沁水盆地南部煤岩储层天然裂缝有效性及对煤层气开发的影响

doi:10.11743/ogg20200317

摘要/Abstract

摘要： 沁水盆地南部煤岩储层天然裂缝普遍发育，天然裂缝有效性是决定煤岩储层渗流能力、影响煤层气井能否高产的重要因素。综合利用野外露头、岩心和扫描电镜等资料，在分析沁水盆地南部上古生界煤岩储层天然裂缝类型和发育特征的基础上，对裂缝有效性及其主控因素开展研究，并结合单井生产动态资料，探讨了裂缝有效性对煤层气开发的影响。结果表明：沁水盆地南部煤岩储层主要发育割理和构造裂缝，其中割理包括面割理和端割理，构造裂缝包括剪切裂缝和张性裂缝。受多种地质因素影响，不同类型裂缝的有效性存在明显差异。割理形成于煤化作用阶段，多被方解石和粘土矿物等全充填或半充填，整体上其裂缝有效性较差。构造裂缝多未被矿物充填，其有效性主要受控于裂缝规模、倾角、储层埋深及与现今地应力最大主应力方向夹角。构造裂缝开度大、延伸较远，裂缝有效性好；高角度构造裂缝有效性好于斜交缝；受地应力状态变化影响，随储层埋深的增加，裂缝有效性依次表现为较差、较好、较差；NE-SW向裂缝有效性最好，其次为近EW向和近NS向裂缝，NW-SE向裂缝有效性最差。相比于割理，构造裂缝在规模和裂缝有效性方面均好于前者，可作为煤层主要的渗流和产出通道，对煤层气的开发具有明显积极作用。然而，过大规模尺度的构造裂缝，尤其当构造裂缝穿过煤层在顶底板发育时，不仅会造成煤岩储层内煤层气散失和储层压力降低，同时还将导致外来地层水对煤层的补充，不利于煤层气的保存和有效开采。

关键词: 天然裂缝, 有效性, 煤岩储层, 煤层气开发, 上古生界, 沁水盆地

Abstract: Natural fractures were well developed in coalbed mathane (CBM) reservoirs in the southern Qinshui Basin,and their effectiveness is an important factor affecting the seepage ability of CBM reservoirs and the high production of CBM wells.In this study,the types and development characteristics of natural fractures in the Upper Paleozoic CBM re-servoirs,southern Qinshui Basin,are investigated by using outcrop,core and scanning electron microscopy (SEM) data.Then,the fracture effectiveness and its main controlling factors are analyzed.Finally,the influence of effective fractures on CBM development is discussed in combination with single-well dynamic production performance.The results show that cleats and tectonic fractures were mainly developed in the study area.The cleats include face and butt cleats,and the tectonic fractures include shear and tension fractures.There are marked differences in the fracture effectiveness of various types under the influence of multiple geological factors.The cleats were formed at the stage of coalification and mostly filled or semi-filled by calcites and clay minerals,resulting in poor effectiveness of fractures.Most tectonic fractures were not filled with minerals,and their effectiveness is mainly controlled by fracture size,dip angle,reservoir depth and their included angle with the direction of the in-situ maximum principal stress at present.The tectonic fractures feature large aperture,longer propagation and good fracture effectiveness.High-angle tectonic fractures are more effective than oblique fractures.Affected by the change of in-situ stress state,the fracture effectiveness varies systematically with the increasing burial depth,i.e.,from fair to good and then fair again.The NE-SW-trending fractures are the most effective,followed by nearly EW-trending and nearly NS-trending fractures,and the NW-SE-trending fractures coming at last.The tectonic fractures,better in terms of both scale and fracture effectiveness compared with the cleats,are the main seepage and production channels of coalbeds,and play a positive role in the CBM development.However,over-sized tectonic fractures,especially when cutting through the coal seam and extending into the roof and floor,will result in the loss of CBM,the decrease of reservoir pressure,and the incursion of external formation water.Therefore,it is not conducive to the preservation and effective exploitation of CBM.

Key words: natural fracture, effectiveness, CBM reservoir, CBM development, Upper Paleozoic, Qinshui Basin

中图分类号:

TE122.2

史今雄,曾联波,谭青松,等. 沁水盆地南部煤岩储层天然裂缝有效性及对煤层气开发的影响[J]. 石油与天然气地质, 2020, 41(3): 617-626. doi: 10.11743/ogg20200317 Shi Jinxiong,Zeng Lianbo,Tan Qingsong,et al. Effectiveness of natural fractures in CBM reservoirs and its influence on CBM development in the southern Qinshui Basin[J]. Oil & Gas Geology, 2020, 41(3): 617-626. doi: 10.11743/ogg20200317

参考文献

[1] 刘成林,朱杰,车长波,等.新一轮全国煤层气资源评价方法与结果[J].天然气工业,2009,29(11):130-132. Liu Chenglin,Zhu Jie,Che Changbo,et al.Methodologies and results of the latest assessment of coalbed methane resources in China[J].Natural Gas Industry,2009,29(11):130-132.
[2] 马平华,邵先杰,霍梦颖,等.煤储层地质建模思路与方法——以鄂尔多斯盆地东南缘韩城矿区为例[J].石油与天然气地质,2018,39(3):601-610. Ma Pinghua,Shao Xianjie,Huo Mengying,et al.Concepts and methods for coalbed geology modeling:A case study in the Hancheng mining area,Southeastern margin of Ordos Basin[J].Oil & Gas Geology,2018,39(3):601-610.
[3] 王勃,姚红星,王红娜,等.沁水盆地成庄区块煤层气成藏优势及富集高产主控地质因素[J].石油与天然气地质,2018,39(2):366-372. Wang Bo,Yao Hongxing,Wang Hongna,et al.Favorable and major geological controlling factors for coalbed methane accumulation and high production in the Chengzhuang Block,Qinshui Basin[J].Oil & Gas Geology,2018,39(2):366-372.
[4] 康永尚,孙良忠,张兵,等.中国煤储层渗透率主控因素和煤层气开发对策[J].地质论评,2017,63(5):1401-1418. Kang Yongshang,Sun Liangzhong,Zhang Bing,et al.The controlling factors of coalbed reservoir permeability and CBM development strategy in China[J].Geological Review,2017,63(5):1401-1418.
[5] 陈振宏,贾承造,宋岩,等.高、低煤阶煤层气藏物性差异及其成因[J].石油学报,2008,29(2):179-184. Chen Zhenhong,Jia Chengzao,Song Yan,et al.Differences and origin of physical properties of low-rank and high-rank coal-bed methanes[J].Acta Petrolei Sinica,2008,29(2):179-184.
[6] 刘大锰,李振涛,蔡益栋,等.煤储层孔裂隙非均质性及其地质影响因素研究进展[J].煤炭科学技术,2015,43(2):10-15. Liu Dameng,Li Zhentao,Cai Yidong,et al.Study progress on pore crack heterogeneity and geological influence factors of coal reservoir[J].Coal Science and Technology,2015,43(2):10-15.
[7] 苏现波,张丽萍,林晓英.煤阶对煤的吸附能力的影响[J].天然气工业,2005,25(1):19-21. Su Xianbo,Zhang Liping,Lin Xiaoying.Influence of coal rank on coal and sorption capacity[J].Natural Gas Industry,2005,25(1):19-21.
[8] Laubach S E,Marrett R A,Olson J E,et al.Characteristics and origins of coal cleat:A review[J].International Journal of Coal Geology,1998,35(1-4):175-207.
[9] 姚艳斌,刘大锰,黄文辉,等.两淮煤田煤储层孔-裂隙系统与煤层气产出性能研究[J].煤炭学报,2006,31(2):163-168. Yao Yanbin,Liu Dameng,Huang Wenhui,et al.Research on the pore-fractures system properties of coalbed methane reservoirs and recovery of coalbed methane in Huainan and Huaibei coal-field[J].Journal of Coal Society,2006,31(2):163-168.
[10] 王镜惠,梅明华,梁正中,等.沁水盆地南部高煤阶煤层气高产区定量评价[J].油气藏评价与开发,2019,9(4):68-72. Wang Jinghui,Mei Minghua,Liang Zhengzhong,et al.Quantitative evaluation of high production areas of CBM with high coal rank in southern Qinshui Basin[J].Reservoir Evaluation and Development,2019,9(4):68-72.
[11] 唐书恒.煤储层渗透性影响因素探讨[J].中国煤田地质,2001,13(1):28-30. Tang Shuheng.Probe into the influence factors on permeability of coal reservoirs[J].Coal Geology of China,2001,13(1):28-30.
[12] 傅雪海,秦勇,李贵中,等.山西沁水盆地中、南部煤储层渗透率影响因素[J].地质力学学报,2001,7(1):45-52. Fu Xuehai,Qin Yong,Li Guizhong,et al.An analysis of the principal control factor of coal reservoir permeability in central and southern Qinshui Basin,Shanxi[J].Journal of Geomechanics,2001,7(1):45-52.
[13] 丁文龙,梅永贵,尹帅,等.沁水盆地煤系地层孔-裂隙特征测井反演[J].煤炭科学技术,2015,43(2):53-56. Ding Wenlong,Mei Yonggui,Yin Shuai,et al.Logging inversion on pore-crack features of coal measure strata in Qinshui Basin[J].Coal Science and Technology,2015,43(2):53-56.
[14] 王生维,陈钟惠.煤储层孔隙、裂隙系统研究进展[J].地质科技情报,1995,4(1):53-59. Wang Shengwei,Chen Zhonghui.Advances in the research of pore fracture system in coal reservoir[J].Geological Science and Technology Information,1995,4(1):53-59.
[15] 刘大锰,李振涛,蔡益栋.煤储层孔-裂隙非均质性及其地质影响因素研究进展[J].煤炭科学技术,2015,43(2):10-15. Liu Dameng,Li Zhentao,Cai Yidong.Study progress on pore-crack heterogeneity and geological influence factors of coal reservoir[J].Coal Science and Technology,2015,43(2):10-15.
[16] 秦勇,张德民,傅雪海,等.山西沁水盆地中、南部现代构造应力场与煤储层物性关系之探讨[J].地质论评,1999,45(6):576-583. Qin Yong,Zhang Demin,Fu Xuehai,et al.A discussion on correlation of modern tectonic stress field to physical properties of coal reservoirs in central and southern Qinshui Basin[J].Geological Review,1999,45(6):576-583.
[17] 王镜惠,梅明华,梁正中,等.煤层气储层应力敏感性定量表征及影响因素研究[J].石油实验地质,2018,40(6):859-863. Wang Jinghui,Mei Minghua,Liang Zhengzhong,et al.Controls and quantitative characterization of stress sensitivity for coal seams[J].Petroleum Geology & Experiment,2018,40(6):859-863.
[18] Close J C.Natural Fractures in Coal[J].1993,180:119-132.
[19] Liu S Q,Sang S X,Liu HH,et al.Growth characteristics and genetic types of pores and fractures in a high-rank coal reservoir of the southern Qinshui Basin[J].Ore Geology Reviews,2015,64(1):140-151.
[20] 陈世达,汤达祯,陶树,等.沁南-郑庄区块深部煤层气"临界深度"探讨[J].煤炭学报,2016,41(12):3069-3075. Chen Shida,Tang Dazhen,Tao Shu,et al.Discussion about "critical depth" of deep coalbed methane in Zhengzhuang area,Qinshui Basin[J].Journal of China Coal Society,2016,41(12):3069-3075.
[21] 房璐,王硕,徐珂,等.山西沁水盆地现今地应力特征[J].断块油气田,2018,25(4):413-418. Fang Lu,Wang Shuo,Xu Ke,et al.Characteristics of current in-situ stress of Qinshui Basin[J].Fault-Block Oil and Gas Field,2018,25(4):413-418.
[22] Teng J,Yao Y B,Liu D M,et al.Evaluation of coal texture distributions in the southern Qinshui basin,North China:Investigation by a multiple geophysical logging method[J].International Journal of Coal Geology,2015,140:9-22.
[23] 陈振宏,王一兵,杨焦生,等.影响煤层气井产量的关键因素分析——以沁水盆地南部樊庄区块为例[J].石油学报,2009,30(3):409-412. Chen Zhenhong,Wang Yibing,Yang Jiaosheng,et al.Influencing factors on coalbed methane production of single well:a case of Fanzhuang block in the south part of Qinshui Basin[J].Acta Petrolei Sinica,2009,30(3):409-412.
[24] 孟召平,田永东,李国富.沁水盆地南部地应力场特征及其研究意义[J].煤炭学报,2010,35(6):975-981. Meng Zhaoping,Tian Yongdong,Li Guofu.Characteristics of in-situ stress field in Southern Qinghai Basin and its research significance[J].Journal of China Coal Society,2010,35(6):975-981.
[25] Su X B,Lin X Y,Liu S B,et al.Geology of coalbed methane reservoirs in the Southeast Qinshui Basin of China[J].International Journal of Coal Geology,2005,62(4):197-210.
[26] Su X B,Feng Y L,Chen J F,et al.The characteristics and origins of cleat in coal from Western North China[J].International Journal of Coal Geology,2001,47(1):51-62.
[27] Shi J X,Zeng L B,Dong S Q,et al.Identification of coal structures using geophysical logging data in Qinshui Basin,China:Investigation by kernel Fisher discriminant analysis[J].International Journal of Coal Geology,2020,217,103314.
[28] 曾联波,巩磊,祖克威,等.柴达木盆地西部古近系储层裂缝有效性的影响因素[J].地质学报,2012,86(11):1809-1814. Zeng Lianbo,Gong Lei,Zu Kewei,et al.Influence factors on fracture validity of the Paleogene reservoir,western Qaidam Basin[J].Acta Geologica Sinica,2012,86(11):1809-1814.
[29] 赵向原,胡向阳,曾联波,等.四川盆地元坝地区长兴组礁滩相储层天然裂缝有效性评价[J].天然气工业,2017,37(2):52-61. Zhao Xiangyuan,Hu Xiangyang,Zeng Lianbo,et al.Evaluation on the effectiveness of natural fractures in reef-flat facies reservoirs of Changxing Fm in Yuanba area,Sichuan Basin[J].Natural Gas Industry,2017,37(2):52-61.
[30] 张玉银.溶蚀作用对火山岩有效储层形成的控制作用——以松辽盆地徐家围子断陷营城组为例[J].石油与天然气地质,2018,39(3):587-593. Zhang Yuyin.Controlling effect of dissolution on valid volcanic reservoir formation:A case study of the Yingcheng Formation in the Xujiaweizi Fault Depression,Songliao Basin[J].Oil & Gas Geology,2018,39(3):587-593.
[31] 童亨茂,钱祥麟.储层裂缝的研究和分析方法[J].石油大学学报(自然科学版),1994,18(6):14-20. Tong Hengmao,Qian Xianglin.Research and analysis on natural fracture[J].Journal of the University of Petroleum,China(Edition of Natural Science),1994,18(6):14-20.
[32] Marrett R,Laubach SE,Olson J E.Anisotropy and beyond:Geologic perspectives on geophysical prospecting for natural fractures[J].The Leading Edge,2007,26(9):1106-1111.
[33] Bordet E,Malo M,Kirkwood D.A structural study of western Anticosti Island,St.Lawrence platform,Québec:A fracture analysis that integrates surface and subsurface structural data[J].Bulletin of Canadian Petroleum Geology,2010,58(1):36-55.
[34] 赵向原,胡向阳,肖开华,等.川西彭州地区雷口坡组碳酸盐岩储层裂缝特征及主控因素[J].石油与天然气地质,2018,39(1):30-39,152. Zhao Xiangyuan,Hu Xiangyang,Xiao Kaihua,et al.Characteristics and major control factors of natural fractures in carbonate reservoirs of Leikoupo Formation in Pengzhou area,western Sichuan Basin[J].Oil & Gas Geology,2018,39(1):30-39,152.
[35] 刘大锰,周三栋,蔡益栋,等.地应力对煤储层渗透性影响及其控制机理研究[J].煤炭科学技术,2017,45(6):1-8. Liu Dameng,Zhou Sandong,Cai Yidong,et al.Study on effect of geo-stress on coal permeability and its controlling mechanism[J].Coal Science and Technology,2017,45(6):1-8.
[36] Ju W,Jiang B,Miao Q,et al.Variation of in situ stress regime in coal reservoirs,eastern Yunnan region,South China:Implications for coalbed methane production[J].AAPG Bulletin,2018,102(11),2283-2303.
[37] Chen S D,Tang D Z,Tao S,et al.In-situ stress measurements and stress distribution characteristics of coal reservoirs in major coalfields in China:Implication for coalbed methane(CBM) development[J].International Journal of Coal Geology,2017,182:66-84.
[38] Shi J X,Zeng L B,Zhao X Y,et al.Characteristics of natural fractures in the upper Paleozoic coal bearing strata in the southern Qinshui Basin,China:Implications for coalbed methane(CBM) development[J].Marine and Petroleum Geology,2020,113,104152.
[39] Shen J,Qin Y,Li Y P,et al.In situ stress field in the FZ Block of Qinshui Basin,China:Implications for the permeability and coalbed methane production[J].Journal of Petroleum Science and Engineering,2018,170:744-754.
[40] Ju W,Jiang B,Qin Y,et al.The present-day in-situ stress field within coalbed methane reservoirs,Yuwang Block,Laochang Basin,South China[J].Marine and Petroleum Geology,2019,102:61-73.