Complex fractures propagations of infill well based on reservoir stress evolution after long-time shale gas production

With a specific case of Fuling shale gas reservoir, an integrated geomechanics workflow was proposed to investigate stress evolution during production and the complex hydraulic fractures propagation of infill well. In the integrated modelling, a natural fractures network was embedded in the geological model firstly. Secondly, a fracturing model was built to simulate the hydraulic fractures of parent wells. Thirdly, a flow-geomechanical coupling model was built to study the stress field evolution after long-time production.Finally, the complex hydraulic fractures propagation of the infill well was stimulated. It can be concluded from the simulation results that (1) the pre-existing complex fracture network exerts a considerable contribution on the pore pressure drop; (2) stress evolution is affected by the geomechanicalheterogeneity; (3) the horizontal principal stresses difference is found to increase, and a weak stress re-orientation appears after production; (4) the stress field changes are much smaller near the infill well; (5) the hydraulic fractures initiate preferentially at the perforations with the high density of natural fractures during the infill fracturing; (6) closing to the early producing well fractured region, the fractures complexity of the infill well reduces sharply, and that is well matched with the microseismic monitor results. Copyright 2019 ARMA, American Rock Mechanics Association