Estimating Drainage-Area Pressure With Flow-After-Flow Testing

摘要

Estimating the average drainage-area pressure (p_(av)) of individual wells is a cornerstone to any reservoir-management practice. Yet conventional methods do not always offer reliable solutions to this vexing problem. This study shows that transient flow-after-flow (FAF) testing offers an excellent opportunity to establish p_(av) in a time-lapse mode, when conducted following operational shutdowns. Instrumented wells are natural candidates for FAF testing. Real-time surveillance offers the opportunity to perform rate-transient analysis that results in drainage volume and, consequently, p_(av). However, gathering quality rate data commensurate with pressure over a long producing period is fraught with uncertainty, which raises questions about the validity of the p_(av) so obtained. In addition, continuous changes in drainage-boundary conditions pose modeling challenges with a given reservoir model. Therefore, the independent estimation of p_(av) cannot be overemphasized. This paper presents a theroretical framework for transient FAF testing and also shows a pragmatic approach to handling pressure/rate data incoherence.