| Recently, decline-curve analysis has expanded to permit engineers to analyze a petroleum reservoir directly in regard to its fluid-flow characteristics and its volumetric extent using rate-time type-curves of the constant terminal pressure solution of the diffusivity equation. This analysis is of enormous value to reservoir managers whose goal is to maximize oil and gas production from a petroleum reservoir. Reservoir extent, continuity, and flow capacity are paramount characteristics that are considered when developing models that predict reservoir performance while using alternative depletion strategies, such as during fluid-injection projects or enhanced recovery.; Reservoir producing conditions to which this technique can be readily applied are those whose actual bottom-hole flowing pressure (BHFP) closely approximates a constant value. Most wells, however, produce with variable BHFP. The work presented here focuses on an alternative rate-cumulative type-curve format whereby variable BHFP is incorporated into dimensionless variables containing both the production rate and the cumulative production providing a unified approach that can be applied to any reasonable variability in the producing rate or flowing pressure history.; The proposed method, with application to single phase and multiphase flow, provides the practicing engineer a better method for decline curve analysis and therefore propagates better reservoir characterization from production data. |
