海陆过渡相煤系页岩气成藏条件及储层特征——以四川盆地南部龙潭组为例
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摘要
结合扬子地区海陆过渡相煤系页岩分布与地质特征,以四川盆地南部二叠系龙潭组为例,采用有机碳、Rock-eval热解、显微组分定量、X射线衍射(XRD)、扫描电镜(SEM)、高压压汞、低温气体吸附等多种实验分析方法,对海陆过渡相煤系页岩气成藏条件及储层特征进行了研究。结果表明:海陆过渡相煤系页岩,累计厚度较大,多在100 m以上,而单层厚度较小,一般小于40 m,通常与煤层和致密砂岩甚至与灰岩互层。四川盆地南部海陆过渡相龙潭组煤系页岩有机碳含量较高(TOC含量为0.85%~35.70%,平均6.73%),有机质类型以腐殖型为主(干酪根碳同位素δ13C为-28.0‰~-23.5‰),有机质成熟度达高—过成熟阶段(Ro为1.95%~2.40%,平均2.22%);页岩中黏土矿物较为发育(20.3%~92.3%,平均61.9%),脆性矿物含量较低(6.3%~65.7%,平均27.7%),页岩储层可压裂性较海相页岩差。龙潭组煤系页岩孔隙度多大于3%,孔隙类型多样,常见粒间孔(含量占29.08%)和溶蚀孔(占30.18%),其次是有机质孔(占16.74%)和粒内孔(占10.56%),还有晶间孔(占4.94%)和微裂缝(占8.5%),为页岩气赋存提供了储集空间;页岩含气性较好,含气量主要介于1.0~3.0 m3/t。
Combined with the shale distribution and geological characteristics of marine-terrigenous facies coal measures in the Yangtze area,taking the Permian Longtan Formation in South Sichuan Basin as example,the authors investigated the accumulation conditions and the reservoir characteristics of marine-terrigenous facies coal measures shale gas using many experimental methods,such as organic carbon,Rock-eval pyrolysis,maceral identification,X-ray dif-fraction( XRD),scanning electron microscope( SEM),high pressure mercury injection,low temperature gas sorption,etc. The results show that the marine-terrigenous facies coal measures shale has the features of rapid vertical-lateral variation,huge cumulative thickness( mainly over 100 m),small individual thickness( generally < 40 m),and commonly accompanied with coal bed,limestone and tight sand. The marine-terrigenous facies coal measures shale from Longtan Formation in South Sichuan Basin,which featured with high organic matter abundance( TOC = 0. 85%-35. 70%,average 6. 73%),mainly with humic type organic matter( kerogen δ13C =-28. 0‰--23. 5‰),high-over thermal evolution level( Ro= 1. 95%-2. 4%,average 2. 22%),rich in clay minerals content( 20. 3%-92. 3%,average 61. 9%),and relatively low brittle minerals content( 6. 3%-65. 7%,average 27. 7%). The shale reservoir fracturing from Longtan Formation is worse than that of marine shale. The porosity of the Longtan Formation shale in South Sichuan Basin is mainly over 3%. Many types of pores were developed,including intergranular pore( 29.08%),dissolution pore( 30. 18%),organic pores( 16. 74%),intragranular( 10. 56%),inter-crystalline( 4. 94%)and microfracture( 8. 5%),which provide reservoir space for the accumulation of shale gas. Gas generation capability from the Longtan Formation shale is relatively better,and its main gas content can be 1. 0-3. 0 m3/ t.
Combined with the shale distribution and geological characteristics of marine-terrigenous facies coal measures in the Yangtze area,taking the Permian Longtan Formation in South Sichuan Basin as example,the authors investigated the accumulation conditions and the reservoir characteristics of marine-terrigenous facies coal measures shale gas using many experimental methods,such as organic carbon,Rock-eval pyrolysis,maceral identification,X-ray dif-fraction( XRD),scanning electron microscope( SEM),high pressure mercury injection,low temperature gas sorption,etc. The results show that the marine-terrigenous facies coal measures shale has the features of rapid vertical-lateral variation,huge cumulative thickness( mainly over 100 m),small individual thickness( generally < 40 m),and commonly accompanied with coal bed,limestone and tight sand. The marine-terrigenous facies coal measures shale from Longtan Formation in South Sichuan Basin,which featured with high organic matter abundance( TOC = 0. 85%-35. 70%,average 6. 73%),mainly with humic type organic matter( kerogen δ13C =-28. 0‰--23. 5‰),high-over thermal evolution level( Ro= 1. 95%-2. 4%,average 2. 22%),rich in clay minerals content( 20. 3%-92. 3%,average 61. 9%),and relatively low brittle minerals content( 6. 3%-65. 7%,average 27. 7%). The shale reservoir fracturing from Longtan Formation is worse than that of marine shale. The porosity of the Longtan Formation shale in South Sichuan Basin is mainly over 3%. Many types of pores were developed,including intergranular pore( 29.08%),dissolution pore( 30. 18%),organic pores( 16. 74%),intragranular( 10. 56%),inter-crystalline( 4. 94%)and microfracture( 8. 5%),which provide reservoir space for the accumulation of shale gas. Gas generation capability from the Longtan Formation shale is relatively better,and its main gas content can be 1. 0-3. 0 m3/ t.
引文
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[9]李贤庆,赵佩,孙杰,等.川南地区下古生界页岩气成藏条件研究[J].煤炭学报,2013,38(5):864-869.Li Xianqing,Zhao Pei,Sun Jie,et al.Study on the accumulation conditions of shale gas from the Lower Paleozoic in the south region of Sichuan Basin[J].Journal of China Coal Society,2013,38(5):864-869.
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[14]周东升,许林峰,潘继平,等.扬子地块上二叠统龙潭组页岩气勘探前景[J].天然气工业,2012,32(12):6-10.Zhou Dongsheng,Xu Linfeng,Pan Jiping,et al.Prospect of shale gas exploration in the Upper Permian Longtan Formation in the Yangtze Massif[J].Natural Gas Industry,2012,32(12):6-10.
[15]徐猛.湘东南坳陷上二叠统龙潭组页岩气研究[D].成都:成都理工大学,2013:40-49.
[16]李娟,于炳松,夏响华,等.黔西北地区上二叠统龙潭组泥页岩储层特征[J].地学前缘,2015,22(1):301-311.Li Juan,Yu Bingsong,Xia Xianghua,et al.The characteristics of the Upper Permian shale reservoir in the northwest of Guizhou Province,China[J].Earth Science Hrontiers,2015,22(1):301-311.
[17]梁狄刚,郭彤楼,陈建平,等.中国南方海相生烃成藏研究的若干新进展(二):南方四套区域性海相烃源岩的地球化学特征[J].海相油气地质,2009,14(1):1-15.Liang Digang,Guo Tonglou,Chen Jianping,et al.Geochemical characteristics of four suits of regional marine source rocks,Southern China(part 2)[J].Marine Petroleum Geology,2009,14(1):1-15.
[18]翟光明.中国石油地质志(卷10)[M].北京:石油工业出版社,1989:1-109.
[19]郭正吾,邓康龄,韩永辉.四川盆地形成演化[M].北京:地质出版社,1996:20-105.
[20]Rowe H D,Loucks R G,Ruppel S C,et al.Mississippian Barnett Formation,Fort Worth Basin,Texas:Bulk geochemical inferences and Mo-TOC constraints on the severity of hydrographic restriction[J].Chemical Geology,2008,257(1/2):16-25.
[21]Reed R M,Loucks R G.Imaging nanoscale pores in the Mississippian Barnett Shale of the northern Fort Worth Basin[J].AAPG Annual Convention Abstracts,2007,16:115.
[22]张吉振,李贤庆,刘洋,等.川南地区龙潭组页岩气成藏条件及有利区分析[J].中国煤炭地质,2014,26(12):1-6.Zhang Jizhen,Li Xianqing,Liu Yang,et al.Analysis on the accumulation conditions and favorable area of shale gas from Longtan Formation in the south region of Sichuan Basin[J].Coal Geology of China,2014,26(12):1-6.
[23]Loucks R C,Reed R M,Ruppel S C,et al.Morphology,genesis,and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett shale[J].Journal of Sedimentary Research,2009,79(12):848-861.
[24]Roger M S,Neal R B.Pore types in the Barnett and Woodford gas shales:Contribution to understanding gas storage and migration pathways in fine-grained rocks[J].AAPG Bulletin,2011,95(12):2017-2030.
[25]Martini A M,Walter I M,Ku T C W,et al.Microbial production and modification oi1 gases in sedimentary basins,A geochemical case study from a Devonian shale gas play,Michigan basin[J].AAPG Bulletin,2003,87(8):1355-1375.
[26]王中鹏,张金川,孙睿,等.西页1井龙潭组海陆过渡相页岩含气性分析[J].地学前缘,2015,22(2):243-250.Wang Zhongpeng,Zhang Jinchuan,Sun Rui,et al.The gas-bearing characteristics analysis of the Longtan Formation transitional shale in Well Xiye 1[J].Earth Science Frontiers,2015,22(2):243-250.
[27]孙全宏.黔西北地区龙潭组页岩气形成条件与分布预测[D].北京:中国地质大学(北京),2014:57-77.
[28]秦连杰.巢湖地区姚家山剖面龙潭组页岩气富集关键地质因素研究[D].徐州:中国矿业大学,2014:59-63.
[2]张大伟,李玉喜,张金川,等.全国页岩气资源潜力调查评价[M].北京:地质出版社,2012:1-138.
[3]张金川,姜生玲,唐玄,等.我国页岩气富集类型及资源特点[J].天然气工业,2009,29(12):109-114.Zhang Jinchuan,Jiang Shengling,Tang Xuan,et al.Accumulation types and resources characteristics of shale gas in China[J].Natural Gas Industry,2009,29(12):109-114.
[4]Curtis J B.Fractured shale-gas systems[J].AAPG Bulletin,2002,86(11):1921-1938.
[5]Jarvie D M,Hill R J,Ruble T E,et al.Unconventional shale-gas systems:The Mississippian Barnett Shale of north-central Texas as one model for thermogenic shale-gas assessment[J].AAPG Bulletin,2007,91(4):475-499.
[6]Bowker K A.Barnett shale gas production,Fort Worth basin:Issues and discussion[J].AAPG Bulletin,2007,91(4):523-533.
[7]张金川,金之钧,袁明生.页岩气成藏机理和分布[J].天然气工业,2004,24(7):15-18.Zhang Jinchuan,Jin Zhijun,Yuan Mingsheng.Reservoiring mechanism of shale gas and its distribution[J].Natural Gas Industry,2004,24(7):15-18.
[8]邹才能,董大忠,杨桦,等.中国页岩气形成条件及勘探实践[J].天然气工业,2011,31(12):26-39.Zou Caineng,Dong Dazhong,Yang Hua,et al.Conditions of shale gas accumulation and exploration practices in China[J].Natural Gas Industry,2011,31(12):26-39.
[9]李贤庆,赵佩,孙杰,等.川南地区下古生界页岩气成藏条件研究[J].煤炭学报,2013,38(5):864-869.Li Xianqing,Zhao Pei,Sun Jie,et al.Study on the accumulation conditions of shale gas from the Lower Paleozoic in the south region of Sichuan Basin[J].Journal of China Coal Society,2013,38(5):864-869.
[10]贾承造,郑民,张永峰.中国非常规油气资源与勘探开发前景[J].石油勘探与开发,2012,39(2):129-136.Jia Chengzao,Zheng Min,Zhang Yongfeng.Unconventional hydrocarbon resources in China and the prospect of exploration and development[J].Petroleum Exploration and Development,2012,39(2):129-136.
[11]郭彤楼,张汉荣.四川盆地焦石坝页岩气田形成与富集高产模式[J].石油勘探与开发,2014,41(1):28-36.Guo Tonglou,Zhang Hanrong.Formation and enrichment mode of Jiaoshiba shale gas field,Sichuan Basin[J].Petroleum Exploration and Development,2014,41(1):28-36.
[12]吴浩,姚素平,焦堃,等.下扬子区上二叠统龙潭组页岩气勘探前景[J].煤炭学报,2013,38(5):870-876.Wu Hao,Yao Suping,Jiao Kun,et al.Shale-gas exploration prospect of Longtan Formation in the Lower Yangtze area of China[J].Journal of China Coal Society,2013,38(5):870-876.
[13]陈宗清.论四川盆地二叠系乐平统龙潭组页岩气勘探[J].天然气技术与经济,2011,5(2):21-26.Chen Zongqing.Exploration for shale gas of Longtan member in Permian Leping Formation,Sichuan Basin[J].Natural Gas Technology and Economy,2011,5(2):21-26.
[14]周东升,许林峰,潘继平,等.扬子地块上二叠统龙潭组页岩气勘探前景[J].天然气工业,2012,32(12):6-10.Zhou Dongsheng,Xu Linfeng,Pan Jiping,et al.Prospect of shale gas exploration in the Upper Permian Longtan Formation in the Yangtze Massif[J].Natural Gas Industry,2012,32(12):6-10.
[15]徐猛.湘东南坳陷上二叠统龙潭组页岩气研究[D].成都:成都理工大学,2013:40-49.
[16]李娟,于炳松,夏响华,等.黔西北地区上二叠统龙潭组泥页岩储层特征[J].地学前缘,2015,22(1):301-311.Li Juan,Yu Bingsong,Xia Xianghua,et al.The characteristics of the Upper Permian shale reservoir in the northwest of Guizhou Province,China[J].Earth Science Hrontiers,2015,22(1):301-311.
[17]梁狄刚,郭彤楼,陈建平,等.中国南方海相生烃成藏研究的若干新进展(二):南方四套区域性海相烃源岩的地球化学特征[J].海相油气地质,2009,14(1):1-15.Liang Digang,Guo Tonglou,Chen Jianping,et al.Geochemical characteristics of four suits of regional marine source rocks,Southern China(part 2)[J].Marine Petroleum Geology,2009,14(1):1-15.
[18]翟光明.中国石油地质志(卷10)[M].北京:石油工业出版社,1989:1-109.
[19]郭正吾,邓康龄,韩永辉.四川盆地形成演化[M].北京:地质出版社,1996:20-105.
[20]Rowe H D,Loucks R G,Ruppel S C,et al.Mississippian Barnett Formation,Fort Worth Basin,Texas:Bulk geochemical inferences and Mo-TOC constraints on the severity of hydrographic restriction[J].Chemical Geology,2008,257(1/2):16-25.
[21]Reed R M,Loucks R G.Imaging nanoscale pores in the Mississippian Barnett Shale of the northern Fort Worth Basin[J].AAPG Annual Convention Abstracts,2007,16:115.
[22]张吉振,李贤庆,刘洋,等.川南地区龙潭组页岩气成藏条件及有利区分析[J].中国煤炭地质,2014,26(12):1-6.Zhang Jizhen,Li Xianqing,Liu Yang,et al.Analysis on the accumulation conditions and favorable area of shale gas from Longtan Formation in the south region of Sichuan Basin[J].Coal Geology of China,2014,26(12):1-6.
[23]Loucks R C,Reed R M,Ruppel S C,et al.Morphology,genesis,and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett shale[J].Journal of Sedimentary Research,2009,79(12):848-861.
[24]Roger M S,Neal R B.Pore types in the Barnett and Woodford gas shales:Contribution to understanding gas storage and migration pathways in fine-grained rocks[J].AAPG Bulletin,2011,95(12):2017-2030.
[25]Martini A M,Walter I M,Ku T C W,et al.Microbial production and modification oi1 gases in sedimentary basins,A geochemical case study from a Devonian shale gas play,Michigan basin[J].AAPG Bulletin,2003,87(8):1355-1375.
[26]王中鹏,张金川,孙睿,等.西页1井龙潭组海陆过渡相页岩含气性分析[J].地学前缘,2015,22(2):243-250.Wang Zhongpeng,Zhang Jinchuan,Sun Rui,et al.The gas-bearing characteristics analysis of the Longtan Formation transitional shale in Well Xiye 1[J].Earth Science Frontiers,2015,22(2):243-250.
[27]孙全宏.黔西北地区龙潭组页岩气形成条件与分布预测[D].北京:中国地质大学(北京),2014:57-77.
[28]秦连杰.巢湖地区姚家山剖面龙潭组页岩气富集关键地质因素研究[D].徐州:中国矿业大学,2014:59-63.