A comprehensive analysis of transient rate and rate derivative data of an oil well intercepted by infinite-conductivity hydraulic fracture in closed systems

Abstract

This paper presents a method for analyzing constant-pressure drawdown test of infinite-conductivity fractured wells in bounded reservoirs. The presented method is based on the Tiab direct synthesis approach. The fracture and reservoir parameters are directly determined from the rate and rate derivative of the well test data. New equations describing the elliptical flow regime and the transition from the pseudoradial regime to the boundary-dominated regime of different rectangular reservoirs are also presented. The various flow regimes occurring during the well test are easily identified based on the shape of the plotted data and the slope of each flow regime. The unique features of the slopes of the various regimes and their intersection points are utilized to determine the fracture half-length, formation permeability, skin factor, well drainage area, and reservoir shape factor. Moreover, new equations defining the intersection points of the straight lines corresponding to different flow regimes are presented. These equations are very important for confirming the precision of the calculated results. A systematic process demonstrating the application of the proposed method to linear, elliptical, pseudoradial, and boundary-dominated regimes is well delineated. Comprehensive examples are presented to validate the efficiency of the proposed technique. The examples show that even if some of the flow regimes are not fully developed, the method can still be used to determine the formation and fracture properties using information obtained from the remaining flow regimes. This is one of several advantages of the proposed technique over conventional techniques.