Bakken低孔低渗页岩油藏之勘探与开发

1、一、概况Bakken页岩位于Williston盆地，面积约51.8万平方公里，横跨美国和加拿大，在美国北达科他州、蒙大拿州和加拿大的马尼托巴省、萨斯喀彻温省均有分布（图一）。据美国地质调查局于2008年估计，Bakken页岩的原始地质储量为3000亿桶，可采储量为36.5亿桶的原油外加1.85 TCFG的溶解气。  图一 Williston盆地和Bakken页岩位置图Williston盆地是美国陆上最大的内克拉通沉积盆地。该盆地的形状呈半圆形，盆地内主要构造有Nesson背斜、Billings背斜和Cedar Creek等背斜。从寒武纪到第四纪该盆地均接受沉积，盆地的最大沉

2、积厚度大于4573米（15000英尺）。该盆地的油气勘探开发活动从1953年Antelope油田的发现而开始。Bakken页岩为Williston盆地重要的烃源岩。在Williston盆地，Bakken地层的最大厚度约为44米（145英尺），属上泥盆系到下密西西比系沉积；从下到上可以划分为三个段：下Bakken段；中Bakken岩性多变段；上Bakken页岩段（图二）。上、下Bakken页岩段在整个盆地岩性比较均一，由灰黑色、坚硬的、含硅质和钙质及黄铁矿的黑色 有机质、粘土、泥粒大小的石英颗粒和部分方解石及白云石组成，有机质含量丰富，为Bakken页岩的烃源岩。但在上Bakken段中，缺少灰岩

3、和绿灰色泥岩小层。中Bakken段在垂向上岩性多变，由泥质白云岩或灰岩及砂岩组成。 图二 Bakken及其邻近地层的地层柱状图二、勘探开发历程 Stanolind石油公司于1953年在北达科他州Antelope油田的Woodrow Starr 1号井在Bakken层中发现石油，这口井本来打算开发Madison地层，但是在目的层中没有发现油气。该井在Bakken页岩层中的初始产量为536桶每天，基本不含水。但随后对Bakken层的滚动勘探却不甚成功，到1956年，Northern Pump公司的Ella Many Ribs 1号井才又在Bakken层发现石油，产量为320桶每

4、天。Antelope油田的主要钻井活动集中在上世纪50年代到60年代之间，该油田的完井层段主要为Bakken页岩层及其下伏的Sanish砂岩层。Antelope油田早期井采用盐基泥浆钻井，后来为了防止上覆Madison层盐类溶解造成的套管损坏而采用油基泥浆；典型的完井方式是先射孔，然后使用油加砂的压裂增产措施。自然裂缝对Antelope油田开发的成功起到很重要的作用。截止到2011年5月份，Antelope油田在Sanish地层中的累积产油量为1397万桶，天然气累积产量超过13 .4 BCFG。（数据来源：/oilgas/feeservices/fi

5、eldprodinj.asp ）但是，在Antelope油田成功开发后，对Bakken页岩的勘探进展缓慢，这种致密的低渗页岩需要自然裂缝才能投产。壳牌公司与1961年使用地震方法，在现在称之为“Bakken河道区(Bakken Fairway)”发现了Elkhorn Ranch油田，发现井为#41X-5-1 Government井，该井的试油产量为136桶每天。但是，壳牌公司这口井位于边远地区，在气候不好时经常需要关井，在1964年的平均产量为50桶每天；该井由于套管损坏而于1964年封堵并放弃。1976年，Pan American石油公司的#I B.E. Hove井在Hoffund油田的Ba

6、kken层中发现石油，试井的产油量为756桶每天，产水量为3桶每天。该井在1969年由于套管损坏而被封堵。接下来对Bakken页岩的勘探主要集中在Bakken河道区。该区的地层表现为上超沉积，Bakken页岩覆盖在Three Forks地层上，而以碳酸岩为主的Lodgepole地层又覆盖在Bakken页岩上。在这一时期，成功的生产井都钻遇自然裂缝，没有钻遇自然裂缝的井都不太成功。由于Bakken页岩的润湿性为油湿，所以成功的勘探开发井都以油基泥浆进行钻井。从1953年到1987年，Bakken页岩都是以直井进行勘探开发。从直井的生产历史的递减曲线上看，单井生产一年后，产量急剧下降，然后是基本没

7、有递减的稳定生产。三、地层与沉积 图三、Williston盆地Bakken地层剖面示意图，四、构造演化五、储层表征六、开发技术七、结论1. Continental Resources Reports Successful Two-Reservoir Test in North Dakota Bakken Shale Play (2010)2. Bakken Shale (2008)3. Surface microseismic monitoring of hydraulic fracture stimulations, Bakken Formation

8、(2009)9. Bakken shale_ North Dakota Geological Survey10. Seismic anisotropy - geological causes and its implications to reservoir geophysics (PhD) (2009)11. Improving well productivity and profitability in the Bakken (spe110679) (2007)13. State North Dakota Bakken Formation resou

9、rce study project (2008)14. State of North Dakota Probable (2P50) Oil Reserves Project (2006)15. Bakken Tricks Work on Three Forks (2011)17. Williston Basin and Paris Basin, same hydrodynamics, same potential for unconventional resources (2010)18. Spatial variation of Bakken or L

10、odgepole oils in the Canadian Williston Basin (2009)19. Determination of recovery factor in the Bakken Formation (SPE133719) (2009)20. The North Dakota Bakken (2007) 21. Technicak evaluation of resource plays(2009)22. Unconventional resource play evaluation - A look at the B

11、akken shale (SPE114171) (2008)23. Petroleum geology of the Parshall Field area, Mountrail County, North Dakota (2009)27. Bakken Success Beckons Players (2008)28. Unconventionally conventional - facies and sequence stratigraphy . Bakken Formation reservoir (2010)29. Bakken Shale p

12、lay_ map (2010) 31. Gas Potential Of Seclected Shale Formations In The WCSB (2004)32. Introduction and Early History of the Bakken Play in Montana33. Integrated analysis of the Bakken Petroleum sysytem (2006)34. Bakken Shale Formation Oil - North Dakota and Montana - USGS (2

13、008)35. From source to trap - a review of the Bakken petroleum system(2007)36. Middle Bakken Play technical problems and questions (2005)37. Bakken has huge reserves potential (2008)38. North Dakota vs. Montana - a tale of two Bakkens (2007)39. Bitumen filled fractures in th

14、e Bakken Formation (2010)40. Gas generation and retention in the Bakken shale, Williston Basin (2008)41. Bakken-Madison petroleum systems in the Canadian Williston Basin Part 3 (2002)42. Bakken-Madison petroleum systems in the Canadian Williston Basin Part 4 (2002)43. Bakken sour

15、ced oils in the Madison pools, new insights on the Weyburn Midale field (2000)44. Bakken-Madison petroleum systems in the Canadian Williston Basin Part 2 (2001)45. Williston Basin petroleum conference discovery of Parshall Field (2010)46. Horizontal well stimulation applications in th

16、e Bakken (2007)47. Hydrocarbon potential of the Bakken and Torquay Formations (2005)48. New prospectives on the hydrocarbon potential of Bakken and Torquay Formations (2005)49. Hydrocarbon potential of Bakken and Torquay Formations, southeastern Saskatchewan (2006)50. Bakken tigh

17、t oil - update and challenges (2010)51. Bakken horizontal best practice review (2005)52. Bakken Reserve Estimates (2006) 55. Bakken Middle Member A Core Workshop (2004)56. The potential for horizontally drilling the middle member of the Bakken Formation (2004)57. North

18、Dakota Middle member Bakken Horizontal play (2005)58. Williston Basin correlation cross-section - Bakken Formation (2005)59. Oil production from the Bakken Formation - a short history (2006)60. Evolution of oil production in the Bakken Formation (2007)61. Bakken Formation middle

19、member lithofacies & CBF (2007)62. Bakken Shale_ Rock Eval data (2008)65. LeFever, 200x Montana - North Dakota - Middle member Bakken Play ()66. LeFever, 200x. Horizontal drilling potential of the middle member Bakken ()67. LeFever, 200x. Hydrocarbon potential of the Bakken F

20、ormation, N Dakota ()68. Lefever, 200x. Overview of Bakken stratigraphy and mini-core workshop (RMS-PTTC Workshop) ()69. LeFever, 200x. Overview of Bakken Stratigraphy and Mini-Core Workshop ()70. The North Dakota Bakken Play Observations (2006)71. Bakken-Madison petroleum system

21、s in the Canadian Williston Basin_ Part 1 (2001)72. Seismic and rockphysics diagnostics of multiscale reservoir textures (2004)73. State of North Dakota 1P90 oil reserves project (2006)74. Computer Simulation of Hydrocarbon Generation, Migration, and Accumulation (2005)75. The su

22、ccessful aplication of a compartmental completion technique . Bakken Shale (SPE116469) (2008)76. Unlocking tight oil - selective multi-stage Bakken Shale (SPE116105) (2008)77. Three dimensional reservoir characterization of the Bakken geologic system (2008)79. Organic geochemical patt

23、erns in the Bakken Source system (2009)80. Time-temperature index of the Bakken Formation in North Dakota (2008)81. Nordeng, 200x. The Bakken source system - Emphasis on the Three Forks Formation ()82. A brief history of oil production from the Bakken Formation in the Williston Basin

24、(2010)83. Oil generation rates and subtle structural flexure (2010)84. Structural transect of the Sanish and Parshall fields, Bakken Formation, N Dakota_ Sheet 1 map (2010)85. The Bakken, A Question of Maturity (2006)86. Williston Three Forks-Sanish interval tapped (2008)87. 

25、;Bakken, Barnett, Manitoba fuel EOGs liquids binge_ Williston Basin (2009)88. Continental Resources slows Bakken program (2009)89. Montana's Elm Coulee to top 200 million bbl (2009)90. OGJ Newsletter - Plains to build Bakken north crude pipeline (2010)92. Brigham's Bakken

26、 operation accelerating (2011)94. Stimulation results and completion implications from the consortium (spe124686) (2009)96. A case study in the Bakken Formation - changes to hydraulic fracture (SPE108045) (2007)97. Diagenesis and fracture development in the Bakken Formation, williston

27、 Basin (2001)98. Assessment of Undiscovered Technically Recoverable Oil and Gas Resources, Part 1 (2008)100. Assessment of Undiscovered Technically Recoverable Oil and Gas Resources, Part 3 (2008)101. North Dakota and the Bakken shale rig fleet profile (2010)104. Bakken Shale - P

28、atchwork of prospectivity (2007)105. Formation resistivity as an indicator of oil generation - Bakken Formation (1990)106. New chemical EOR process for Bakken Shale (2010)108. Basin margin gas is worthy target in Williston basin (2000)109. Petroleum geology of the giant Elm Coule

29、e field, Williston Basin (2009)110. Abnormal pressure analysis in the Bakken Formation, Williston Basin (2010)111. Petroleum geology of the giant Elm Coulee Field, Williston Basin (2010)112. Quantitative mineralogy and microfractures in the Middle Bakken Formation, williston Basin (20

30、10)113. Bakken Shale Evolution of a Giant Oil Field (2011)114. Role of natural fracturing in production from thew Bakken Formation, Williston Basin (2009)115. Evaluating the performance of hydraulically fractured horizontal wells in the Bakken Shale (SPE122570) (2009)116. The Bakken Formation How Much Will It Help (2008)117. AADE Mid Continent Chapter - Bakken Shale resource play (2009)118. Three Forks-Sanish Field - Bakken Shal