AUSTRALIAN MEGASURVEYS—THE KEY TO NEW DISCOVERIES IN MATURING AREAS?

Abstract

In a maturing province such as the North West Shelf, it is time-critical to find remaining hydrocarbon resources as well as to develop small finds before existing big field installations and their associated infrastructure are decommissioned. Finding the remaining smaller fields with subtle geophysical expression is a challenge, and a thorough understanding of the petroleum geology is essential. To achieve this, the subsurface structure and depositional systems must be understood in a regional as well as a local context.To date, exploration companies’ regional models have been based on a mixture of 2D and 3D seismic of varying vintages, orientations, and quality. Consequently they have been incomplete and lacking detail. To address this problem, PGS initiated the MegaSurvey Project, merging a number of 3D surveys into large, consistent 3D data sets. For the first time, the regional picture and prospect-size detail are both available from a single dataset.Two MegaSurveys for the North West Shelf are now available; the Vulcan Sub-Basin MegaSurvey (VMS) and the Carnarvon MegaSurvey (CMS).The MegaSurvey seismic data and consistent horizon interpretation (tied to released well control) enables asset- focussed oil companies to concentrate on the more detailed search-for-the-subtle-trap to find, understand, and develop remaining reserves. Interpretation of the first MegaSurvey (Vulcan Sub-Basin) was completed in 2004 and work is focussed on the Carnarvon MegaSurvey, the interpretation of which will be completed in March 2005.The PGS 3D MegaSurveys allow visualisation of the subsurface both on a scale and resolution that has hitherto been unavailable. They provide an essential new tool to help fully unlock the remaining potential of the North West Shelf.