页岩储层可压性评价关键指标体系

从美国的页岩压裂作业经验看,压裂后产能高的气井并非压裂过程复杂、破裂压力高的地层,而是可压裂性好的地层。借鉴美国典型页岩气田的成功压裂经验,从地质评价指标、页岩体积压裂评价指标和工程技术评价指标三方面探索国内页岩可压性评价体系,对页岩气储层的地质特点进行评价,确定总地质储量、地质"甜点"区、成熟度等;获得储层岩石的脆性参数、天然裂缝、地层倾角、地应力等数据,对储层形成体积裂缝的可行性进行评价;探讨压裂增产的方式、射孔方式、压裂液性能等工程技术指标。从中优选影响储层可压性的主导因素,挑选出最能直接反应页岩地质力学可压性的指标,建立一套适合国内复杂地质和工程条件下的页岩气储层可压裂性评价指标体系,为构建页岩可压性评价模型与风险控制方法提供参考指标。

The Key Index System of Fracability Evaluation in Gas Shale Reservior

Through analyzing the fracture of gas shale in America,the fractured gas wells with high-productivity are these with good fracability,not the ones with complex fracturing process or high break-down pressure.Using the useful fracturing experience of the typical shale gas reservoir in Amecica for reference,this paper tried to explore the fracability evaluation system of gas shale in China from three orientations-geological evaluation index,volume fracture evaluation index for gas shale, engineering technology evaluation index.Through evaluating the geological characteristics of shale gas reservoir,the geological indexs like the total geological reserves,the geological “sweet spot”,and the maturity can be comfirmed;the volumn fracture indexs like the rock brittleness parameters of the reservoir,the natural fractures,the dig angle,the crustal stress can be get to evaluate the feasibility of volumn fracture;the engineering indexs like the way of fracturing stimulation,the casing perforation type,the behavior of fracturing fluid can be optimized.This paper optimizes the dominant factors that can affect the reservoir’s fracability and chooses the indexs that can reflect the geological mechanical fracability most directly to establish one key index system of fracability evaluation of gas shale reservoir on the base of the domestic complex geological condition and engineering condition.The index system can provide reference index for establishing the model of gas shale fracability and forming the hazard-control methods.