应力敏感煤层气藏水平井压力动态分析

Pressure Performance Analyses of a Horizontal Well of Stress-sensitive Coal Seams

应用正则摄动、拉普拉斯变换和有限傅里叶余弦变换方法,并通过修正Langmuir等温吸附公式,得到应力敏感煤层气藏水平井和垂直裂缝井的压力动态分析模型。与常规气藏模型对比可知,所推导的公式合理,适用于煤层气藏压力动态分析。从压力特征曲线可知:Lang-muir极限吸附量、压力常数和残余吸附量主要影响导数曲线偏离0.5水平线的时间以及"V"形曲线的深浅;渗透率模数主要影响曲线的中晚期形态。该研究对煤层气藏的压力动态分析具有重要指导意义。

The model of pressure performance analyses of a horizontal well and a well with vertical fractures in stress-sensitive coal seams is obtained by using the methods of regular perturbation and Laplace transform and by modifying finite Fourier cosine transform.Compared with conventional models of gas reservoirs,the formula derived are rational and applicable to pressure performance analyses of gas reservoirs.The pressure characteristic curves show that Langmuir maximum adsorption amount,pressure constant and residual adsorption amount mainly affects the time during which the derivative curve deviates from the 0.5 horizontal line and the depth of the' V' shape curve;and the permeability modulus mainly affects curve shapes in mid-late period.The study is significance to pressure performance analyses of coal seams.