A Simplified Method for Water Coning Predictions

Abstract

ABSTRACT Numerical simulation was used to determine the sensitivity of water coning behavior to various reservoir parameters. The simulation results were then used to develop a simplified correlation for water coning predictions. The correlation is general since the sensitivity studies cover a wide range of reservoir parameters (ratio of vertical to horizontal permeability from 0.01 to 1.0; perforated interval from 20 percent to 80 percent of oil zone thickness; production rate from 500 to 2000 RB/D gross fluid; mobility ratio from 1.0 to 10). The correlation is valid to predict watercut performance for most reservoirs with strong bottom water drives except those with local barriers present, those with a high degree of stratification (Dykstra-Parsons Permeability Variation > 0.8), or those with a thick oil-water transition zone. With the correlation programmed on a hand-held calculator, field engineers can conveniently predict critical rate, breakthrough time and watercut performance. Compared to complicated numerical models, the correlation is particularly useful when detailed reservoir data are not available, or when decision time and project cost are limited. Field engineers can use the simplified correlation to compare watercut performance for various operating strategies and make appropriate decisions for production operations.