Gorgon Project: Subsurface Evaluation of Carbon Dioxide Disposal Under Barrow Island

Abstract

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 116372, "Gorgon Project: Subsurface Evaluation of Carbon Dioxide Disposal Under Barrow Island," by Matthew Flett, SPE, Graeme Beacher, Jeroen Brantjes, SPE, Aaron Burt, Chris Dauth, SPE, Fiona Koelmeyer, SPE, Robert Lawrence, Seb Leigh, and Jason McKenna, Chevron Australia; Randal Gurton, and William F. Robinson IV, SPE, Chevron Energy Technology Company; and Terrell Tankersley, SPE, TengizChevroil, prepared for the 2008 SPE Asia Pacific Oil & Gas Conference and Exhibition, Perth, Australia, 20-22 October. The paper has not been peer reviewed. The Gorgon Project is a major liquefied-natural-gas (LNG) development in northwestern Australia. The reservoir fluids of several fields contain carbon dioxide (CO2), which will be extracted from the produced gas before liquefaction into LNG. The Gorgon joint-venture participants have proposed geological disposing of the produced reservoir CO2 at the Barrow Island LNG plant. Key drivers are maximizing per-well injection of CO2 and ensuring containment of CO2 within the reservoir. Effective subsurface and economic evaluation enabled building a phased and flexible development plan for CO2 disposal. Introduction The Gorgon and Io/Jansz gas fields will be developed initially as a subsea development with a tieback to Barrow Island, where the raw gas will undergo liquefaction for export. Production of gas also is considered for supply into the Australian domestic market. The Gorgon gas field has 14% CO2 in the reservoir-fluid composition. Reservoir CO2 must be removed from the raw-gas stream before manufacture of LNG because the liquefaction process occurs at process conditions at which CO2 is solid. A large-volume of high-pressure CO2 will be a byproduct from the necessary gas processing. Rather than emit the CO2 to the atmosphere, it is proposed to dispose of the separated CO2 into an unused saline aquifer, the Dupuy formation, more than 2000 m beneath Barrow Island. Over the life of the project, it is expected that more than 120 million tonnes of CO2 will be injected into the Dupuy formation at rates of approximately 3.8 Mt/a. Environmental Approvals The CO2-injection project was documented extensively, reviewed, and subjected to public comment as part of the Gorgon Project environmental-impact-assessment process for a 10-Mt/a LNG development. Following this process, the Western Australia (WA) Environmental Protection Authority found that the environmental risks associated with the CO2-injection project were acceptable and recommended that CO2 injection must proceed as an integral component of the Gorgon Project.