Reservoir Performance History Matching Using Type-Curves.

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