裂缝性油气藏压裂压降分析研究与应用

PRESSURE DRAWDOWN ANALYTICAL STUDY AND ITS APPLICATION ON FRACTURING OF FRACTURED RESERVOIRS

传统的压降分析解释技术适用于低渗透均质油气藏的压降分析,而对于裂缝性油气藏就不能很好地解释压裂后裂缝的参数。为了克服传统压降分析解释技术中的不足,文章在前人研究的基础上,综合考虑了储层中流体的可压缩性和天然裂缝的影响,以及压后立即放喷的情况,建立了裂缝性油气藏的压裂压力递减分析模型,从而形成了裂缝性油气藏的压降分析理论和解释技术,并研制了相应的解释软件。该软件可较好地用于裂缝性油气藏的压裂压力降落分析,解释并获得一些重要的裂缝及储层参数(如裂缝滤失系数、初滤失系数、闭合压力、闭合时间、裂缝长度、裂缝宽度以及压裂液效率等)。通过实例计算,说明了本解释模型、方法及软件具有一定的可靠性和实用性,这对裂缝性油气藏压裂裂缝参数的解释,以及运用获得的参数进行压裂施工效果评价和压裂设计具有一定的指导意义。

The existent pressure drawdown analysis technologies interpret nothing but low-permeability and isotrop reservoirs, instead of interpreting pressure decline analysis of nonisotropic fractured reservoir where there are a lot of natural fracture. To overcome the deficiency of the traditional pressure drawdown analysis technologies, based on the research results made by the predecessors, this paper has developed and consummated the pressure decline analysis and interpreting technology for fractured reservoirs,and formed new pressure drawdown analysis interpretation method and homologous interpretation software. With the software, the fracture pressure decline analysis of fractured reservoirs can be dealt up with very well, and meanwhile some important parameters on fracturing and reservoir can be obtained, such as leakoff coefficent, spurt loss coefficient,matching pressure,shut-in pressure,closing time,fracturing extend time,fracture length,fracture width,fluid efficiency and so on. It is proved by some examples that interpretation models, methods and software in this paper are reliable and applicable in actual use, which can help interpret those parameters of the fractured reservoirs. Those parameters obtained are very significant in both fracturing design and effect evaluation on the fracturing construction.