低渗透煤层气非线性流动分析  

NONLINEAR FLOW ANALYSIS OF METHANE IN LOW PERMEABILITY COAL SEAMS

作　　者：张先敏[1] 同登科[1] 

机构地区：[1]中国石油大学(华东)石油工程学院,山东东营257061

出　　处：《工程力学》2010年第10期219-223,共5页Engineering Mechanics

基　　金：国家自然科学基金项目(40974056);国家973计划项目(2009219606);国家油气重大专项项目(2009ZX05038-006)

摘　　要：在考虑井筒储存和表皮效应影响的情况下,建立了存在启动压力梯度的低渗透煤层气流动数学模型,利用Laplace变换和Green函数方法求得了煤层气井的无因次井底压力的Laplace空间解析解,并通过数值求解绘制了典型样板曲线。通过对特征曲线的分析发现:在定产量生产的情况下,启动压力梯度对初期压力动态无显著影响;在生产的中后期,启动压力梯度值越大,则压力及其导数曲线上升趋势越明显,这代表启动压力梯度对煤层渗流的影响也就越严重,压力导数曲线上的径向流水平直线段消失;弹性储容比和介质间窜流系数主要影响煤基质孔隙向裂隙发生窜流的时间。Considering the wellbore storage and skin effects, a mathematical model of methane flowing in low permeability coal seams was presented with the starting pressure gradient. The analytical solutions for dimensionless bottom-hole pressure in Laplace space were obtained by Laplace transform and Green function method when the constant flow rate was specified in an infinitely large reservoir, and then converted to numerical solutions in real space by Stehfest numerical inversion method. The parameter sensitivity analysis has shown that the starting pressure gradient has no effect on the initial pressure behavior, but the ascending tendency of dimensionless bottom-hole pressure and its derivative curves becomes more obvious with increasing starting pressure gradient values in the middle-late production stage, that is, the starting pressure gradient has brought more serious influence to the methane flow in coal seams.

关 键 词：应用力学 煤层气 启动压力梯度 井筒储存 LAPLACE变换 

分 类 号：TE311[石油与天然气工程—油气田开发工程] TE312