页岩可压裂性声学模型及应用*

页岩气作为一种非常规能源,储量巨大,因此针对页岩储层地质勘探和有效压裂改造的研究具有重大的意义。常规的脆性模型评价可压裂性通常只考虑单一影响因素,具有一定的工区适用性。该文在弹性参数脆性评价模型和断裂韧性指标的基础上,提出一种表征页岩可压裂性的声学评价模型。选取渝东南目的层页岩岩样,通过超声波实验获取相关实验数据,测量岩石参数,得到了目的层储层特征及声学特征变化规律。结合断裂韧性指标,建立了可压裂性评价模型。通过新评价模型对研究区进行可压裂性反演预测,结果表明储层可压裂性反演结果与页岩气实际产量具有较好的符合,分析可知,新方法预测或评价效果要优于前人模型,具有更好的适用性与可靠性。

Acoustic model for shale fracability and related application

As one type of unconventional energy resources, there is huge reserves of shale gas. It is of great significance in the studies of geological exploration and effective fracturing for shale gas reservoirs. Fractability evaluated by the conventional brittle models mainly considers a single influencing factor, which is applicable in certain related working areas. Based on the elastic parameter brittleness evaluation model and fracture toughness index, this paper presents an acoustic evaluation model for characterizing the fractability of shale. The shale rock samples are collected from the target layers in southeast Chongqing, China. Relevant measurement data and rock physics parameters are obtained by ultrasonic experimental measurements. We obtain the variation of reservoir characteristics and acoustic characteristics of the target layer. By combining brittleness index by elastic parameters with fracture toughness index, the fractability evaluation model is established. Based on the new evaluation model, the fracability prediction is carried out in the study area. The results show that the inversion results of the reservoirs are in good agreement with the actual gas production report of shale gas. The analysis shows that the better prediction or evaluation results can be obtained by the new method than those by the previous models, validating that the new model is more efficient and reliable.