Boscan is a giant multi-billion-barrels heavy oil (10.5° API gravity and asphaltic) field in Venezuela. Although, a large part of the field is on primary production with a low recovery factor (<6%), water injection has been successfully implemented in portions of the field for over 15 years with improved recovery. High mobility ratio waterflood (HMRWF) behavior and associated key production mechanisms obtained from detailed field data analysis and dynamic modeling are presented. A novel and unique infill configuration is also proposed to further improve recovery in this high (or adverse) mobility ratio environment.
Water injection in such heavy oil (10.5° API) was considered not effective by the industry previously, due to adverse mobility ratio. However, water injection for pressure maintenance (WIPM) was successfully implemented using a pattern configuration, pseudo 1-3-1 inverted 7-spot (an additional row of producer between conventional pattern rows). Field data and reservoir simulation models show increased reservoir pressure up to the second row of producers from the injector. The pressure support is utilized to significantly improve recovery using the unique configuration at low water cut. WIPM has already resulted in significant reserves addition. Current production from water injection areas is ~40 MBOPD (or ~ 47% field production).
However, it is estimated that because of high oil viscosity, a significant amount of oil remains bypassed in the WIPM area. An infill opportunity was identified from an integrated reservoir management study that included detailed WIPM data analysis and dynamic (mechanistic and full field) modeling. A unique infill configuration is proposed that conceptually uses the current injectors with an additional row of producers between the existing first and second row of the producers. This configuration has the potential to economically unlock millions of barrels of bypassed oil and significantly increase recovery in this prolific heavy oil field.
This study provides insights into HMRWF behavior evaluating relative impact of displacement vs. pressure. The unique and novel infill configuration can be used to improve recovery, a step vital to monetize this large resource in the low-price environment.