Pressure Transient Analysis of Hydraulically Fractured Wells in Multilayered Reservoirs

Abstract

New equations for bilinear, formation linear and pseudo-radial flow regimes in an infinite commingled fractured multilayered reservoir have been developed. The equations have been extended to Tiab’s Direct Synthesis Technique that makes it easy to estimate the individual layer properties without type curve matching. Regardless of the flow regime, the rate normalized pressure derivative with respect to the appropriate time function has been found analytically to be constant, which depicts a horizontal line on the derivative curve. This precludes the need to calculate the slope as is conventionally done and aids in easy model diagnosis or system identification and estimation of layered parameters. Dimensionless pressure and pressure derivative functions which were derived by Bennet et al 1 for an infinite commingled fractured multilayered reservoir have been extended to Tiab’s Direct Synthesis Technique to evaluate the average fracture and layer properties without type curve matching. These equations make it possible to predict the pressure response of a fractured multilayered commingle reservoir. A procedure for estimating the individual layered properties without type curve matching is included. This procedure is applicable to the interpretation of pressure and pressure derivative analysis, rate and rate derivative analysis, rate normalized pressure and derivative analysis and deconvolution both in real space and Laplace space.