Sand Production Management While Increasing Oil Production of a Gravel Packed Well Equipped with RCP Autonomous Inflow Control Devices in a Thin Heavy Oil Reservoir in Offshore China

Abstract In the 2018 infill development campaign, improved production was targeted by the operator through the installation of Autonomous Inflow Control Devices (AICDs) in a horizontal well at Offshore China. However, as the well requires gravel packing to manage the sand, the integration of AICD and gravel pack was an issue. The well was expected to intersect heterogeneous formations with varying properties resulting in an uneven reservoir influx toward the wellbore. In addition, water mobility in the reservoir is at least 150 times bigger than oil mobility and a strong aquifer is located near the well. Therefore, similar to the analogue wells completed with gravel packs, oil production from this well was expected to suffer severely from an early water breakthrough in a couple of weeks. These challenges can be mitigated by deploying AICDs that can manage the reservoir fluid influx toward the wellbore and therefore optimise the well performance. AICD, an active flow control device, delivers a variable flow restriction in response to the properties of the fluid and the rate of flow passing through. An integrated workflow was followed to deliver successfully the AICD application for CNOOC in an offshore heavy oil reservoir with huge uncertainties in remaining oil thickness and water-oil contacts. The well with the horizontal length of 440m was drilled in a thin formation with the oil column of 4.5m on average. The well intersected three different geological layers with different rock properties. The lower well completions comprised gravel pack, sand screens and RCP AICD valves were connected to an ESP pump lifting the fluids to the surface. The well was segmented in 4 compartments and a tailored AICD completions based on the real-time log data from the well was designed to properly restrict the production of unwanted fluid. Through teamwork between the companies, the well was successfully completed with AICD and gravel pack. The final modelling was performed just in the time span between reaching target depth and running the completion. Over a period of 12 months production, the offset well with no AICD devices encountered water production in the first two weeks and water cut has kept increasing to 88%. However, the AICD well not only has no problem in terms of sand production and has limited water cut to less than 15% but also has successfully delivered 200% increase in total oil production compared to the offset well. This well is an example that demonstrates the possibility of a successful combination of AICD and gravel packs. AICD completions ensured a balanced contribution from all reservoir sections and limited water production significantly while gravel pack kept the valves safe from impacts of sands.