煤层气藏缝网压裂直井生产动态规律
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摘要
体积压裂技术在煤层气藏开发中已得到广泛应用,针对体积压裂形成的裂缝网络(SRV),矩形边界复合模型相比于传统的径向复合模型能够更加准确合理地描述流体的渗流规律。解析或半解析函数方法无法对考虑SRV的矩形复合模型进行求解,而应用线性流模型对其求解则又会产生较大的误差。为此,利用双重介质模型对煤层气藏体积压裂区进行描述,综合考虑煤层气的吸附与解吸、扩散、渗流等多重运移机制,建立了基于非稳态扩散的煤层气藏矩形复合压裂井试井模型。结合Laplace变换、Stehfest数值反演以及计算机编程技术,采用边界元方法对模型进行求解,得到了煤层气藏生产动态变化的规律。对试井典型曲线进行了流动阶段划分,并分析了气藏边界尺寸、体积压裂区渗透率、吸附气含量、储层渗透率以及SRV尺寸等参数对生产动态规律变化的影响,实现了对体积压裂改造后的煤层气藏更为准确合理的描述。该项研究成果为深入认识煤层气运移规律和高效合理评价及开发煤层气藏提供了理论依据。
Volume fracturing technology has been widely applied in the development of coalbed methane(CBM) reservoirs. As for the simulated reservoir volume(SRV) created by volume fracturing, the seepage laws of fluids are described more accurately and rationally in the rectangular composite model than in the traditional radial composite model. However, the rectangular composite model considering SRV cannot be solved by using the analytical or semi-analytical function method, and its solution from the linear flow model has larger errors. In view of this, volume fracturing areas of CBM reservoirs were described by means of dual-medium model in this paper. The complex CBM migration mechanisms were investigated comprehensively, including adsorption, desorption, diffusion and seepage. A well testing model for rectangular composite fracturing wells in CBM reservoirs based on unsteady-state diffusion was built and solved by using the boundary element method combined with Laplace transformation, Stehfest numerical inversion and computer programming technology. Thus, production performance laws of CBM reservoirs were clarified. The flow regimes of typical well testing curves were divided and the effects on change laws of production performance from the boundary size of gas reservoirs, permeability of volume fractured areas, adsorption content, reservoir permeability and SRV size were analyzed. Eventually, CBM reservoirs after the volume fracturing stimulation were described more accurately and rationally. This study provides a theoretical basis for a better understanding of the CBM migration laws and an approach to evaluating and developing CBM reservoirs efficiently and rationally.
Volume fracturing technology has been widely applied in the development of coalbed methane(CBM) reservoirs. As for the simulated reservoir volume(SRV) created by volume fracturing, the seepage laws of fluids are described more accurately and rationally in the rectangular composite model than in the traditional radial composite model. However, the rectangular composite model considering SRV cannot be solved by using the analytical or semi-analytical function method, and its solution from the linear flow model has larger errors. In view of this, volume fracturing areas of CBM reservoirs were described by means of dual-medium model in this paper. The complex CBM migration mechanisms were investigated comprehensively, including adsorption, desorption, diffusion and seepage. A well testing model for rectangular composite fracturing wells in CBM reservoirs based on unsteady-state diffusion was built and solved by using the boundary element method combined with Laplace transformation, Stehfest numerical inversion and computer programming technology. Thus, production performance laws of CBM reservoirs were clarified. The flow regimes of typical well testing curves were divided and the effects on change laws of production performance from the boundary size of gas reservoirs, permeability of volume fractured areas, adsorption content, reservoir permeability and SRV size were analyzed. Eventually, CBM reservoirs after the volume fracturing stimulation were described more accurately and rationally. This study provides a theoretical basis for a better understanding of the CBM migration laws and an approach to evaluating and developing CBM reservoirs efficiently and rationally.
引文
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[12]苏玉亮,王文东,赵广渊,袁彬,任龙.体积压裂缝网渗流特征与注水开发适配性研究[J].西南石油大学学报(自然科学版),2015,37(5):106-110.Su Yuliang,Wang Wendong,Zhao Guangyuan,Yuan Bin&Ren Long.Researches on fluid flow features and water flooding suitability in network fractured well[J].Journal of Southwest Petroleum University(Science&Technology Edition),2015,37(5):106-110.
[13]张义,鲜保安,孙粉锦,王一兵,鲍清英.煤层气低产井低产原因及增产改造技术[J].天然气工业,2010,30(6):55-59.Zhang Yi,Xian Bao'an,Sun Fenjin,Wang Yibing&Bao Qingying.Reason analysis and stimulation measures of low coalbed methane gas production wells[J].Natural Gas Industry,2010,30(6):55-59.
[14]李景明,巢海燕,聂志宏.煤层气直井开发概要——以鄂尔多斯盆地韩城地区煤层气开发为例[J].天然气工业,2011,31(12):66-71.Li Jingming,Chao Haiyan&Nie Zhihong.Outlines of vertical well development for CBM:A case study of CBM gas development in the Hancheng district of the Ordos Basin[J].Natural Gas Industry,2011,31(12):66-71.
[15]同登科,刘珊.变形介质煤层气不稳定渗流问题[J].天然气工业,2005,25(1):74-76.Tong Dengke&Liu Shan.Unsteady percolation flow of coal bed methane through deformed coal seam[J].Natural Gas Industry,2005,25(1):74-76.
[16]Kazemi H.Pressure transient analysis of naturally fractured reservoirs with uniform fracture distribution[J].SPE Journal,1969,9(4):451-462.
[17]Xu Bingxiang,Haghighi M,Li Xiangfang&Cooke D.Development of new type curves for production analysis in naturally fractured shale gas/tight gas reservoirs[J].Journal of Petroleum Science and Engineering,2013,105:107-115.
[18]Clarkson CR,Bustin RM&Seidel JP.Production-data analysis of single-phase(gas)coalbed-methane wells[J].SPE Reservoir Evaluation&Engineering,2007,10(3):312-331.
[19]贾永禄,邓祺,聂仁仕,蔡明金,王一丞.低渗透压裂井非对称区域三线性渗流模型[J].西南石油大学学报(自然科学版),2016,38(2):95-102.Jia Yonglu,Deng Qi,Nie Renshi,Cai Mingjin&Wang Yicheng.Trilinear-flow model of fractured well on asymmetric regions for low-permeability reservoir[J].Journal of Southwest Petroleum University(Science and Technology Edition),2016,38(2):95-102.
[20]Yuan Bin,Su Yuliang,Moghanloo RG,Rui Zhenhua,Wang Wending&Shang Yangyang.A new analytical multi-linear solution for gas flow toward fractured horizontal wells with different fracture intensity[J].Journal of Natural Gas Science and Engineering,2015,23:227-238.
[21]赵丽娟.超声波作用下的煤层气吸附—解吸规律实验[J].天然气工业,2016,36(2):21-25.Zhao Lijuan.Experiment on CBM adsorption-desorption rules under the effect of ultrasonic pressure waves[J].Natural Gas Industry,2016,36(2):21-25.
[22]庄惠农.气藏动态描述和试井[M].北京:石油工业出版社,2004.Zhuang Huinong.Dynamic gas reservoir description and well test[M].Beijing:Petroleum Industry Press,2004.
[23]宋岩,柳少波,赵孟军,洪峰.煤层气与常规天然气成藏机理的差异性[J].天然气工业,2011,31(12):47-53.Song Yan,Liu Shaobo,Zhao Mengjun&Hong Feng.Difference of gas pooling mechanism between coalbed methane gas and conventional natural gas[J].Natural Gas Industry,2011,31(12):47-53.
[24]宋岩,张新民.煤层气成藏机制及经济开采理论基础[M].北京:科学出版社,2005.Song Yan&Zhang Xinmin.Coalbed gas mining mechanism and economic exploitation theory[M].Beijing:Science Press,2005.
[25]牛丛丛,刘曰武,蔡强,李海生.煤层气井气水两相分布不稳定试井模型[J].力学与实践,2013,35(5):35-41.Niu Congcong,Liu Yuewu,Cai Qiang&Li Haisheng.Transient well test model for the well with gas and water distributed in coalbed[J].Mechanics in Engineering,2013,35(5):35-41.
[26]Anbarci K&Ertekin T.A comprehensive study of pressure transient analysis with sorption phenomena for single-phase gas flow in coal seams[C]//SPE Annual Technical Conference and Exhibition,23-26 September 1990,New Orleans,Louisiana,USA.DOI:http://dx.doi.org/10.2118/20568-MS.
[2]张遂安.煤层气资源特点与开发模式[J].煤田地质与勘探,2007,35(4):27-30.Zhang Sui'an.Features and development model of coalbed methane resources[J].Coal Geology&Exploration,2007,35(4):27-30.
[3]李传亮,彭朝阳.煤层气的开采机理研究[J].岩性油气藏,2011,23(4):9-11.Li Chuanliang&Peng Chaoyang.Research on the flow mechanism of coalbed methane[J].Lithologic Reservoirs,2011,23(4):9-11.
[4]徐锐,汤达祯,陶树,耿昀光,崔义,魏宁.沁水盆地安泽区块煤层气藏水文地质特征及其控气作用[J].天然气工业,2016,36(2):36-44.Xu Rui,Tang Dazhen,Tao Shu,Geng Yunguang,Cui Yi&Wei Ning.Hydrogeological characteristics of CBM reservoirs and their controlling effects in Block Anze,Qinshui Basin[J].Natural Gas Industry,2016,36(2):36-44.
[5]朱庆忠,左银卿,杨延辉.如何破解我国煤层气开发的技术难题——以沁水盆地南部煤层气藏为例[J].天然气工业,2015,35(2):106-109.Zhu Qingzhong,Zuo Yinqing&Yang Yanhui.How to solve the technical problems in the CBM development:A case study of a CMB gas reservoir in the southern Qinshui Basin[J].Natural Gas Industry,2015,35(2):106-109.
[6]Chu WC&Shank GD.A new model for a fractured well in a radial,composite reservoir[J].SPE Formation Evaluation,1993,8(3):225-232.
[7]Zhao Yulong,Zhang Liehui,Luo Jianxin&Zhang Boning.Performance of fractured horizontal well with stimulated reservoir volume in unconventional gas reservoir[J].Journal of Hydrology,2014,512:447-456.
[8]Thompson LG,Manrique JL&Jelmert TA.Efficient algorithms for computing the bounded reservoir horizontal well pressure response[C]//Low Permeability Reservoir Symposium,15-17 April 1991,Denver,Colorado,USA.DOI:http://dx.doi.org/10.2118/21827-MS.
[9]Ozkan E&Raghavan R.New solutions for well-test-analysis problems:Part 1—analytical considerations[J].SPE Formation Evaluation,1991,6(3):359-368.
[10]Ozkan E&Raghavan R.New solutions for well-test-analysis problems:Part 2—computational considerations and applications[J].SPE Formation Evaluation,1991,6(3):369-378.
[11]Ozkan E&Raghavan R.New Solutions for well-test-analysis problems:PartⅢ—additional algorithms[C]//SPE Annual Technical Conference and Exhibition,25-28 September 1994,New Orleans,Louisiana.USA.DOI:http://dx.doi.org/10.2118/28424-MS.
[12]苏玉亮,王文东,赵广渊,袁彬,任龙.体积压裂缝网渗流特征与注水开发适配性研究[J].西南石油大学学报(自然科学版),2015,37(5):106-110.Su Yuliang,Wang Wendong,Zhao Guangyuan,Yuan Bin&Ren Long.Researches on fluid flow features and water flooding suitability in network fractured well[J].Journal of Southwest Petroleum University(Science&Technology Edition),2015,37(5):106-110.
[13]张义,鲜保安,孙粉锦,王一兵,鲍清英.煤层气低产井低产原因及增产改造技术[J].天然气工业,2010,30(6):55-59.Zhang Yi,Xian Bao'an,Sun Fenjin,Wang Yibing&Bao Qingying.Reason analysis and stimulation measures of low coalbed methane gas production wells[J].Natural Gas Industry,2010,30(6):55-59.
[14]李景明,巢海燕,聂志宏.煤层气直井开发概要——以鄂尔多斯盆地韩城地区煤层气开发为例[J].天然气工业,2011,31(12):66-71.Li Jingming,Chao Haiyan&Nie Zhihong.Outlines of vertical well development for CBM:A case study of CBM gas development in the Hancheng district of the Ordos Basin[J].Natural Gas Industry,2011,31(12):66-71.
[15]同登科,刘珊.变形介质煤层气不稳定渗流问题[J].天然气工业,2005,25(1):74-76.Tong Dengke&Liu Shan.Unsteady percolation flow of coal bed methane through deformed coal seam[J].Natural Gas Industry,2005,25(1):74-76.
[16]Kazemi H.Pressure transient analysis of naturally fractured reservoirs with uniform fracture distribution[J].SPE Journal,1969,9(4):451-462.
[17]Xu Bingxiang,Haghighi M,Li Xiangfang&Cooke D.Development of new type curves for production analysis in naturally fractured shale gas/tight gas reservoirs[J].Journal of Petroleum Science and Engineering,2013,105:107-115.
[18]Clarkson CR,Bustin RM&Seidel JP.Production-data analysis of single-phase(gas)coalbed-methane wells[J].SPE Reservoir Evaluation&Engineering,2007,10(3):312-331.
[19]贾永禄,邓祺,聂仁仕,蔡明金,王一丞.低渗透压裂井非对称区域三线性渗流模型[J].西南石油大学学报(自然科学版),2016,38(2):95-102.Jia Yonglu,Deng Qi,Nie Renshi,Cai Mingjin&Wang Yicheng.Trilinear-flow model of fractured well on asymmetric regions for low-permeability reservoir[J].Journal of Southwest Petroleum University(Science and Technology Edition),2016,38(2):95-102.
[20]Yuan Bin,Su Yuliang,Moghanloo RG,Rui Zhenhua,Wang Wending&Shang Yangyang.A new analytical multi-linear solution for gas flow toward fractured horizontal wells with different fracture intensity[J].Journal of Natural Gas Science and Engineering,2015,23:227-238.
[21]赵丽娟.超声波作用下的煤层气吸附—解吸规律实验[J].天然气工业,2016,36(2):21-25.Zhao Lijuan.Experiment on CBM adsorption-desorption rules under the effect of ultrasonic pressure waves[J].Natural Gas Industry,2016,36(2):21-25.
[22]庄惠农.气藏动态描述和试井[M].北京:石油工业出版社,2004.Zhuang Huinong.Dynamic gas reservoir description and well test[M].Beijing:Petroleum Industry Press,2004.
[23]宋岩,柳少波,赵孟军,洪峰.煤层气与常规天然气成藏机理的差异性[J].天然气工业,2011,31(12):47-53.Song Yan,Liu Shaobo,Zhao Mengjun&Hong Feng.Difference of gas pooling mechanism between coalbed methane gas and conventional natural gas[J].Natural Gas Industry,2011,31(12):47-53.
[24]宋岩,张新民.煤层气成藏机制及经济开采理论基础[M].北京:科学出版社,2005.Song Yan&Zhang Xinmin.Coalbed gas mining mechanism and economic exploitation theory[M].Beijing:Science Press,2005.
[25]牛丛丛,刘曰武,蔡强,李海生.煤层气井气水两相分布不稳定试井模型[J].力学与实践,2013,35(5):35-41.Niu Congcong,Liu Yuewu,Cai Qiang&Li Haisheng.Transient well test model for the well with gas and water distributed in coalbed[J].Mechanics in Engineering,2013,35(5):35-41.
[26]Anbarci K&Ertekin T.A comprehensive study of pressure transient analysis with sorption phenomena for single-phase gas flow in coal seams[C]//SPE Annual Technical Conference and Exhibition,23-26 September 1990,New Orleans,Louisiana,USA.DOI:http://dx.doi.org/10.2118/20568-MS.