Optimization of Oil Field Production Under Gas Coning Conditions Using the Optimal Closed-Loop Estimator

In an oil field that has reached its maximum gas handling capacity, and where wells are producing under gas coning conditions such that the gas-oil ratio (GOR) depends on the wells production rate, oil production is maximized if the marginal GOR (mGOR) is equal for all wells. The GOR and the mGOR are not readily available measurements, but they can be predicted using detailed reservoir models. In this paper we propose predicting the mGOR for each well from measurements like pressure and valve position by using the static linear optimal closed-loop estimator. The estimator can be generated for each well individually, and it is not necessary to consider the production network as a whole. The optimal closed-loop estimator is intended for use in combination with feedback. Based on a simple two-well case study, we show that the method is effective and results in close-to-optimal production.