In order to maximize oil production, it is desirable to have a balanced influx of oil from the entire completion. Non-uniform production rates from each zone along the completion may not be evident early in the well’s production life, but they can become problematic when water and gas break through. If water and gas break through in select zones, they will produce at higher rates than the oil, which in turn will impede oil production rates from the remaining zones.
Formation permeability variations or toe-to-heel friction loss can cause flow rate differences between zones, and in a heavy-oil well, these variations may be even greater. Viscous fluids experience larger frictional losses both in the formation and the wellbore flow conduit; thus, when low viscosity water or gas breaks through, the flow from a high water or gas cut zone can quickly dominate the flow from the well. Inflow Control Devices (ICDs) have been developed to balance the influx of oil by creating additional back-pressure in the zones that produce at higher rates. Using ICDs can delay water or gas breakthrough, but once unwanted fluids break through, conventional passive ICDs are not able to maintain the balanced flow.
This paper discusses a new ICD, an autonomous inflow control device (AICD), which performs similar to a passive ICD during oil production and can be used to balance reservoir influx. Unlike passive ICDs, when unwanted fluids (water, gas) flow through the AICD, they take a different path than oil, and a much higher pressure drop is created. This behavior can be used to restrict the flow of unwanted fluids when they break through in a zone, allowing the oil production from other zones in a well to continue at the maximum rate.
Simulations are presented that will compare a stand-alone screen completion to a completion with passive ICDs, to a completion with an autonomous ICD. The simulation results will show a clear distinction in each type of completion, and it will highlight the benefits that are provided with the ICD and the even greater benefits derived from use of the AICD, both onshore and offshore.