An Oil Selective Inflow Control System

Abstract

A system has been developed and tested that reduces the production from zones producing high water cut in open hole screen completions. By use of flotation balls with neutral density in formation water, the system automatically reduces a nozzle area on each joint with increasing water cut. The oil selective inflow control system (OS) is used to reduce flow from zones that significantly contribute to the water cut in a well. A reservoir simulation tool has been configured to incorporate the OS functionality. Introduction Most oil wells that penetrate more than one reservoir zone or penetrate long reservoir intervals may benefit from inflow control to limit water and gas production. Sliding sleeves or smart well systems are expensive and time consuming to install and are proven to pose reliability challenges, flow area constraints and other limitations. Inflow control devices (ICD) (passive chokes or capillary flow paths) have been used in long horizontal wells primarily in the Norsk Hydro Troll Field with success to delay gas coning. By sizing the chokes, the sandface pressure along the wellbore is made more uniform. This results in better areal drainage. ICDs were in the Grane field simulated with ECLIPSE and NETool reservoir simulation software, but did not provide gains in production rates or ultimate recovery to increase the NPV of the field. This is mainly decided by high oil viscosity and the larger importance of water influxes in Grane, than on Troll. It was decided to study the possibilities and impact of an Oil Selective inflow control system (OS). A test and simulation program was set up between EWS and Norsk Hydro to verify the functionality and operational limitations for an OS in the Grane field. The Grane Field Grane is operated by Norsk Hydro and lies in the southern part of the North Sea, Norwegian Sector. The reservoir has excellent reservoir properties.