One of the basic requirements of the engineering advisory world is to provide independent certifications of oil and gas reserves and resources. GCA has extensive experience throughout the world’s petroleum basins in conducting grass-roots reserves and resource estimations and audits utilising the Securities Exchange Commission (SEC) and other stock exchanges’ (UK, Australia, Canada) rules and/or definitions promulgated by the Society of Petroleum Engineers (SPE), World Petroleum Congress (WPC), American Association of Petroleum Geologists (AAPG), Canadian Institute of Mining, Metallurgy and Petroleum (CIM) and other professional engineering bodies worldwide. GCA's work in this field is used for clients’ annual reporting, for corporate restructuring, for fund-raising through IPOs or Rights Issues, for project financing, in field and reservoir management and development, and in acquisitions and disposals.

GCA has well established reservoir evaluation services.  Our capabilities and experience span a wide spectrum: from single-well petrophysical analyses to 3D geological modelling; and from material balance calculations to fully compositional reservoir simulation.  Over the years, GCA has evaluated reservoirs in virtually every oil and gas basin in the world, and in all types of geological environments.  Our briefs have ranged from assessing and critiquing the work of others, to grass-roots reservoir analysis.