The production life of a typical well may be split into three stages. The first stage is the start-up stage, which includes flowing back completion fluid that was initially in the well. This is followed by the production of the targeted reservoir fluid and finally the last stage, which can include production of unwanted fluids such as gas or water from the reservoir.
Passive Inflow Control Devices (PICDs) have been proven to be an effective solution for controlling influx to a well in the early stages of production life. However, breakthrough of unwanted fluid is inevitable. It is at this stage that PICDs should provide a larger level of restriction at the zones in which breakthrough occurs. The level of restriction is a function of the influx rate and more importantly, the fluid properties. For fluids flowing at a higher velocity and lower viscosity, the PICDs will behave in a manner that will passively result in a larger pressure drop. In the PICD world, this phenomenon is referred to as the "Autonomous" effect.
The question remains, what level of autonomy is optimum so as not to restrict the targeted hydrocarbon production that could stem from flowing through breakthrough zones? A water cresting scenario has been simulated as a base case to demonstrate the proper level of autonomy required of a PICD. Several hypothetical PICD designs and a field proven hybrid design, with varying levels of autonomy, are demonstrated.
Simulations have been carried out for each design to assess the performance in terms of oil sweep and cumulative production. Results have shown that there is an optimum level of autonomy required before the effect becomes detrimental to the cumulative target production.