During 2019 and 2020 the field operator conducted development campaigns in a thin oil rim carbonate reservoir offshore Malaysia. The horizontal development wells were expected to intersect heterogeneous formations with varying properties resulting in an uneven reservoir influx toward the wellbore. Oil production from these wells was expected to suffer severely from an early gas breakthrough. These challenges were recognized to be mitigated by deploying Autonomous Inflow Control Devices (AICDs), installed at reservoir interface along the horizontal section of the wells. The AICDs can manage the reservoir fluid influx entering the wellbore and therefore optimise the well performance.

To improve oil production and ultimate recovery, AICDs were incorporated in the lower completion design for the development wells. The Rate Controlled Production (RCP) AICD was chosen for this application. It is an active flow control device, delivering a variable flow restriction in response to the properties of the fluid and the rate of flow passing through it. This paper summarizes the integrated technical learnings from this project.

An integrated workflow was followed to design and deliver the AICD applications successfully for the operator in an offshore light oil reservoir with huge uncertainties in remaining oil thickness and reservoir properties. The wells with a horizontal length of ~6000 ft were drilled in a relatively thin oil formation. The well intersected different geological layers with different rock properties. The lower well completions comprised of RCP AICD valves, shrouded with debris filter screens with an in-situ gas lift system in the upper completions helping to lift the fluids to the surface. The wells were segmented into compartments with blank joints and swell packers and tailored AICD placements based on individual well's real-time log data to properly restrict the production of unwanted fluids. Through teamwork between the companies, the wells were successfully completed with AICDs.

The final modelling was performed just in the time span between reaching target depth and running the completion. Over two years of production, the wells completed with AICD not only have not seen any problem in terms of solid production, but they have also successfully exhibited limited GOR development which enabled oil production optimization. A PLT was also run recently in one of the wells to analyze further the zonal contribution of each section of the well and how AICD has effectively choked back the gas in selective zones.

The results show that the AICD completion ensured a balanced contribution from the entire 6000 ft long horizontal section in the well despite the heterogeneity of the carbonate reservoir and has potentially reduced the gas production significantly to enable more optimized oil production within gas offtake limits in the reservoir management plan.

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