Program for designing pressure transient tests

Abstract

Well tests provide valuable information for reservoir characterization. Formation permeability, wellbore conditions, average pressure, drainage volume, directional permeability, and orientation are useful information that can be derived from analysis of well tests. However, for well tests to be useful, there is a need for proper design of the test. Well-test design involves using assumed reservoir properties to calculate the time when wellbore storage effect will cease, duration of the transient period and the expected pressure change during the test period. This information will be useful for selecting the type of gauge, clock, and other equipment to be used for the test. In addition, the appropriate duration of the test will be determined. This paper explains the procedure for well-test design and also gives a computer program for designing drawdown, buildup, and interference tests. By supplying the required data, the program calculates the necessary information. Example calculations are made with typical rock and fluid properties from the Niger Delta. The results obtained with the computer program agree with the results obtained using a desktop calculator. However, the use of the computer program enhances the speed with which the design can be made and also allows for more investigation of factors that can influence tests.