基于动态弹性力学模型的煤系致密砂岩储层裂缝预测方法

为了提高强非均质性煤系致密砂岩储层裂缝识别效果，根据测井资料，利用动态弹性力学模型对该类储层进行裂缝预测。首先利用寻优算法及阵列声波测井资料获取岩石各模量参数，然后利用微分等效介质（DEM）理论模型计算岩石孔隙纵横比（α），进而对裂缝进行定量表征。单井裂缝预测结果与岩心裂缝实际发育情况的符合率较高，约为90%，表明利用DEM模型预测煤系致密砂岩储层裂缝的可靠性较高。在此基础上，根据测井资料，利用DEM模型对沁水盆地南部地区山西组Ⅱ砂组的裂缝平面分布进行了预测，裂缝预测结果与断裂性质、构造部位及岩心裂缝观察结果均较为吻合。研究表明，动态弹性力学模型适用于煤系致密砂岩储层的裂缝定量表征。 

Fracture Prediction Method for Coal-Bearing Tight Sandstone Reservoirs Based on a Dynamic Elastic Mechanics Model

In order to improve fracture identification for tight sandstone reservoirs with strong heterogeneity,the dynamic elastic mechanics theoretical model has been used with loggin data to predict fractures in tight reservoirs.First,the optimization algorithm and the array acoustic data were applied to obtain various modulus parameters of rocks,and then to calculate the rock pore aspect ratio (α) with the differential equivalent medium (DEM) theoretical model,so as to quantitatively characterize the fracture.Predictions of fractures in single wells achieved an accuracy level of 90% when predicted fractures were compared with actual.Such a high rate of coincidence between predicted and actual confirmed the reliability of DEM model in predicting fractures in coal-bearing tight sandstone reservoirs.Based on those results,the DEM model was used to predict the fracture plane distribution of the sand group Ⅱ of Shanxi Formation in the southern part of the Qinshui Basin based on well log data.Further,the fracture prediction results were consistent with fracture properties,structural locations and core fracture observations.The research showed that the dynamic elastic mechanics model was applicable to the quantitative characterization of fractures in coal-bearing sandstone reservoirs.