非线性井底流压条件下煤层气试验井产能预测模型及应用
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摘要
为了探索水力压裂条件下焦作"三软"(软煤、软顶和软底)矿区低渗煤层煤层气渗透机理及产出规律,首先基于储层压裂缝扩展模型,根据压裂后裂缝孔隙度与渗透率的关系,建立了储层压裂渗透模型,着重考虑了井底流压的非线性动态变化对煤层气产出的影响,建立了产能预测模型,并进行了试验单井的应用及分析;其次,根据压裂缝几何参数与井底流压,计算得到试验期理论产气量,通过历史拟合法将试验期实采数据、试验期理论产出及试验期模拟产出3者进行对比分析,从而验证了产能预测模型的正确性;最后,结合相关参数,运用产能预测模型对矿区GW-002试验井进行生产期2 450 d的产能预测及经济评价期内的采收率计算。结果表明,该试验井生产期内平均日产气量可达587 m~3,累计产气量可达1.05×10~6 m~3,经济评价期内采收率可达32.86%,满足了煤层气开采技术要求。研究成果可用于指导"三软"矿区煤层气井压裂抽采实践与产能预测。
In order to explore the permeability mechanism and production law of coalbed methane in low permeability coal seam(soft coal,soft top and soft bottom) in Jiaozuo"three soft"mining area under hydraulic fracturing condition,the reservior tracture permeable model was established based on the reservoir fracture propagation model and the relationship between fracture porosity and permeability after fracturing.At the same time,the influence of nonlinear dynamic change of bottom hole flow pressure on coalbed methane production was mainly considered,and the productivity prediction model was established.The application and analysis of single test well were carried out.Then,theoretical gas production during test period was calculated according to the geometric parameters of fracture crack and flowing bottom hole pressures.The data were collected during the test period,the theoretical output during the test period and the simulated output during the test period were compared and analyzed through the historical fitting method,and the correctness of the productivity prediction model was verified.Finally,combining with the relevant parameters,the productivity prediction model was used to predict GW-002 test well for 2 450 d,and to calculate the recovery ratio during the economic evaluation period.The results showed that the average daily gas production,cumulative gas production and recovery ratio could reach 587 m~3,1.05×10~6 m~3 and 32.86% respectively,which met the technical requirements of CBM mining.The results could guide fracturing extraction practices and productivity prediction in the "three soft" mining area.
In order to explore the permeability mechanism and production law of coalbed methane in low permeability coal seam(soft coal,soft top and soft bottom) in Jiaozuo"three soft"mining area under hydraulic fracturing condition,the reservior tracture permeable model was established based on the reservoir fracture propagation model and the relationship between fracture porosity and permeability after fracturing.At the same time,the influence of nonlinear dynamic change of bottom hole flow pressure on coalbed methane production was mainly considered,and the productivity prediction model was established.The application and analysis of single test well were carried out.Then,theoretical gas production during test period was calculated according to the geometric parameters of fracture crack and flowing bottom hole pressures.The data were collected during the test period,the theoretical output during the test period and the simulated output during the test period were compared and analyzed through the historical fitting method,and the correctness of the productivity prediction model was verified.Finally,combining with the relevant parameters,the productivity prediction model was used to predict GW-002 test well for 2 450 d,and to calculate the recovery ratio during the economic evaluation period.The results showed that the average daily gas production,cumulative gas production and recovery ratio could reach 587 m~3,1.05×10~6 m~3 and 32.86% respectively,which met the technical requirements of CBM mining.The results could guide fracturing extraction practices and productivity prediction in the "three soft" mining area.
引文
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[12] 徐兵祥,李相方,胡小虎,等.煤层气典型曲线产能预测方法[J].中国矿业大学学报,2011,40(5):743-747.XU B X,LI X F,HU X H,et al.Type curves for production prediction of coalbed methane wells[J].Journal of China University of Mining & Technology,2011,40(5):743-747.
[13] KING G R.Material-balance techniques for coal-seam and devonian shale gas reservoirs with limited water influx[J].SPE Reservoir Engineering,1993,8(1):67-72.
[14] AHMED T,CENTILMEN A,ROUX B.A generalized material balance equation for coalbed methane reservoirs[C]// San Antonio,Texas.USA:Society of Petroleum Engineers,2006.
[15] 张健,汪志明.物质平衡法在煤层气藏生产动态预测中的应用[J].煤田地质与勘探,2009,37(3):23-26.ZHANG J,WANG Z M.Application of material balance method to productivity forecast in coalbed methane reservoir[J].Coal Geology & Exploration,2009,37(3):23-26.
[16] 邹明俊,刘帅,张苗.基于三孔两渗产出模型的煤层气井产能数值模拟研究[J].煤炭技术,2015,34(2):301-302.ZOU M J,LIU S,ZHANG M.Production prediction of coalbed methane well based on triple porosity /dual permeability model[J].Coal Technology,2015,34(2):301-302.
[17] 杨兴东.煤层气开采过程中裂缝系统与渗透率演化关系[J].辽宁化工,2013,42(10):1187-1189.YANG X D.Evolution of fracture system and permeability during coal-bed methane extraction[J].Liaoning Chemical Industry,2013,42(10):1187-1189.
[18] 张琪.采油工程原理与设计[M].东营:中国石油大学出版社,2006:250-255.ZHANG Q.Principles and design of oil recovery engineering[M].Dongying:China University of Petroleum Press,2006,250-255.
[19] 李宏欣.焦作九里山井田煤层气赋存特征分析[J].中州煤炭,2012,9(4):4-7.LI H X.Analysis on CBM occurrence characteristics of Jiulishan coalfield in Jiaozuo[J].Zhongzhou Coal ,2012,12(9):4-7.
[20] 刘新福,綦耀光,刘春花,等.气水两相煤层气井井底流压预测方法[J].石油学报,2010,31(6):998-1003.LIU X F,QI Y G,LIU C H,et al.Prediction of flowing bottomhole pressures for two-phase coalbed methane wells[J].Acta Petrolei Sinica,2010,31(6):989-1003.
[21] 杨焦生,王一兵,王宪花.煤层气井井底流压分析及计算[J]天然气工业,2010,30(6):66-68.YANG J S,WANG Y B,WANG X H.Analysis and computation of flowing bottom-hole pressure in coalbed methane wells[J].Natural Gas Industry,2010,30(6):66-68.
[22] 冯国庆,刘启国,石广志,等.考虑启动压力梯度的低渗透气藏不稳定渗流模型[J]石油勘探与开发,2008,35(4):457-461.FENG G Q,LIU Q G,SHI G Z,et al.An unsteady seepage flow model considering kickoff pressure gradient for low-permeability gas reservoirs[J].Petroleum Exploration and Development,2008,35(4):457-461.
[23] 王晓梅,张群,张培河,等.煤层气储层数值模拟研究的应用[J].天然气地球科学,2004,15(6):664-668.WANG X M,ZHANG Q,ZHANG P H,et al.Application of coalbed methane reservoir simulation[J].Natural Gas Geoscience,2004,15(6):664-668.
[24] 张小东,张鹏,刘浩,等.高煤级煤储层水力压裂裂缝扩展模型研究[J].中国矿业大学学报,2013,42(4):573-579.ZHANG X D,ZHANG P,LIU H,et al.Fracture extended model under hydraulic fracturing engineering for high rank coal reservoirs[J].Journal of China University of Mining & Technology,2013,42(4):573-579.
[25] 赵群,王红岩,李景明,等.快速排采对低渗透煤层气井产能伤害的机理研究[J].山东科技大学学报,2008,27(3):27-31.ZHAO Q,WANG H Y,LI J M,et al.Study on mechanism of harm to CBM well capability in low permeability seam with quick drainage method[J].Journal of Shandong University of Science and Technology,2008,27(3):27-31.
[26] 徐刚,马瑞峰,牟全斌.煤层水力裂缝参数对煤层气井产气量的影响[J].煤炭技术,2014,33(5):243-246.XU G,MA R F,MOU Q B.Impact of hydraulic fracture parameters on production of coalbed methane wells[J].Coal Technology,2014,33(5):243-246.
[2] 王志荣,郭志伟,贺平,等.基于PKN分析的煤层气垂直井水力压裂时间计算模型[J].河南理工大学学报(自然科学版),2018,37(4):24-30.WANG Z R,GUO Z W,HE P,et al.Calculation model on hydraulic fracturing time in gas vertical well based on PKN analysis[J].Journal of Henan Polytechnic University(Natural Science),2018,37(4):24-30.
[3] 孙越英,卢耀东,王佩钰,等.焦作煤田煤层气资源特征及开发利用研究[J].河南理工大学学报(自然科学版),2007,26(1):46-51.SUN Y Y,LU Y D,WANG P Y,et al.Study on the charactersitics and exploitation of coalbed methane in Jiaozuo[J].Journal of Henan Polytechnic University(Natural Science),2007,26(1):46-51.
[4] 李寨东,常会珍,刘坤鹏.焦作位村矿二1煤煤层气地质特征及采收率预测[J].中国煤层气,2012,9(6):25-28.LI Z D,CHANG H Z,LIU K P.Geological characteristics of CBM in No.2-1 seam and prediction of recovery rate in Weicun Mine in Jiaozuo[J].China Coal-bed Methane,2012,9(6):25-28.
[5] 吴晓东,王国强,李安启.煤层气井产能预测研究[J].天然气工业,2004,24(8):82-85.WU X D,WANG G Q,LI A Q,et.al.Productivity prediction of coal-bed gas wells[J].Natural Gas Industry,2004,24(8):82-85.
[6] 曹代勇,张守仁,任德贻.构造变形对煤化进程的影响——以大别造山带北麓地区石炭纪含煤岩系为例[J].地质论评,2002,48(3):313-317.CAO D Y,ZHANG S R,REN D Y.The influence of structural deformation on coalification:A case study of carboniferous coal measures in northern foothills of the Dabie orogenic belt[J].Geological Review,2002,48(3):313-317.
[7] 侯泉林,李会军,范俊佳,等.构造煤结构与煤层气赋存研究进展[J].中国科学:地球科学,2012,42(10):1487-1495.HOU Q L,LI H J,FAN J J,et al.Structure and coalbed methane occurrence in tectonically deformed coals.[J].Sci China Earth Sci,2012,42(10):1487-1495.
[8] 倪小明,苏现波,张小东.煤层气开发地质学[M].北京:化学工业出版社,2012:27-36.NI X M,SU X B,ZHANG X D.Coalbed methane development geology[M].Beijing:Chemical Industry Press,2012:27-36.
[9] 伊向艺,雷群,丁云宏.煤层气压裂技术及应用[M].北京:石油工业出版社,2012:124-148.YI X Y,LEI Q,DING Y H.Application of hydraulic fracture in coalbed methane[M].Beijing:Petroleum Industry Press,2012:124-148.
[10] 吕玉民,汤达祯,李治平,等.煤层气井动态产能拟合与预测模型[J].煤炭学报,2011,36(9):1481-1485.LYU Y M,TANG D Z,LI Z P,et al.Fitting and predicting models for coalbed methane wells dynamic productivity[J].Journal of China Coal Society,2011,36(9):1481-1485.
[11] AGARWAL A,MANDAL A,KARMAKAR B,et al.Modeling and performance prediction for water production in CBM wells of an eastern India coalfield[J].Journal of Petroleum Science and Engineering,2013,103(3):115-120.
[12] 徐兵祥,李相方,胡小虎,等.煤层气典型曲线产能预测方法[J].中国矿业大学学报,2011,40(5):743-747.XU B X,LI X F,HU X H,et al.Type curves for production prediction of coalbed methane wells[J].Journal of China University of Mining & Technology,2011,40(5):743-747.
[13] KING G R.Material-balance techniques for coal-seam and devonian shale gas reservoirs with limited water influx[J].SPE Reservoir Engineering,1993,8(1):67-72.
[14] AHMED T,CENTILMEN A,ROUX B.A generalized material balance equation for coalbed methane reservoirs[C]// San Antonio,Texas.USA:Society of Petroleum Engineers,2006.
[15] 张健,汪志明.物质平衡法在煤层气藏生产动态预测中的应用[J].煤田地质与勘探,2009,37(3):23-26.ZHANG J,WANG Z M.Application of material balance method to productivity forecast in coalbed methane reservoir[J].Coal Geology & Exploration,2009,37(3):23-26.
[16] 邹明俊,刘帅,张苗.基于三孔两渗产出模型的煤层气井产能数值模拟研究[J].煤炭技术,2015,34(2):301-302.ZOU M J,LIU S,ZHANG M.Production prediction of coalbed methane well based on triple porosity /dual permeability model[J].Coal Technology,2015,34(2):301-302.
[17] 杨兴东.煤层气开采过程中裂缝系统与渗透率演化关系[J].辽宁化工,2013,42(10):1187-1189.YANG X D.Evolution of fracture system and permeability during coal-bed methane extraction[J].Liaoning Chemical Industry,2013,42(10):1187-1189.
[18] 张琪.采油工程原理与设计[M].东营:中国石油大学出版社,2006:250-255.ZHANG Q.Principles and design of oil recovery engineering[M].Dongying:China University of Petroleum Press,2006,250-255.
[19] 李宏欣.焦作九里山井田煤层气赋存特征分析[J].中州煤炭,2012,9(4):4-7.LI H X.Analysis on CBM occurrence characteristics of Jiulishan coalfield in Jiaozuo[J].Zhongzhou Coal ,2012,12(9):4-7.
[20] 刘新福,綦耀光,刘春花,等.气水两相煤层气井井底流压预测方法[J].石油学报,2010,31(6):998-1003.LIU X F,QI Y G,LIU C H,et al.Prediction of flowing bottomhole pressures for two-phase coalbed methane wells[J].Acta Petrolei Sinica,2010,31(6):989-1003.
[21] 杨焦生,王一兵,王宪花.煤层气井井底流压分析及计算[J]天然气工业,2010,30(6):66-68.YANG J S,WANG Y B,WANG X H.Analysis and computation of flowing bottom-hole pressure in coalbed methane wells[J].Natural Gas Industry,2010,30(6):66-68.
[22] 冯国庆,刘启国,石广志,等.考虑启动压力梯度的低渗透气藏不稳定渗流模型[J]石油勘探与开发,2008,35(4):457-461.FENG G Q,LIU Q G,SHI G Z,et al.An unsteady seepage flow model considering kickoff pressure gradient for low-permeability gas reservoirs[J].Petroleum Exploration and Development,2008,35(4):457-461.
[23] 王晓梅,张群,张培河,等.煤层气储层数值模拟研究的应用[J].天然气地球科学,2004,15(6):664-668.WANG X M,ZHANG Q,ZHANG P H,et al.Application of coalbed methane reservoir simulation[J].Natural Gas Geoscience,2004,15(6):664-668.
[24] 张小东,张鹏,刘浩,等.高煤级煤储层水力压裂裂缝扩展模型研究[J].中国矿业大学学报,2013,42(4):573-579.ZHANG X D,ZHANG P,LIU H,et al.Fracture extended model under hydraulic fracturing engineering for high rank coal reservoirs[J].Journal of China University of Mining & Technology,2013,42(4):573-579.
[25] 赵群,王红岩,李景明,等.快速排采对低渗透煤层气井产能伤害的机理研究[J].山东科技大学学报,2008,27(3):27-31.ZHAO Q,WANG H Y,LI J M,et al.Study on mechanism of harm to CBM well capability in low permeability seam with quick drainage method[J].Journal of Shandong University of Science and Technology,2008,27(3):27-31.
[26] 徐刚,马瑞峰,牟全斌.煤层水力裂缝参数对煤层气井产气量的影响[J].煤炭技术,2014,33(5):243-246.XU G,MA R F,MOU Q B.Impact of hydraulic fracture parameters on production of coalbed methane wells[J].Coal Technology,2014,33(5):243-246.