ABSTRACT
Gas-lift has been practiced for many years using principles developed in the 1940's and 1950's. For the most part, these principles have been developed based on experience and "rules of thumb" with little or no regard for actual valve performance. This paper describes the use of a software program that simulates the unloading and lifting of a gas lift well using scientific principles and valid valve performance data.
A brief explanation of the function of the program is provided and then investigated in more detail as it is applied to a planned gas lifted completion in the North Sea. A conventional design methodology is presented and its validity examined with the simulation software. The paper highlights areas of current design methodology which may lead to problems such as multi-point injection, unstable gas injection rate, and excessive lift gas use.
Explanations are given for the occurrence of the problems and suggested modifications are presented to avoid the problems.
