Waterflooding Surveillance and Optimization for a Super-Giant Carbonate Reservoir

Abstract

Waterflooding performance determines the recovery and life cycle of carbonate reservoirs. This paper presents a waterflooding surveillance and development plan optimization of a super-giant carbonate reservoir, which is a Cretaceous carbonate reservoir in Middle East, with OOIP of 4000 MM bbls.This carbonate reservoir started to produce since 1970's without any energy supply, and the current reservoir pressure is just above the bubble point pressure. Therefore, water flooding project has been launched over the past 2 years. We presented a method to integrate the geology, production and injection data, PLT (Production Logging Test), saturation test, and pressure test. Based on the valuable data, we presented a comprehensive surveillance of the water flooding project and the careful evaluation about its effect. Then, based on the surveillance, reservoir simulation is conducted to optimize the pressure maintenance target, production rate, well pattern, well spacing etc. for different types of formation, and eventually an optimized development plan is proposed.Workflow of waterflooding surveillance is established, and results and analysis for this field are shared. Important information such as the main flow direction of water and increased reservoir pressure are determined. Productions of several oil wells near the injectors are enhanced more than 45%, which indicates that the effect of waterflooding is significant. In addition, optimized parameters are obtained from reservoir simulation, and some interesting observations are found, such as that if we maintain the reservoir pressure just below the bubble point, the recovery is one of the best of the 6 scenarios. Furthermore, the optimized development plan increased more than 15% oil recovery compared with the base development strategy.This study offers a comprehensive case study that supports engineers and geologists for better understanding the formation, monitoring the waterflooding process, and optimizing production plan on this carbonate.