1962 Paper H

PETROPHYSICAL INTERPRETATION OF FORMATION TESTER PRESSURE BUILD-UP RECORDS

by Sylvain J. Pirson Petroleum Engineering Department The University of Texas Austin, Texas

ABSTRACT

The common analysis of Formation Tester pressure build-up records consists in the determination of the flow capacity of the formation and of the static pressure. By applying the Pollard Analysis Method of Pressure Build-up tests as extended by Richard S. Pirson and the present writer (SPE paper 101 - Dallas Meeting, October 8-11, 1961) it is possible to evaluate the total porosity partition into fine pore volume (matrix porosity) and coarse pore volume (fracture, fissure, vug, joint porosity). This information is of importance in the proper evaluation of logs from reservoir rocks of multiple type porosity systems, especially in carbonate rocks, by either the method proposed originally in 1957 by the writer or by the method proposed by Hilchie and the writer (SPWLA Dallas Meeting, May 18-19, 1961). The porosity partition parameter is also useful as a measure of the conformance factor to fluid injection operations in reservior engineering. Examples of application are given. When the fluid recovered is mostly water (either formation or mud filtrate) the interpretation is simple and straightforward. When the fluid recovered is gas primarily, the analysis method must be modified in order to take into account the gas compressibility and its deviation from Boyle's law.