煤层气产能预测新模型
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摘要
煤层气藏通常采用压裂直井开发,由于其吸附、解吸和扩散特征,运用常规二项式产能方程分析煤层气藏稳态产能会产生较大误差。根据煤层气藏天然裂缝发育的地质特征,运用平行板理论、等值渗流阻力原理,首次建立了针对煤层气藏,考虑其吸附、解吸、扩散特征的连续等效介质模型。该模型将裂缝性双重孔隙介质的煤层气藏转化为运用等效渗透率表征的常规均质气藏,但对各相关参数赋予特殊值时,可简化得到各类常规气藏模型。通过计算分析煤层气藏压裂直井的IPR曲线,可以看出当考虑解吸扩散时,其IPR曲线异于常规气藏。兰格缪尔压力越小,曲线下凹越严重,绝对无阻流量越大;兰格缪尔体积越小,扩散系数越小,曲线下凹越严重,绝对无阻流量越小。通过实际对比分析,该模型误差小于10%,具有较好的适应性。
Vertical well with hydraulic fractures is applied to develop coal-bed methane reservoir.Besides,due to the existence of adsorption,desorption and diffusion,it can induce large errors to analyze well performance of coal-bed methane with conventional binomial production equation. Therefore,in terms of natural fractured coal-bed methane reservoir,this paper initially establishes the equivalent continuous medium model with consideration of adsorption, desorption and diffusion using parallel-plate theory,equivalent seepage resistance principle. This new model can convert fractured dual-porosity coal-bed methane reservoir into homogeneous gas reservoirs characterized with certain equivalent permeability. It also can be simplified to various conventional gas reservoirs with special values of the relevant parameters.Taking the desorption and diffusion of coal-bed methane into consideration,IPR curves are different from that of conventional gas reservoirs,the smaller the Langmuir pressure,the deeper the curve concaves and the larger the absolute open-flow potential,while the smaller the Langmuir volume or the smaller the diffusion coefficient,the deeper the curve concaves and the smaller the absolute open-flow potential.Through the actual comparative analysis,the error of this model is less than 10 % and this model has certain practical value.
Vertical well with hydraulic fractures is applied to develop coal-bed methane reservoir.Besides,due to the existence of adsorption,desorption and diffusion,it can induce large errors to analyze well performance of coal-bed methane with conventional binomial production equation. Therefore,in terms of natural fractured coal-bed methane reservoir,this paper initially establishes the equivalent continuous medium model with consideration of adsorption, desorption and diffusion using parallel-plate theory,equivalent seepage resistance principle. This new model can convert fractured dual-porosity coal-bed methane reservoir into homogeneous gas reservoirs characterized with certain equivalent permeability. It also can be simplified to various conventional gas reservoirs with special values of the relevant parameters.Taking the desorption and diffusion of coal-bed methane into consideration,IPR curves are different from that of conventional gas reservoirs,the smaller the Langmuir pressure,the deeper the curve concaves and the larger the absolute open-flow potential,while the smaller the Langmuir volume or the smaller the diffusion coefficient,the deeper the curve concaves and the smaller the absolute open-flow potential.Through the actual comparative analysis,the error of this model is less than 10 % and this model has certain practical value.
引文
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[15]陆家亮,涂梅桂,刘晓华,等.产水气井稳定点二项式产能方程及其应用[J].科学技术与工程,2016,16(6):66-69.Lu Jialiang,Tu Meigui,Liu Xiaohua,et al.Stable Point Binomial Productivity Equation of Water-Being Gas Well and Application[J].Science Technology and Engineering,2016,16(6):66-69.
[16]幸明刚,尹俊禄,赵丁楠,等.考虑非稳态扩散的煤层气井产能预测模型[J].天然气与石油,2012,30(6):49-51.Xing Minggang,Yin Junlu,Zhao Dingnan,et al.Productivity Prediction Model of Coalbed Methane Well Considering Nonsteady-State Diffusion[J].Natural Gas and Oil,2012,30(6):49-51.
[17]张昊,李宝荣,李治平,等.考虑应力敏感的煤层气井流入动态曲线研究[J].石油化工应用,2012,31(6):33-34.Zhang Hao,Li Baorong,Li Zhiping,et al.Study on StressSensitive CBM Well Inflow Dynamic Curves[J].Petrochemical Industry Application,2012,31(6):33-34.
[18]万军凤,李凯,冉超,等.考虑应力敏感的煤层气产能模型研究[J].煤炭技术,2016,35(8):311-313.Wan Junfeng,Li Kai,Ran Chao,et al.Coalbed Methane Deliverability Correlation Research Considering Stress Sensitivity[J].Coal Technology,2016,35(8):311-313.
[19]徐严波,齐桃,杨凤波,等.压裂后水平井产能预测新模型[J].石油学报,2006,27(1):89-96.Xu Yanbo,Qi Tao,Yang Fengbo,et al.New Model for Productivity Test of Horizontal Well After Hydraulic Fracturing[J].Acta Petrolei Sinica,2006,27(1):89-91.
[20]付玉,郭肖,龙华.煤层气储层压裂水平井产能计算[J].西南石油学院学报,2003,25(3):44-46.Fu Yu,Guo Xiao,Long Hua.Productivity Method of Fractured Horizontal Wells in Coalbed Gas[J].Journal of Southwest Petroleum Institute,2003,25(3):44-46.
[2]孔庆利.煤层气在双孔介质中解吸及渗流机理研究[D].大庆:东北石油大学,2012.Kong Qingli.Study on Desorption and Seepage Mechanism of Coalbed Methane in Double Porosity[J].Daqing:Northeast University of Petroleum,2012.
[3]乌效鸣,屠厚泽.煤层水力压裂典型裂缝形态分析与基本尺寸确定[J].地球科学——中国地质大学学报,1995,20(1):112-116.Wu Xiaoming,Tu Houze.Morphological Analysis and Geometrical Size Determination of Representative Hydraulic Fractures in Coal Seam[J].Earth Science—Journal of China University of Geosciences,1995,20(1):112-116.
[4]杨朝蓬,高树生,刘广道,等.致密砂岩气藏渗流机理研究现状及展望[J].科学技术与工程,2012,20(32):8606-8613.Yang Chaopeng,Gao Shusheng,Liu Guangdao,et al.The Research Status and Progress on Percolation Mechanism of Tight Gas Reservoir[J].Science Technology and Engineering,2012,12(32):8606-8613.
[5]康毅力,罗平亚.煤岩气藏开发分类探讨[J].西南石油学院学报:自然科学版,2003,25(6):19-22.Kang Yili,Luo Pingya.Discussion on Classification of Coalbed Methane Reservoirs for Developments[J].Journal of Southwest Petroleum Institute:Natural Science Edition,2003,25(6):19-22.
[6]欧成华,梁成钢,蒋建立,等.考虑吸附、变形的煤层气分阶段流动模型[J].天然气工业,2011,31(3):48-51.Ou Chenghua,Liang Chenggang,Jiang Jianli,et al.A Stage-by-Stage Flow Model of Coalbed Methane Gas Considering Adsorption and Deformation[J].Natural Gas Industry,2011,31(3):48-51.
[7]张志刚.井下煤层气抽采产能预测模型研究[D].北京:煤炭科学研究总院,2008.Zhang Zhigang.Study on Prediction Model for the Capacity to the Undermine Coalbed-gas Drainage Production[D].Beijing:China Coal Research Institute,2008.
[8]李士才.煤层气井产能预测模型建立及数值模拟[D].秦皇岛:燕山大学,2016.Li Shicai.The Prediction Model Establishment and Numerical Simulation of CBM Well Productivity[D].Qinhuangdao:Yanshan University,2016.
[9]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):301-303.Zou Mingjun,Liu Shuai,Zhang Miao.Production Prediction of Coalbed Methane Well Based on Triple Porosity/Dual Permeability Model[J].Coal Technology,2015,34(2):301-303.
[10]王艳.煤层气产能数值模拟及预测方法研究[D].北京:中国矿业大学,2015.Wang Yan.Study of Methods of CBM Productivity Numerical Simulation and Its Prediction[D].Beijing:China University of Mining and Technology,2015.
[11]宁正福,韩树刚,程林松,等.低渗透油气藏压裂水平井产能计算方法[J].石油学报,2002,23(2):68-71.Ning Zhengfu,Han Shugang,Cheng Linsong,et al.Productivity Calculation Method of Fractured Horizontal Wells in Low Permeability Oil or Gas Field[J].Acta Petrolei Sinica,2002,23(2):68-71.
[12]朗兆新,张丽华,程林松.压裂水平井产能研究[J].石油大学学报:自然科学版,1994,18(2):43-46.Lang Zhaoxin,Zhang Lihua,Cheng Linsong.Investigation on Productivity of Fractured Horizontal Well[J].Journal of University of Petroleum,China:Edition of Natural Science,1994,18(2):43-46.
[13]Ezulike D O,Dehghanpour H.A Model for Simultaneous Matrix Depletion into Natural and Hydraulic Fracture Networks[J].Journal of Natural Gas Science and Engineering,2014,16(2):57-69.
[14]张宏宇,陈华强.建立气井二项式产能方程的一种新方法[J].中国石油和化工标准与质量,2012,32(3):255.Zhang Hongyu,Chen Huaqiang.A New Method for Establishing a Binomial Productivity Equation for Gas Wells[J].China Petroleum and Chemical Standards and Quality,2012,32(3):255.
[15]陆家亮,涂梅桂,刘晓华,等.产水气井稳定点二项式产能方程及其应用[J].科学技术与工程,2016,16(6):66-69.Lu Jialiang,Tu Meigui,Liu Xiaohua,et al.Stable Point Binomial Productivity Equation of Water-Being Gas Well and Application[J].Science Technology and Engineering,2016,16(6):66-69.
[16]幸明刚,尹俊禄,赵丁楠,等.考虑非稳态扩散的煤层气井产能预测模型[J].天然气与石油,2012,30(6):49-51.Xing Minggang,Yin Junlu,Zhao Dingnan,et al.Productivity Prediction Model of Coalbed Methane Well Considering Nonsteady-State Diffusion[J].Natural Gas and Oil,2012,30(6):49-51.
[17]张昊,李宝荣,李治平,等.考虑应力敏感的煤层气井流入动态曲线研究[J].石油化工应用,2012,31(6):33-34.Zhang Hao,Li Baorong,Li Zhiping,et al.Study on StressSensitive CBM Well Inflow Dynamic Curves[J].Petrochemical Industry Application,2012,31(6):33-34.
[18]万军凤,李凯,冉超,等.考虑应力敏感的煤层气产能模型研究[J].煤炭技术,2016,35(8):311-313.Wan Junfeng,Li Kai,Ran Chao,et al.Coalbed Methane Deliverability Correlation Research Considering Stress Sensitivity[J].Coal Technology,2016,35(8):311-313.
[19]徐严波,齐桃,杨凤波,等.压裂后水平井产能预测新模型[J].石油学报,2006,27(1):89-96.Xu Yanbo,Qi Tao,Yang Fengbo,et al.New Model for Productivity Test of Horizontal Well After Hydraulic Fracturing[J].Acta Petrolei Sinica,2006,27(1):89-91.
[20]付玉,郭肖,龙华.煤层气储层压裂水平井产能计算[J].西南石油学院学报,2003,25(3):44-46.Fu Yu,Guo Xiao,Long Hua.Productivity Method of Fractured Horizontal Wells in Coalbed Gas[J].Journal of Southwest Petroleum Institute,2003,25(3):44-46.