Significant effort usually goes into deciding the optimum completion and generating production forecast of new wells. However, due to uncertainty of certain reservoir parameters, the completion decision may not be optimum and may result in non-economic well. We focus in this paper on answering the following questions:(1) what is/are the optimum perforated interval(s)?, and (2) what is the optimum economic production rate for vertical wells in water drive oil reservoirs?. Obtaining the right answer for these two questions will give us the opportunity to make the right completion decision.

Several models are available to predict the critical coning rate. In many cases, the calculated critical rates are too low, and for economic reasons, wells are frequently produced at higher rates. In this paper, we present a new approach for the determination of the economically optimal production controlling parameters from water drive oil reservoirs.

In this approach, static and dynamic models are constructed to model the well and the surrounding reservoir properties. Two experimental design techniques are used to test the uncertainties in reservoir parameters and identify the most important optimization parameters. The model is linked to an economical model to calculate certain economic indicators. Then an optimization process is applied to find the optimum production controlling parameters to achieve maximum economic oil recovery.

Many cases were tested with this approach. Then, the optimization results were compared with the critical rate correlations' results. It was found that the chosen drawdown and perforation interval(s) provided safe operation range for water cut, while allowing reasonable economic gain. Therefore, this new approach is recommended over the available critical rate coning models, to define the optimum production controlling parameters to achieve optimum economic recoverable oil volumes in water drive oil reservoirs.

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