油井压裂过程中岩石破裂压力计算公式的理论研究

A THEORETICAL STUDY ON ROCK BREAKDOWN PRESSURE CALCULATION EQUATIONS OF FRACTURING PROCESS

李传亮 孔祥言

Li Chuanliang Kong Xiangyan

中国科学技术大学力学系, 安徽合肥 230027

根据多孔介质的双重有效应力概念,研究了油井压裂过程中岩石破裂压力的计算问题,提出了一个新的综合计算公式。该公式参数取不同的数值,可预测不同类型岩石的破裂压力。应用新公式还分析了现有公式的应用范围,指出:H-W公式只能计算非渗透岩石的破裂压力,因而给出了破裂压力的上限值;H-F公式只能计算高渗透岩石的破裂压力,因而给出了破裂压力的下限值。新公式可预测任何渗透状况岩石的破裂压力,它包括了早期提出的2个计算公式,并把渗透性岩石和非渗透性岩石完全统一起来。

Based on the dual effective stress concept of porous media formation, the calculation method for rock breakdown pressure is studied in the paper, and a new composite calculating formula is provided. It is possible to predict breakdown pressure for different types of rocks if different parameters are used in the formula. The application scope of currently used equations is analyzed by using of new formula. The H-W equation can only be used to calculate the breakdown pressure of non-permeable rock; therefore it gives the upper limited value of breakdown pressure. The H-F equation can be used to calculate the breakdown pressure of high permeability rock, therefore, it gives the lower limited value of breakdown pressure. It is available to predict the breakdown pressure of any kinds of rocks by the new calculation formula. It consists of previous two calculation equations, and totally combines the calculation of non-permeable rock and that of permeable rock in one.

10.3969/j.issn.1000-7393.2000.02.015