裂缝性油藏压后压降分析

Pressure decline curve analysis of naturally fractured reservoir after being fractured

对于裂缝性低渗透储层,由于其基质孔隙度小、渗透率低,天然微裂隙成为决定压裂液滤失的主要因素。在总结Nolte经典G函数压降曲线分析方法的基础上,根据裂缝性地层存在微裂隙的特征,建立了裂缝性油藏小型压裂压降曲线分析模型。应用无因次压力函数图和叠加导数图,做出了压降特征曲线,可以判断天然裂缝闭合压力。通过对已压裂井压降曲线的分析和解释,能够计算出与压力相关的滤失系数、基质的滤失量和经天然裂缝的滤失量,以及人工裂缝的几何尺寸,从而为裂缝性地层压裂施工参数的设计提供依据。

Micro fissure is a significant factor for determining the fluid loss in low permeability fractured reservoir, due to small porosity and low permeability in the matrix. By investigating and summarizing the classical Nolte G-function method and studying the special features of fractures in the fractured formation, the pressure decline curve analysis model for the fractured reservoir was developed. The closure pressure of naturally fractured can be obtained from the characteristic curves of pressure decline, which were achieved by using dimensionless pressure function and superposition derivative. Through the curve analysis and interpretation of the fractured wells, we can get the coefficient dependent of pressure, fluid loss that is from the fissure or matrix, and the parameters of the fracture as well as the geometry of the artificial cracks. This method can provide a reference for design of the fracturing parameters in the fractured reservoir.