裂缝性地层压降曲线分析方法及其应用

Pressure-decline curve analysis method and its application in fracture reservoir

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 ,建立了裂缝性油气藏小型压裂压力降曲线分析模型。应用无因次压力函数图和叠加导数图 ,作出了压降特征曲线 ,判断出压降曲线类型 ,进而对裂缝参数进行了修正和求解。通过对已压裂井压降曲线的分析和解释 ,能够明显地判别依赖于压力变化的滤失特征 ,以及天然裂缝对滤失的影响 ,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 its small porosity and low permeability in the matrix. By investigating and summarizing the classical Nolte G function method and studying the special features of the fractures in the fractured formation, the pressure-decline curve analysis models for the fractured reservoirs were established. Some characteristic curves of pressure decline were achieved by using dimensionless pressure function and superposition derivative. The pressure-decline curve type was estimated in the fractured reservoir, and the fracture parameters were modified and solved. The analysis and interpretation on the curves of the fractured wells are available for identifying the features of fluid loss dependent leak off coefficient and fissure opening pressure. This method can provide a reference for design of the fracturing parameters in the fractured reservoir.