Analytical Expressions for Pseudoskin for Partially Penetrating Wells Under Various Reservoir Conditions

Abstract

Abstract Many times, oil reservoirs are accompanied by bottom-water zones and/or gas caps, and these reservoirs are produced using partially-penetrating wells. An extra pressure drop occurs around such wells during production because of partial penetration. Several correlations have been presented in the literature to estimate pseudoskin for a partially-penetrating well located in either a homogeneous or a layered reservoir with closed top and bottom boundaries. This study aims to develop new analytical expressions for pseudoskin for partially-penetrating wells in multi-layered reservoirs with both closed top and bottom boundaries, and with bottom-water zones and/or gas caps. A pseudosteady-state interlayer crossflow has been assumed in this study. These new analytical expressions are simple and easy to use. Evaluaion of pseudoskin using these expressions requires a knowledge of two parameters when the top and the bottom boundaries are closed, and three parameters in the presence of a bottom-water zone or a gas cap, regardless of the number of layers. The estimated pseudoskin is very close to the actual pseudoskin obtained from the complete analytical solution. These new analytical expressions are also applicable to the corresponding homogeneous and single-layered cases. The estimated pseudoskin values have been compared with those estimated by other researchers. Effects of the open interval location, the presence of bottom-water zone and/or gas cap, and the layer refinement on pseudoskin have also been studied.