The Research On Perturbation Law Of Reservoir Stress Fields In Horizontal Well Fracturing

Horizontal well fracturing is one of the main means to transform and develop the unconventional reservoir. Unlike the conventional fracturing, its goal is to form a complex fracture network. The stress field is a key factor to affect the fracture initiation and propagation. So the in-depth research on the stress field around fracture in the process of horizontal well fracturing is carried out.Firstly, based on the existing model by the predecessors, the calculation mathematical model of the disturbance stress in horizontal well fracturing with multiple construction conditions is established and the main affecting factors is determined. Then applying the flow-solid-thermal field coupling theory, its finite element model is built. Trough the verification, the finite element method is proposed. Using the finite element numerical simulation software COMSOL Multiphysics, the local stress field of single well single fracture, single well multi-fracture and multi-well multi-fracture are simulated. Varying the affecting factors, the perturbation law of each factor to the fracturing stress field is determined. In which the main controlling can be divided into four categories, including the formation parameters, angle between fracture and horizontal wellbore, fracture parameters and fracturing well spacing way. Finally, considering the impact of natural fractures, the Baecher elliptic disk model is applied to characterize the shapes of random natural fractures. Combined with Markov Chain and Monte Carlo, that is MCMC method, the random sampling is conducted in order to reconstruct the reservoir natural fracture. Through analyzing the perturbations law of its stress field, under the synergy disturbance between the artificial fractures and natural fractures the propagation path of artificial fracture is determined.According to the above study, the distribution law of reservoir stress field in horizontal well fracturing can be understood more clearly. It provides a theoretical basis to control the reservoir stress field for the formation of complex fracture network, which has a great significance to realize the unconventional reservoir development.