低孔多裂缝气藏不稳定渗流分析

Analysis on Unsteady Seepage in Non-porous and Multi-fracture Gas Reservoir

越来越多的砂岩油藏或气藏测井研究发现,地层裂缝十分发育,塔里木油田大北地区部分井每米裂缝发育多达十几条,为此建立了低孔多裂缝气藏渗流模型。对模型进行了数值求解,绘制并分析了油藏参数、裂缝条数和裂缝分布影响下的压力动态典型曲线。结果表明:流体在多裂缝系统的流动特征与裂缝条数和裂缝分布有关,压力动态曲线主要分为三个流动阶段:线性流段、椭圆流段和拟径向流段。裂缝导流能力和裂缝半长越大,裂缝线性流段越明显,椭圆形流段出现得越晚。

It is found in logging researches on more and more sandstone oil reservoir or gas reservoir that formation fractures are well developed and up to more than ten fractures each meter develop in some wells of northern Tarim Oilfield.For this reason,establish was the seepage flow model for non-porous and multi-fracture gas reservoir and the model was solved by numerical method.Drawn were typical curves of dynamic pressure according to reservoir parameters,fracture number and distribution and analyzed were these curves.Analysis results show that flow characteristics of fluids in multi fracture system are related to fracture number and distribution and these curves of dynamic pressure are divided into three main flow stages:linear flow section,elliptical flow section and pseudoradial flow section.The more fracture flow conductivity and fracture half-length are,the more obvious fracture linear flow section is and the later elliptical flow section appears.