Effective Simulation of Thick Carbonate Reservoirs

Abstract

Worldwide, substantial oil and gas resources are contained in low permeability sandstone reservoirs and variable permeability carbonate reservoirs. Matrix or fracture stimulation treatments are typically required to effectively and optimally produce these resources. Many of the larger resources are characterized by thick intervals and/or multiple reservoir targets. ExxonMobil has undertaken multi-disciplinary approaches to the development and integration of technologies for design, implementation, and evaluation of acid and fracture stimulation treatments for these reservoirs. Specifically for matrix stimulation of thick carbonate reservoirs, acid placement and diversion are extremely important and challenging. Additional challenges associated with stimulating thick reservoirs include increased rock heterogeneity, development of differential reservoir pressures, and impact of the hydrostatic pressure of the fluid in the wellbore. Successful stimulation of moderate thickness intervals (100-500 ft) has been achieved through a combination of high-rate injection, viscous diversion, and selective perforating. However, for thicker reservoirs these methods may not be sufficient. ExxonMobil continues to advance the development of mechanical, chemical, and engineering methods to improve acid placement in very thick reservoirs (500 ft).