A calculation method of optimal water injection pressures in natural fractured reservoirs

摘要

Injection pressures usually play a great role in the stimulation of low permeability fractured reservoirs. In this study, the stress state around an injection well was analyzed, and a three-collinear fracture model was established. Based on this model, the mode II fracture criterion was expressed in tel of a new form without stress intensity factor and fracture toughness involved. Based on this new form of fracture criterion, a calculation method of water injection pressures was proposed, and its effectiveness has been confirmed by the measurement results from Fuyu reservoir of Toutai oilfield. The factors that affecting optimal injection pressures have been investigated, and the results show that the water injection pressure is largely affected by the state of natural factures and the in-situ stress; According to Fuyu reservoir geological property and natural fracture distribution, the water injection pressure has been predicted and the result agrees well with that adopted in Fuyu reservoir. This study will have a beneficial application in the design and optimization of hydraulic fracturing in naturally fractured reservoirs. (C) 2015 Elsevier B.V. All rights reserved