基于致密砂岩岩石物理模型的静态模量预测方法

岩石静态模量是油气勘探开发过程中重要的力学性质参数, 直接实验测量的成本较高, 而且数量有限。以前的通过经验公式实现动静态模量转换的方法, 物理意义不明确、精度不高, 不能满足工程需要。为此, 提出了一种基于岩石物理模型的静态模量预测方法, 即先利用测井数据构建孔隙裂缝型岩石物理模型来计算动态模量, 在动态模量的基础上考虑频散效应和排水效应获得岩石低频干燥的模量, 最后考虑动静态模量之间应变振幅的差异, 模拟岩石发生静态形变的过程, 实现从动态到静态模量的预测。该方法考虑了动静态模量转换的微观因素, 理论上更严谨。对川西实际工区实验数据进行了静态模量预测, 预测结果与实验数据吻合较好, 其中动态杨氏模量的误差为4%, 静态杨氏模量的误差为8%, 证明了方法的适用性。

The static elastic modulus of rocks is an important mechanical property for oil and gas exploration and development.However, the number of direct experimental measurements is relatively small and expensive, and the original method of realizing dynamic and static modulus conversion through empirical formulas has an unclear physical meaning and low precision.This means it cannot meet the requirements of drilling, fracturing, and other projects.Therefore, a prediction method based on a rock physical model was proposed.A pore-fracture rock physical model was constructed using logging data to calculate the dynamic modulus.Based on the dynamic modulus, the elastic modulus of low-frequency drying of rock was obtained by considering the frequency dispersion effect and drainage effect, considering the difference in strain amplitude between the dynamic and static moduli, simulating the process of rock static deformation, and realizing the prediction from the dynamic to static modulus.This method considered the micro-factors of dynamic and static modulus conversion and was theoretically more rigorous.Finally, the static modulus was predicted using the experimental data from the actual working area.The predicted results are in line with the experimental data.The error in the dynamic elastic Young's modulus was 4%, and the error in the static Young's modulus was 8%, demonstrating the method's applicability.