一个精度较高的超压史数值模型

A numerical model of overpressure history with higher accuracy

超压史是盆地模拟的重要计算结果之一,其精度主要取决于有效骨架应力的计算。但有效骨架应力的模拟计算尚存在精度较低的问题(尤其在中、深部地层),从而影响着随后的生烃史、排烃史及运移聚集史的计算精度。在前人和作者以往的工作基础上,使用达西定律和质量守恒法则,对有效骨架应力数学模型做了改进,使之适用于盆地模拟;研制了相应软件模块。通过几个盆地的实际模拟,尤其是克拉2井和依南2井超压的现今值模拟结果接近于压力实测数据,证明该模型具有较高的精度,既可避免通过岩石力学实验来测试有效骨架应力,又能使超压史的模拟达到实用水平。

Overpressure history is one of the important results of basin modeling. Its accuracy mainly depends on the calculation of effective stress of rock matrix. There exists the problem that the accuracy of the stress calculated is so low, especially in the middle and deep formations, that it affects the accuracy of the subsequent histories of hydrocarbons generation, expulsion and migration- accumulation. Based on the works from pioneer contributors and the author, and by using Darcy＇s law and mass conservation law, the mathematical model of the stress is improved so that it can be used in basin modeling, and the corresponding module is programmed. In the application to several basins and especially to the present values of overpressure histories of Well Kela 2 and Well Yinan 2, the results closely match the field-measured pressure data, showing that the model is of higher accuracy and enables the practical stress simulation without rock mechanics experiment.