6.4.3 Latrobe Valley and Otway Basin, Australia

The Chevron-Shell-ExxonMobil Gorgon Project will store CO2 resulting from the production of natural gas in the Greater Gorgon area fields (coast of Western Australia). On September 14, 2009, Chevron Australia and its Foundation Participants, ExxonMobil and Shell announced a Final Investment Decision on the Gorgon Project. In August 2009 the Gorgon Project also completed its environmental assessment process. The environmental approvals were the result of 6 years of preparation, including the research and contributions of numerous independent experts and extensive community consultation. The EIS (Environmental Impact Statement) completed in May 2006 details the risk process used as well as its results. The environmental risk process has evaluated the likelihood (using a qualitative scoring system) and consequences of adverse environmental impacts. Potential risks and environmental consequences were identified by technical experts in a broad range of fields through a series of workshops. Some deterministic "what if" scenarios as well as a probabilistic approach were taken with respect to managing uncertainties associated with CO2 storage, including identifying, evaluating, and generating options for managing subsurface risks. Extensive monitoring activities are planned to manage and reduce uncertainty associated with CO2 injection / storage activities. A plan has been proposed to manage events such as unpredicted migration of the CO2, unacceptable formation pressures, corrosion of pipelines and wells, and others. The probability of CO2 migrating to the surface has been determined to be remote. Studies of the area have determined that the containment risk (risk of containment failure) is extremely low, and unacceptable risk associated with CO2 storage at any point would likely result in venting of the CO2 to the atmosphere. Potential impacts on the project were evaluated in terms of: health, safety, and environmental issues; containment; monitoring and verification; injectivity; capacity; risk to hydrocarbon / other assets; cost. Responses to these potential impacts (such as using relief wells, if necessary, to release formation pressure and mitigate the risk of migration along faults or fractures) were developed and are described in the EIS (CSLF, 2009; Chevron Australia Pty Ltd, 2006; http://www.chevronaustralia.COm/ ourbusinesses/gorgon.aspx).