煤-砂岩复合储层煤系气渗流模型及数值模拟研究
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摘要
煤系气在复合储层中的渗流比单一储层复杂的多,目前煤系气渗流模型及规律的研究主要以单一储层为主,对煤系气在复合储层中的渗流模型及渗流规律研究较少。据此,建立煤-砂岩复合储层煤系气合采渗流模型,并采用COMSOL数值模拟软件对建立的数学模型进行了数值求解;比较有无层间窜流时煤-砂岩复合储层煤系气合采储层压力变化规律。模拟结果显示:层间窜流的存在对煤层和砂岩层储层压力变化情况均有明显影响。在近井筒区域,煤系气由砂岩层向煤层窜流,考虑层间窜流后煤层储层压力下降幅度较不考虑有明显减小,砂岩层储层压力较不考虑明显增大;在远井筒区域,煤系气由煤层向砂岩层窜流,考虑层间窜流后煤层储层压力较不考虑有明显减小,砂岩层储层压力较不考虑时有明显增大。建立的煤-砂岩复合储层煤系气合采渗流模型为研究煤系气合采问题奠定基础,具有重要的理论价值。
The percolation of coal-based gas in composite reservoirs is more complicated than that in single reservoirs.At present,the studies of coal-based gas percolation models and laws are mainly based on the single reservoir,and that based on composite reservoirs were few.Hereby,apercolation model of combined production of coal-based gas in coal-sandstone composite reservoir was established,and the mathematical model was numerically solved by COMSOL numerical simulation software.The pressure variation law of combined production of coal-based gas in coal-sandstone composite reservoir with or without interlayer crossflow was compared.The simulation results showed that the existence of interlayer crossflow had a significant impact on the reservoir pressure changes in coal seams and sandstone layers.In the near-wellbore area,the coalbased gas flew from the sandstone layer to the coal seam.The pressure drop of coal reservoir after considering interlayer crossflow was obviously smaller than that without considering it,and the pressure of sandstone reservoir was obviously higher than that without considering it.In the far-wellbore area,the coal-based gas flew from the coal seam to the sandstone layer.After considering interlayer crossflow,the pressure of coal reservoir was clearly lower and the pressure of sandstone reservoir was clearly higher than that without considering it.The established percolation model in this paper laid a foundation for the study of combined production of coal-based gas and had an important theoretical value.
The percolation of coal-based gas in composite reservoirs is more complicated than that in single reservoirs.At present,the studies of coal-based gas percolation models and laws are mainly based on the single reservoir,and that based on composite reservoirs were few.Hereby,apercolation model of combined production of coal-based gas in coal-sandstone composite reservoir was established,and the mathematical model was numerically solved by COMSOL numerical simulation software.The pressure variation law of combined production of coal-based gas in coal-sandstone composite reservoir with or without interlayer crossflow was compared.The simulation results showed that the existence of interlayer crossflow had a significant impact on the reservoir pressure changes in coal seams and sandstone layers.In the near-wellbore area,the coalbased gas flew from the sandstone layer to the coal seam.The pressure drop of coal reservoir after considering interlayer crossflow was obviously smaller than that without considering it,and the pressure of sandstone reservoir was obviously higher than that without considering it.In the far-wellbore area,the coal-based gas flew from the coal seam to the sandstone layer.After considering interlayer crossflow,the pressure of coal reservoir was clearly lower and the pressure of sandstone reservoir was clearly higher than that without considering it.The established percolation model in this paper laid a foundation for the study of combined production of coal-based gas and had an important theoretical value.
引文
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[2]临兴地区煤系生储盖组合及其层序地层格架控制[D].徐州:中国矿业大学,2016.
[3]申建,张春杰,秦勇,等.鄂尔多斯盆地临兴地区煤系砂岩气与煤层气共采影响因素和参数门限[J].天然气地球科学,2017,28(3):479-487.
[4]梁冰,石迎爽,孙维吉,等.中国煤系“三气”成藏特征及共采可能性[J].煤炭学报,2016,41(1):167-173.
[5]苏育飞.山西省海陆过渡相煤系“三气”共探共采展望[J].中国煤层气,2016(6):7-11.
[6]李五忠,孙斌,孙钦平,等.以煤系天然气开发促进中国煤层气发展的对策分析[J].煤炭学报,2016,41(1):67-71.
[7]郭兆元.以煤系天然气开发促进中国煤层气发展研究[J].煤炭与化工,2017,40(6):66-67.
[8]吴宜禄.多层气藏压力动态特征及试井分析理论研究[D].成都:西南石油学院,2004.
[9]刘启国,王辉,王瑞成,等.多层气藏井分层产量贡献计算方法及影响因素[J].西南石油大学学报(自然科学版),2010,32(1):80-84.
[10]张铭洋,李菊花,位云生.苏里格致密气田多层合采压裂直井产能影响因素分析[J].石油天然气学报,2015(3):38-42.
[11]周长静,郝瑞芬,肖元相,等.致密砂岩气藏多层压裂改造多层产能测试评价研究[J].油气井测试,2016,25(2):1-5.
[12]顾岱鸿,丁道权,刘军,等.层间非均质性致密气藏多层合采产量变化规律研究[J].科学技术与工程,2015,15(8):53-59.
[13]郭肖,汪志明,曾泉树,等.煤层气藏煤与砂岩层间窜流模型构建及影响因素分析[J].煤炭科学技术,2018,46(11).
[14]Russell D G,Prats M.The practical aspects of interlaver crossflow[J].Journal of Petroleum Technology,1962,14(6):589-594.
[15]Prijambodo R,Raghavan R,Reynolds A C.Well test analysis for wells producing layered reservoirs with crossflow[J].Society of Petroleum Engineers Journal,1985,25(3):380-396.
[16]Huang R J,Li S C,Pu J,et al.A new method for solving the model of the seepage in multilavered reservoir[J].Image Processing for Cinema,2014(4):305.
[17]李成勇,蒋裕强,伍勇,等.多层合采气藏井底压力响应模型通解[J].天然气工业,2010,30(9):39-41.
[18]孙贺东,周芳德,高承泰.部分打开的多层气藏不稳定试井的半透壁模及数值模拟研究[J].天然气工业,2001,21(4):77-80.
[19]孙贺东,王跃社,周芳德,等.具有越流的多层气藏的数值模拟研究[J].应用力学学报,2002,19(4):14-18.
[20]孙贺东,高承泰,周芳德.具有越流的多层气藏的压力曲线特征[J].西安石油大学学报(自然科学版),2001,16(6):25-29.
[21]贾英兰.多层油气藏复杂渗流理论与试井分析方法研究[D].成都:西南石油大学,2014.
[22]肖晓春,潘一山.考虑滑脱效应的煤层气渗流数学模型及数值模拟[J].岩石力学与工程学报,2005,24(16):2966-2970.
[23]李立功,康天合,李彦斌.考虑动态克林伯格系数的煤储层渗透率预测模型[J].地球物理学报,2018,61(1):304-310.