Stratigraphic Architecture and Evolution of Submarine Canyons and Other Sediment Conduits in the SE Loppa High, Barents Sea

Abstract

Hydrocarbon discovery in SE Loppa High comes from Triassic fluvial system. The Jurassic deep marine system on the other hand remains a budding topic as they are perceived as conduits for Middle Jurassic to Cretaceous submarine wedges and slope deposits, which are in turn are high quality reservoir and source rocks. Two seismic reflection cubes and four exploration wellbore comprising of checkshot, gamma-ray, density, and sonic wireline logs are the primary data for this study. The aim of this work is to evaluate the architecture and evolution of canyons, sediments conduits and hydrocarbon leads in the SE Loppa High. Seismic interpretation entails wellbore analysis, horizon and fault interpretation, morphometry analysis, seismic facies and attribute analysis, which led to the mapping of ten V-shaped and two U-shaped canyons from the data. These canyons are associated with two main seismic depositional elements i.e., conformable and thalweg high amplitude reflections. Slope gradient (E) is key to the development and evolution of the canyons. In proximal area where the slope is less than 50, V-shaped meandering canyons with width of 1-2 km are present while distal area with slope gradient of greater than 50 is mostly dominated by straight canyons. The U-shaped canyons have width of 3-6 km and are associated with mass-transport deposits in contrast to the V-shaped canyons that have turbidites within them. Both kinds of canyon show strong affinity to faults. On seismic sections, the mass-transport deposits are reflected as chaotic, transparent to high amplitude reflections. Turbidites in contrast show significant variation from very high amplitude reflection at the base to chaotic and heterogeneous mixture of low and high amplitude reflections towards the top. In this work, we demonstrate that canyons and other sediment conduits in the study area evolved in two phases. In the Early Jurassic when sand-rich erosional systems predominate and in Middle Jurassic to Cretaceous when fine-grained hemipelagic sediments and mass-transport deposits infilled the canyon and slope. The classification scheme presented in this study can help predict depositional processes, reservoir quality, reservoir distributions, and petroleum prospectivity of any submarine canyon and sediment conduits.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017