Determination of Fissure Volume and Block Size in Fractured Reservoirs by Type-Curve Analysis

Abstract

ABSTRACT A new type-curve is presented for analyzing wells with wellbore storage and skin in double porosity systems. This type-curve applies to damaged, acidized, and fractured wells in fissured reservoirs. In addition to the usual well and reservoir parameters (permeability, skin, wellbore storage constant and length of the fracture intersecting the well), analysis yields characteristic parameters that can provide quantitative information on the volume of fissures and the size of porous blocks in the reservoir. These, in classical methods, could only be obtained if semilog radial flow were present at both early and late times, (thus yielding two characteristic parallel semi-log straight lines on a Horner plot), a condition that is seldom satisfied in practice. The analysis method presented in the paper is illustrated with actual field examples from several different fissured reservoirs.