SOLAG: An Intelligent Gas Lift Optimization System for Continuous and Intermittent Gas Lift Wells

Abstract

Abstract Offshore production operations in Lake Maracaibo field are characterized by having an average of 4,500 gas lifted wells, producing from more than 400 different reservoirs. These complex processes require constant surveillance to allocate the proper gas injection rate for each well, based on available gas from each one of the seven existing gas compression and distribution systems. To determine the required gas injection rate for each well in a distribution system, we developed in 1980 a computerised system celled SOLAG which stands for Gas Lift Optimization System. This system has been upgraded during the past 12 years and it capable of analyzing and selecting the appropriate production data from field measurements, determining individually the optimum gas injection rate based on the actual gas lift method, and finally allocating the required gas injection rate based on two situations that could be present in a distribution system: (1) available gas is greater than required, and (2) available gas is less than required. In-house mathematical correlations are used to estimate optimum gas injection ratea for continuous and intermittent gas lift wells. Another feature is the application of artificial intelligence to represent the knowledge needed to interpret and select proper data from field measurements. In this paper we describe the system, the mathematical correlations used to estimate optimum gas injection rates for each well, and our approach for allocating a total volume of available gas in a group of wells. Examples are used to illustrate the application of the system.