Methodfor obtaining a dimensionless representation of well pressure data without the use of type-curves

摘要

A method for determining desired physical characteristics of an underground formation is provided. The present invention is characterized by a determination of dimensionless pressure parameters without resort to a series of type-curves. The method includes finding a pressure match that relates a dimensionless function of pressure with experimental pressure data and finding a time match that relates a dimensionless function of time with dimensioned time. In one embodiment, this determination is made using a pressure derivative curve plotted on a computer terminal display screen. An interactive graphics software package is utilized in which the user selects certain values associated with the experimental data for which corresponding dimensionless values are known. From the determined values of pressure match and time match, a dimensionless function of pressure curve and a dimensionless pressure function derivative curve are provided on the display screen. Type-curves represented by dimensionless parameters are also provided. A selection of an appropriate interpretation model is made using the experimental pressure function curve and one of the series of type-curves. From the selection, the user is able to determine the physical characteristics of the underground formation.