2)primary and secondary cracking of kerogen and retained oil,respectively;(3)retention of oil for cracking to gas by adsorption;(4)porosity resulting from organic matter decomposition; and(5)brittle mineralogical composition. The calculated total gas in place(GIP)based on estimated ultimate recovery that is based on production profiles and operator estimates is about 204 bcf/section(5.78×109M-3/1.73×104m3). We estimate that the Barnett Shale has a total generation potential of about 609 bbl of oil equivalent/ac-ft or the equivalent of 3657 mcf/ac-ft(84.0 m3/m3). Assuming a thickness of 350 ft(107 m)and only sufficient hydrogen for partial cracking of retained oil to gas,a total generation potential of 820 bcf/section is estimated. Of this potential,approximately 60% was expelled,and the balance was retained for secondary cracking of oil to gas,if sufficient thermal maturity was reached. Gas storage capacity of the Barnett Shale at typical reservoir pressure,volume,and temperature conditions and 6% porosity shows a maximum storage capacity of 540 mcf/ac-ft or 159 scf/ton.

Keywords: Sichuan Basin; middle paleo-uplift; pyrobitumen; natural gas potential; upper Proterozoic strata

來源出版物:AAPG Bulletin,2007,91(4): 475-499

Shale gas potential of the Lower Jurassic Gordondale Member,northeastern British Columbia,Canada

Ross,DJK; Bustin,RM

Abstract: The Lower Jurassic Gordondale Member is an organic-rich mudrock and is widely considered to have potential as a shale gas reservoir. Influences of Gordondale mudrock composition on total gas capacities(sorbed and free gas)have been determined to assess the shale gas resource potential of strata in the Peace River district,northeastern British Columbia. Sorbed gas capacities of moisture-equilibrated samples increase over a range of 0.5 to 12 weight percent total organic carbon content(TOC). Methane adsorption capacities range from 0.05 cc/g to over 2 cc/g in organic-rich zones(at 6 MPa and 30 degrees C). Sorption capacities of mudrocks under dry conditions are greater than moisture equilibrated conditions due to water occupation of potential sorption sites. However,there is no consistent decrease of sorption capacity with increasing moisture as the relationship is masked by both the amount of organic matter and thermal maturation level. Clays also affect total gas capacities in as much as clay-rich mudrocks have high porosity which may be available for free gas. Gordondale samples enriched with carbonate(calcite and dolomite)typically have lower total porosities than carbonate-poor rocks and hence have lower potential free gas contents. On a regional reservoir scale,a large proportion of the Gordondale total gas capacity is free gas storage(intergranular porosity),ranging from 0.1-22 Bcf/section(0.003-0.66 m3/section). Total gas-in-place capacity ranges from 1-31.4 Bcf/section(0.03-0.94 m3/section). The greatest potential for gas production is in the south of the study area(93-P)due to higher thermal maturity,TOC enrichment,higher reservoir pressure,greater unit thickness and improved fracture-potential.

Keywords: shaly sand; pore-scale model; conductivity; clays

來源出版物:Bulletin of Canadian Petroleum Geology,2007,55(1): 51-75

Characterizing the shale gas resource potential of Devonian-Mississippian strata in the Western Canada sedimentary basin: Application of an integrated formation evaluation

Ross DJK,Bustin RM

Abstract: Devonian-Mississippian strata in the northwestern region of the Western Canada sedimentary basin(WCSB)were investigated for shale gas potential. In the subsurface,thermally mature strata of the Besa River,Horn River,Muskwa,and Fort Simpson formations attain thicknesses of more than 1 km(0.6 mi),encompassing an area of approximately 125000 km2(48300 mi2)and represent an enormous potential gas resource. Total gas capacity estimates range between 60 and 600 bcf/section. Of particular exploration interest are shales and mudrocks of the Horn River Formation(including the laterally equivalent lower Besa River mudrocks),Muskwa Formation,and upper Besa River Formation,which yield total organic carbon(TOC)contents of up to 5.7 wt.%. Fort Simpson shales seldom have TOC contents above 1 wt.%. Horn River and Muskwa formations have excellent shale gas potential in a region between longitudes 122°W and 123°W and latitudes 59°N and 60°N(National Topographic System [NTS] 94O08 to 94O15). In this area,which covers an areal extent of 6250 km2(2404 mi2),average TOC contents are higher(>3 wt.% as determined by wire-line-log calibrations),and have a stratal thickness of more than 200 m(656 ft). Gas capacities are estimated to be between 100 and 240 bcf/section and possibly greater than 400 tcf gas in place. A substantial percentage of the gas capacity is free gas caused by high reservoir temperatures and pressures. Muskwa shales have adsorbed gas capacities ranging between 0.3 and 0.5 cm3/g(9.6-16 scf/t)at reservoir temperatures of 60-80°C(140-176°F),whereas Besa River mudrocks and shales have low adsorbed gas capacities of less than 0.01 cm3/g(0.32 scf/t; Liard Basin region)because reservoir temperatures exceed 130°C(266°F). Potential free gas capacities range from 1.2 to 9.5 cm3/g(38.4 to 304 scf/t)when total pore volumes(0.4%-6.9%)are saturated with gas. The mineralogy has a major influence on total gas capacity. Carbonate-rich samples,indicative of adjacent carbonate platform and embayment successions,commonly have lower organic carbon content and porosity and corresponding lower gas capacity(<1% TOC and <1% porosity). Seaward of the carbonate Slave Point edge,Muskwa and lower Besa River mudrocks can be both silica and TOC rich(up to 92% quartz and 5 wt.% TOC)and most favorable for shale gas reservoir exploration because of possible fracture enhancement of the brittle organic- and siliceous-rich facies. However,an inverse relation between silica and porosity in some regions implies that zones with the best propensity for fracture completion may not provide optimal gas capacity,and a balance between favorable reservoir characteristics needs to be sought.

來源出版物:AAPG Bulletin,2008,92(1): 87-125

·推薦綜述·

中國頁巖氣勘探開發進展與發展前景*

董大忠1,鄒才能1,楊樺1,王玉滿1,李新景1,陳更生2,王世謙2,呂宗剛2,黃勇斌2

(1. 中國石油勘探開發研究院,北京100083;2. 中國石油西南油氣田公司,四川成都650001)

頁巖氣是典型的非常規天然氣,產自極低孔滲、以富有機質頁巖為主的儲集巖系中.頁巖氣的形成與富集為自生自儲、以游離氣和吸附氣為主、原位飽和富集于以頁巖為主的儲集巖系的微—納米級孔隙—裂縫與礦物顆粒表面[1-2].頁巖氣常被稱為“人造氣藏”,開采必須通過大型人工儲層造縫(網)才能形成工業生產能力,初期產量一般較高、早期遞減較快,后期低產穩產且生產時間長(一般30-50年).頁巖氣是國外最早認識的天然氣,自1821年在美國阿帕拉契亞盆地成功鉆探第1口頁巖氣井以來,頁巖氣的發展已近200年歷史.但20世紀90年代前,當時只重視了致密(巖石)氣與煤層氣,頁巖氣在天然氣大家族中的地位微不足道[3],21世紀以來,隨著頁巖氣地質與開發理論的創新和勘探開發關鍵技術的進步,尤其是水平井鉆完井與分段壓裂技術的進步及規模推廣應用,頁巖氣邁進了大發展階段.2005年以來,中國借鑒北美經驗,開始了中國頁巖氣地質條件評價與勘探開發先導性試驗[1,3-4].迄今,不僅在地質認識上取得進展,在勘探開發實踐上也取得突破,成為全球除北美以外地區率先發現頁巖氣的國家.筆者在全球頁巖氣發展現狀與中國頁巖氣勘探開發實踐現狀把握基礎上,初步探討了中國頁巖氣形成與富集條件,對中國頁巖氣勘探開發前景做了預測,以期對推動中國頁巖氣的發展有所幫助.

1全球頁巖氣資源發展概況

在全球,北美地區的頁巖氣資源勘探開發最為成功,2000年北美地區的頁巖氣年產量突破了100×108m3,至2010年該地區的頁巖氣年產量達到1500×108m3[3-7],10年間增長了10倍以上.美國能源信息署預測統計(圖1)[5-7],2010年北美地區在約50個富有機質頁巖區帶中證實存在頁巖氣資源,在其中9個主要頁巖區帶進行頁巖氣生產,頁巖氣年產量1500×108m3,占北美天然氣總產量的20%左右.

北美頁巖氣的快速發展,改變了北美天然氣供應格局,影響到了全球能源供給格局的變化,頁巖氣在全球迅速成為重要的天然氣勘探開發新目前.目前,全球掀起了轟轟烈烈的綠色“頁巖氣革命”(圖2),各國政府和油氣/能源公司幾乎都將頁巖氣提到了重要日程[8],北美以外地區已有20余個國家在進行頁巖氣資源的前期評價和勘探開發先導試驗,中國、英國、印度、新西蘭等國已紛紛宣稱在本國發現了頁巖氣.

中國為全球除北美以外地區率先發現頁巖氣的國家.至2010年,中國已在富有機質頁巖地質特征、頁巖氣形成與富集地質條件、頁巖氣遠景區帶優選等基礎地質理論與認識上取得重要了進展;在四川盆地南部古生界、四川盆地北部中生代、鄂爾多斯盆地三疊系等多個地區和多個時代的海相、陸相富有機質頁巖中取得重要頁巖氣突破和發現.

2中國頁巖氣勘探開發進展

2.1中國頁巖氣勘探歷程

與北美的頁巖氣勘探開發成就相比,中國的頁巖氣勘探開發起步較晚,而與全球其他地區相比,中國的頁巖氣勘探開發則處于領先地位,為全球除北美以外地區率先進入頁巖氣勘探評價突破和工業化開發先導性試驗的國家[1-4].實際上,從歷史發展分析,中國的油氣勘探開發對頁巖氣并不陌生,過去的常規油氣勘探開發中頁巖氣的發現已屢見不鮮.自20世紀60年代以來,不斷在松遼、渤海灣、四川、鄂爾多斯、柴達木等幾乎所有陸上含油氣盆地中都發現了頁巖氣或泥頁巖裂縫性油氣藏,典型代表有1966年在四川盆地威遠構造上鉆探的威5井,在古生界寒武系筇竹寺組海相頁巖中獲得了日產氣2.46×104m3.1994—1998年間中國還專門針對泥、頁巖裂縫性油氣藏做過大量工作,此后許多學者也在不同含油氣盆地探索過頁巖氣形成與富集的可能性[2].2000—2005年中國廣大石油地質學者再次關注北美在富有機質頁巖中勘探開發天然氣的新成就,從2005年起把視角投向中國本土,尋求中國頁巖氣形成與富集的地質條件,調查頁巖氣資源潛力,探索中國頁巖氣的發展前景.歸納起來,中國頁巖氣勘探開發歷史暫可劃分為泥頁巖裂縫性油氣藏勘探開發、頁巖氣地質條件研究與關鍵開發技術儲備、勘探評價突破與開發先導性試驗等過程,其里程碑事件總結于表1.

2.2中國頁巖氣勘探開發進展

中國的頁巖氣資源的勘探開發熱潮始于2005年.在前期對北美頁巖氣資源發展進程的跟蹤、研究基礎上,于2005年起,中國主要石油企業、石油與地質類高等院校、國土資源部與國家能源局等相關政府機構[4],從老資料復查、露頭地質調查等基礎著手,開展了中國頁巖氣形成與富集地質條件研究和頁巖氣資源潛力評價,在頁巖氣遠景區帶進行了地質淺井、地質評價參數井等的鉆探,取得了早期頁巖氣地質評價與頁巖氣資源潛力預測等關鍵參數,優選了一批有利頁巖氣區帶,鉆探了頁巖氣評價井和頁巖氣開發先導性試驗井,建立了四川威遠—長寧、云南昭通等多個國家級頁巖氣工業化開發先導性示范區(圖3).

2006年中國石油與美國新田石油公司進行了國內首次頁巖氣研討,依據四川盆地南部威遠、陽高寺等地區的常規天然氣勘探開發過程中,鉆遇寒武系筇竹寺組和志留系龍馬溪組時出現的豐富含氣顯示現象,提出中國具備海相頁巖氣形成與富集的基本地質條件[9-10].2007年即與新田石油合作,開展了威遠地區寒武系筇竹寺組頁巖氣資源潛力評價與開發可行性的聯合研究,該研究項目為中國與國外的第一個頁巖氣聯合研究項目.與此同時,對整個蜀南地區古生代海相頁巖地層開展了露頭地質調查與老資料(井)復查.為探索頁巖氣地質與資源前景評價方法,2008年中國石油勘探開發研究院在四川盆地南部長寧構造志留系龍馬溪組露頭區鉆探了中國第一口頁巖氣地質評價淺井即長芯1井,井深154.3 m,取心151.6 m[1].通過2007—2008年的前期地質研究與選區評價,初步認識到上揚子地區古生界發育多套海相富有機質頁巖,厚度大,有機碳含量高,具有較好的頁巖氣形成條件.2009年中國石油率先在四川盆地威遠—長寧、云南昭通等地區進行頁巖氣鉆探評價,與殼牌(shell)公司在四川盆地富順—永川地區進行中國第一個頁巖氣國際合作勘探開發項目.同時,國土資源部在全國油氣資源戰略選區調查與評價專項中設立了“中國重點地區頁巖氣資源潛力評價和有利區帶優選”項目,中國石化在貴州大方—凱里方深1井區開展了寒武系牛蹄塘組頁巖氣老井復

查.2010年以來,中國頁巖氣勘探開發陸續取得單井突破,進入到了開發先導性試驗區建設階段.初步統計,迄今中國已在四川、鄂爾多斯、渤海灣、沁水、泌陽等盆地,重慶黔江、云南昭通、貴州大方湖北建南、湖南漣源、貴州銅仁等地區,鉆探頁巖氣井(直井與水平井,直井為主)50余口,水力壓裂試氣井近20口,獲工業頁巖氣(油)流井10口,多口井初期產量超過了1×104m3/d(圖4),實現了中國海相(古生界)頁巖氣的突破,海陸過渡相煤系(二疊系)頁巖氣與陸相(中生界)頁巖氣/油的發現.

3中國頁巖氣勘探開發前景

3.1中國頁巖氣形成條件

與北美相比,中國頁巖氣形成與富集條件具明顯特殊性,中國沉積盆地發育3類富有機質頁巖[1-3,11-14],包括海相富有機質頁巖、海陸過渡相與湖沼相煤系富有機質頁巖和湖相富有機質頁巖.不同時代、不同地區發育不同類型富有機質頁巖組合,頁巖成氣潛力差異明顯.

3.1.1海相富有機質頁巖

中國海相富有機質頁巖分布廣泛,主要發育在中國南方地區、華北地區及西部塔里木盆地的上震旦統、下寒武統、上奧陶統—下志留統等(表2).海相富有機質泥頁巖分布面積大、橫向變化穩定,厚度一般在100~500 m.海相富有機質頁巖有機質豐富,平均含量1.0%~5.12%,其中高TOC含量(TOC含量大于2%)的富含有機質頁巖段發育,厚度一般為20~180 m.海相富有機質頁巖有機質類型以腐泥型—混合型為主,屬傾成油型母質,熱演化程度處在裂解成氣階段(1.0%<Ro<5.2%)[11],頁巖氣以原油熱裂解氣為主.海相高演化頁巖基質孔隙、有機質微—納米級孔隙發育,構成了頁巖氣良好的儲集空間.海相頁巖脆性礦物豐富,黏土礦物單一.海相頁巖成氣藏條件優越,勘探開發前景好.

中國南方地區是海相頁巖氣較有利地區,尤以上揚子地區為好,如四川盆地筇竹寺組富有機質頁巖分布面積18.5×104km2,厚200~600 m,有效頁巖厚度110~163 m,TOC含量0.82%~4.68%,平均2.3%,頁巖含氣量0.13~5.02 m3/t,石英、長石和碳酸鹽巖等脆性礦物為49%~58%;五峰組—龍馬溪組富有機質頁巖分布面積13.7×104km2,厚300~500 m,有效頁巖厚度40~125 m,TOC含量0.5%~7.12%,平均2.1%,頁巖含氣量0.2~6.5 m3/t,石英、長石和碳酸鹽巖等脆性礦物含量為33.0%~51.2%.2010年鉆探的W201、N201兩口頁巖氣評價井(直井),經大型水力壓裂,在筇竹寺組頁巖和五峰組—龍馬溪組頁巖中均獲得了初始頁巖氣產量過1.0×104m3/d的高產頁巖氣流,實現了中國頁巖氣首次突破.

3.1.2海陸過渡相—煤系富有機質頁巖

海陸過渡相—煤系富有機質頁巖可劃分為海陸過渡相、湖沼相煤系富有機質泥頁巖[1-2,11-14].海陸過渡相富有機質泥頁巖主要分布在中國東部的石炭系—二疊系[15]、南方的二疊系;湖沼相煤系富有機質泥頁巖包括四川盆地及周緣的上三疊統—下侏羅統、中國西部地區的侏羅系,具有分布面積大、有機質類型復雜、熱演化程度適中等特點[1-2](表3).

研究發現,中國海陸過渡相—煤系富有機質泥頁巖除上揚子及滇黔桂地區單層厚度較大外,其余多數地區的海陸過渡相—煤系富有機質泥頁巖單層厚度都不大,不利于頁巖氣單層獨立開發.但海陸過渡相—煤系富有機質泥頁巖總有機碳含量較高、演化程度一般在過成熟早期以下,有利于成氣且泥頁巖層多與煤、致密砂巖互層,易形成頁巖氣、煤層氣和致密砂巖氣等多種類型天然氣藏疊置.

3.1.3陸相富有機質泥頁巖

中國中生代、新生代盆地多為陸相沉積,深湖和半深湖相形成的富有機質黑色泥頁巖是盆地的主力烴源巖[1-2,11-14].研究發現,現階段多數泥頁巖正進入大量生油期,僅在埋深較大的凹陷中的部分烴源巖才演化至生氣階段,因此,湖相頁巖氣勘探開發領域,將會是頁巖油和頁巖氣并存的局面,縱向上具有“上油下氣”的展布特點,橫向上埋深大的凹陷區及近凹陷斜坡區是頁巖氣的主要富集區.渤海灣盆地沙河街組、松遼盆地青山口組、鄂爾多斯盆地延長組、四川盆地侏羅系等都具備湖相頁巖氣形成基本地質條件(表4).

3.2中國頁巖氣資源發展前景

有關中國頁巖氣資源發展前景,國內不少機構/學者對此做出了較為樂觀的預測(表5).預測顯示中國頁巖氣資源豐富,其中地質資源量為(30~166)×1012m3,技術可采資源量為(7~45)×1012m3.無論是從地質資源量還是技術可采資源量上看,中國頁巖氣資源都具備良好發展基礎.甚至已有機構/學者根據資源預測結果及目前進展,認為中國未來5年將實現頁巖氣規?;a,頁巖氣產量達到65×108m3,至2020年前后,突破頁巖氣勘探開發關鍵技術,頁巖氣產量有望達到(600~1000)×108m3[4].頁巖氣儲層比任何致密油氣儲層都還要致密,實現有效開發難度非常大.中國的頁巖氣勘探開發雖已在先導性試驗井中取得突破,但仍為起步階段.中國頁巖氣地質條件與開發條件都與北美不同(表6).首先,從地質條件上看,中國的富有機質頁巖,尤其是古生界海相富有機質頁巖大多經歷了復雜的構造改造,在盆地周緣頁巖地層抬升出露、斷裂切割嚴重,保存條件是海相頁巖氣勘探開發面臨的嚴峻挑戰;中國富有機質頁巖熱成熟度復雜,海相頁巖形成時間早,演化程度高,陸相頁巖形成時間晚,演化程度低,兩個端元的熱演化程度都將直接導致中國富有機質頁巖含氣量變化大、含氣量偏低.其次,從開發條件上看,中國富有機質頁巖在盆地內主體埋深較大,超過了3500 m或更大,在南方海相頁巖發育區,地表多以山地和丘陵等復雜地表區為主,且不是常規油氣生產的主產區,地面設施與管網缺乏.由此可見,中國頁巖氣資源豐富,具有良好發展前景,但是,中國頁巖氣地質與開發條件復雜,決定了中國頁巖氣勘探開發不會一蹴而就,需要一定時間準備與探索.未來5~10年需要堅持深化地質認識與技術攻關,突出基礎地質研究、核心區評價和先導試驗區建設.海相富有機質頁巖氣重在深化基礎地質研究,落實經濟可采資源,優選開發核心區,強化關鍵技術攻關,推進先導試驗區建設,形成一定規模頁巖氣產量.海陸過渡相—煤系與湖相富有機質頁巖以地質條件評價為重點,以技術可采資源潛力落實為核心,鉆探一批先導試驗井,優選有利頁巖氣區帶和層系,實現中國頁巖氣持續穩定發展.

4結論

(1)中國頁巖氣勘探開發起步較晚,但在全球為北美以外地區率先進入頁巖氣勘探突破和工業化開發先導性試驗的國家.中國頁巖氣地質條件研究與關鍵開發技術儲備已有較好基礎,在古生界海相、石炭-二疊系海陸過渡相—煤系與中生界-新生界陸相(湖相)頁巖氣/油上陸續取得單井突破與發現,正進入開發先導性試驗區建設階段.

(2)中國發育海相、海陸過渡相—陸相煤系與陸相湖相3類富有機質頁巖,頁巖氣資源潛力大.古生界海相頁巖分布面積廣,厚度大,有機碳含量豐富,成熟度高,頁巖氣形成與富集條件優越,是中國頁巖氣開發的重點領域.

(3)中國頁巖氣資源發展前景良好,目前勘探開發程度低,與北美典型頁巖氣產區地質與開發條件有明顯差異,未來發展,需要借鑒北美的成功經驗,針對中國的特點,加強基礎地質條件和關鍵開發技術攻關,努力尋求環境友好、低成本的開發模式.

中國頁巖氣形成機理、地質特征及資源潛力*

鄒才能1,2,董大忠1,2,王社教1,2,李建忠1,2,李新景1,2,王玉滿1,2,李登華1,2,程克明1,2

(1. 中國石油勘探開發研究院;2. 提高石油采收率國家重點實驗室)

1頁巖氣勘探開發現狀

油氣工業的生命周期大致有300年(1880—2180年)歷史,發展主要歷經構造油氣藏、巖性地層油氣藏、非常規油氣藏(場)勘探開發3個階段和三大領域.油氣藏分布方式分別有單體型、集群型、連續型3種類型.從構造油氣藏向巖性地層油氣藏轉變是第一次理論技術創新,以尋找油氣圈閉為核心;從巖性地層圈閉油氣藏向非常規連續型油氣藏轉變是第二次理論技術創新或革命,以尋找有利油氣儲集體為核心,致密化“減孔成藏”機理新論點突破了常規儲集層物性下限與傳統圈閉找油的理念[1].隨著勘探開發技術不斷進步,占有80%左右資源的非常規油氣(一般將空氣滲透率大于1×10-3μm2或地層滲透率大于0.1×10-3μm2儲集層內的油氣稱為常規油氣,把空氣滲透率小于1×10-3μm2或地層滲透率小于0.1×10-3μm2的油氣稱為非常規油氣)如頁巖氣、煤層氣、致密氣、致密油、頁巖油等已引起廣泛關注(見圖1),并得到有效開發,在油氣儲、產量中所占比例也逐年提高.傳統觀點僅認識到頁巖可生油、生氣,沒認識到頁巖亦可儲油、儲氣,更未認識到還能聚集工業性頁巖油、頁巖氣.近年來,典型頁巖氣的發展尤為迅速,地質認識不斷進步,優選核心區方法、實驗分析技術、測井評價技術、資源評價技術、頁巖儲集層水平井鉆完井、同步多級并重復壓裂等先進技術獲得應用,形成“人造氣”是頁巖氣快速發展的關鍵因素.頁巖氣突破的意義在于:突破資源禁區,增加資源類型與資源量;挑戰儲集層極限,實現油氣理論技術升級換代,水平井多級壓裂等核心技術應用于其他致密油氣等非常規和常規油氣儲集層中更加經濟有效,可大幅度提高油氣采收率;帶動非常規油氣技術發展,推動致密油氣、頁巖油等更快成為常規領域.

全球頁巖氣勘探開發自1821年在美國東部泥盆系頁巖中鉆成第1口頁巖氣井、1914年發現第1個頁巖氣田——Big Sandy氣田[2]以來,歷經1821—1978年偶然發現、1978—2003年認識創新與技術突破、2003—2006年水平井與水力壓裂等技術推廣應用、2007—2010年全球化發展(頁巖氣中國年、歐州年)等4個階段.1981年被譽為“頁巖氣之父”的喬治·米歇爾對Barnet t頁巖C. W. Slay No. 1井實施大規模壓裂并獲成功以來,實現了真正意義的頁巖氣突破.至2009年底,北美發現頁巖氣盆地30個,開發井50000余口,井深2500~4500 m;2009年年產量950×108m3[3],占北美天然氣總產量的12%(其中美國產量889×108m3).中國頁巖氣走過了裂縫油氣藏勘探與偶然發現(2005年以前)、基礎研究與技術準備(2005—2009年)和工業化突破(2010年)等3個階段.1966年四川威5井在寒武系筇竹寺組頁巖中獲日產氣2.46×104m3,為中國最早的頁巖產氣井[4];2008年中國石油勘探開發研究院在四川長寧地區鉆探的長芯1井[5]為中國第1口頁巖氣地質井;2009年中國石油在四川威遠-長寧、富順-永川等地區啟動了首批頁巖氣工業化試驗區建設;2010年中國石油勘探開發研究院在四川長寧地區建立了第1條中國頁巖氣數字化標準剖面;2010年中國石油鉆探的四川盆地威201井在寒武系、志留系頁巖中獲工業氣流,實現中國頁巖氣首次工業化突破.

北美地區經過多年的研究和開發實踐,在頁巖氣形成機理、富集條件等方面已形成重要認識和技術[6-15].本文重點分析中國頁巖氣基本特征、形成機理與富集條件、面臨的難題等,對中國頁巖氣資源潛力進行預測,以期為中國頁巖氣的研究和勘探開發提供依據.

2中國富有機質頁巖分布特征

源巖油氣是一種新資源類型,包括頁巖油、頁巖氣、煤層氣等,自生自儲,主要產自源巖內儲集層中.

頁巖(shale)是由粒徑小于0.0039 mm的細粒碎屑、黏土、有機質等組成,具頁狀或薄片狀層理、易碎裂的一類沉積巖,亦即美國所稱的粒徑小于0.0039 mm的細粒沉積巖.

頁巖氣(shale gas)是指從富有機質黑色頁巖中開采的天然氣,或自生自儲、在頁巖納米級孔隙中連續聚集的天然氣.

中國3類富有機質頁巖泛指海相、海陸交互相以及陸相頁巖和泥巖,重點指含油氣盆地中的優質泥質烴源巖,圖2為依據中國頁巖發育的層系和分布特點編制的3類頁巖分布圖.中國南方揚子地區海相頁巖多為硅質頁巖(如揚子地區牛蹄塘組底部頁巖)、黑色頁巖、鈣質頁巖和砂質頁巖,風化后呈薄片狀,頁理發育.海陸過渡相頁巖多為砂質頁巖和炭質頁巖.陸相頁巖頁理發育,渤海灣盆地、柴達木盆地新生界陸相頁巖鈣質含量高,為鈣質頁巖,鄂爾多斯盆地中生界陸相頁巖石英含量較高.

2.1富含頁巖氣的核心區特征

目前進行頁巖氣經濟開發的核心區有5個富集高產條件(見表1),通常是指TOC值大于2%、處在生氣窗內、脆性礦物含量大于40%的有效頁巖.有效頁巖厚度大于30~50 m(有效頁巖連續發育時大于30 m,斷續發育或TOC值小于2%時,累計厚度大于50 m)時亦足以滿足商業開發要求.北美產氣頁巖有效厚度最小為6 m(Fayet teville),最大為304 m(Marcellus),核心區有效頁巖厚度均大于30 m.

基于北美頁巖氣勘探開發實踐、統計分析及關鍵實驗等結果,認為有利頁巖氣及核心區具有4方面主要地質特征和3方面主要開發特點,詳見表1.

2.2中國頁巖形成的區域地質背景

古生代,在中國南方、華北及塔里木地區形成了廣泛的海相和海陸過渡相沉積,發育多套海相富有機質頁巖和海陸過渡相煤系炭質頁巖[6].在后期改造過程中,部分古生界海相頁巖經歷了擠壓變形或隆升,如南方的揚子地區,多為后期隆升改造.四川盆地、華北地區、塔里木盆地構造相對穩定,地層保存條件較好.

中、新生代以來,形成了中國獨特的陸相湖盆沉積[6].陸相沉積盆地一般面積不大,但在盆地穩定沉降階段常形成分布廣泛的陸相生油巖,生烴潛力很大[6],如松遼盆地下白堊統青山口組、鄂爾多斯盆地上三疊統延長組陸相頁巖,均是盆地主要烴源巖.

2.3頁巖的沉積特征

盆地不同演化階段直接控制富有機質頁巖的發育與分布[16].根據沉積環境,可將富有機質頁巖劃分為海相頁巖、海陸交互相煤系炭質頁巖、陸相頁巖3種基本類型(見表2).

中國南方、華北地臺及塔里木地臺發育的古生界海相黑色頁巖多形成于水深200 m左右、生物化石豐富、強還原環境的深水陸棚相,如四川盆地發育的寒武系筇竹寺組、志留系龍馬溪組黑色頁巖為受大陸邊緣坳陷控制的深水陸棚相沉積[17](見圖3),富有機質黑色頁巖面積13.5×104~18.0×104km2,厚200~400 m,有機質豐富,含海洋浮游生物筆石化石及自生黃鐵礦等,有機碳含量1.85% ~4.36%,最高達11.0%~22.3%.在這兩套黑色頁巖中均發現了大量頁巖氣.

海陸過渡相形成的煤系頁巖,如鄂爾多斯盆地石炭系本溪組及下二疊統山西組-太原組、準噶爾盆地石炭-二疊系、塔里木盆地石炭-二疊系、華北地區石炭-二疊系、中國南方地區的二疊系龍潭組等,也是大型油氣田的主要烴源巖,如鄂爾多斯盆地上古生界炭質頁巖是蘇里格等大氣區的主要氣源巖.三疊系-侏羅系和第三系發育多套與煤層相伴生的炭質頁巖,同樣亦是優質氣源巖,吐哈盆地發現的油氣田多數來源于侏羅系煤系頁巖.

中國發育陸相含油氣盆地頁巖:渤海灣盆地古近紀、松遼盆地白堊紀、鄂爾多斯盆地三疊紀、四川盆地侏羅紀、塔里木盆地三疊紀)侏羅紀、準噶爾盆地侏羅紀均為大型湖盆沉積,在湖盆的擴張期,形成了分布廣泛且厚度大的湖相頁巖,有機質十分豐富,含介形蟲、孢粉、細菌、高等植物等化石,厚度200~2500 m,有機碳含量2%~3%,最高達到7%~14%.在中新生代發現了眾多規模不等的油氣聚集帶[18],大慶油田、勝利油田、遼河油田、鄂爾多斯中生界油氣聚集區等,其油氣就源于該套湖相泥巖.

2.4頁巖的分布特征

中國海相頁巖十分發育,分布廣、厚度大[19].主要發育在古生界的陡山沱組(Z2)、筇竹寺竹組(-C1)、大乘寺組(O1)、五峰-龍馬溪組(O3-S1)、羅富組(D2)、德塢組-大塘組(C1)、龍潭組(P2)(見表3).發育最好的頁巖分布在下寒武統、上奧陶統頂部-下志留統底部,以揚子克拉通地區最為典型.

下寒武統海相頁巖在中上揚子區發育好,有機質類型為腐泥型-混合型.從沉積環境看,川東-鄂西、川南及湘黔3個深水陸棚區下寒武統海相頁巖最發育[20],平均厚度100 m,TOC值平均高達8%左右.四川盆地下寒武統海相頁巖全盆地發育,以硅質頁巖、炭質頁巖、粉沙質頁巖和黑色頁巖為主,厚度平均為139 m,TOC值平均1.0%~5.5%,盆地南部頁巖埋藏淺于4000 m.

上奧陶統-下志留統海相頁巖在川東南、川東北、鄂西渝東、中下揚子等區廣泛發育[5],以黑色頁巖、炭質頁巖、黑色筆石頁巖、鈣質頁巖為主,平均厚120 m,TOC值平均4%左右,干酪根為腐泥型.四川盆地上奧陶統-下志留統海相頁巖在川南-川東地區發育較好.據筆者綜合運用伽馬能譜、元素捕獲、探地雷達及陸地激光三維全信息掃描等手段建立的長寧雙河上奧陶統五峰組-下志留統龍馬溪組海相頁巖地層數字化標準剖面(見圖4)統計,川南上奧陶統五峰組-下志留統龍馬溪組黑色頁巖厚度大于308 m,有機質類型為腐泥型,TOC值平均2.94%,最高達8.75%.

海陸交互相及陸相煤系炭質頁巖在華北、華南地區和塔里木盆地廣泛分布(見表4).北部主要發育在天山-興蒙海槽.鄂爾多斯盆地海陸交互相山西組-太原組-本溪組頁巖厚40~120 m,單層厚度不大,多數與煤層、致密砂巖甚至薄層灰巖交互出現.準噶爾盆地石炭系滴水泉組炭質頁巖最厚達249 m,二疊系蘆草溝組黑色頁巖累計厚度超過200 m.中國南方地區的二疊系龍潭組(P2)炭質頁巖厚20~200 m,最厚達670 m,分布面積約30×104~50×104km2.其中,滇黔桂地區上二疊統龍潭組頁巖厚度為20~60 m,四川盆地上二疊統頁巖厚10~125 m,川中和川西南一帶厚80~110 m,四川盆地西北緣、北緣及東北緣較薄,多小于20 m.中新生代陸相煤系炭質頁巖主要發育在坳陷和斷陷湖盆中,如鄂爾多斯盆地和準噶爾盆地侏羅系、四川盆地上三疊統(厚150~1000m)、吐哈盆地侏羅系(厚50~400 m,最厚達1200 m)等.

總體上,中國海陸交互相和中新生代陸相炭質頁巖除上揚子及滇黔桂地區單層厚度較大外,多數地區單層厚度都不大,常與煤和致密砂巖甚至灰巖互層,單層平均厚度一般小于15 m,單獨開發這套薄層煤系頁巖氣將面臨很大的挑戰,進行頁巖氣、致密氣、煤層氣等多目的層聯合開發是有效開發的新途徑.

主要分布于陸相含油氣盆地的湖相頁巖沉積范圍最廣(見表5),廣泛發育湖相頁巖油、致密砂巖油與致密頁巖油.松遼、鄂爾多斯、四川等中新生代坳陷盆地[21]及渤海灣新生代斷陷盆地都沉積了厚層湖相富有機質頁巖、砂巖與泥巖[22].如松遼盆地嫩江組和青山口組兩套頁巖十分發育,嫩江組在全盆地穩定分布,中央坳陷區厚度超過250 m,青山口組一段在中央坳陷區幾乎全部為黑色頁巖,厚度為60~80 m,干酪根類型為ⅳ—型,Ro值為0.9%~1.8%.鄂爾多斯盆地延長組長7段主要為深湖相沉積,富有機質頁巖平均厚度20~40 m,分布面積超過4×104km2,有機碳含量平均高達14%,干酪根類型為ⅳ—型,Ro值為0.6%~1.2%.最近,在該套湖相頁巖地層內發現了大量致密油,油層為厚10~20 m、孔隙度10.2%、滲透率0.21×10-3μm2的致密粉砂巖,有工業油氣流井近200口,平均產量8.6 t/d.該特征與北美在Williston盆地Bakken頁巖層中發現的致密油極為相似[23].Bakken地層位于上泥盆統頂部,由下向上分9段,最下面第1段頁巖厚度12~15 m,TOC值高達14%~18%,Ro值為1.1%~1.3%,為富有機質頁巖層.上覆第2段致密粉砂巖油層孔隙度10%~13%,滲透率0.01×10-3~1×10-3μm2,厚5~15 m,面積約75563 km2,1999年USGS專家估算頁巖中致密油地質資源量為578×108t,一般預測為241×108~518×108t.致密油是繼頁巖氣突破后又一重大發現,成為新亮點.

3中國頁巖氣地球化學特征

頁巖氣是富有機質烴源巖層系中以甲烷為主的天然氣.作為一種重要的“有機礦物顆?!?,有機質不僅為常規油氣藏提供豐富的物質基礎,其自身也可以儲集并產出油氣.大量研究表明,對于熱成因頁巖氣區帶的初步篩選,通常要求頁巖達到某些地球化學指標,如:有機質豐度(TOC)大于2%,成熟度(Ro)大于1.1%,滿足這些約束條件的地區,可有效降低頁巖氣勘探開發風險.

3.1頁巖的基本地球化學特征

中國海相、海陸交互相以及陸相頁巖廣泛分布[24-27],不同沉積環境形成的有機質類型不同,傾油、傾氣性也有差別,很多盆地或區塊達到富集頁巖氣所需基本地球化學標準(見表6).四川盆地下古生界寒武系筇竹寺組和志留系龍馬溪組兩套海相黑色頁巖屬ⅳ—1型干酪根,顯示良好的傾油性,當Ro值高于1.2%時,在高過成熟的頁巖地層中,先生油,后裂解成氣,形成海相頁巖“連續”生氣與聚氣.中國北方古生界石炭-二疊系、中生界侏羅系含煤層系炭質頁巖作為重要的氣源巖,已形成了大規模天然氣聚集,有機質主要是型,屬腐殖型干酪根,在整個成熟演化階段,以成氣為主:Ro值為1.0%時,天然氣轉化率已達到40%以上;Ro值為2.5%時,天然氣轉化率達到95%;Ro值為0.8%~2.5%是煤系有機質主生氣期[28].富氫組分含量相對較高區塊,更有利于形成頁巖氣富集區.可見,中國的3類主要頁巖具備形成頁巖氣資源的條件.

中國頁巖氣潛力區的部分地球化學特征不同于北美頁巖氣主產區.如:包括四川盆地在內的揚子地臺大部分地區古生界烴源巖是區域主力烴源,雖屬ⅳ型干酪根,但成熟度普遍為高或過成熟,連續生油、生氣、聚氣,殘余生烴潛力低;中國大中型煤型氣田,如鄂爾多斯、塔里木、華北地區上古生界石炭-二疊系炭質頁巖,其有機質豐度一般都比較高,Ro值為1.1%~2.5%,有機質類型則多為型;鄂爾多斯盆地中生界三疊系長7黑色頁巖為優質烴源巖,呈較高自然伽馬、高電阻率、較低密度、高聲波時差,有機質類型為ⅳ型,具有很高的生烴潛力,但Ro值為0.90%~1.16%,尚屬生油高峰階段.

中國陸相地層中廣泛發育頁巖油.頁巖油是生油巖內納米-微米級孔隙與裂縫聚集的石油,如在松遼盆地古龍凹陷已發現下白堊統青山口組和嫩江組頁巖油聚集,頁巖富有機質,總厚300~620 m,一般異常高壓,干酪根為ⅳ—型,Ro值為0.9%~1.2%.最早在大安構造大4井青山口組泥巖段獲日產油2.66 t,另有50余口井見油氣顯示,4口井產少量油氣-古501井、英15井、英3井、大111井),5口井獲工業油氣流(英12井、英18井、英16井、古1井、大4井).盆地南部新北油田泥巖裂縫性油藏幾口井已開采10余年,累計產油超過3×104t.鄂爾多斯、渤海灣等盆地生油層系中也發育頁巖油.頁巖油是頁巖氣之后又一“源巖油”領域,值得重視.

3.2關鍵地球化學參數與頁巖儲集能力的相關性

自生自儲的頁巖氣儲集層,其有機地球化學關鍵參數,如有機質豐度和成熟度等,與頁巖儲集層含氣性、儲集空間的發育密不可分.北美地區頁巖含氣量往往與有機質豐度(TOC)呈正相關性,ⅳ、型干酪根往往具有較高的吸附能力[29].中國四川盆地高)過成熟海相頁巖實驗測試數據也證明,有機質豐度高者,含氣量相對豐富,更有條件成為優質頁巖儲集層.

隨著成熟度增加,干酪根、原油熱裂解大量生烴,除了生成大量油氣、為常規油氣藏提供豐富的物質來源之外,有機質本身可產生5~200 nm左右納米級孔隙[30].筆者在對中國四川盆地寒武系和志留系高-過成熟海相頁巖儲集層的研究中首次發現,這兩套地層下部不僅有機質豐度高、含氣量高,而且呈分散狀、紋層狀分布的“有機質顆?!眱炔啃纬纱罅课⒚?納米級孔隙(見圖5),這些孔隙大者3~4 μm,小至幾個納米,一般都大于100~200 nm,為豐富的頁巖氣資源提供了充足的儲集空間,有力地說明中國南方致密的海相頁巖具備優質儲集條件,在有機質豐度比較高的層段和區域,勘探開發前景良好.澳大利亞Beetaloo盆地在全球最老地層(約14×108a)——元古界發現了頁巖氣,有機碳含量4%,Ro值高達3.49%,預測頁巖氣資源量5600×108m3.

4頁巖氣形成機理及儲集層特征

4.1頁巖氣形成機理

頁巖氣形成機制是原位“滯留成藏”,連續型分布.甲烷在頁巖微孔(孔徑小于2 nm)中順序填充,在介孔(孔徑為2~50 nm)中多層吸附至毛細管凝聚,在大孔(孔徑大于50 nm)中甲烷以壓縮或溶解態賦存.成藏中經過吸附、解吸、擴散等作用.有機質生氣或油裂解成氣,天然氣先在有機質孔內表面飽和吸附;之后解吸擴散至基質孔中,以吸附、游離相原位飽和聚集;過飽和氣初次運移至上覆無機質頁巖孔中;氣再飽和后,二次運移形成氣藏(見圖6)[31,32].

4.2巖石礦物組成

脆性礦物含量是影響頁巖基質孔隙和微裂縫發育程度、含氣性及壓裂改造方式等的重要因素.頁巖中黏土礦物含量越低,石英、長石、方解石等脆性礦物含量越高,巖石脆性越強,在人工壓裂外力作用下越易形成天然裂縫和誘導裂縫,形成多樹-網狀結構縫,有利于頁巖氣開采.而高黏土礦物含量的頁巖塑性強,吸收能量,以形成平面裂縫為主,不利于頁巖體積改造.美國產氣頁巖中石英含量為28%~52%、碳酸鹽含量4%~16%,總脆性礦物含量為46%~60%.筆者對中國3種不同類型頁巖的礦物組成進行測試后發現,無論是海相頁巖、海陸過渡相炭質頁巖,還是陸相頁巖,其脆性礦物含量總體比較高,均達到40%以上,如:上揚子區古生界海相頁巖石英含量24.3%~52.0%、長石含量4.3%~32.3%、方解石含量8.5%~16.9%,總脆性礦物含量40%~80%(見表7、圖7);四川盆地上三疊統須家河組黏土礦物含量一般為15%~78%,平均為50%左右,石英、長石等脆性礦物含量一般為22%~85%,平均為50%左右.鄂爾多斯盆地上古生界含煤層系炭質頁巖石英含量32%~54%,平均48%,總脆性礦物含量40%~58%;鄂爾多斯盆地中生界陸相頁巖石英含量27% 47%,平均40%,總脆性礦物含量58%~70%.

巖石礦物組成對頁巖氣后期開發至關重要,具備商業性開發條件的頁巖,一般其脆性礦物含量要高于40%,黏土礦物含量小于30%.

4.3孔滲特征與微裂縫

4.3.1孔滲特征

巖石孔隙是儲存油氣的重要空間和確定游離氣含量的關鍵參數.據統計,有平均50%左右的頁巖氣存儲在頁巖基質孔隙中.頁巖儲集層為特低孔滲儲集層,以發育多類型微米甚至納米級孔隙為特征,包括顆粒間微孔、黏土片間微孔、顆粒溶孔、溶蝕雜基內孔、粒內溶蝕孔及有機質孔等.孔隙大小一般小于2 μm,有機質孔喉一般100~200 nm,比表面積大,結構復雜,豐富的內表面積可以通過吸附方式儲存大量氣體[33].一般頁巖的基質孔隙度為0.5%~6.0%,眾數多為2%~4%.四川盆地華鎣山紅巖煤礦龍馬溪組和威遠地區筇竹寺組頁巖實測結果:龍馬溪組頁巖孔隙度為2. 43%~15.72%,平均4.83%;筇竹寺組頁巖孔隙度為0.34%~8.10%,平均3.02%.鄂爾多斯盆地中生界陸相頁巖實測孔隙度0.4%~1.5%,滲透率0.012×10-3~0.653×10-3μm2.

中國海相富有機質頁巖微米-納米孔十分發育(見圖5),既有粒間孔,也有粒內孔和有機質孔,尤其有機質成熟后形成的納米級孔喉甚為發育,這些納米級孔喉是頁巖氣賦存的主要空間.

4.3.2微裂縫

裂縫包括地下原始裂縫和后期人造裂縫,可為頁巖氣提供充足的儲集空間、運移通道,更能有效提高頁巖氣產量[2].在不發育裂隙情況下,頁巖滲透能力非常低.石英含量的高低是影響裂縫發育的重要因素,富含石英的黑色泥頁巖段脆性好,裂縫的發育程度比富含方解石的泥頁巖更強[34].Nelson認為,除石英外,長石和白云石也是泥頁巖中脆性組分[35].一般頁巖中具有高含量的黏土礦物,但暗色富有機質頁巖中的黏土礦物含量通常則較低.頁巖氣勘探必須尋找能夠壓裂成縫的頁巖,即頁巖的黏土礦物含量足夠低(<50%)、脆性礦物含量豐富,使其易于成功壓裂.中國海相頁巖、海陸交互相炭質頁巖和陸相頁巖均具有較好的脆性特征,無論是野外地質剖面還是井下巖心觀察,發現其均發育較多的裂縫系統.如:上揚子地區寒武系筇竹寺組、志留系龍馬溪組黑色頁巖性脆、質硬,節理和裂縫發育,在三維空間成網絡狀分布,巖石薄片顯示,微裂縫細如發絲,部分被方解石、瀝青等次生礦物充填;鄂爾多斯盆地上古生界山西組巖心切片可看到呈網狀分布的微裂縫;鄂爾多斯盆地中生界長7段黑色頁巖頁理十分發育,風化后呈薄片狀.

4.4含氣性

頁巖氣區根據含氣性可劃分為核心區、外圍區.頁巖含氣量是衡量頁巖氣核心區是否具經濟開采價值和進行資源潛力評估評價的重要指標,頁巖含氣量包括游離氣、吸附氣及溶解氣等.哈里伯頓公司認為商業開發遠景區的頁巖含氣量最低為2.8 m3/t,目前北美已商業開發的頁巖氣,其含氣量最低約為1.1 m3/t,最高達9.91 m3/t.實測發現四川盆地下寒武統寒武系筇竹寺組黑色頁巖含氣量為1.17~6.02 m3/t,平均2.82 m3/t,龍馬溪組黑色頁巖含氣量為1.73~3.28 m3/t,與北美產氣頁巖的含氣量(見表7)相比,均達到了商業性頁巖氣開發下限,具備商業性開發價值.由于中國頁巖氣尚未進入開發階段,鉆探頁巖氣井少,因此無法獲取更多的頁巖含氣量數據.但根據老井復查結果,在已往的鉆井中,鉆遇的黑色頁巖段發現了大量的氣測顯示,有井涌和井噴現象發生,證明頁巖段含氣性很好.如:四川盆地威遠地區鉆穿筇竹寺組的107口井中,32口井52個井段出現不同級別氣測顯示,威5井在鉆至2795~2798 m筇竹寺組頁巖層段時發生井噴,中途測試獲日產2.46×104m3的天然;鉆穿川南地區下志留統龍馬溪組頁巖層段的15口井中32個層段見良好氣測顯示,陽63井3505~3518 m龍馬溪組頁巖段測試后獲日產天然氣3500 m3.

5資源潛力及特殊性

有不少學者或機構對中國頁巖氣資源潛力做過預測,總體評價偏樂觀[36-38].

頁巖氣與常規氣存在明顯差異,不僅包括地質條件的不確定性,也有開發中的經濟風險性,尤其是采收率的確定需要依賴井控數據.因此,客觀、準確預測頁巖氣資源潛力具挑戰性.

中國頁巖氣勘探開發尚處于起步階段,可用于頁巖氣資源潛力預測的資料非常有限.盡管中國不同地區在富有機質頁巖發育規模、頁巖質量等方面具廣泛的相似性,但中國地質條件復雜,尤其是構造演化、沉積環境、熱演化過程等,使不同地區頁巖氣形成、富集存在許多差異.中國古生界海相富有機質頁巖分布范圍廣、連續厚度大、有機質豐度高,但演化程度高、構造變動多;中新生界陸相富有機質頁巖橫向變化大,以厚層泥巖或砂泥互層為主,有機質豐度中等,熱成熟度低.因此,基于地質類比對中國頁巖氣資源潛力進行預測.中國古生界海相富有機質頁巖有利領域展布面積63×104~90×104km2,中新生界陸相富有機質泥頁巖有利領域展布面積23×104~33×104km2,有效頁巖厚度20~300 m,有機碳含量0.50%~25.71%,Ro值為0.8%~4.5%,預測頁巖氣資源量30×1012~100×1012m8,這些預測數據都是初步結果,而中國頁巖氣的技術與經濟可采資源量正在研究之中.

目前,中國已在四川盆地南部等地區啟動了多個頁巖氣工業化生產試驗區建設,已取得突破;正在開展的中下揚子、鄂爾多斯、塔里木等地區的前期評價,將優選出頁巖氣有利接替地區.開發頁巖氣對緩解中國天然氣資源緊缺現狀、改變能源結構、保障國家能源安全具有戰略意義,同時對石油地質理論創新與勘探開發技術革新也有重大科學價值.

中國頁巖氣與北美頁巖氣對比,有3個特殊性:海相頁巖熱演化程度較高(Ro值為2.5%~5.0%)、構造活動較強,需尋找保存條件有利的地區,避開露頭和斷裂破壞區;陸相頁巖熱演化程度較低、分布非均質性較強,有效開發需針對性技術;地面多山地、丘陵等復雜地表,埋藏較深(5000~7000 m),還面臨水資源與環保等問題,需采用適用技術降低成本.因此,中國頁巖氣勘探開發應特別注意復雜地表、埋藏深度、后期保存等特殊地質條件,如塔里木盆地海相頁巖埋藏深度大,南方部分地區頁巖出露后面臨保存、開發中地表多山地等難題,因此,要加強有利核心區優選與經濟評價.

6結論

中國陸上廣泛發育海相、海陸過渡相、陸相三大套富有機質黑色泥頁巖,均具備形成頁巖氣的基本地質條件.它們有共性,也有特殊性,勘探開發實踐與研究中一定要注意區別對待.盆地內古生界頁巖以海相沉積為主,區域穩定分布,厚度大,有機質豐富,演化程度高,已見大量氣顯示,是頁巖氣勘探開發的現實領域.

中國石炭-二疊系、三疊-侏羅系煤系中發育高炭泥頁巖、煤層,與砂巖伴生,連續分布有頁巖氣與致密氣.中新生界陸相泥頁巖、泥巖與砂巖、灰巖互層,成熟度低,連續分布的頁巖油與致密油是戰略新領域.

源巖油氣是新領域,包括頁巖油、頁巖氣、煤層氣等形成機制是原位“滯留成藏”.頁巖氣與上下連續型分布的致密砂巖氣、煤層氣等同步開發,可提高產量和效益.

四川盆地內發育海相、海陸過渡相、陸相多套頁巖氣層系,是中國頁巖氣勘探開發最現實的地區.四川盆地古生界頁巖地層發育豐富的微米-納米級孔隙,頁巖含氣飽和度較高,盆地中南部的威遠-長寧等地區是頁巖氣有利分布區,也是勘探開發突破的重要核心區之一.對中國其他盆地要加強核心區優選與經濟評價.

·高被引論文摘要·

被引頻次:628

頁巖氣成藏機理和分布

張金川,金之鈞,袁明生

對頁巖氣成藏機理進行了全面分析,獲得了四個方面的認識.①頁巖氣成藏機理兼具煤層吸附氣和常規圈閉氣藏特征,體現出了復雜的多機理遞變特點.②在頁巖氣的成藏過程中,天然氣的賦存方式和成藏類型逐漸改變,含氣豐度和富集程度逐漸增加.③完整的頁巖氣成藏與演化可分為3個主要的作用過程,自身構成了從吸附聚集、膨脹造隙富集到活塞式推進或置換式運移的機理序列.④相應的成藏條件和成藏機理變化對頁巖氣的成藏與分布產生了控制和影響作用,巖性特征變化和裂縫發育狀況對頁巖氣藏中天然氣的賦存特征和分布規律具有控制作用.研究了我國的情況,認為我國的許多盆地存在工業性頁巖氣藏發育的基本地質條件,其中,吐哈盆地吐魯番坳陷的水西溝群是頁巖氣發育的重要區域之一.

頁巖氣;賦存狀態;成藏機理;序列遞變

來源出版物:天然氣工業,2004,24(7): 15-18聯系郵箱:張金川,zhangjc@cugb.edu.cn

被引頻次:352

中國頁巖氣形成機理、地質特征及資源潛力

鄒才能,董大忠,王社教,等

摘要:以四川盆地為重點,介紹中國海相、海陸過渡相、陸相三大類型頁巖形成的沉積環境、地球化學與儲集層特征、含氣量與遠景資源量.中國海相頁巖是一套高有機質豐度(TOC為1.0%~5.5%)、高—過成熟(Ro值為2.0%~5.0%)、富含頁巖氣(含氣量1.17~6.02 m3/t)、以陸棚相為主的沉積,主要分布在華南揚子地區古生界、華北地臺古生界和塔里木盆地寒武系—奧陶系;海陸過渡相煤系炭質頁巖有機質豐度高(TOC為2.6%~5.4%)、成熟度適中(Ro值為1.1%~2.5%);中新生界陸相頁巖有機質豐度高(TOC為0.5%~22.0%)、低熟—成熟(Ro值為0.6%~1.5%).在對四川盆地下古生界頁巖儲集層研究中首次發現,寒武系和志留系海相頁巖發育大量與北美地區相似的微米—納米級孔隙.綜合評價認為四川盆地發育的多套頁巖氣層系是勘探開發的現實領域,四川盆地中南部威遠—長寧等地區的寒武系和志留系是頁巖氣勘探開發的核心區與層系,其特點是:熱演化程度較高(Ro值為2.0%~4.0%)、孔隙度較高(3.0%~4.8%),含氣量較高(2.82~3.28 m3/t)、脆性礦物含量較高(40%~80%)、埋深適中(1500~4500 m),有利于開采.

關鍵詞:非常規油氣;頁巖氣;納米級孔喉;頁巖油;致密油;源巖油氣

來源出版物:石油勘探與開發,2010,37(6): 641-653

被引頻次:327

中國頁巖氣資源勘探潛力

張金川,徐波,聶海寬,等

摘要:頁巖氣是以吸附和游離狀態同時存在于泥頁巖地層中的天然氣,它分別在天然氣的成因機理、賦存相態、成藏聚集機理、分布變化特點及其與其他類型氣藏關系之間存在廣泛的變化性.由于頁巖氣成藏邊界條件可有適度地放寬且變化較大,各成藏地質要素之間具有明顯的互補性.基于地質、測井、地震等方法和手段,可對頁巖氣進行快速識別.研究表明,中國存在頁巖氣大量發育的區域地質條件,初步計算中國頁巖氣資源量約為(15~30)×1012m3.平面上以中國南方和西北地區最為有利(也包括鄂爾多斯盆地及其周緣),剖面上以古生界資源量為最大,中生界位居其次.

關鍵詞:中國;頁巖氣;地質特征;有利區;分布;資源量;潛力

來源出版物:天然氣工業,2008,28(6): 136-140聯系郵箱:張金川,zhangjc@cugb.edu.cn

被引頻次:313

北美裂縫性頁巖氣勘探開發的啟示

李新景,胡素云,程克明

摘要:北美實踐證明,非常規油氣資源——頁巖氣是現實的接替能源了,勘探風險在于能否從低滲透的頁巖儲集層中獲取經濟可采儲量,勘探目標是有機質和硅質含量高、裂縫發育的脆性優質烴源巖.頁巖氣生產機制復雜,涉及吸附氣與游離氣、天然裂縫與誘導裂縫系統之間的相互關系.在地質、地化、測井和地震綜合評價基礎上,通過水力壓裂等增產措施提高儲集層滲透能力是頁巖氣開采的關鍵.中國廣泛分布海相和湖相細粒碎屑巖,有效烴源巖多富含炭質、灰質或硅質,已陸續發現裂縫性油氣藏,有條件尋找豐富的頁巖氣資源,特別是液態烴在高成熟或過成熟階段裂解產生的甲烷氣滯留在烴源巖內形成的連續分布式非常規頁巖氣資源.

關鍵詞:頁巖氣;吸附氣;裂縫;壓裂;烴源巖儲集層

來源出版物:石油勘探與開發,2007,34(4): 392-400

被引頻次:283

頁巖氣成藏控制因素及中國南方頁巖氣發育有利區預測

聶海寬,唐玄,邊瑞康

摘要:在系統研究美國頁巖氣成藏理論和成藏條件的基礎上,分析了頁巖氣成藏的主要控制因素,分為內部因素和外部因素:前者指頁巖本身的因素,包括有機質類型和含量、成熟度、裂縫、孔隙度和滲透率、礦物組成、厚度、濕度等;后者主要包括深度、溫度和壓力等.其中,有機質類型和含量、成熟度、裂縫及孔隙度和滲透率是控制頁巖氣成藏的主要因素.結合主要影響參數,建立了預測頁巖含氣的種類、比例和頁巖氣藏發育有利區的參數模型.運用此模型類比研究發現,中國南方古生界海相頁巖層中,寒武系和志留系是頁巖氣發育的最有利層系.寒武系頁巖氣藏發育最有利區位于四川盆地和米倉山—大巴山前陸以及渝東、黔北、湘西—江南隆起北緣一線;志留系頁巖氣藏發育最有利區位于上揚子的四川盆地和米倉山—大巴山前陸和渝東—鄂西一帶、中揚子鄂北以及下揚子蘇南等地.并對各有利區的泥頁巖指標進行分析,以期為中國頁巖氣早期評價提供參考.

關鍵詞:頁巖氣;主控因素;中國南方;寒武系;志留系;頁巖氣有利區

來源出版物:石油學報,2009,30(4): 484-491聯系郵箱:聶海寬,niehaikuan@126.com

被引頻次:250

四川盆地頁巖氣成藏地質條件

張金川,聶海寬,徐波,等

摘要:與傳統上的“泥頁巖裂縫氣”并不完全相同,頁巖氣是主體上以吸附相和游離相同時賦存于泥巖及頁巖地層中的天然氣.四川盆地經歷了克拉通和前陸盆地演化過程中復雜的構造變動,形成了與美國典型頁巖氣盆地相似的構造演化特點和地質條件,其中的古生界頁巖不僅是盆地內常規氣藏的烴源巖,而且還是頁巖氣成藏及勘探的主要對象,目前已發現了頁巖氣存在的大量證據.根據演化及勘探地質特點,四川盆地非常規天然氣具有兩分格局,東南部以頁巖氣為主而西北部以根緣氣為主,古生界主體發育頁巖氣而中生界主體發育根緣氣.川東和川南地區(包括川西南)古生界生氣頁巖發育厚度大、有機質含量高、埋藏深度小,下寒武統和下志留統具有良好的頁巖氣成藏及勘探地質條件;川中地區同時發育中、古生界烴源巖,上三疊統、下志留統和下寒武統可作為頁巖氣勘探的有利層位;川西中生界泥/頁巖常與致密砂巖形成頻繁互層并產生具有砂巖底部含氣特點的根緣氣,整體上存在著頁巖氣發育和勘探的遠景條件,局部埋藏相對較淺的高碳泥/頁巖是頁巖氣勘探的基本對象.

關鍵詞:四川盆地;頁巖氣;成藏條件;勘探前景

來源出版物:天然氣工業,2008,28(2): 151-156聯系郵箱:張金川,zhangjc@cugb.edu.cn

被引頻次:192

我國頁巖氣富集類型及資源特點

張金川,姜生玲,唐玄,等

摘要:根據頁巖氣聚集的機理條件和中、美頁巖氣地質條件的相似性對比結果認為:中國頁巖氣富集地質條件優越,具有與美國大致相同的頁巖氣資源前景及開發潛力.中國含氣頁巖具有高有機質豐度、高有機質熱演化程度及高后期改造程度等“三高”特點,頁巖氣具有海陸相共存、沉積分區控制以及分布多樣復雜等特點.以間接型和直接型頁巖氣劃分方法為基礎并結合中國區域地質特點,將中國的頁巖氣富集模式劃分為南方型、北方型及西北型等3種,分別具有以下特點:①以揚子地臺為核心的南方型頁巖氣聚集條件有利并以改造較為嚴重的海相古生界海相頁巖聚氣為主,具有單層厚度大、發育層位多、分布面積廣、熱演化程度高、后期改造強等特點;②以華北地臺為主體的北方型頁巖氣具有古—中—新生界頁巖發育齊全、沉積遷移特征明顯、薄互層變化頻率高、沉積相帶分隔明顯等特點;③以塔里木地臺為基礎的西北型頁巖氣儲層以中—古生界為主,沉積類型多、有機碳豐度高、有機質熱演化程度相對較低.結論認為:中國頁巖氣可采資源量約為26×1012m3,大致與美國的28×1012m3相當.

關鍵詞:中國;頁巖氣;資源評價;分區特點;富集模式;開發潛力;華北地臺;揚子地臺;塔里木地臺

來源出版物:天然氣工業,2009,29(12): 109-114

被引頻次:189

常規與非常規油氣聚集類型、特征、機理及展望——以中國致密油和致密氣為例

鄒才能,朱如凱,吳松濤,等

摘要:油氣勘探開發領域從常規油氣向非常規油氣跨越,是石油工業發展的必然趨勢,二者在油氣類型、地質特征及聚集機理等方面明顯不同.常規油氣研究的靈魂是成藏,目標是回答圈閉是否有油氣;非常規油氣研究的靈魂是儲層,目標是回答儲集有多少油氣.非常規油氣主要表現在連續分布、無自然工業產量.目前,常規油氣面臨非常規的問題,非常規需要發展成新的“常規”.伴隨技術的進步,非常規可向常規轉化.常規油氣聚集包括構造油氣藏、巖性-地層油氣藏,油氣以孤立的單體式或較大范圍的集群式展布,圈閉界限明顯,儲集體發育毫米級—微米級孔喉系統,浮力成藏.非常規油氣聚集包括致密砂巖油和氣、致密碳酸鹽巖油和氣、頁巖油和氣等,一般源儲共生,大面積連續或準連續分布于盆地斜坡或中心,圈閉界限不明顯,頁巖系統儲集體廣泛發育納米級孔喉,浮力作用受限,油氣以原位滯留或短距離運移為主.以中國重點盆地致密油和致密氣為例,系統分析了其地質特征與勘探潛力.非常規油氣儲集空間主體為納米級孔喉系統,局部發育微米—毫米級孔隙,其中頁巖氣儲層孔徑為5~200 nm,致密灰巖油儲層孔徑為40~500 nm,致密砂巖油儲層孔徑為50~900 nm,致密砂巖氣儲層孔徑為40~700 nm.針對全球石油工業和納米等技術的快速發展,提出了“納米油氣”的概念,指出“納米油氣”是未來石油工業的發展方向,需要發展納米油氣透視觀測鏡、納米油氣驅替劑、納米油氣開采機器人等換代技術,油氣智能化時代將隨之到來.

關鍵詞:常規油氣;非常規油氣;頁巖系統油氣;納米油氣;致密油;致密氣;頁巖氣;頁巖油;連續型油氣聚集

來源出版物:石油學報,2012,33(2): 173-187聯系郵箱:鄒才能,zcn@petrochina.com.cn

被引頻次:187

頁巖氣儲層的基本特征及其評價

蔣裕強,董大忠,漆麟,等

摘要:頁巖氣獨特的賦存狀態,“連續成藏”的聚集模式,區別于常規天然氣儲層的特征以及評價內容等決定了頁巖氣儲層研究的特殊性.目前,國內針對頁巖氣儲層特征及評價的工作開展得相對較少,需要建立相應的評價標準.在大量調研國外文獻的基礎上,綜合利用四川盆地最新的淺井鉆探和野外露頭取樣資料,從常規儲層研究思路入手,詳細分析了頁巖氣儲層的基本特征(有機質特征、礦物組成、物性特征、儲滲空間特征),進而總結了頁巖氣儲層評價的主要內容;同時,借鑒美國頁巖氣勘探成功經驗,從實際資料出發,篩選出有機質豐度、熱成熟度、含氣性等8大關鍵地質因素,進而提出了一套較為適用的儲層評價標準.據該標準評價后認為,四川盆地下古生界筇竹寺組和龍馬溪組2套海相黑色頁巖具有良好的勘探開發前景.

關鍵詞:頁巖氣;儲集層;溶蝕孔隙;有機孔隙;裂縫;評價內容;評價標準;關鍵地質因素

來源出版物:天然氣工業,2010,30(10): 7-12聯系郵箱:蔣裕強,xnsjij93055@126.com

被引頻次:168

頁巖氣資源評價方法及其在四川盆地的應用

董大忠,程克明,王世謙,等

摘要:近10年來,在高天然氣價格、水平井鉆井技術和壓裂技術進步的推動下,頁巖氣成為美國最重要的天然氣開發目標,形成了適合于不同勘探開發階段的頁巖氣資源潛力評價方法,對頁巖氣資源的認識不斷得到深化.在詳細研究美國頁巖氣資源評價方法基礎上,探索了我國現階段頁巖氣資源評價方法,并針對四川盆地西南部地區及威遠氣田區下古生界下寒武統筇竹寺組的頁巖氣資源做了初步預測.結果認為四川盆地頁巖氣資源豐富,不少于盆地常規天然氣資源量,是未來值得重視的重要天然氣勘探開發新領域.

關鍵詞:頁巖氣;資源;評價方法;四川盆地;應用;

來源出版物:天然氣工業,2009,29(5): 33-39聯系郵箱:董大忠,ddz@petrochina.com.cn

被引頻次:194

Methane and the greenhouse-gas footprint of natural gas from shale formations

Howarth,Robert W; Santoro,Renee; Ingraffea,Anthony

Abstract: We evaluate the greenhouse gas footprint of natural gas obtained by high-volume hydraulic fracturing from shale formations,focusing on methane emissions. Natural gas is composed largely of methane,and 3.6% to 7.9% of the methane from shale-gas production escapes to the atmosphere in venting and leaks over the life-time of a well. These methane emissions are at least 30% more than andperhaps more than twice as great as those from conventional gas. The higher emissions from shale gas occur at the time wells are hydraulically fractured-as methane escapes from flow-back return fluids-and during drill out following the fracturing. Methane is a powerful greenhouse gas,with a global warming potential that is far greater than that of carbon dioxide,particularly over the time horizon of the first few decades following emission. Methane contributes substantially to the greenhouse gas footprint of shale gas on shorter time scales,dominating it on a 20-year time horizon. The footprint for shale gas is greater than that for conventional gas or oil when viewed on any time horizon,but particularly so over 20 years. Compared to coal,the footprint of shale gas is at least 20% greater and perhaps more than twice as great on the 20-year horizon and is comparable when compared over 100 years.

Keywords: Methane; Greenhouse gases; Global warming; Natural gas; Shale gas; Unconventional gas; Fugitive emissions; Lifecycle analysis; LCA; Bridge fuel; Transitional fuel; Global warming potential; GWP

來源出版物:Climatic Change,2011,106(4): 679-690聯系郵箱:Howarth,Robert W; rwh2@cornell.edu

被引頻次:158

Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment

Jarvie,Daniel M; Hill,Ronald J; Ruble,Tim E; Pollastro,Richard M

Abstract: Shale-gas resource plays can be distinguished by gas type and system characteristics. The Newark East gas field,located in the Fort Worth Basin,Texas,is defined by thermogenic gas production from low-porosity and low-permeability Barnett Shale. The Barnett Shale gas system,a self-contained source-reservoir system,has generated large amounts of gas in the key productive areas because of various characteristics and processes,including(1)excellent original organic richness and generation potential;(2)primary and secondary cracking of kerogen and retained oil,respectively;(3)retention of oil for cracking to gas by adsorption;(4)porosity resulting from organic matter decomposition; and(5)brittle mineralogical composition. The calculated total gas in place(GIP)based on estimated ultimate recovery that is based on production profiles and operator estimates is about 204 bcf/section(5.78×109M-3/1.73×104m3). We estimate that the Barnett Shale has a total generation potential of about 609 bbl of oil equivalent/ac-ft or the equivalent of 3657 mcf/ac-ft(84.0 m3/m3). Assuming a thickness of 350 ft(107 m)and only sufficient hydrogen for partial cracking of retained oil to gas,a total generation potential of 820 bcf/section is estimated. Of this potential,approximately 60% was expelled,and the balance was retained for secondary cracking of oil to gas,if sufficient thermal maturity was reached. Gas storage capacity of the Barnett Shale at typical reservoir pressure,volume,and temperature conditions and 6% porosity shows a maximum storage capacity of 540 mcf/ac-ft or 159 scf/ton.

Keywords: primary migration; organic-matter; source rocks; carbon; basin; hydrocarbons; adsorption; diffusion; kerogen; play

來源出版物:AAPG Bulletin,2007,91(4): 475-499聯系郵箱:Jarvie,DM; danjarvie@humble-inc.com

被引頻次:157

Fractured shale-gas systems

Curtis,JB

Abstract: The first commercial United States natural gas production(1821)came from an organic-rich Devonian shale in the Appalachian basin. Understanding the geological and geochemical nature of organic shale formations and improving their gas producibility have subsequently been the challenge of millions of dollars worth of research since the 1970s. Shale-gas systems essentially are continuous-type biogenic(predominant),thermogenic,or combined biogenic-thermogenic gas accumulations characterized by widespread gas saturation,subtle trapping mechanisms,seals of variable lithology,and relatively short hydrocarbon migration distances. Shale gas may be stored as free gas in natural fractures and intergranular porosity,as gas sorbed onto kerogen and clay-particle surfaces,or as gas dissolved in kerogen and bitumen. Five United States shale formations that presently produce gas commercially exhibit an unexpectedly wide variation in the values of five key parameters: thermal maturity(expressed as vitrinite reflectance),sorbed-gas fraction,reservoir thickness,total organic carbon content,and volume of gas in place. The degree of natural fracture development in an otherwise low-matrix-permeability shale reservoir is a controlling factor in gas producibility. To date,unstimulated commercial production has been achievable in only a small proportion of shale wells,those that intercept natural fracture networks. In most other cases,a successful shale-gas well requires hydraulic stimulation. Together,the Devonian Antrim Shale of the Michigan basin and Devonian Ohio Shale of the Appalachian basin accounted for about 84% of the total 380 bcf of shale gas produced in 1999. However annual gas production is steadily increasing from three other major organic shale formations that subsequently have been explored and developed: the Devonian New Albany Shalein the Illinois basin,the Mississippian Barnett Shale in the Fort Worth basin,and the Cretaceous Lewis Shale in the San Juan basin. In the basins for which estimates have been made,shale-gas resources are substantial,with in-place volumes of 497-783 tcf. The estimated technically recoverable resource(exclusive of the Lewis Shale)ranges from 31 to 76 tcf. In both cases,the Ohio Shale accounts for the largest share.

Keywords: subsequent thermal history; appalachian basin; organic-matter; rome trough; accumulation; methane

來源出版物:AAPG Bulletin,2002,86(11): 475-499

被引頻次:123

Mississippian Barnett Shale,Fort Worth basin,north-central texas: Gas-shale play with multi-trillion cubic foot potential

Montgomery,SL; Jarvie,DM; Bowker,KA; et al.

Abstract: The Mississippian Barnett Shale serves as source,seal,and reservoir to a world-class unconventional natural-gas accumulation in the Fort Worth basin of north-central Texas. The formation is a lithologically complex interval of low permeability that requires artificial stimulation to produce. At present,production is mainly confined to a limited portion of the northern basin where the Barnett Shale is relatively thick(>300 ft; >92 m),organic rich(present-day total organic carbon>3.0%),thermally mature(vitrinite reflectance>1.1%),and enclosed by dense limestone units able to contain induced fractures. The most actively drilled area is Newark East field,currently the largest gas field in Texas. Newark East is 400 mi2(1036 km2)in extent,with more than 2340 producing wells and about 2.7 tcf of booked gas reserves. Cumulative gas production from Barnett Shale wells through 2003 was about 0.8 tcf. Wells in Newark East field typically produce from depths of 7500 ft(2285 m)at rates ranging from 0.5 to more than 4 mmcf/day. Estimated ultimate re coveries per well range from 0.75 to as high as 7.0 bcf. Efforts to extend the current Barnett play beyond the field limits have encountered several challenges,including westward and northward increases in oil saturation and the absence of lithologic barriers to induced fracture growth. Patterns of oil and gas occurrence in the Barnett,in conjunction with maturation and burial-history data,indicate a complex,multiphased thermal evolution,with episodic expulsion of hydrocarbons and secondary cracking of primary oils to gas in portions of the basin where paleotemperatures were especially elevated. These and other data imply a large-potential Barnett resource for the basin as a whole(possibly >200 tcf gas in place). Recent assessment by the U.S. Geological Survey suggests a mean volume of 26.2 tcf of undiscovered,technically recoverable gas in the central Fort Worth basin. Recovery of a significant portion of this undiscovered resource will require continued improvements in geoscientific characterization and approaches to stimulation of the Barnett reservoirs.

來源出版物:AAPG Bulletin,2005,89(2): 155-175聯系郵箱:Montgomery,SL; scott.montgomery@prodigy.net

被引頻次:110

The importance of shale composition and pore structure upon gas storage potential of shale gas reservoirs

Ross,Daniel J.K; Bustin,R. Marc

Abstract: The effect of shale composition and fabric upon pore structure and CH4sorption is investigated for potential shale gas reservoirs in the Western Canadian Sedimentary Basin(WCSB). Devonian-Mississippian(D-M)and Jurassic shales have complex,heterogeneous pore volume distributions as identified by low pressure CO2and N2sorption,and high pressure Hg porosimetry. Thermally mature D-M shales(1.6%-2.5% VRo)have Dubinin-Radushkevich(D-R)CO2micropore volumes ranging between 0.3 and 1.2 cc/100 g and N2BET surface areas of 5-31 m2/g. Jurassic shales,which are invariably of lower thermal maturity ranging from 0.9 to 1.3% VRo,than D-M shales have smaller D-R CO2micropore volumes and N2BET surface areas,typically in the range of 0.23-0.63 cc/100 g(CO2)and 1-9 m2/g(N2). High pressure CH4isotherms on dried and moisture equilibrated shales show a general increase of gas sorption with total organic carbon(TOC)content. Methane sorption in D-M shales increases with increasing TOC and micropore volume,indicating that microporosity associated with the organic fraction is a primary control upon CH4sorption. Sorption capacities for Jurassic shales,however,can be in part unrelated to micropore volume. The large sorbed gas capacities of organic-rich Jurassic shales,independent of surface area,imply a portion of CH4is stored by solution in matrix bituminite. Solute CH4is not an important contributor to gas storage in D-M shales. Structural transformation of D-M organic matter has occurred during thermal diagenesis creating and/or opening up microporosity onto which gas can sorb. As such,D-M shales sorb more CH4per weight percent(wt %)TOC than Jurassic shales. Inorganic material influences modal pore size,total porosity and sorption characteristics of shales. Clay minerals are capable of sorbing gas to their internal structure,the amount of which is dependent on clay-type. Illite and montmorillonite have CO2micropore volumes of 0.78 and 0.79 cc/100 g,N2BET surface areas of 25 and 30 m2/g,and sorb 2.9 and 2.1 cc/g of CH4,respectively(dry basis)-a reflection of microporosity between irregular surfaces of clay platelets,and possibly related to the size of the clay crystals themselves. Mercury porosimetry analyses show that total porosities are larger in clay-rich shales compared to silica-rich shales due to open porosity associated with the aluminosilicate fraction. Clay-rich sediments(low Si/Al ratios)have unimodal pore size distributions <10 nm and average total porosities of 5.6%. Siliceous/quartz-rich shales(high Si/Al)exhibit no micro- or mesopores using Hg analyses and total porosities average 1%,analogous to chert.

Keywords: Pore structure; Microporosity; Sorption; Shale gas reservoirs

來源出版物:Marine and Petroleum Geology,2009,26(6): 916-927

聯系郵箱:Ross,Daniel J.K; daniel.ross@shell.com

被引頻次:70

Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale-gas succession in the Fort Worth Basin,Texas

Loucks,Robert G; Ruppel,Stephen C

Abstract: The Mississippian Barnett Formation of the Fort Worth Basin is a classic shale-gas system in which the rock is the source,reservoir,and seal. Barnett strata were deposited in a deeper water foreland basin that had poor circulation with the open ocean. For most of the basin's history,bottom waters were euxinic,preserving organic matter and,thus,creating a rich source rock,along with abundant framboidal pyrite. The Barnett interval comprises a variety of facies but is dominated by fine-grained(clay-to silt-size)particles. Three general lithofacies are recognized on the basis of mineralogy,fabric,biota,and texture:(1)laminated siliceous mudstone;(2)laminated argillaceous lime mudstone(marl); and(3)skeletal,argillaceous lime packstone. Each facies contains abundant pyrite and phosphate(apatite),which are especially common at hardgrounds. Carbonate concretions,a product of early diagenesis,are also common. The entire Barnett biota is composed of debris transported to the basin from the shelf or upper oxygenated slope by hemipelagic mud plumes,dilute turbidites,and debris flows. Biogenic sediment was also sourced from the shallower,better oxygenated water column. Barnett deposition is estimated to have occurred over a 25-m.y. period,and despite the variations in sublithofacies,sedimentation style remained remarkably similar throughout this span of time.

來源出版物:AAPG Bulletin,2007,91(4): 579-601聯系郵箱:Loucks,Robert G; bob.loucks@beg.utexas.edu

被引頻次:68

Water Management Challenges Associated with the Production of Shale Gas by Hydraulic Fracturing

Gregory,Kelvin B; Vidic,Radisav D; Dzombak,David A

Abstract: Development of unconventional,onshore natural gas resources in deep shales is rapidly expanding to meet global energy needs. Water management has emerged as a critical issue in the development of these inland gas reservoirs,where hydraulic fracturing is used to liberate the gas. Following hydraulic fracturing,large volumes of water containing very high concentrations of total dissolved solids(TDS)return to the surface. The TDS concentration in this wastewater,also known as “flowback”,can reach 5 times that of sea water. Wastewaters that contain high TDS levels are challenging and costly to treat. Economical production of shale gas resources will require creative management of flowback to ensure protection of groundwater and surface water resources. Currently,deep-well injection is the primary means of management. However,in many areas where shale gas production will be abundant,deep-well injection sites are not available. With global concerns over the quality and quantity of fresh water,novel water management strategies and treatment technologies that will enable environmentally sustainable and economically feasible natural gas extraction will be critical for the development of this vast energy source.

Keywords: shale gas; hydraulic fracturing; produced water; flowback

來源出版物:Elements,2011,7(3): 181-186聯系郵箱:Gregory,Kelvin B; kelvin@cmu.edu

被引頻次:58

Impact of Shale Gas Development on Regional Water Quality

Vidic,R.D; Brantley,S.L; Vandenbossche,J.M; et al.

Abstract: Unconventional natural gas resources offer an opportunity to access a relatively clean fossil fuel that could potentially lead to energy independence for some countries. Horizontal drilling and hydraulic fracturing make the extraction of tightly bound natural gas from shale formations economically feasible. These technologies are not free from environmental risks,however,especially those related to regional water quality,such as gas migration,contaminant transport through induced and natural fractures,wastewater discharge,and accidental spills. We review the current understanding of environmental issues associated with unconventional gas extraction. Improved understanding of the fate and transport of contaminants of concern and increased long-term monitoring and data dissemination will help manage these water-quality risks today and in the future.

Keywords: potential contaminant pathways; hydraulically fractured shale; marcellus shale; methane contamination; appalachian basin;pennsylvania; aquifers; wells; extraction; challenges

來源出版物:Science,2013,340(6134)文獻號:1235009聯系郵箱:Vidic,R.D; vidic@pitt.edu

被引頻次:58

Nanoscale gas flow in shale gas Sediments

Javadpour,F; Fisher,D; Unsworth,M

Abstract: Production of gas out of low permeability shale packages is very recent in the Western Canadian Sedimentary Basin(WCSB). The process of gas release and production from shale gas sediments is not well understood. Because of adsorptive capacity of certain shaleconstituents,including organic carbon content: coalbed methane models are sometimes being applied to model and simulate tight shale gas production behaviour. Alternatively,conventional Darcy flow models are sometimes applied to tight shale gas. However,neither of these approaches takes into account the differences in transport mechanisms in shale due to additional nanopore networks. Hence,the application of existing models for shale results in erroneous evaluation and predictions. Our analysis shows that a combination of a nanopore network connected to a micrometre pore network controls the gas flow in shale. Mathematical modelling of gas flow in nanopores is difficult since the standard assumption of no-slip boundary conditions in the Navier-Stokes equation breaks down at the nanometre scale,while the computational times of applicable molecular-dynamics(MD)codes become exorbitant. We found that the gas flow in nanopores of the shale can be modelled with a diffusive transport regime with a constant diffusion coefficient and negligible viscous effects. The obtained diffusion coefficient is consistent with the Knudsen diffusivity which supports the slip: boundary condition at the nanopore surfaces. This model can be used for shale gas evaluation and production optimization.

來源出版物:Journal of Canadian Petroleum Technology,2007,46(10): 55-61

被引頻次:58

Life-Cycle Greenhouse Gas Emissions of Shale Gas,Natural Gas,Coal,and Petroleum

Burnham,Andrew; Han,Jeongwoo; Clark,Corrie E; et al.

Abstract: The technologies and practices that have enabled the recent boom in shale gas production have also brought attention to the environmental impacts of its use. It has been g debated whether the fugitive methane emissions during natural gas production and transmission outweigh the lower carbon dioxide emissions during combustion when compared to coal and petroleum. Using the current state of knowledge of methane emissions from shale gas,conventional natural gas,coal,and petroleum,we estimated up-to-date life-cycle greenhouse gas emissions. In addition,we developed distribution functions for key parameters in each pathway to examine uncertainty and identify data gaps such as methane emissions from shale gas well completions and conventional natural gas liquid unloadings that need to be further addressed. Our base case results show that shale gas life-cycle emissions are 6% lower than conventional natural gas,23% lower than gasoline,and 33% lower than coal. However,the range in values for shale and conventional gas overlap,so there is a statistical uncertainty whether shale gas emissions are indeed lower than conventional gas. Moreover,this life-cycle analysis,among other work in this area,provides insight on critical stages that the natural gas industry and government agencies can work together on to reduce the greenhouse gas footprint of natural gas.

來源出版物:Environmental Science & Technology,2012,46(2): 619-627聯系郵箱:Burnham,Andrew; aburnham@anl.gov

·推薦論文摘要·

頁巖油形成機制、地質特征及發展對策

鄒才能,楊智,崔景偉,等

摘要:頁巖油是儲存于富有機質、納米級孔徑為主頁巖地層中的成熟石油,是常規—非常規“有序聚集”體系的重要類型之一,對中國陸相頁巖油形成的沉積環境、儲集空間、地球化學特征和聚集機制等基本石油地質問題進行了分析總結.富有機質頁巖主要發育在半深湖—深湖環境,不同巖性組合共生沉積;發育紋層結構,微米—納米級孔喉和微裂縫是主要儲集空間;有利頁巖以Ⅰ型和AⅡ 型干酪根為主、Ro 值為0.7%~2.0%、TOC值大于2.0%、有效厚度大于10 m;揭示了頁巖孔隙演化和頁巖油滯留聚集模式,儲集空間、脆性指數、黏度、壓力、滯留量等是頁巖油“核心區”評價的關鍵.中國陸相頁巖油在湖盆中心連續聚集,初步預測可采頁巖油資源量約30×108~60×108t,水平井體積壓裂、改造“天然裂縫”、注粗顆?!叭嗽靸瘜印钡瓤赡苁琼搸r油工業化發展的核心技術,提出加快頁巖油“分布區”研究、加強“核心區”評選、加大“試驗區”建設的“三步走”發展思路.借鑒北美海相頁巖氣突破成功經驗,陸相頁巖油工業化有望在中國首先突破.

關鍵詞:頁巖油;頁巖氣;頁巖系統油氣;納米級孔喉;非常規油氣;常規—非常規“有序聚集”體系

來源出版物:石油勘探與開發,2013,40(1): 14-26聯系郵箱:鄒才能,zcn@petrochina.com.cn

川南下寒武統筇竹寺組頁巖氣形成條件及資源潛力

黃金亮,鄒才能,李建忠,等

摘要:利用四川盆地南部地區最新鉆探的井下資料、周邊露頭地質調查資料及大量樣品的分析測試結果,從富有機質頁巖區域展布、地球化學特征、巖石儲集特征、含氣性等方面研究川南地區下寒武統筇竹寺組頁巖氣形成條件與資源前景.研究區筇竹寺組有機質含量高(TOC值為0.55%~25.70%,平均值大于2%),頁巖有效厚度大(黑色頁巖厚60~300 m),脆性礦物含量較高(大于40%),頁巖中發育豐富的納米一微米級孔隙和微裂縫,含氣量高(頁巖含氣量0.27~6.02 m3/t,平均1.90 m3/t),有利于頁巖氣的形成與富集.鉆井過程中筇竹寺組氣顯示頻繁并獲得了工業性突破,是目前中國最有利的頁巖氣勘探開發層系之一,綜合對比研究認為威遠、敘永一筠連地區是研究區內筇竹寺組頁巖氣勘探開發最有利的地區.

關鍵詞:四川盆地南部;下寒武統;筇竹寺組;頁巖氣;形成條件;資源前景

來源出版物:石油勘探與開發,2012,39(1): 69-75聯系郵箱:黃金亮,huangjl1983@petrochina.com.cn

煤層氣/頁巖氣開發地質條件及其對比分析

孟召平,劉翠麗,紀懿明

摘要:從煤層氣、頁巖氣基本概念入手,系統分析了煤層氣/頁巖氣開發地質條件,主要包括成藏地質條件、賦存環境條件和開發工程力學條件3個方面,進一步對煤層氣/頁巖氣開發地質條件進行了對比分析,揭示了煤層氣/頁巖氣開發地質條件的共性和差異性.煤層氣/頁巖氣賦存于煤層/頁巖中的一種自生自儲式非常規天然氣,其富集成藏主要取決于“生、儲、?!被镜刭|條件是否存在、質量好壞以及相互之間的配合關系.在一定埋藏深度范圍內煤層氣/頁巖氣都發生過解吸-擴散-運移,并普遍存在“垂向分帶”現象,有機質演化程度越高解吸帶深度越小,風化帶越深解吸帶深度越大,解吸帶內煤層氣/頁巖氣富集在一定程度上服從于常規天然氣的構造控氣規律;原生帶內煤層氣/頁巖氣富集卻可能更多地受控于煤儲層/頁巖層的吸附特性.不同賦存環境條件下所形成的煤/頁巖儲層差異性大,使煤/頁巖儲層中吸附氣和游離氣相互轉化,導致煤層氣/頁巖氣成藏類型、規模和質量等方面的差異性.影響煤層氣開發的主要地質因素有:煤層厚度及其穩定性、含氣量大小或煤層氣資源豐度、構造及裂隙發育與滲透性和煤層氣保存條件等方面;影響頁巖氣開發的主要地質因素包括頁巖厚度、有機質含量、熱成熟度、含氣量、天然裂縫發育程度和脆性礦物含量等.

關鍵詞:煤層氣;頁巖氣;開發地質;對比分析

來源出版物:煤炭學報,2013,38(5): 728-736聯系郵箱:孟召平,mzp@ cumtb.edu.cn

中國南方海相頁巖氣高效開發的科學問題

王紅巖,劉玉章,董大忠,等

摘要:中國頁巖氣資源豐富,已在多個地區獲初步發現,其中中國南方古生界寒武系、奧陶系和志留系中發育多套海相富有機質頁巖,技術可采資源量占全國的3/4,將是重點開發地區.與北美相比,中國南方海相頁巖氣儲集層具有構造改造強、地應力復雜、埋藏較深、地表條件特殊等特點,照搬國外現有理論與技術難以有效開發.頁巖氣儲集層納米級孔隙對頁巖氣產能的影響尚不明確,頁巖氣產能預測方法尚未建立,鉆井過程中水平段垮塌嚴重、鉆井周期長,增產改造效果不理想、單井產量較低,需要針對納米級孔隙成因及多尺度儲集空間定量表征、復雜介質多場耦合非線性流動機理、頁巖失穩與縫網形成的力學機制3個科學問題進行研究.

關鍵詞:海相頁巖氣;高效開發;科學問題;中國南方;納米級孔隙

來源出版物:石油勘探與開發,2013,40(5): 574-579

非常規油氣地質學重要理論問題

賈承造,鄭民,張永峰

摘要:2012年常規能源燃料的消費量和生產量達到創紀錄的歷史最高水平,石油和天然氣在能源消費結構中仍然占據主導地位,非常規油氣產量的大幅上升使油氣供需基本達到平衡.但目前對非常規油氣還有很多重要的基礎理論問題沒有解決,對非常規油氣的分布富集規律、勘探開發特點還沒有把握.本文以此為出發點,回顧了近期全球油氣勘探形勢,提出了非常規油氣地質學的4項重要理論問題:①“含油氣系統”理論的深化再認識,提出了含油氣盆地“全含油氣系統”的“全過程成藏”模式,從烴類生-排-運-聚全過程定量化研究的4個關鍵問題出發,分析了非常規油氣成藏機理;②細粒沉積體系與致密相帶沉積學,通過解析細粒沉積與非常規油氣生成關系的角度提出了3個研究結合點;③頁巖與致密儲層中微-納米孔隙系統和流體相態,提出了微-納米孔隙系統在非常規油氣研究方面應重點關注的5個方面,并解析了微-納米孔隙發育特點及微-納米孔隙中流體相態的特征;④非常規油氣富集規律與資源評價,從非常規油氣聚集特征出發,優選建立了非常規油氣資源評價方法體系.

關鍵詞:能源消費結構;非常規油氣;勘探形勢;理論難題;含油氣系統;致密相帶;微-納米孔隙系統

來源出版物:石油學報,2014,35(1): 1-10聯系郵箱:鄭民,zhenmin@petrochina.com.cn

滇黔北地區筇竹寺組高演化頁巖氣儲層微觀孔隙特征及其控制因素

梁興,張廷山,楊洋,等

摘要:頁巖氣鉆探資料表明,滇黔北地區下寒武統筇竹寺組頁巖儲層富氣狀況明顯不如下志留統龍馬溪組頁巖,由此嚴重影響其勘探部署決策,查明其原因是當務之急.為此,以頁巖氣鉆井巖心為基礎,采用環境掃描電鏡、原子力顯微鏡、比表面積測量、低溫液氮吸附等試驗手段,分析了筇竹寺組頁巖儲層的微觀孔隙類型、結構特征等.結果表明:①筇竹寺組頁巖儲層呈現出極為發育的以納米級為主的微觀孔隙結構特征,發育黏土礦物層間孔、有機質孔、晶間孔、礦物鑄???、次生溶蝕孔等多類型的基質孔隙,具有比表面積小和面孔率大的特點;TOC②、干酪根類型、黏土礦物和Ro是控制筇竹寺組微觀孔隙結構的主要因素,以Ro的影響最為明顯,且在頁巖達到過成熟狀態后,其比表面積和孔體積隨著Ro的增大而急劇減小.結論認為:已處于過成熟中后期的該區筇竹寺組頁巖層,長期的地質作用過程和過高熱演化程度嚴重制約了其微觀孔隙發育,呈現微孔隙驟減和比表面積、孔體積明顯較小的情形,不利于頁巖氣的吸附儲集,由此導致該區筇竹寺組頁巖氣富集程度不如龍馬溪組的結果.

關鍵詞:滇黔北地區;頁巖氣;儲集空間類型;微觀孔隙結構;主控因素;富氣程度;早寒武世;比表面積

來源出版物:天然氣工業,2014,34(2): 18-26聯系郵箱:梁興,liangx85@petrochina.com.cn

常規-非常規油氣“有序聚集”理論認識及實踐意義

鄒才能,楊智,張國生,等

摘要:在分析全球常規-非常規油氣發展態勢、梳理中國近10年油氣地質理論與技術創新成果基礎上,系統闡述了常規-非常規油氣“有序聚集”內涵,指出常規油氣供烴方向有非常規油氣共生、非常規油氣外圍空間可能有常規油氣伴生,強調常規油氣與非常規油氣協同發展,找油思想從“源外找油”深入到“進源找油”.非常規油氣甜點著眼于烴源性、巖性、物性、脆性、含油氣性與應力各向異性“六特性”匹配評價,以頁巖氣為例,中國有利頁巖氣TOC大于2%,紋層狀硅質鈣質或鈣質硅質頁巖,孔隙度3%~8%,脆性礦物含量50%~80%,含氣量2.3~4.1 m3/t,壓力系數1.0~2.3,天然裂縫發育;北美有利頁巖氣TOC大于4%,硅質頁巖、鈣質頁巖或泥灰巖,孔隙度4%~9%,脆性礦物含量40%~70%,含氣量2.8~9.9 m3/t,壓力系數1.30~1.85,天然裂縫發育.重點論述了“甜點區”評價、平臺式“工廠化”生產模式等方法與技術:提出非常規油氣富集“甜點區”8項評價標準,其中3項關鍵指標是TOC大于2%(其中頁巖油S1大于2 mg/g)、孔隙度較高(致密油氣大于10%,頁巖油氣大于3%)和微裂縫發育;闡述了多井平臺式“工廠化”生產內涵及其實施需要具備“批量布井、標準設計、流水作業、重復利用”4要素;通過地下含油氣地層各方向水平井體積壓裂,形成大型人工縫網系統“人造油氣藏”.

關鍵詞:非常規油氣;有序聚集;協同發展;“甜點區”評價;平臺式“工廠化”生產;“人造油氣藏”;致密油;頁巖油;頁巖氣;致密氣;“進源找油”

來源出版物:石油勘探與開發,2014,41(1): 14-26

論四川盆地頁巖氣資源勘探開發前景

董大忠,高世葵,黃金亮,等

摘要:四川盆地是目前中國頁巖氣勘探開發的重點地區,也是最成功的地區.四川盆地頁巖氣資源勘探開發前景,將在較大程度上反映和影響中國頁巖氣未來的發展前景.通過全面總結近年來該盆地頁巖氣勘探開發的新進展,得出了以下認識:①四川盆地經歷了海相、陸相兩大沉積演化,發育了海相、海陸過渡相、陸相三類富有機質頁巖,形成了震旦系陡山沱組、寒武系筇竹寺組、奧陶系五峰組—志留系龍馬溪組、二疊系龍潭組、三疊系須家河組、侏羅系自流井組6套有利的頁巖氣富集層系;②深水陸棚相、集中段厚度大、熱演化程度適中、正向構造背景下裂縫發育、儲層超壓是五峰組—龍馬溪組頁巖氣富集的“五大”關鍵要素;③該盆地頁巖氣勘探開發仍面臨資源富集“甜點區”及資源潛力不清、深度超過3500 m的深層頁巖氣勘探開發技術不成熟等兩大挑戰.結論認為:四川盆地已在侏羅系、三疊系和寒武系初步實現了頁巖氣發現,在奧陶系—志留系實現了工業化突破和初步規模生產,未來發展前景較好;該盆地頁巖氣資源可以實現經濟有效勘探開發,預期可實現年產量300×108~600×108m3;對該盆地頁巖氣資源勘探開發將為中國頁巖氣資源規模發展提供重要的理論與技術支撐.

關鍵詞:四川盆地;頁巖氣;勘探開發;新進展;富集條件;發展前景;面臨挑戰;年產量

來源出版物:天然氣工業,2014,34(12): 1-15聯系郵箱:董大忠,ddz@petrochina.com.cn

頁巖氣儲層孔隙發育特征及主控因素分析: 以上揚子地區龍馬溪組為例

黃磊,申維

摘要:運用掃描電鏡、氬離子拋光場發射電子掃描顯微成像與核磁共振測試技術,對渝東南地區Y1井龍馬溪組頁巖的微米級孔隙、納米級孔隙和微裂縫發育特征3個層面分別進行定量表征.結合總有機碳含量、有機質顯微組分及成熟度、黏土礦物及全巖X射線衍射分析等測試數據,對孔隙發育特征主控因素進行分析.對頁巖微米級孔隙發育有促進作用的因素有石英含量和伊利石含量,具有抑制作用的因素有碳酸鹽含量和埋藏深度;對有機質納米級孔隙發育有促進作用的因素有有機質成熟度和伊蒙混層含量,具有抑制作用的因素為方解石含量;對微裂縫發育有促進作用的因素有石英含量、有機質成熟度和總有機碳含量,具有抑制作用的因素是碳酸鹽含量.

關鍵詞:頁巖氣;儲層;孔隙;龍馬溪組;主控因素

來源出版物:地學前緣,2015,22(1): 374-385聯系郵箱:黃磊,huangleicomvn@163.com

涪陵頁巖氣勘探開發重大突破與啟示

王志剛

摘要:中國海相頁巖氣分布領域廣,資源豐富,但與北美相比,具有頁巖時代老、熱演化程度高的特點;同時由于經歷多期次的構造改造,具有保存條件和埋深差異大的特殊性.針對這些特點和特殊性,提出了生烴條件、儲集條件和保存條件為核心的頁巖氣“三元富集”理論.以此為指導,中國石化集團公司的頁巖氣勘探向四川盆地及其近緣聚焦,確定川東南地區下志留統是首選的頁巖氣勘探突破領域.建立了海相頁巖氣區帶和目標評價方法,優選涪陵焦石壩構造為頁巖氣突破目標,2012年部署鉆探焦頁1井,一舉發現了中國首個大型頁巖氣田——焦石壩龍馬溪組海相頁巖氣田.同時,借鑒、集成和研發關鍵技術,形成了中、淺層海相頁巖氣鉆井技術和大井段分段壓裂的海相頁巖儲層改造技術.在勘探開發一體化的工作思路指導下,通過精細高效的組織管理實現焦石壩大型頁巖氣田的快速高效開發.

關鍵詞:三元富集;勘探開發一體化;海相地層;頁巖氣;志留系;焦石壩氣田

來源出版物:石油與天然氣地質,2015,36(1): 1-6

壓裂水平井產能預測方法研究綜述

劉洪平,趙彥超,孟俊,等

摘要:水平井壓裂技術已經在薄層、低滲透油氣藏以及頁巖氣的開發中得到了廣泛的應用,其產能預測方法是進行油氣層評價、合理高效開發的基礎.在對產能影響因素分析的基礎上,系統總結了致密砂巖油氣藏和頁巖氣藏壓裂水平井的產能評價方法;認為除了對儲層基質以及裂縫內流動機理進行表征外,裂縫的分布規律以及儲層應力敏感性對產能的影響不容忽視;同時應重視大量鉆井資料與物理模擬和數值模擬的結合,以提高產能預測的精度.

關鍵詞:壓裂水平井;致密砂巖;頁巖氣;產能預測

來源出版物:地質科技情報,2015,34(1): 131-139聯系郵箱:劉洪平,liuhongping12@126.com

Petrophysical Considerations in Evaluating and Producing Shale Gas Resources

C.H. Sondergeld; K.E. Newsham; J.T. Comisky; et al.

Abstract: We present a practical assessment of petrophysical properties of shales and their measurement in the lab and via logs. Gasbearing shale present unique measurement challenges due to their ultra-low permeability and complicated pore volume connectivity. Thecombination of low intrinsic permeability and gas sorption effects renders these reservoirs “unconventional”. Advances in horizontal drilling and hydraulic stimulation have transformed gas-shale resources into economic reserves. Given their economic significance,there is a strong drive to understand gas shale petrophysical property measurements,both in the laboratory and in the subsurface. We note that various core analysis protocols are used in different laboratories leading to physical property measurements that are inconsistent,even when measured on identical sample sets. In addition,log analysis of kerogen-rich shale is ‘unconventional’ compared to classical techniques used in tight gas sands. As shale gas evaluation is becoming widely practiced among service companies and operators,we will focus on three reservoir assessment categories: storage capacity(gas-in-place),flow capacity(gas deliverability)and mechanical properties impacting hydraulic stimulation. Within each of these categories we have identified influential petrophysical properties such as rock composition,total organic carbon(TOC)content,porosity,saturation,permeability and mechanical properties. Specifically,we demonstrate the importance of estimating accurate mineral and kerogen content as these properties directly impact rock quality,hydraulic fracturing protocols,and gas-in-place estimations. In reviewing these practices,we also will show the need and possible direction of new technologies that will be required for making evaluations more accurate and quantitative in the future.

來源出版物:SPE 2010,131768: 1-34

Thirty Years of Gas Shale Fracturing: What Have We Learned?

George E. King

Abstract: Although high gas flow rates from shales are a relatively recent phenomenon,the knowledge bases of shale-specific well completions,fracturing and shale well operations have actually been growing for more than three decades and shale gas production reaches back almost one hundred ninety years. During the last decade of gas shale development,projected recovery of shale gas-in-place has increased from about 2% to estimates of about 50%; mainly through the development and adaptation of technologies to fit shale gas developments. Adapting technologies,including multi-stage fracturing of horizontal wells,slickwater fluids with minimum viscosity and simultaneous fracturing,have evolved to increase formation-face contact of the fracture system into the range of 9.2 million m2(100 million ft2)in a very localized area of the reservoir by opening natural fractures. These technologies have made possible development of enormous gas reserves that were completely unavailable only a few years ago. Current and next generation technologies promise even more energy availability with advances in hybrid fracs,fracture complexity,fracture flow stability and methods of re-using water used in fracturing. This work surveyed over 350 shale completion,fracturing and operations publications,linking geosciences and engineering information together to relay learnings that will identify both intriguing information on selective opening and stabilizing of micro-fracture systems within the shales and new fields of endeavor needed to achieve the next level of shale development advancement.

來源出版物:SPE 2010,133456: 1-50

Pore structure characterization of North American shale gas reservoirs using USANS/SANS,gas adsorption,and mercury intrusion

Clarkson,CR; Solano,N; Bustin,RM; et al.

Abstract: Small-angle and ultra-small-angle neutron scattering(SANS and USANS),low-pressure adsorption(N2and CO2),and high-pressure mercury intrusion measurements were performed on a suite of North American shale reservoir samples providing the first ever comparison of all these techniques for characterizing the complex pore structure of shales. The techniques were used to gain insight into the nature of the pore structure including pore geometry,pore size distribution and accessible versus inaccessible porosity. Reservoir samples for analysis were taken from currently-active shale gas plays including the Barnett,Marcellus,Haynesville,Eagle Ford,Woodford,Muskwa,and Duvernay shales. Low-pressure adsorption revealed strong differences in BET surface area and pore volumes for the sample suite,consistent with variability in composition of the samples. The combination of CO2and N2adsorption data allowed pore size distributions to be created for micro-meso-macroporosity up to a limit of similar to 1000 angstrom. Pore size distributions are either uni- or multi-modal. The adsorption-derived pore size distributions for some samples are inconsistent with mercury intrusion data,likely owing to a combination of grain compression during high-pressure intrusion,and the fact that mercury intrusion yields information about pore throat rather than pore body distributions. SANS/USANS scattering data indicate a fractal geometry(power-law scattering)for a wide range of pore sizes and provide evidence that nanometer-scale spatial ordering occurs in lower mesopore-micropore range for some samples,which may be associated with inter-layer spacing in clay minerals. SANS/USANS pore radius distributions were converted to pore volume distributions for direct comparison with adsorption data. For the overlap region between the two methods,the agreement is quite good. Accessible porosity in the pore size(radius)range 5 nm-10 μm was determined for a Barnett shale sample using the contrast matching method with pressurized deuterated methane fluid. The results demonstrate that accessible porosity is pore-size dependent.

Keywords: Shale gas; Pore structure; Small-angle neutron scattering; Gas adsorption; Mercury intrusion

來源出版物:Fuel,2013,103: 606-616聯系郵箱:Clarkson,CR; clarksoc@ucalgary.ca

Generation,transport,and disposal of wastewater associated with Marcellus Shale gas development

Lutz,Brian D; Lewis,Aurana N; Doyle,Martin W

Abstract: Hydraulic fracturing has made vast quantities of natural gas from shale available,reshaping the energy landscape of the UnitedStates. Extracting shale gas,however,generates large,unavoidable volumes of wastewater,which to date lacks accurate quantification. For the Marcellus shale,by far the largest shale gas resource in the United States,we quantify gas and wastewater production using data from 2189 wells located throughout Pennsylvania. Contrary to current perceptions,Marcellus wells produce significantly less wastewater per unit gas recovered(approximately 35%)compared to conventional natural gas wells. Further,well operators classified only 32.3% of wastewater from Marcellus wells as flow back from hydraulic fracturing; most wastewater was classified as brine,generated over multiple years. Despite producing less wastewater per unit gas,developing the Marcellus shale has increased the total wastewater generated in the region by approximately 570% since 2004,overwhelming current wastewater disposal infrastructure capacity. Citation: Lutz,B. D.,A. N. Lewis,and M. W. Doyle(2013),Generation,transport,and disposal of wastewater associated with Marcellus Shale gas development,Water Resour.

Keywords: natural-gas; pennsylvania; challenges; methane; brine

來源出版物:Water Resources Research,2013,49(2): 647-656聯系郵箱:Lutz,Brian D; blutz6@kent.edu

Desalination and Reuse of High-Salinity Shale Gas Produced Water: Drivers,Technologies,and Future Directions

Shaffer,Devin L; Chavez,Laura H. Arias; Ben-Sasson,Moshe; et al.

Abstract: In the rapidly developing shale gas industry,managing produced water is a major challenge for maintaining the profitability of shale gas extraction while protecting public health and the environment. We review the current state of practice for produced water management across the United States and discuss the interrelated regulatory,infrastructure,and economic drivers for produced water reuse. Within this framework,we examine the Marcellus shale play,a region in the eastern United States where produced water is currently reused without desalination. In the Marcellus region,and in other shale plays worldwide with similar constraints,contraction of current reuse opportunities within the shale gas industry and growing restrictions on produced water disposal will provide strong incentives for produced water desalination for reuse outside the industry. The most challenging scenarios for the selection of desalination for reuse over other management strategies will be those involving high-salinity produced water,which must be desalinated with thermal separation processes. We explore desalination technologies for treatment of high-salinity shale gas produced water,and we critically review mechanical vapor compression(MVC),membrane distillation(MD),and forward osmosis(FO)as the technologies best suited for desalination of high-salinity produced water for reuse outside the shale gas industry. The advantages and challenges of applying MVC,MD,and FO technologies to produced water desalination are discussed,and directions for future research and development are identified. We find that desalination for reuse of produced water is technically feasible and can be economically relevant. However,because produced water management is primarily an economic decision,expanding desalination for reuse is dependent on process and material improvements to reduce capital and operating costs.

Keywords: contact membrane distillation; mechanical vapor compression; ammonia-carbon dioxide; osmosis desalination; seawater desalination; natural-gas; waste-water; energy-requirements; process performance; fouling behavior

來源出版物:Environmental Science & Technology,2013,47(17): 9569-9583

聯系郵箱:Elimelech,Menachem; menachem.elimelech@yale.edu

A Critical Review of the Risks to Water Resources from Unconventional Shale Gas Development and Hydraulic Fracturing in the United States

Vengosh,Avner; Jackson,Robert B; Warner,Nathaniel; et al.

Abstract: The rapid rise of shale gas development through horizontal drilling and high volume hydraulic fracturing has expanded the extraction of hydrocarbon resources in the U.S. The rise of shale gas development has triggered an intense public debate regarding the potential environmental and human health effects from hydraulic fracturing. This paper provides a critical review of the potential risks that shale gas operations pose to water resources,with an emphasis on case studies mostly from the U.S. Four potential risks for water resources are identified:(1)the contamination of shallow aquifers with fugitive hydrocarbon gases(i.e.,stray gas contamination),which can also potentially lead to the salinization of shallow groundwater through leaking natural gas wells and subsurface flow;(2)the contamination of surface water and shallow groundwater from spills,leaks,and/or the disposal of inadequately treated shale gas wastewater;(3)the accumulation of toxic and radioactive elements in soil or stream sediments near disposal or spill sites; and(4)the over extraction of water resources for high-volume hydraulic fracturing that could induce water shortages or conflicts with other water users,particularly in water-scarce areas. Analysis of published data(through January 2014)reveals evidence for stray gas contamination,surface water impacts in areas of intensive shale gas development,and the accumulation of radium isotopes in some disposal and spill sites. The direct contamination of shallow groundwater from hydraulic fracturing fluids and deep formation waters by hydraulic fracturing itself,however,remains controversial.

Keywords: potential contaminant pathways; disinfection by-products; southern high-plains; natural-gas; marcellus shale; drinking-water;waste-water; sedimentary basin; barnett shale; methane contamination

來源出版物:Environmental Science & Technology,2014,48(15): 8334-8348聯系郵箱:Vengosh,A; vengosh@duke.edu

Life Cycle Greenhouse Gas Emissions and Freshwater Consumption of Marcellus Shale Gas

Laurenzi,Ian J; Jersey,Gilbert R

Abstract: We present results of a life cycle assessment(LCA)of Marcellus shale gas used for power generation. The analysis employs the most extensive data set of any LCA of shale gas to date,encompassing data from actual gas production and power generation operations. Results indicate that a typical Marcellus gas life cycle yields 466 kg CO2eq/MWh(80% confidence interval: 450-567 kg CO2eq/MWh)of greenhouse gas(GHG)emissions and 224 gal/MWh(80% CI: 185-305 gal/MWh)of freshwater consumption. Operations associated with hydraulic fracturing constitute only 1.2% of the life cycle GHG emissions,and 6.2% of the life cycle freshwater consumption. These results are influenced most strongly by the estimated ultimate recovery(EUR)of the well and the power plant efficiency: increase in either quantity will reduce both life cycle freshwater consumption and GHG emissions relative to power generated at the plant. We conclude by comparing the life cycle impacts of Marcellus gas and U.S. coal: The carbon footprint of Marcellus gas is 53%(80% CI: 44-61%)lower than coal,and its freshwater consumption is about 50% of coal. We conclude that substantial GHG reductions and freshwater savings may result from the replacement of coal-fired power generation with gas-fired power generation.

Keywords: natural-gas; footprint; coal

來源出版物:Environmental Science & Technology,2013,47(9): 4896-4903

聯系郵箱:Laurenzi,Ian J; ian.j.laurenzi@exxonmobil.com

Natural gas from shale formation-The evolution,evidences and challenges of shale gas revolution in United States

Wang,Qiang; Chen,Xi; Jha,Awadhesh N; et al.

Abstract: Extraction of natural gas from shale rock in the United States(US)is one of the landmark events in the 21st century. The combination of horizontal drilling and hydraulic fracturing can extract huge quantities of natural gas from impermeable shale formations,which were previously thought to be either impossible or uneconomic to produce. This review offers a comprehensive insight into US shale gas opportunities,appraising the evolution,evidence and the challenges of shale gas production in the US. The history of US shale gas in this article is divided into three periods and based on the change of oil price(i.e.,the period before the 1970s oil crisis,the period from 1970s to 2000,and the period since 2000),the US has moved from being one of the world's biggest importers of gas to being self-sufficient in less than a decade,with the shale gas production increasing 12-fold(from 2000 to 2010). The US domestic natural gas price hit a 10-year low in 2012. The US domestic natural gas price in the first half of 2012 was about $2 per million British Thermal Unit(BTU),compared with Brent crude,the world benchmark price for oil,now about $80-100/barrel,or $14-17 per million BTU. Partly due to an increase in gas-fired power generation in response to low gas prices,US carbon emissions from fossil-fuel combustion fell by 430 million ton CO2-more than any other country-between 2006 and 2011. Shale gas also stimulated economic growth,creating 600000 new jobs in the US by 2010. However,the US shale gas revolution would be curbed,if the environmental risks posed by hydraulic fracturing are not managed effectively. The hydraulic fracturing is water intensive,and can cause pollution in the marine environment,with implications for long-term environmental sustainability in several ways. Also,large amounts of methane,a powerful greenhouse gas,can be emitted during the shale gas exploration and production. Hydraulic fracturing also may induce earthquakes. These environmental risks need to be managed by good practices which is not being applied by all the producers in all the locations. Enforcing stronger regulations are necessary to minimize risk to the environment and on human health. Robust regulatory oversight can however increase the cost of extraction,but stringent regulations can foster an historic opportunity to provide cheaper and cleaner gas to meet the consumer demand,as well as to usher in the future growth of the industry.

Keywords: Natural gas from shale formation; Energy revolution; Environmental challenge; Best practices; US shale gas

來源出版物:Renewable & Sustainable Energy Reviews,2014,30: 1-28聯系郵箱:Wang,Qiang; qiangwang7@gmail.com

Water resource impacts during unconventional shale gas development: The Pennsylvania experience

Brantley,Susan L; Yoxtheimer,Dave ; Arjmand,Sina; et al.

Abstract: Improvements in horizontal drilling and hydrofracturing have revolutionized the energy landscape by allowing the development of so-called “unconventional” gas resources. The Marcellus play in the northeastern U.S.A. documents how fast this technology developed: the number of unconventional Marcellus wells in Pennsylvania(PA)increased from 8 in 2005 to similar to 7234 today. Publicly available databases in PA show only rare evidence of contamination of surface and groundwaters. This could document that incidents that impact PA waters have been relatively rare and that contaminants were quickly diluted. However,firm conclusions are hampered by i)the lack of information about location and timing of incidents; ii)the tendency to not release water quality data related to specific incidents due to liability or confidentiality agreements; iii)the sparseness of sample and sensor data for the analytes of interest; iv)the presence of pre-existing water impairments that make it difficult to determine potential impacts from shale-gas activity; and v)the fact that sensors can malfunction or drift. Although the monitoring data available to assess contamination events in PA are limited,the state manages an online database of violations. Overall,one fifth of gas wells drilled were given at least one non-administrative notice of violation(NOV)from thePA regulator. Through March 2013,3.4% of gas wells were issued NOVs for well construction issues and 0.24% of gas wells received NOVs related to methane migration into groundwater. Between 2008 and 2012,161 of the similar to 1000 complaints received by the state described contamination that implicated oil or gas activity: natural gas was reported for 56% and brine salt components for 14% of the properties. Six percent of the properties were impacted by sediments,turbidity,and/or drill cuttings. Most of the sites of groundwater contamination with methane and/or salt components were in previously glaciated northern PA where fracture flow sometimes allows long distance fluid transport. No cases of subsurface transport of fracking or flow back fluids into water supplies were documented. If Marcellus-related flowback/production waters did enter surface or groundwaters,the most likely contaminants to be detected would be Na,Ca,and Cl,but those elements are already common in natural waters. The most Marcellus-specific "fingerprint" elements are Sr,Ba,and Br. For example,variable Br concentrations measured in southwestern PA streams were attributed to permitted release of wastewaters from unconventional shale gas wells into PA streams through municipal or industrial wastewater treatment plants before 2011. Discharge has now been discontinued except for brines from a few plants still permitted to discharge conventional oil/gas brines after treatment. Overall,drinking water supply problems determined by the regulator to implicate oil/gas activities peaked in frequency in 2010 while spill rates increased through 2012. Although many minor violations and temporary problems have been reported,the picture that emerges from PA is that the fast shale-gas start may have led to relatively few environmental incidents of significant impact compared to wells drilled; however,the impacts remain difficult to assess due to the lack of transparent and accessible data.

Keywords: Unconventional shale gas; Environmental impact; Hydraulic fracturing; Hydrofracturing; Water quality; Marcellus Shale

來源出版物:International Journal of Coal Geology,2014,126(S1): 140-156

Molecular simulation of shale gas adsorption and diffusion in inorganic nanopores

Sharma,Aman; Namsani,Sadanandam; Singh,Jayant K

Abstract: We studied the structural and dynamical properties of methane and ethane in montmorillonite(MMT)slit pore of sizes 10,20 and 30 angstrom using grand canonical Monte Carlo and classical molecular dynamics(MD)simulations. The isotherm,at 298.15 K,is generated for pressures up to 60 bar. The molecules preferentially adsorb at the surface as indicated by the density profile. In case of methane,we observe only a single layer,at the pore wall,whose density increases with increasing pressure. However,ethane also displays a second layer,though of low density in case of pore widths 20 and 30 angstrom. In-plane self-diffusion coefficient,DII,of methane and ethane is of the order of 10-6m2/s. At low pressure,DIIincreases significantly with the pore size. However,DIIdecreases rapidly with increasing pressure. Furthermore,the effect of pore size on DIIdiminishes at high pressure. Ideal adsorbed solution theory is used to understand the adsorption behaviour of the binary mixture of methane(80%)and ethane(20%)at 298.15 K. Furthermore,we calculate the selectivity of the gases at various pressures of the mixture,and found high selectivity for ethane in MMT pores. However,selectivity of ethane decreases with increase in pressure or pore size.

Keywords: methane; shale gas; GCMC; ethane; montmorillonite

來源出版物:Molecular Simulationk,2015,41(5-6): 414-422聯系郵箱:Singh,Jayant K; jayantks@iitk.ac.in

Study on gas flow through nano pores of shale gas reservoirs

Guo,Chaohua; Xu,Jianchun; Wu,Keliu; et al.

Abstract: Unlike conventional gas reservoirs,gas flow in shale reservoirs is a complex and multiscale flow process which has special flow mechanisms. Shale gas reservoirs contain a large fraction of nano pores,which leads to an apparent permeability that is dependent on pore pressure,fluid type,and pore structure. Study of gas flow in nano pores is essential for accurate numerical simulation of shale gas reservoirs. However,no comprehensive study has been conducted pertaining to the gas flow in nano pores. In this paper,experiments for nitrogen flow through nano membranes(with pore throat size: 20 nm,55 nm,and 100 nm)have been done and analyzed. Obvious discrepancy between apparent permeability and intrinsic permeability has been observed; and the relationship between this discrepancy and pore throat diameter(PTD)has been analyzed. Then,based on the advection-diffusion model,a new mathematical model has been constructed to characterize gas flow in nano pores. A new apparent permeability expression has been derived based on advection and Knudsen diffusion. A comprehensive coefficient for characterizing the flow process was proposed. Simulation results were verified against the experimental data for gas flow through nano membranes and published data. By changing the comprehensive coefficient,we found the best candidate for the case of argon with a membrane PTD of 235 nm. We verified the model using experimental data with different gases(oxygen,argon)and different PTDs(235 nm,220 nm). The comparison shows that the new model matches the experimental data very closely. Additionally,we compared our results with experimental data,the Knudsen/Hagen-Poiseuille analytical solution,and existing models available in the literature. Results show that the model proposed in this study yielded a more reliable solution. Shale gas simulations,in which gas flowing in nano pores plays a critical role,can be made more accurate and reliable based on the results of this work.

Keywords: Shale gas; Nano pores; Apparent permeability; Advection-diffusion model; Knudsen diffusion

來源出版物:Fuel,2015,143: 107-117聯系郵箱:wei,mingzhen; weim@mst.edu

編輯:衛夏雯

The first commercial United States natural gas production(1821)came from an organic-rich Devonian shale in the Appalachian basin. Understanding the geological and geochemical nature of organic shale formations and improving their gas producibility have subsequently been the challenge of millions of dollars worth of research since the 1970s. Shale-gas systems essentially are continuous-type biogenic(predominant),thermogenic,or combined biogenic-thermogenic gas accumulations characterized by widespread gas saturation,subtle trapping mechanisms,seals of variable lithology,and relatively short hydrocarbon migration distances. Shale gas may be stored as free gas in natural fractures and intergranular porosity,as gas sorbed onto kerogen and clay-particle surfaces,or as gas dissolved in kerogen and bitumen. Five United States shale formations that presently produce gas commercially exhibit an unexpectedly wide variation in the values of five key parameters: thermal maturity(expressed as vitrinite reflectance),sorbed-gas fraction,reservoir thickness,total organic carbon content,and volume of gas in place. The degree of natural fracture development in an otherwise low-matrix-permeability shale reservoir is a controlling factor in gas producibility. To date,unstimulated commercial production has been achievable in only a small proportion of shale wells,those that intercept natural fracture networks. In most other cases,a successful shale-gas well requires hydraulic stimulation. Together,the Devonian Antrim Shale of the Michigan basin and Devonian Ohio Shale of the Appalachian basin accounted for about 84% of the total 380 bcf of shale gas produced in 1999. However annual gas production is steadily increasing from three other major organic shale formations that subsequently have been explored and developed: the Devonian New Albany Shalein the Illinois basin,the Mississippian Barnett Shale in the Fort Worth basin,and the Cretaceous Lewis Shale in the San Juan basin. In the basins for which estimates have been made,shale-gas resources are substantial,with in-place volumes of 497-783 tcf. The estimated technically recoverable resource(exclusive of the Lewis Shale)ranges from 31 to 76 tcf. In both cases,the Ohio Shale accounts for the largest share.

fractured sandstone; liquid permeability; gas permeability; laboratory study

高影響力文章

文章題目第一作者來源出版物1Fractured shale-gas systemsCurtis JBAAPG Bulletin,2002,86(11): 1921-1938 2 Mississippian Barnett Shale,Fort Worth basin,north-central texas: Gas-shale play with multi-trillion cubic foot potential Montgomery SL AAPG Bulletin,2005,89(2): 155-175 3 Unconventional shale-gas systems: The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment Jarvie DMAAPG Bulletin,2007,91(4): 475-499 4 Shale gas potential of the Lower Jurassic Gordondale Member,Bulletin of Canadian Petroleum Geology,northeastern British Columbia,Canada Ross DJK 2007,55(1): 51-75 5 Characterizing the shale gas resource potential of Devonian-Mississippian strata in the Western Canada sedimentary basin: Application of an integrated formation evaluation Ross DJKAAPG Bulletin,2008,92(1): 87-125

Fractured shale-gas systems

JB Curtis

*摘編自《石油學報》2012年33卷 增刊1:107~114頁

*摘編自《石油勘探與開發》2010年37卷6期:641~653頁

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