Transient Pressure Behavior of Multiple-Fractured Gas Wells

Abstract

ABSTRACT Virtually all studies on transient pressure behavior of fractured gas wells assumed a single fracture of equal half-length emanating from the opposite sides of the wellbore. However, multiple fractures may result from explosive, tailored-pulse fracturing, and hydraulic fracturing treatments. This paper presents the results of using a polar-coordinate simulator to investigate the transient pressure behavior of gas wells with 4-wing, 6-wing, and 8-wing multiple fractures. Results show that the dimensionless pressure, PwD, can be correlated with the dimensionless terms Cr = wkf/πkxf and xfrl2 = xf1/xf2 where Cr is the dimensionless fracture conductivity and Xfr12 is the fracture half-length ratio. The symbols, xf1 and xf2, represent the half-length of the primary fracture and the auxiliary fracture, respectively. Results also show that when Cr ≤ 10, multiple fracture transient pressure behavior is significantly different from that of a single-plane fracture. A family of type curves was constructed using cross-plots of pwD vs. tDxf. Transient pressure data can be analyzed using these type curves to estimate the number of multiple fractures in addition to formation permeability, fracture length, and fracture conductivity. Errors of about 5% in fracture length and 28% in formation permeability could result from the use of singlefracture type curves.