Theoretical Investigation of Factors Affecting Water Breakthrough Time in a Horizontal Well Subject to Bottom Water Drive

Abstract

Water breakthrough marks end of economic life of a reservoir. It has negative influence on recovery, operations, and economics. This means that delaying the encroachment and production of water is a means of maximizing the ultimate oil recovery, operating at higher efficiency and maximizing profit. This theoretical research is aimed at solving for time water will breakthrough a horizontal well placed in bottom-water reservoir. And subsequently, suggest ways to delay the water breakthrough time. Thus the model herein is a repository of three aims of reservoir modeling; predict, optimize and monitor oil production. Well modifications strategies were suggested to achieve significant delay of water breakthrough. The well in a bottom-water reservoir, which is much longer than the well, experiences four flow regimes, namely, early-time radial flow, early-time linear flow, late time pseudo radial flow and late-time linear flow period within which water breakthrough occurred. Each flow regime was represented mathematically. The resulting integrals were evaluated numerically. From the mathematical model, factors affecting water breakthrough were chiefly wellbore, reservoir fluid and reservoir properties. Their effects are evident in computed dimensionlesss pressure,, end of early radial flow, tDe, and dimensionless flow time, tD. Water breakthrough was evidenced by constant PD value. Delayed water breakthrough is favoured by narrow well, shorter well, low viscous fluid, low flow rate and high horizontal permeability relative to vertical permeability. Viscosity of oil can be reduced by gaslifting, EOR thermal process, etc. Higher values of and tDe can be achieved by increasing the horizontal permeability,kh, while vertical permeability,kv, is reduced. Suitable stimulation process can achieve improved permeability.Special functionserf error function =Ei exponential integral function Ei(x) = [