Case Study of Water Injection Frac Strategy at Bahja Rima Field at South Salt Oman Basin to Maximize Efficiency of Fields Recovery

Abstract

Abstract The Bahja Rima cluster consists of multiple fields which primarily target tight Cambro-Ordovician and Carboniforous-Permian oil sandstone reservoirs at the South Oman Salt basin petroleum system. The hydraulic propped fracturing has been the preferred practice of enhancing the well production performance at oil producers, with over 50 hydraulic fracturing works completed at this cluster in the last couple years from none. The well candidates are both from newly drilled wells and existing wells (NFA, No Further Activity) in which some of them are located within the perimeter of highly depleted pressure areas that need further strategy to maintain reservoir drive to flow the hydrocarbon. At the reservoir scale study, it is determined to infill drilled numbers of water injector wells also some conversion injector wells. The same formation waters from the produced layer, presumably as the most compatible water source, were utilized as injection water. Throughout time however, the injectivity index was substantially dropped along with incremental injection pressure due to various issues including self-scaling from single source water at different pressure and temperature exposure. Throughout collaboration of multi-companies and multi-disciplines function, from Reservoir Engineering, Geologist, Petrophysicist, Production Technology and Frac Completion Specialist, it is determined hydraulic propped fracturing as the most economic method of improving the injectivity index hence impacting nearby producer wells production. Several specific boundary and criteria need to be investigated however, in order to properly deploy hydraulic fracturing on injector well candidate, this to include well integrity aspect, frac fluids and source water compatibility, optimum frac penetration, understanding of frac orientation towards water flood aerial sweeping, understanding of frac height towards water injection vertical sweeping effectiveness. This paper describes the lesson learnt from fracturing design execution perspective and review of post fracture well injectivity performance in this cluster from 5 injector wells fracturing works performed in 2022 & 2023, and other offset producers well fracturing. The study results were summarized as best practice and recommendation moving forward for future injector wells fracturing on existing wells and also as drilling and completion strategy for new wells