Immiscible WAG Injection Pilots Performance and Lessons Learnt in Carbonate Reservoir. Onshore Abu Dhabi Oil Field, United Arab Emirates

Abstract

Abstract This paper reviews the performance of two immiscible Water Alternating Gas (WAG) pilots in W Field located in onshore Abu Dhabi- UAE. The main oil bearing reservoirs in the W Field are in the X, Y, & Z Zones. In August 2007, a gas injection pilot in Zone X was converted to a three-month cycle WAG pilot. The next month, a water injection pilot in the same zone was also converted to a three-month cycle WAG (Water Alternating Gas) pilot. The gas, water and WAG injection pilots were designed to increase sweep efficiency and optimize oil recovery from Zone X. The pilots are due to fulfill their objectives by year end 2012. Extensive monitoring programs were implemented in order to assess the performance of the pilots. These programs included frequent pressure measurements (BHCIP, PBU and PFO), production testing, cased-hole logging (RST/CNT/RPM/TDT), Flagship-PLT, PNL and Tracer injection monitoring. The results of the monitoring programs and the lessons learnt are discussed in detail. These results form the basis for the development of Zone X full field development plan. Immiscible WAG injection for 5 years showed improvement in sweep efficiency and recovery in Zone X. Field development plan considered drilling 8 WAGs wells in near future.