Regional Stratal Slice Imaging of the Northern Carnarvon Basin, Western Australia

Summary

Chevron has developed a method for merging, viewing, and interpreting multiple 3D seismic surveys in stratal slice domain. The products of this method are referred to as Regional Stratal Slice Volumes (RSSVs). Within the Northern Carnarvon Basin (NCB), NWS, Australia, local RSSVs have been built using a patchwork of 3D seismic data sets of various vintages and data quality covering an area of approximately 68,000 km². RSSVs have been built within the Triassic post-rift and Jurassic-Cretaceous syn-rift and post rift intervals. The Triassic section is comprised of a 4 plus km-thick interval of alluvial to shallow-marine deposits of the Late Triassic Mungaroo /Brigadier Formations and Early Jurassic North Rankin Formation, whereas the younger Jurassic-Cretaceous succession is comprised of a tectonically influenced Jurassic interval overlain by syn-rift to post rift Barrow Group.

Proprietary and vendor stratal slice imaging was performed in each 3D survey, spliced together, correlated with adjacent surveys, and combined with supporting structural, cultural and well-based data. This has created a temporal series of unbroken, regionally-extensive, chrono-stratigraphic seismic images which, when viewed successively, capture the evolving geomorphology and palaeogeography of the NCB.

RSSVs provide a predictive stratigraphic framework for the NCB. Triassic and Jurassic-Cretaceous RSSV analysis has resulted in an enhanced understanding of changing depositional environments at a regional scale providing insights into the regional distribution of intra-formational seals, presence of potential source rocks, and the distribution of fluvial, shoreline, and marine deposits. This work has been used to support local prospect and field scale evaluations and has influenced Chevron’s acreage position and strategy in the NCB.

• Stratal slice
• Seismic geomorphology
• Northern Carnarvon Basin