Back Analysis of Rock Hydraulic Fracturing by Coupling Numerical Model and Computational Intelligent Technology

Abstract

Hydraulic fracturing is widely used to determine in situ stress of rock engineering. In this paper we propose a new method for simultaneously determining the in situ stress and elastic parameters of rock. The method utilizing the hydraulic fracturing numerical model and a computational intelligent method is proposed and verified. The hydraulic fracturing numerical model provides the samples which include borehole pressure, in situ stress, and elastic parameters. A computational intelligent method is applied in back analysis. A multioutput support vector machine is used to map the complex, nonlinear relationship between the in situ stress, elastic parameters, and borehole pressure. The artificial bee colony algorithm is applied in back analysis to find the optimal in situ stress and elastic parameters. The in situ stress is determined using the proposed method and the results are compared with those of the classic breakdown formula. The proposed method provides a good estimate of the relationship between the in situ stress and borehole pressure and predicts the maximum horizontal in situ stress with high precision while considering the influence of pore pressure without the need to estimate Biot's coefficient and other parameters.

A Biological Immune Mechanism-Based Quantum PSO Algorithm and Its Application in Back Analysis for Seepage Parameters

“…Considering that the back analysis method requires repeated iterations and numerous calculations, many scholars have recently introduced various optimization algorithms into back analysis to solve the global optimal solution. Some intelligent algorithms, such as genetic algorithm (GA) [2], particle swarm optimization (PSO) [3], support vector machine (SVM) [4,5], artificial bee colony (ABC) [6], and artificial neural network (ANN) [7][8][9], have been widely used in back analysis for mechanical parameters. e work in the seepage field has also achieved some progress.…”