页岩储层压裂水平井气-水两相产能分析
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摘要
传统的页岩气产能模型忽略了压裂液返排期间气-水同流对产能的影响,针对该问题,建立综合考虑页岩气吸附解吸、扩散、滑脱效应、应力敏感、毛管渗吸效应的气-水两相渗流数学模型,并基于有限差分,采用SS方法求解得到页岩储层产气规律及地层流体饱和度分布。对比分析不同裂缝网络渗透率、人工主裂缝渗透率、人工主裂缝长度、页岩气吸附解吸、毛管力作用对页岩气产量的影响,结果表明:生产初期,受压裂液返排的影响,日产气量呈先升高后降低的趋势,出现产气峰值,初期产气量明显低于不考虑压裂液返排所预测的产气量,但后期产气量基本一致。裂缝网络渗透率越高、人工主裂缝渗透率越高,产气量峰值出现的时间越早且初期产气量越高。人工主裂缝越长,产气量峰值出现的时间越晚,初期产气量越高。页岩气吸附解吸对初期产气量的影响不明显。考虑毛管力作用,压裂液返排率越低,产气量越高。
Traditional shale gas productivity models do not consider the effect of gas-water two-phase flow on the productivity during the backflow of fracturing fluid.This study proposes a new shale gas productivity model that considers the effect of gas-water two-phase flow as well as the effect of shale gas adsorption,desorption,diffusion,slippage,stress sensitivity,and capillary imbibition.The model calculates the productivity of shale gas and the distribution of formation fluid saturation using the SS method based on the finite difference theory.The model was applied to a real field case to analyze how shale gas productivity was affected by the permeability of fracture network,the permeability of artificial major fractures,the length of artificial major fractures,the adsorption and desorption of shale gas,and the capillary force on shale gas.The results were compared to field observations.In the early period of production,the daily shale gas production first raised,peaked,and then dropped due to the backflow of the fracturing fluid.Compared to the case considering no backflow of fracturing fluid,the case considering the backflow of fracturing fluid has significantly lower shale gas production at the early period but similar production at the later period.The shale gas production at the early period increased with increasing fracture network permeability,artificial major fracture permeability,and artificial major fracture length.The shale gas adsorption and desorption had little effect on the shale gas production at the early period.The capillary force,however,would lower the backflow rate of the fracturing fluid,thus increasing the shale gas production,which is consistent with field observations.
Traditional shale gas productivity models do not consider the effect of gas-water two-phase flow on the productivity during the backflow of fracturing fluid.This study proposes a new shale gas productivity model that considers the effect of gas-water two-phase flow as well as the effect of shale gas adsorption,desorption,diffusion,slippage,stress sensitivity,and capillary imbibition.The model calculates the productivity of shale gas and the distribution of formation fluid saturation using the SS method based on the finite difference theory.The model was applied to a real field case to analyze how shale gas productivity was affected by the permeability of fracture network,the permeability of artificial major fractures,the length of artificial major fractures,the adsorption and desorption of shale gas,and the capillary force on shale gas.The results were compared to field observations.In the early period of production,the daily shale gas production first raised,peaked,and then dropped due to the backflow of the fracturing fluid.Compared to the case considering no backflow of fracturing fluid,the case considering the backflow of fracturing fluid has significantly lower shale gas production at the early period but similar production at the later period.The shale gas production at the early period increased with increasing fracture network permeability,artificial major fracture permeability,and artificial major fracture length.The shale gas adsorption and desorption had little effect on the shale gas production at the early period.The capillary force,however,would lower the backflow rate of the fracturing fluid,thus increasing the shale gas production,which is consistent with field observations.
引文
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[15]HUANG Ting,LI Erpeng,TAO Zhengwu,et al.A nonlinear seepage model of gas and water transport in multi-scale shale gas reservoirs based on dynamic permeability[J].Journal of Geophysics&Engineering,2018,15(4):1 255-1 268.
[16]赵金洲,任岚,胡永全.页岩储层压裂缝成网延伸的受控因素分析[J].西南石油大学学报:自然科学版,2013,35(1):1-9.ZHAO Jinzhou,REN Lan,HU Yongquan.Controlling factors of hydraulic fractures extending into network in shale formations[J].Journal of Southwest Petroleum University:Science&Technology Edition,2013,35(1):1-9.
[17]黄睿哲,姜振学,高之业,等.页岩储层组构特征对自发渗吸的影响[J].油气地质与采收率,2017,24(1):111-115.HUANG Ruizhe,JIANG Zhenxue,GAO Zhiye,et al.Effect of composition and structural characteristics on spontaneous imbibition of shale reservoir[J].Petroleum Geology and Recovery Efficiency,2017,24(1):111-115.
[18]STALGOROVA K,MATTAR L.Analytical model for unconventional multifractured composite systems[J].SPE Reservoir Evaluation&Engineering,2013,16(3):246-256.
[19]刘嘉璇,尚新春,朱维耀.页岩气直井非稳态非线性渗流的数值计算及产能预测[J].中国科学:技术科学,2015,45(7):737-746.LIU Jiaxuan,SHANG Xinchun,ZHU Weiyao.Numerical computation for nonlinear unsteady percolation of shale gas and prediction of production[J].Scientia Sinica:Technologica,2015,45(7):737-746.
[20]JAVADPOUR F,FISHER D,UNSWORTH M.Nanoscale gas flow in shale gas sediments[J].Journal of Canadian Petroleum Technology,2007,46(10):55-61.
[21]PINDER George F.Essentials of multiphase flow in porous media[M].Hoboken:Wiley-Interscience,2008.
[22]SONG Bo.Model for fracturing fluid flowback and characterization of flowback mechanisms[D].Texas:Texas A&M University,2014.
[23]GDANSKI R D,FULTON D D,SHEN C.Fracture-face-skin evolution during cleanup[J].SPE Production and Operations,2009,24(1):22-34.
[2]LI Yongming,JIANG Youshi,ZHAO Jinzhou,et al.Extended finite element method for analysis of multi-scale flow in fractured shale gas reservoirs[J].Environmental Earth Sciences,2015,73(10):6 035-6 045.
[3]TAEYEOB Lee,DAEJIN Park,CHANGHOON Shin,et al.Efficient production estimation for a hydraulic fractured well considering fracture closure and proppant placement effects[J].Energy Exploration&Exploitation,2016,34(4):643-658.
[4]段永刚,李建秋.页岩气无限导流压裂井压力动态分析[J].天然气工业,2010,30(10):26-29.DUAN Yonggang,LI Jianqiu.Transient pressure analysis of infinite conductivity fractured wells for shale gas[J].Natural Gas Industry,2010,30(10):26-29.
[5]赵金洲,李志强,胡永全,等.考虑页岩储层微观渗流的压裂产能数值模拟[J].天然气工业,2015,35(6):53-58.ZHAO Jinzhou,LI Zhiqiang,HU Yongquan,et al.Numerical simulation of productivity after fracturing with consideration to microseepage in shale reservoirs[J].Natural Gas Industry,2015,35(6):53-58.
[6]赵金洲,符东宇,李勇明,等.基于改进三线性流模型的多级压裂页岩气井产能影响因素分析[J].天然气地球科学,2016,27(7):1 324-1 331.ZHAO Jinzhou,FU Dongyu,LI Yongming,et al.Analysis of sensitive factors about multi-stage fractured well productivity in shale gas reservoirs based on modified trilinear flow model[J].Natural Gas Geoscience,2016,27(7):1 324-1 331.
[7]赵金洲,符东宇,李勇明,等.基于格子Boltzmann方法的页岩气藏气体滑脱效应分析[J].油气地质与采收率,2016,23(5):65-70.ZHAO Jinzhou,FU Dongyu,LI Yongming,et al.Analysis on slippage effect in shale gas reservoir based on lattice Boltzmann method[J].Petroleum Geology and Recovery Efficiency,2016,23(5):65-70.
[8]赵谦平,王博涛,姜磊,等.页岩气多场耦合渗透率计算模型[J].特种油气藏,2017,24(2):125-130.ZHAO Qianping,WANG Botao,JIANG Lei,et al.Computational model for multi-field coupling permeability of shale gas[J].Special Oil&Gas Reservoirs,2017,24(2):125-130.
[9]任岚,傅燕鸣,胡永全,等.基于LBM页岩微观尺度气体流动模拟研究[J].特种油气藏,2017,24(3):70-75.REN Lan,FU Yanming,HU Yongquan,et al.Simulation of microscopic gas flowing in shale based on LBM[J].Special Oil&Gas Reservoirs,2017,24(3):70-75.
[10]李玉丹,董平川,张荷,等.基于分形理论的页岩基质表观渗透率研究[J].油气地质与采收率,2017,24(1):92-99,105.LI Yudan,DONG Pingchuan,ZHANG He,et al.Analysis on apparent permeability of shale matrix based on fractal theory[J].Petroleum Geology and Recovery Efficiency,2017,24(1):92-99,105.
[11]ADEFIDIPE O A,DEHGHANPOUR H,VIRUES C J.Immediate gas production from shale gas wells:A two-phase flowback model[C].The Woodlands:SPE Unconventional Resources Conference,2014.
[12]尹虎,王新海,张芳,等.吸附气对气水两相流页岩气井井底压力的影响[J].断块油气田,2013,20(1):74-76.YIN Hu,WANG Xinhai,ZHANG Fang,et al.Influence of adsorbed gas on bottomhole pressure of shale gas wells with gas-water two-phase flow[J].Fault-Block Oil&Gas Field,2013,20(1):74-76.
[13]王怀龙.页岩气藏渗流理论及单井数值模拟研究[D].成都:西南石油大学,2015.WANG Huailong.Research on percolation mechanism and numerical simulation of the single well in the shale gas reservoir[D].Chengdu:Southwest Petroleum University,2015.
[14]郭小哲,王晶,刘学锋.页岩气储层压裂水平井气-水两相渗流模型[J].石油学报,2016,37(9):1 165-1 170.GUO Xiaozhe,WANG Jing,LIU Xuefeng.Gas-water two phase porous flow model of fractured horizontal well in shale gas reservoir[J].Acta Petrolei Sinica,2016,37(9):1 165-1 170.
[15]HUANG Ting,LI Erpeng,TAO Zhengwu,et al.A nonlinear seepage model of gas and water transport in multi-scale shale gas reservoirs based on dynamic permeability[J].Journal of Geophysics&Engineering,2018,15(4):1 255-1 268.
[16]赵金洲,任岚,胡永全.页岩储层压裂缝成网延伸的受控因素分析[J].西南石油大学学报:自然科学版,2013,35(1):1-9.ZHAO Jinzhou,REN Lan,HU Yongquan.Controlling factors of hydraulic fractures extending into network in shale formations[J].Journal of Southwest Petroleum University:Science&Technology Edition,2013,35(1):1-9.
[17]黄睿哲,姜振学,高之业,等.页岩储层组构特征对自发渗吸的影响[J].油气地质与采收率,2017,24(1):111-115.HUANG Ruizhe,JIANG Zhenxue,GAO Zhiye,et al.Effect of composition and structural characteristics on spontaneous imbibition of shale reservoir[J].Petroleum Geology and Recovery Efficiency,2017,24(1):111-115.
[18]STALGOROVA K,MATTAR L.Analytical model for unconventional multifractured composite systems[J].SPE Reservoir Evaluation&Engineering,2013,16(3):246-256.
[19]刘嘉璇,尚新春,朱维耀.页岩气直井非稳态非线性渗流的数值计算及产能预测[J].中国科学:技术科学,2015,45(7):737-746.LIU Jiaxuan,SHANG Xinchun,ZHU Weiyao.Numerical computation for nonlinear unsteady percolation of shale gas and prediction of production[J].Scientia Sinica:Technologica,2015,45(7):737-746.
[20]JAVADPOUR F,FISHER D,UNSWORTH M.Nanoscale gas flow in shale gas sediments[J].Journal of Canadian Petroleum Technology,2007,46(10):55-61.
[21]PINDER George F.Essentials of multiphase flow in porous media[M].Hoboken:Wiley-Interscience,2008.
[22]SONG Bo.Model for fracturing fluid flowback and characterization of flowback mechanisms[D].Texas:Texas A&M University,2014.
[23]GDANSKI R D,FULTON D D,SHEN C.Fracture-face-skin evolution during cleanup[J].SPE Production and Operations,2009,24(1):22-34.