Evaluation of Fracture Asymmetry of Finite-Conductivity Fractured Wells

Abstract

This paper presents a graphical technique to evaluate asymmetry of hydraulically fractured wells. This technique is based on a new analytical solution for the pressure behavior of a finite-conductivity, asymmetrically fractured well during the pseudolinear flow period and the known bilinear flow solution. A semianalytical solution for transient flow toward finite-conductivity, asymmetrically fractured wells producing at constant rate is also presented. This solution was used with the analytical solution to analyze the pseudolinear flow pressure behavior. An expression relating dimensionless fracture conductivity, C{sub fD}, and asymmetry factor, a, with a parameter calculated from analysis of well-test data, {beta}{sub a}, was developed by combining the pseudolinear and bilinear flow solutions; a graph of a vs. {beta}{sub a} with C{sub fD} as a parameter is then constructed. The parameters {beta}{sub a} and C{sub fD} are calculated as follows: {beta}{sub a} = 0.309 m{sup 2}{sub bf}/(b{sub Lf}m{sub Lf}) and C{sub fD} = 2.944 m{sub Lf}m/m{sup 2}{sub bf}, with m{sub bf} as the slope of the bilinear {Delta}p-vs-t{sup 1/4} straight line, m{sub Lf} and b{sub Lf} as the slope and intercept of the pseudolinear {Delta}p-vs-t{sup 1/2} straight line, respectively, and m as the slope of the semilog {Delta}p-vs.-log t straight line obtained during themore » pseudoradial flow period. Correlations developed apply indistinctly to oil and gas wells. Published field data were reanalyzed with the technique presented here and asymmetry was detected.« less