ABSTRACT:

This paper focuses on a new methodology for increasing the critical oil rate, based on the attempt of dynamically controlling the water cresting phenomenon by resorting to a stacked dual multilateral well, with the upper drain drilled above the oil-water contact to produce oil and the lower drain producing from the aquifer beneath, thus controlling the water level rise and increasing final oil recovery. Also, if optimized rates can be imposed, one fluid only is produced by each drain, considerably reducing costs for wellhead separation. Numerical models were generated to investigate the influence of geometrical, petrophysical and fluid parameters as a function of the imposed production oil rates. Water rate to control water cresting strongly depends on the reservoir geometry and petrophysical properties, but also on the aquifer geometry and strength. The position of the two drains with respect to each other and to the oil-water contact rather than their length seemed to affect the simulation results. Preliminary results indicated that water control can be effectively achieved under certain conditions, and that oil recovery mainly depends on the ratio between the upper and lower drain production rates. However, the technique might become not economic when relatively high mobility ratios exist. Basic guidelines for optimal dual flow horizontal well configuration to anticipate and maximize cumulative oil recovery are provided, based on the numerical simulation of the reservoir dynamic behavior under a wide range of possible scenarios.

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