Abstract
The added value of greater reservoir contacts with horizontal wells will be minimisedby an uneven reservoir sweep along thewellbore as the well may intersect heterogeneous formationswith varying properties. This results in early water and/or gas production in thewell. These challenges can be mitigated by deploying Autonomous Inflow Control Devices (AICDs)that can manage the reservoir fluid influx alongthe wellbore and therefore optimise the performance of well.The design of the well completion with inflow control devices is oneof the important steps in field development planning with a strong influenceon the production profileand thereby the economics. An integrated workflow was followed to deliver successfully the first AICDapplication for PETRONAS-Malaysia in an offshore oil reservoir with huge uncertainties in remaining oilthickness and current fluid contacts. The workflow comprised pre-drilling studies including AICD flow looptesting, well candidate selection, flow performance evaluation (static/dynamic modelling) and post-drillinganalyses including real-time completion design, history matching and comparison ofproduction data with neighbouring wells.
In the 2018 infill development campaign, improved productionwas targeted by the installation of AICDs in wells atoffshore Sarawak. AICD completions ensurebalanced contribution from all reservoir sections and limit gas and water production. The chosenhorizontal well was drilled in a very thin formation with the oil rim average thickness of 13ft, the thinnestAICD application to date. The well intersected two geological layers with differentproperties.Alarge gas cap and an aquifer were located above and below the well. The oilproduction from this well was expected to be impaired significantly due to a high probability of early waterand gas breakthrough, potentially within days or weeks. Two analogue wells drilled in 2013 suffer from both issues despite being completed with passive ICDs. Through teamwork between the companiesinvolved in the campaign, the well was successfully completed with an RCP AICD completion. The wellwas segmented in several compartments and a tailored AICD completions was designed to restrict theproduction of unwanted fluids properly. The AICD completion has delivered a 200% increase in oilproduction while it has significantly reduced GOR (up to 90%) and water cut compared to several offset wellswith various other completions.The AICD is an active flow control device that delivers a variable flowrestriction in response to the properties of the fluid and the rate of flow passing through. The lessonslearnt from pre and post-installation studies will be discussed here. The AICD completions enabled theoperator to implement an optimum reservoir drainage strategy that uses downhole control which willbe manipulated autonomously based on well dynamic condition instead of surface control.
