低渗透气藏压裂井气水两相产能计算方法
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摘要
存在边、底水的低渗透气藏易形成气水两相流动,无法准确预测产水气井产能。基于低渗气藏典型渗流特征,考虑气井产水影响,结合压裂气井单相渗流特征,建立了计算低渗气藏压裂气井气水两相产能计算公式,结合气水两相相渗曲线,得到求解气水两相广义拟压力以及压裂直井储层-裂缝气水两相渗流耦合模型。苏东南区A气井实例计算表明,根据线性回归方程求得无阻流量3.370 9×10~4 m~3/d,利用本文模型计算气井无阻流量3.291 9×10~4 m~3/d,与产能测试结果对比,绝对误差和相对误差仅为0.079×10~4 m~3/d和2.34%,验证了新公式的准确性及适用性。同时,分析了启动压力梯度、应力敏感指数、水气体积比、裂缝半长,以及裂缝导流能力对压裂气井流入动态的影响,为低渗气藏气水两相压裂气井产能研究提供新思路。
Low permeability gas reservoirs with edge and bottom water are easy to form gas-water two-phase flow and cannot accurately predict the productivity of water-producing gas wells. Based on the typical percolation characteristics of low permeability gas reservoirs, considering the influence of water production of gas wells and the single-phase percolation characteristics of fractured gas wells, a formula for calculating gas-water two-phase productivity of fractured gas wells in low permeability gas reservoirs was established. Then combining with the gas-water two-phase permeability curve, the generalized pseudo-pressure of gas-water two-phase and the gas-water two-phase percolation coupling model of straight wells fractured were obtained. The calculation result of a gas well in southeastern of Jiangsu shows that the absolute open flow rate calculated by the linear regression equation was 3.370 9×10~4 m~3/d and the absolute open flow rate calculated by the new model was 3.291 9×10~4 m~3/d. Compared with the productivity test results, the absolute and relative errors of result calculated by the new model were only 0.079×10~4 m~3/d and 2.34%, which verified the accuracy and applicability of the new model. In addition, the effects of starting pressure gradient, stress sensitivity index, water-gas volume ratio, half-length of fracture and fracture conductivity on the inflow performance of fractured gas wells were also analyzed in this paper, which provided a new idea for the productivity study of gas-water two-phase fractured gas wells in low permeability gas reservoirs.
Low permeability gas reservoirs with edge and bottom water are easy to form gas-water two-phase flow and cannot accurately predict the productivity of water-producing gas wells. Based on the typical percolation characteristics of low permeability gas reservoirs, considering the influence of water production of gas wells and the single-phase percolation characteristics of fractured gas wells, a formula for calculating gas-water two-phase productivity of fractured gas wells in low permeability gas reservoirs was established. Then combining with the gas-water two-phase permeability curve, the generalized pseudo-pressure of gas-water two-phase and the gas-water two-phase percolation coupling model of straight wells fractured were obtained. The calculation result of a gas well in southeastern of Jiangsu shows that the absolute open flow rate calculated by the linear regression equation was 3.370 9×10~4 m~3/d and the absolute open flow rate calculated by the new model was 3.291 9×10~4 m~3/d. Compared with the productivity test results, the absolute and relative errors of result calculated by the new model were only 0.079×10~4 m~3/d and 2.34%, which verified the accuracy and applicability of the new model. In addition, the effects of starting pressure gradient, stress sensitivity index, water-gas volume ratio, half-length of fracture and fracture conductivity on the inflow performance of fractured gas wells were also analyzed in this paper, which provided a new idea for the productivity study of gas-water two-phase fractured gas wells in low permeability gas reservoirs.
引文
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[14] 朱光亚,刘先贵,高树生,等.低渗透气藏气水两相渗流模型及其产能分析[J].天然气工业,2009,29(9):67-70.ZHU Guangya,LIU Xiangui,GAO Shusheng,et al.A gas-water two-phase flow model for low permeability gas reservoirs and deliverability analysis thereof [J].Natural Gas Industry,2009,29(9):67-70.
[15] 文华,刘义坤,孙娜.基于广义拟压力法的深层火山岩产水气井产能方程[J].大庆石油学院学报,2010,34(1):43-46.WEN Hua,LIU Yikun,SUN Na.The productivity equation for water-producing gas well in deep volcanic gas reservoir based on generalized pseudo-pressure [J].Journal of Daqing Petroleum Institute,2010,34(1):43-46.
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[17] 邓英尔,刘慈群,王允诚.垂直裂缝井两相非达西椭圆渗流特征线解、差分解及开发指标计算方法[J].石油勘探与开发,2000,27(1):60-63,75.DENG Yinger,LIU Ciqun,WANG Yuncheng.Characteristic solution and finite difference solution of two-phase percolation in the direction of normal of ellipse and calculation of development indexes [J].Petroleum Exploration and Development,2000,27(1):60-63,75.
[2] 常宝华,强小龙,杨亚涛,等.低渗透气藏压裂水平井试井曲线特征及影响因素[J].油气井测试,2018,28(2):1-6.CHANG Baohua,QIANG Xiaolong,YANG Yatao,et al.Well testing curves of fractured horizontal wells in low-permeability gas reservoirs:characteristics and influencing factors [J].Well Testing,2018,28(2):1-6.
[3] 张小龙,杨志兴.启动压力梯度对低渗气藏不稳定渗流特征的影响[J].油气井测试,2018,27(3):7-13.ZHANG Xiaolong,YANG Zhixing.Impacts of start-up pressure gradient on features of transient seepage flow in low-permeability gas reservoirs [J].Well Testing,2018,27(3):7-13.
[4] 梅海燕,唐勇,贾生龙,等.低渗气藏压裂水平井渗流与井筒压降耦合模型[J].断块油气田,2018,25(6):771-775.MEI Haiyan,TANG Yong,JIA Shenglong,et al.Coupled model of seepage and wellbore pressure drop in fracturing horizontal wells for low permeability gas reservoirs [J].Fault-Block Oil & Gas Field,2018,25(6):771-775.
[5] 戴强,段永刚,陈伟,等.低渗透气藏渗流研究现状[J].特种油气藏,2007,14(1):11-14.DAI Qiang,DUAN Yonggang,CHEN Wei,et al.Present state of low permeability reservoir percolation study [J].Special Oil & Gas Reservoirs,2018,41(5):92-94.
[6] 张烈辉,梁斌,刘启国,等.考虑滑脱效应的低渗低压气藏的气井产能方程[J].天然气工业,2009,29(1):76-78.ZHANG Liehui,LIANG Bin,LIU Qiguo,et al.A new deliverability equation considering slippage effect for gas reservoirs with low permeability and low pressure [J].Natural Gas Industry,2009,29(1):76-78.
[7] 王德龙,王宪文,闫娟,等.非达西效应对低渗气藏气井产能影响研究[J].特种油气藏,2012,19(5):97-99.WANG Delong,WANG Xianwen,YAN Juan,et al.Study on the influence of non-Darcy effects on the gas well productivity in low-permeability gas reservoirs [J].Special Oil and Gas Reservoirs,2012,19(5):97-99.
[8] 汪永利,蒋廷学,曾斌.气井压裂后稳态产能的计算[J].石油学报,2003,24(4):65-68.WANG Yongli,JIANG Tingxue,ZENG Bin.Productivity performances of hydraulically fractured gas well [J].Acta Petrolei Sinica,2003,24(4):65-68.
[9] 李冬瑶,程时清,郑春峰.考虑滑脱效应的低渗透气藏压裂井产能分析[J].特种油气藏,2009,16(2):59-61.LI Dongyao,CHENG Shiqing,ZHENG Chunfeng.Productivity analysis for fractured well in low-permeability gas reservoirs considering slippage effect [J].Special Oil & Gas Reservoirs,2009,16(2):59-61.
[10] 熊健,刘向君,陈朕.低渗气藏压裂井动态产能预测模型研究[J].岩性油气藏,2013,25(2):82-85,91.XIONG Jian,LIU Xiangjun,CHEN Zhen.Dynamic productivity prediction model for fracturing wells in low permeability gas reservoir [J].Lithologic Reservoirs,2013,25(2):82-85,91.
[11] 罗天雨,赵金洲,郭建春.求取压裂后气井产能的椭圆流方法[J].天然气工业,2005,25(10):94-96.LUO Tianyu,ZHAO Jinzhou,GUO Jianchun.Elliptical flow method to calculate productivity of gas wells after fracturing [J].Natural Gas Industry,2005,25(10):94-96.
[12] 吕栋梁,唐海,吕渐红,等.气井产水时产能方程的确定[J].岩性油气藏,2010,22(4):112-115.LYU Dongliang,TANG Hai,LYU Jianhong,et al.Deliverability equation for water-production gas well [J].Lithologic Reservoirs,2010,22(4):112-115.
[13] 程时清,谢林峰,李相方,等.产水凝析气井三相流产能方程[J].天然气工业,2004,24(12):99-101.CHENG Shiqing,XIE Linfeng,LI Xiangfang,et al.Productivity equation of 3-phase flow for water-producing condensate wells [J].Natural Gas Industry,2004,24(12):99-101.
[14] 朱光亚,刘先贵,高树生,等.低渗透气藏气水两相渗流模型及其产能分析[J].天然气工业,2009,29(9):67-70.ZHU Guangya,LIU Xiangui,GAO Shusheng,et al.A gas-water two-phase flow model for low permeability gas reservoirs and deliverability analysis thereof [J].Natural Gas Industry,2009,29(9):67-70.
[15] 文华,刘义坤,孙娜.基于广义拟压力法的深层火山岩产水气井产能方程[J].大庆石油学院学报,2010,34(1):43-46.WEN Hua,LIU Yikun,SUN Na.The productivity equation for water-producing gas well in deep volcanic gas reservoir based on generalized pseudo-pressure [J].Journal of Daqing Petroleum Institute,2010,34(1):43-46.
[16] 孙恩慧,李晓平,王伟东.低渗透气藏气水两相流井产能分析方法研究[J].岩性油气藏,2012,24(6):121-124.SUN Enhui,LI Xiaoping,WANG Weidong.Productivity analysis method of water and gas two-phase flow well in low permeability gas reservoirs [J].Lithologic Reservoirs,2012,24(6):121-124.
[17] 邓英尔,刘慈群,王允诚.垂直裂缝井两相非达西椭圆渗流特征线解、差分解及开发指标计算方法[J].石油勘探与开发,2000,27(1):60-63,75.DENG Yinger,LIU Ciqun,WANG Yuncheng.Characteristic solution and finite difference solution of two-phase percolation in the direction of normal of ellipse and calculation of development indexes [J].Petroleum Exploration and Development,2000,27(1):60-63,75.