Decline Curve Analysis Using Type Curves — Fractured Wells

Abstract

AbstractThis work provides the development, validation, and application of new decline type curves for a well with a finite conductivity vertical fracture centered in a bounded, circular reservoir. This work fills a significant void in the modern inventory of decline type curves. In particular, this work is directly applicable to production data analysis for cases taken from low permeability gas reservoirs.Using an appropriate analytical solution for this case, we prepared "decline" type curves for FcD values from 0.1 to 1000 -individual type curves are generated for each FcD value using a range of reD values from 2 to 1000. The following "type curves" are provided: "Fetkovich" format rate-time decline type curves (constant pressure case): qDd versus tDd"Fetkovich-McCray" format rate-time decline type curves (equivalent constant rate case): qDd versus tDd"Fetkovich-McCray" format rate-cumulative decline type curves: qDd versus NpDdWe provide an example demonstration of the methodology for decline type curve analysis using a field case of continuously measured production rate and surface pressure data obtained from a low permeability gas reservoir.These solutions/type curves provide an analysis/interpretation mechanism that has not previously been available in the petroleum literature. Compared to field data, we find that the traditional type curve solutions for an infinite conductivity vertical fracture are typically inadequate — and, the new solutions for a well with a finite conductivity vertical fracture clearly show much more representative behavior. This validation suggests that the proposed type curves will have broad utility in the petroleum literature — particularly for applications in low permeability gas reservoirs.