Transient Rate Behavior of Finite-Conductivity Asymmetrically Fractured Wells Producing at Constant Pressure

The transient rate behavior of finite-conductivity asymmetrically fractured wells producing at constant pressure is presented in this work. A new semi-analytical solution is obtained by means of the Green’s functions method. Two sets of type curves are developed: log-log curves of l/q_wD versus $tDxf$⁠, intended for rate performance forecasting, and log-log curves of $(1/qwD)/(2∂(1/qwD)∂lntDxf)$ versus $CfD2tDxf$⁠, for use in fracture characterization. The various transient flow periods are documented.

Asymmetry is measured by the parameter a, which varies from zero, in the symmetric case, to one, in the case of a well located at the tip of the fracture. Analysis of results indicate that the occurrence and duration of the bilinear flow period is greatly influenced by the asymmetry of the fracture. It is also found that the late time transient rate behavior of the well is not practically affected by asymmetry when a ≤ 0.4, in the whole range of fracture conductivities examined, 0.1 ≤ C_fD ≤ ∞. No effects are either evidenced when C_fD is larger than approximately 30. Correlations to calculate pseudo-skin factors caused by fracture asymmetry are provided.

An example of application is included to illustrate the use of the type curves for fracture characterization and for production forecasting of the well.