Method for measuring in-situ hydraulic properties of anisotropic formations at depth

The pressure decay during the so-called pressure pulse test is analyzed for a formation with anisotropy in hydraulic properties and, based on the analysis, a method is proposed for evaluating in-situ anisotropic hydraulic properties. The basic idea of the method comes from the fact that the pressure decay is almost completely governed by the radial-flow of permeation from the well bore into the formation when the pressurization interval is long enough, but it depends on-both of the radial- and axial-flows when the pressurization interval is short. The method consists of two steps of the so-called type-curve-fitting and utilizes two sets of pressure decay datum which can be obtained by conducting the pressure pulse test twice in one well bore at a same depth for two pressurization intervals of different length from each other. The process of the type-curve-fitting requires very subtle observation and it seems very difficult to perform the type-curve-fitting manually by visual inspection in the anisotropic cases. Here, in the present paper, an automatic and objective method for the type-curve-fitting is also developed by using a technique of three-dimensional optimization.