Title: Determination of earth stresses using inverse analysis based on coupled numerical modelling and soft computing

Authors: Shike Zhang; Shunde Yin

Addresses: Department of Civil Engineering, Anyang Normal University, Anyang City, Henan Province 455000, China ' Department of Chemical and Petroleum Engineering, University of Wyoming, Laramie, WY 82071, USA

Abstract: An inverse analysis method based on coupled numerical modelling and soft computing has been investigated for estimating the magnitude of horizontal earth stresses based on borehole displacements. The method integrates genetic algorithm (GA), artificial neural network (ANN) and numerical computation. In the displacement-based inverse analysis method, a hybrid ANN-GA model is used to identify horizontal earth stresses. An ANN is used to represent the non-linear relationship between the maximum and minimum horizontal earth stresses (σ_H, σ_h) and borehole displacements. GA is used to search the set of unknown horizontal earth stresses based on the objective function. Numerical computation is used to create the necessary training and testing samples for the hybrid ANN-GA model. Results of numerical experiments demonstrate that a hybrid ANN-GA model for displacement-based inverse analysis can effectively identify horizontal earth stresses based on wellbore movements during drilling.

Keywords: earth stresses; wellbore stability analysis; fractured reservoirs; numerical modelling; soft computing; genetic algorithms; GAs; artificial neural networks; ANNs; drilling; displacement-based inverse analysis; borehole displacements; horizontal stress; oil and gas industry; hydraulic fracturing; fracking; geomechanics.

DOI: 10.1504/IJCAT.2015.071416

International Journal of Computer Applications in Technology, 2015 Vol.52 No.1, pp.18 - 28

Published online: 27 Aug 2015 *

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