Continuous flow gas lift is one of the most common artificial lift methods in use. It works by injecting a continuous volume of high pressure gas into the tubing or tubing/casing annulus to lighten the column of oil and thus facilitate extraction. Excessive gas input is costly because of high gas prices and compressing costs. Inefficient gas allocation in a field with limited gas availability also reduces production and profitability.
Historically, a sensible allocation was achieved using a technique called the equal slope allocation method. This method uses graphical procedures to optimally allocate gas to a group of wells in order to optimize total oil production. However, there is a disadvantage in this method, as it can not be applied to wells where there is not an instantaneous response to gas injection.
The purpose of this paper is to present a methodology for automatically determining the optimum gas injection rate for a group of wells in order to maximize the total oil production rate for a given total amount of gas.
The search algorithm proposed is a combination of stochastic domain exploration and a heuristic calculation of a descent direction, in order to avoid stopping the algorithm at a local optimum.