沁水盆地煤层地应力模型及压裂裂缝形态预测方法
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摘要
以沁水盆地煤层气井为研究目标,通过压后压力降落曲线求取目标煤层的闭合压力,并结合破裂压力及水平地应力模型建立了沁水盆地煤层地应力模型;基于准确预测的闭合应力、破裂压力及水平地应力模型建立了沁水盆地煤层地应力的计算方法,通过建立破裂压力判据和闭合压力判据评价裂缝破裂和闭合时的裂缝垂直延伸或水平延伸形态,进而预测煤层压裂裂缝形态。通过破裂压力判据预测的目标区块岩样裂缝形态与室内实验结果一致;通过闭合压力判据预测目标区块形成垂直缝的井日平均产水量为5.79 m~3/d,而形成水平缝的井日平均产水量为1.09 m~3/d,即形成垂直缝的井因垂直延伸沟通了上覆水层导致产水量普遍较大,而形成水平缝的井因水平延伸没有进入上覆水层而含水量较小。上述判据结果与室内实验和现场生产效果相一致,验证了本文压裂裂缝形态预测方法的正确性,对沁水盆地煤层气压裂裂缝形态预测、压裂施工出水风险及压后生产效果评估具有指导作用。
With coal bed methane wells in the Qinshui basin as research targets,the closure pressure of targeted coal beds was predicted using post-fracturing pressure drawdown curves,and the coal bed in-situ stress model was established in combination with the fracturing pressure and horizontal in-situ stress model. The calculation method of coal bed in-situ stress for the Qinshui basin is established on the basis of the accurately predicted closure stress,fracturing pressure and horizontal in-situ stress model. And further the criteria to judge fracturing pressure and closure pressure were set up,which can be used to evaluate the vertical or horizontal fracture extension geometry when fractures are open or close and then predict the fracture geometry of coal beds. The coal fracture geometry in the target area derived from the fracturing pressure criterion is consistent with laboratory experimental results. It is predicted based on the closure pressure judgment criterion that the vertical fractures in the target area can result in the daily water production of 5. 79 m~3/d in contrast with that of 1. 09 m~3/d due to horizontal fractures,and the difference in daily water production should be attributed to vertical fractures rather than horizontal fractures stretching vertically to and communicating with overlying water layers. The results of the criteria are consistent with laboratory experiments and field production performance,which verify the correctness of the proposed fracture geometry prediction methods. The method is of guiding function for predicting fracture geometry and evaluating water risk and post-fracturing production performance of coal-bed methane in the Qinshui basin.
With coal bed methane wells in the Qinshui basin as research targets,the closure pressure of targeted coal beds was predicted using post-fracturing pressure drawdown curves,and the coal bed in-situ stress model was established in combination with the fracturing pressure and horizontal in-situ stress model. The calculation method of coal bed in-situ stress for the Qinshui basin is established on the basis of the accurately predicted closure stress,fracturing pressure and horizontal in-situ stress model. And further the criteria to judge fracturing pressure and closure pressure were set up,which can be used to evaluate the vertical or horizontal fracture extension geometry when fractures are open or close and then predict the fracture geometry of coal beds. The coal fracture geometry in the target area derived from the fracturing pressure criterion is consistent with laboratory experimental results. It is predicted based on the closure pressure judgment criterion that the vertical fractures in the target area can result in the daily water production of 5. 79 m~3/d in contrast with that of 1. 09 m~3/d due to horizontal fractures,and the difference in daily water production should be attributed to vertical fractures rather than horizontal fractures stretching vertically to and communicating with overlying water layers. The results of the criteria are consistent with laboratory experiments and field production performance,which verify the correctness of the proposed fracture geometry prediction methods. The method is of guiding function for predicting fracture geometry and evaluating water risk and post-fracturing production performance of coal-bed methane in the Qinshui basin.
引文
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[12]李志强,鲜学福,黄滚.地应力地温场中煤层气富集区高精度定量预测的力学方法[J].煤炭学报,2012,37(增刊2):395-400.LI Zhiqiang,XIAN Xuefu,HUANG Gun.High precision and quantitative prediction mechanics method of coalbed methane enrichment area in geo-stress and geothermal field[J].Journal of China Coal Society,2012,37(S2):395-400.
[13]孟召平,田永东,李国富,等.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,et al.Characteristicsof in-situ stress field in Southern Qinshui Basin and its research significance[J].Journal of China Coal Society,2010,35(6):975-981.
[14]康红普,林健,张晓.深部矿井地应力测量方法研究与应用[J].岩石力学与工程学报,2007,26(5):929-933.KANG Hongpu,LIN Jian,ZHANG Xiao.Research and application of in-situ stress measurement in deep mines[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(5):929-933.
[15]邓金根,陈峥嵘,耿亚楠,等.页岩储层地应力预测模型的建立和求解[J].中国石油大学学报(自然科学版),2013,37(6):59-64.DENG Jingen,CHEN Zhengrong,GENG Yanan,et al.Prediction model for in-situ formation stress in shale reservoirs[J].Journal of China University of Petroleum(Edition of Natural Science),2013,37(6):59-64.
[16]WU Jianguang,SUN Hansen,LIU Xinghui,et al.CBM development in the qinhui basin:hydraulic fracture complexities revealed by modeling analysis and microseismic monitoring.[R].SPE167045,2013.
[17]ABASS H H,HEDAYATI S,KIM C M.Mathematical and experimental simulation of hydraulic fracturing in shallow coal seams[R].SPE 23452,1991.
[18]ABASS H H,DOMELEM M L,RABAA W M.Experimental observations of hydraulic fracture propagation through coal blocks[R].SPE 21289,1990.
[19]石欣雨,文国军,白江浩,等.煤岩水力压裂裂缝扩展物理模拟实验[J].煤炭学报,2016,41(5):1145-1151.SHI Xinyu,WEN Guojun,BAI Jianghao,et al.A physical simulation experiment on fracture propagation of coal petrography in hydraulic fracturing[J].Journal of China Coal Society,2016,41(5):1145-1151.
[20]吴晓东,席长丰,王国强.煤层气井复杂水力压裂裂缝模型研究[J].天然气工业,2006,26(12):124-126.WU Xiaodong,XI Changfeng,WANG Guoqiang.The mathematic model research of complicated fracture system in coalbed methane wells[J].Natural Gas Industry,2006,26(12):124-126.
[21]侯冰,张儒鑫,刁策,等.大斜度井水力压裂裂缝扩展模拟实验分析[J].中国海上油气,2016,28(5):85-91.DOI:10.11935/j.issn.1673-1506.2016.05.014.HOU Bing,ZHANG Ruxin,DIAO Ce,et al.Experimental study on hydraulic fracture propagation in highly deviated wells[J].China Offshore Oil and Gas,2016,28(5):85-91.DOI:10.11935/j.issn.1673-1506.2016.05.014.
[22]郭天魁,刘晓强,顾启林.射孔井水力压裂模拟实验相似准则推导[J].中国海上油气,2015,27(3):108-112.DOI:10.11935/j.issn.1673-1506.2015.03.017.GUO Tiankui,LIU Xiaoqiang,GU Qilin.Deduction of similarity laws of hydraulic fracturing simulation experiments for perforated wells[J].China Offshore Oil and Gas,2015,27(3):108-112.DOI:10.11935/j.issn.1673-1506.2015.03.017.
[23]THIERCELIN M J,PLUMB R A.A core-based prediction of lithologic stress contrasts in east Texas formations[J].SPE Formation Evaluation,1994,9(4):251-258.
[24]俞绍诚.水力压裂技术手册[M].北京:石油工业出版社,2010:409-410.
[25]陈勉,金衍,张广清.石油工程岩石力学[M].北京:科学出版社,2008:99-106.
[2]刘会虎,桑树勋,李梦溪,等.沁水盆地煤层气井压裂影响因素分析及工艺优化[J].煤炭科学技术,2013,41(11):98-102.LIU Huihu,SANG Shuxun,LI Mengxi,et al.Analysis on affecting factors and technique optimizing of fractured coalbed methane well[J].Coal Science and Technology,2013,41(11):98-102.
[3]鲜保安,崔思华,蓝海峰,等.中国煤层气开发关键技术及综合利用[J].天然气工业,2004,24(5):104-106.XIAN Baoan,CUI Sihua,LAN Haifeng,et al.Key techniques and integrative utilization of coal-bed gas development in China[J].Natural Gas Industry,2004,24(5):104-106.
[4]刘世奇,桑树勋,李仰民,等.沁水盆地南部煤层气井压裂失败原因分析[J].煤炭科学技术,2012,40(6):108-112.LIU Shiqi,SANG Shuxun,LI Yangmin,et al.Analysis on fracturing failure cause of coal bed methane well in south part of Qinshui basin[J].Coal Science and Technology,2012,40(6):108-112.
[5]黄炳香,程庆春,刘长友,等.煤岩体水力致裂理论及其工艺技术框架[J].采矿与安全工程学报,2011,28(2):167-173.HUANG Bingxiang,CHENG Qingchun,LIU Changyou,et al.Hydraulic fracturing theory of coal-rock mass and its technical framework[J].Journal of Mining and Safety Engineering,2011,28(2):167-173.
[6]陈添,汪志明,杨刚.煤岩T型缝压裂实验及压力曲线分析[J].特种油气藏,2013,20(3):123-126.CHEN Tian,WANG Zhiming,YANG Gang.Experiments of fracturing and pressure curve analysis of T-shape fractures of coal bed[J].Special Oil and Gas Reservoirs,2013,20(3):123-126.
[7]蔺海晓,杜春志.煤岩拟三轴水力压裂实验研究[J].煤炭学报,2011,36(11):1801-1805.LIN Haixiao,DU Chunzhi.Experimental research on the quasi three-axis hydraulic fracturing of coal[J].Journal of China Coal Society,2011,36(11):1801-1805.
[8]王鹏,茅献彪,杜春志,等.煤层钻孔水压致裂的裂缝扩展规律研究[J].采矿与安全工程学报,2009,26(1):31-35.WANG Peng,MAO Xianbiao,DU Chunzhi,et al.Study on the propagation mechanism of the crack for the borehole hydraulic fracturing in coal seam[J].Journal of Mining&Safety Engineering,2009,26(1):31-35.
[9]单学军,张士诚,李安启,等.煤层气井压裂裂缝扩展规律分析[J].天然气工业,2005,25(1):130-132.SHAN Xuejun,ZHANG Shicheng,LI Anqi,et al.Analyzing the fracture extended law of hydraulic fracturing in coalbed gas wells[J].Natural Gas Industry,2005,25(1):130-132.
[10]陈峥嵘,邓金根,朱海燕,等.定向射孔压裂起裂与射孔优化设计方法研究[J].岩土力学,2013,34(8):2309-2315.CHEN Zhengrong,DENG Jingen,ZHU Haiyan,et al.Research on initiation of oriented perforation fracturing and perforation optimization design method[J].Rock and Soil Mechanics,2013,34(8):2309-2315.
[11]陈勉.我国深层岩石力学研究及在石油工程中的应用[J].岩石力学与工程学报,2004,23(14):2455-2462.CHEN Mian.Review of study on rock mechanics at great depth and its applications to petroleum engineering of china[J].Chinese Journal of Rock Mechanics and Engineering,2004,23(14):2455-2462.
[12]李志强,鲜学福,黄滚.地应力地温场中煤层气富集区高精度定量预测的力学方法[J].煤炭学报,2012,37(增刊2):395-400.LI Zhiqiang,XIAN Xuefu,HUANG Gun.High precision and quantitative prediction mechanics method of coalbed methane enrichment area in geo-stress and geothermal field[J].Journal of China Coal Society,2012,37(S2):395-400.
[13]孟召平,田永东,李国富,等.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,et al.Characteristicsof in-situ stress field in Southern Qinshui Basin and its research significance[J].Journal of China Coal Society,2010,35(6):975-981.
[14]康红普,林健,张晓.深部矿井地应力测量方法研究与应用[J].岩石力学与工程学报,2007,26(5):929-933.KANG Hongpu,LIN Jian,ZHANG Xiao.Research and application of in-situ stress measurement in deep mines[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(5):929-933.
[15]邓金根,陈峥嵘,耿亚楠,等.页岩储层地应力预测模型的建立和求解[J].中国石油大学学报(自然科学版),2013,37(6):59-64.DENG Jingen,CHEN Zhengrong,GENG Yanan,et al.Prediction model for in-situ formation stress in shale reservoirs[J].Journal of China University of Petroleum(Edition of Natural Science),2013,37(6):59-64.
[16]WU Jianguang,SUN Hansen,LIU Xinghui,et al.CBM development in the qinhui basin:hydraulic fracture complexities revealed by modeling analysis and microseismic monitoring.[R].SPE167045,2013.
[17]ABASS H H,HEDAYATI S,KIM C M.Mathematical and experimental simulation of hydraulic fracturing in shallow coal seams[R].SPE 23452,1991.
[18]ABASS H H,DOMELEM M L,RABAA W M.Experimental observations of hydraulic fracture propagation through coal blocks[R].SPE 21289,1990.
[19]石欣雨,文国军,白江浩,等.煤岩水力压裂裂缝扩展物理模拟实验[J].煤炭学报,2016,41(5):1145-1151.SHI Xinyu,WEN Guojun,BAI Jianghao,et al.A physical simulation experiment on fracture propagation of coal petrography in hydraulic fracturing[J].Journal of China Coal Society,2016,41(5):1145-1151.
[20]吴晓东,席长丰,王国强.煤层气井复杂水力压裂裂缝模型研究[J].天然气工业,2006,26(12):124-126.WU Xiaodong,XI Changfeng,WANG Guoqiang.The mathematic model research of complicated fracture system in coalbed methane wells[J].Natural Gas Industry,2006,26(12):124-126.
[21]侯冰,张儒鑫,刁策,等.大斜度井水力压裂裂缝扩展模拟实验分析[J].中国海上油气,2016,28(5):85-91.DOI:10.11935/j.issn.1673-1506.2016.05.014.HOU Bing,ZHANG Ruxin,DIAO Ce,et al.Experimental study on hydraulic fracture propagation in highly deviated wells[J].China Offshore Oil and Gas,2016,28(5):85-91.DOI:10.11935/j.issn.1673-1506.2016.05.014.
[22]郭天魁,刘晓强,顾启林.射孔井水力压裂模拟实验相似准则推导[J].中国海上油气,2015,27(3):108-112.DOI:10.11935/j.issn.1673-1506.2015.03.017.GUO Tiankui,LIU Xiaoqiang,GU Qilin.Deduction of similarity laws of hydraulic fracturing simulation experiments for perforated wells[J].China Offshore Oil and Gas,2015,27(3):108-112.DOI:10.11935/j.issn.1673-1506.2015.03.017.
[23]THIERCELIN M J,PLUMB R A.A core-based prediction of lithologic stress contrasts in east Texas formations[J].SPE Formation Evaluation,1994,9(4):251-258.
[24]俞绍诚.水力压裂技术手册[M].北京:石油工业出版社,2010:409-410.
[25]陈勉,金衍,张广清.石油工程岩石力学[M].北京:科学出版社,2008:99-106.