Gas Re-Injection in the Laminaria and Corallina Fields, Timor Sea: Established Techniques, New Environmental and Commercial Benefits

This paper describes a gas re-injection project designed with the dual objectives of emissions reduction and enhanced oil recovery in an Australian offshore oil field. While gas injection for enhancing oil recovery is common oilfield practice, there are fewer projects that look exclusively at greenhouse gas (GHG) control (either by sequestration or emission reduction), although there is increasing environmental awareness in the industry on the benefits of doing so. The predominant contribution to total GHG CO₂-e emissions is from flaring. Significant reductions in flaring have been achieved since completion of commissioning of injection. Flare CO₂ emissions at the beginning of 2000 (February-March) reduced from approximately 163,000 tonnes per month to an average of approximately 26,000 tonnes per month over the remainder of 2000, and to 9,800 tonnes per month, over the first half of 2001. GHG efficiency, evident in the ratio of GHGs emitted per tonne of hydrocarbon produced, reduced from approximately 0.4 tonnes CO₂-e per tonne of total hydrocarbon produced before injection to 0.08 after injection over the remainder of 2000, and to 0.06 over the first half of 2001. Miscible displacement is expected to add around 6 million barrels to ultimate recovery from the Corallina reservoir. The use of stored gas as a fuel is expected to achieve significant reductions in operational expenditure later in field life.