Assessment of NPV uncertainty on heterogeneous reservoirs during polymer flood

Abstract

This study shows net present value (NPV) distribution by considering uncertainties in porosity, oil viscosity, water saturation, and permeability for polymer flood with Monte Carlo simulation. For high and low average permeability conditions, differences of NPV between polymer flooding and water flooding have been investigated. According to results both average NPV and range of NPV distribution tend to increase with porosity and permeability in all cases. Although water saturation and oil viscosity affect NPV, they are not important parameters that conclude uncertainty of NPV under the conditions considered in this study. For high permeability model which has Dykstra-Parsons coefficient (DP) as 0.72 and porosity as 0.3088, Monte Carol simulations for polymer flood show that 50th percentile (P50) of NPV is 352.81 M$. If porosity is decreased from 0.3088 to 0.1912, the P50 is also decreased 63.8%. The reduction of NPV during polymer flooding in low permeability reservoirs are almost 40% higher than that of water flood. These differences come from polymer adsorption and permeability reduction that easily occurs in low permeability zone. The procedure has proven to be useful tool to generate probability distribution of NPV when polymer flood is selected as a tertiary flood process.