Integrated Simulation Study of a Gas Condensate Field with Nitrogen and Hydrocarbon Recycling

Abstract

This paper presents a feasibility study for the development of the unexploited outlying area of a gas condensate field operating under gas recycling mode to optimize condensate recovery. Heavier components have migrated to the flanks which is the motivation to exploit this area. To maintain reservoir pressure the voidage replacement ratio must be maintained at 100%. However, due to high demand for natural gas, a certain percentage is replaced with non-hydrocarbon makeup gas. This strategy has the potential to reduce the condensate recovery as well as affect the quality of the produced gas.A reservoir simulation study was conducted to maximize the condensate and clean gas recovery through development of the flanks. Two major scenarios were created consisting of more than twenty different development strategies based on well location, number of wells and well production rates. Additional sensitivities on blow down time, under-injection, injection stream composition and compression were considered for both scenarios. The influence of the surface infrastructure on production performance has been quantified by the application of Integrated Asset Modeling, which improves the accuracy of the standalone reservoir simulation scenarios.The study highlighted a significant upside in terms of oil recovery by exploiting the outlying area of the field. Multiple optimization scenarios were performed and a maximum gain of approximately 10% in recovery was observed above the base case. Integrated Asset Modeling led to more optimistic estimates of future recovery and reduced makeup gas production, through the removal of simplifying assumptions related to back pressure and injection composition.