考虑解吸扩散过程的煤层气压裂直井产能模型研究  

Productivity Model of Gas flow in CBM Fractured Reservoirs Considering Desorption and Diffusion

作　　者：朱维耀[1] 岳明[1] 宋洪庆[1] 杨焦生[2] 王一兵[2] 于明旭[1] 

机构地区：[1]北京科技大学土木与环境工程学院,北京100083 [2]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出　　处：《应用基础与工程科学学报》2013年第5期953-960,共8页Journal of Basic Science and Engineering

基　　金：国家自然科学基金重点项目(50934003);中国石油科技创新基金项目(2010D50060201);中央高校基本科研业务费专项资金(FRFTP12003A)

摘　　要：压裂直井开发煤层气是中国地面开采煤层气的最主要手段.储层压裂开发过程中,流体的流动分为两个不同的区域:一是裂缝控制的椭圆流动区,二是裂缝内的高速非线性渗流区.针对两种不同的流动,考虑煤层气的解吸扩散过程,基于质量和动量守恒方程,建立了二区耦合的稳态流动数学模型,推导出压裂直井开发煤层气的解析解和产能方程.根据此模型可以模拟计算压裂井的产能及分析压裂裂缝参数对产能的影响.通过实例计算可以看出,煤层气解吸量的大小对单井产量有直接影响,解吸量越大,产量越大;另外,水力压裂裂缝半长及宽度越大,单井产量越高,但增幅逐渐变小,存在一个合理范围.Fractured vertical wells are the most frequently adopted means in development of coalbed methane. For hydraulic fracturing wells, gas flow field could be divided into two regions with different flow mechanisms： Darcy flow in elliptical region around artificial fractures, and nonlinear high-velocity flow in artificial fractures. Considering methane desorption and diffusion equilibrium, a mathematical model for steady gas flow in hydraulic fracturing wells was established based on conservation laws of mass and motion. According to the analytical solution derived here, productivity equation was presented considering the effect of fracture parameters. Numerical results illuminated the effect of desorption rate and fracture parameters on productivity. Production of coalbed methane grew with the increase of desorption rate. With increasing half-length and width of hydraulic fracture, production of single fractured well increased with decreasing increment and approached a plateau. The quantitative analysis in the paper could provide a theoretical foundation for reasonable development design.

关 键 词：煤层气 压裂直井 解吸 椭圆渗流 产能 

分 类 号：TE312[石油与天然气工程—油气田开发工程] P618.11[天文地球—矿床学]