致密气储层可压裂性测井评价方法

从致密砂岩脆性指数和断裂韧性2个方面对致密气储层可压裂性测井评价方法进行了研究。总结并对比分析了室内实验测定和利用测井数据计算致密气储层脆性指数的方法,建立了研究区适用性较好的脆性指数预测模型;为克服单纯依赖脆性指数进行可压裂性评价时的不足,应用线弹性断裂理论构建脆性指数和断裂韧性相结合的可压裂性指数。指示了筛选优良可压裂层段的标准:较高的脆性指数和较强的水力压裂造缝能力。从而,具有较高可压裂性指数的地层被认为是可压裂层段,具有较低可压裂性指数的地层被认为是压裂遮挡层。以鄂尔多斯盆地致密砂岩地层S井为例进行致密气储层可压裂性指数建模,形成基于可压裂性指数模型的可压裂性测井评价技术流程。

Log evaluation method of fracturing performance in tight gas reservoir

The logging evaluation methods for fracturing performance in tight gas reservoirs were studied from two aspects, i.e., brittleness index and fracture toughness of the tight sandstone. Summarization and comparative analysis were made on the experimental determination method and the method for calculating brittleness index of the tight gas reservoir based on logging data. Then a brittleness index prediction model with favorable applicability was established in this study. To avoid the shortage due to the single use of brittleness index for fracturing evaluation, linear elastic fracture theory was adopted to create the fracturing performance index through combination of brittleness index and fracture toughness, indicating the criterion of screening favorable fracturing strata, i.e., higher brittleness index and stronger hydraulic fracturing ability. Therefore, those with higher and lower fracturing performance index can be considered as fracturing strata and fracturing barriers respectively. Taking Well S in tight sandstone strata of the Ordos Basin as a case, a model for fracturing performance index of the tight gas reservoir was built, thus forming the flows of fracturing logging evaluation technology.