A General Method for the Flow Diagnosis and Interpretation of Well Tests

Abstract

This paper presents a new technique for transient pressure analysis, based on a general diffusivity equation for any of the different coordinate systems. Essentially, this method consists in the identification of a flow exponent n for which the pressure resposne graphed in a log-log scale in terms of versus t would show a horizontal behavior. It is demonstrated that the value of this exponent corresponds to the flow pattern (diagnosis; for example, linear, radial, spherical, etc., flows), and the intercept is inversely related to the formation conductivity . For cases of highly heterogeneous formations of fractal propeties, the value of the n exponent could be different from any of the most well known exponenet values (linear;1/2; radial, 0; spherical: -1/2 ; bilinear: ¼; and pseudosteady state: 1). Introduction Multiplying the general diffusivity for any coordinate system by the formation thicknes h; (1) This version of the fundamental fluid flow equation that has been the basis of the well test analysis, includes the following three reservoir engineering parameters,Formation conductivity, .Porosity-thickness product, , related to the volume of hydrocarbons in place.Reservoir pressure(energy), , The main purpose of this paper is to present a new technique for transient pressure analysis, based on a general diffusivity equation for any of the different coordinate systems. This method consists in the identification of a flow exponent n for which the pressure resposne graphed in a log-log scale in terms of versus t would show a horizontal behavior.