Gas coning control for smart wells using a dynamic coupled well-reservoir simulator

A strong increase in gas inflow due to gas coning and the resulting bean-back because of Gas to Oil Ratio (GOR) constraints can severely limit oil production and reservoir drive energy. In this paper we will use a coupled reservoir-well model to demonstrate that oil production can be increased by using controlled inflow from a gas cone as a natural lift. This model was developed in the knowledge centre Integrated System Approach Petroleum Production (ISAPP) of TNO, TU Delft and Shell, and is based on a commercially available dynamic multiphase well simulation tool (OLGA) and a dynamic multi-phase reservoir simulator (MoReS). In order to give a proof of principle we have implemented a PID feedback controller, which controls the gas fraction in a well by changing its wellhead choke or inflow control valve (ICV) settings, on a realistic test case. We introduce a strategy to find an optimal production set point for this controller and the benefits of using downhole ICVs in comparison to the wellhead choke are investigated. Simulation experiments show that a PID controller is an effective means to prevent a full gas breakthrough and, moreover, can be used to increase the produced oil rate by tuning ICV settings to achieve an optimal well gas fraction. Results show that the coupled simulations could be significantly more accurate in comparison to stand-alone well or reservoir simulations. In current operations ICVs are mostly used to completely shut down well segments that experience gas coning. We show that by keeping these ICVs open in a controlled way the - otherwise undesirable - phenomenon of gas coning can be used to increase oil production. Copyright 2008, Society of Petroleum Engineers.