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Discerning the temporal and spatial generation of the Alpha and Beta closures in the Smeaheia prospect by 3D seismic interpretation and cross-section restoration

The Smeaheia CO2 storage prospect envisages safely injecting and storing up to 1.3Mt of CO2 within Jurassic siliciclastic reservoirs (Sognefjord and Fensfjord formations of the Viking Group) of the Horda Platform (Blocks 32/4 and 32/1 of the North Sea) over a 25-year period. The area which lies approx. 20km east of the Troll A platform is structurally complex owing to rift phases during the Permo-Triassic and Mid-Jurassic which have resulted in north-south trending basement-involved faults and a population of northwest to southeast striking subsidiary faults.

Two of these basement-involved faults, i.e., the Vette fault to the west, and the Øygarden fault to the east bound the Smeaheia prospect. Two main closures, Alpha and Beta (Figure 1), have been defined as trapping structures, which developed as fault-propagation features during accrual of displacement on the aforementioned faults. The overburden consists of the Draupne Formation, a mudstone-rich marine deposit, which forms the main top-seal and the overlying Cromer Knoll, and Shetland groups, which comprise carbonates and deep-water sediments. The overlying sequence comprises the mud-dominated Cenozoic succession. Structurally, the overburden is affected by tectonic and polygonal faulting, glacial scouring, and pockmarks, the inter-connectivity of which (if any) have to date not been adequately described.

Figure 1. Details of the structural architecture of the Alpha and Beta prospects

We seek a motivated MSc student to address knowledge gaps in the structural framework and evolution of the Smeaheia area that will help de-risk the proposed injection and storage of CO2 in the prospect. Students will primarily work with high quality 3D seismic workflows (e.g., Figure 2), which will be beneficial for future careers/research in CO2 storage or hydrocarbon exploration. Work on the projects will begin in spring 2018, with a completion date of 1st June 2019.

Figure 2. Workflow diagram illustrating seismic investigation and fault analyses methods being applied to the structural de-risking of the Smeaheia prospect

The Alpha and Beta structures form potential trapping enclosures both of which abut against large basement-involved faults, the Vette and Øygarden faults, respectively. The closures appear to have formed due to fault bends and up-section propagation of faults. Given that the Alpha structure formed in a footwall, and the Beta formed in a hanging wall, they show different large-scale geometry and internal architecture. Neither structure has been charged by hydrocarbons despite similarity with the neighbouring hydrocarbon prolific fault blocks.

This project seeks to describe the spatial and temporal evolution of these closures and associated faults with an aim to reconcile the observed lack of hydrocarbons with potential paleo-hydrocarbon migration routes.

The study has further potential of addressing how the Vette and Øygarden faults act as barriers to fluid flow both presently and during their development.   

Seismic interpretation of 3D datasets, cross-section restoration, application of basic fault-seal analysis.

Learning and skillsets:
Proficiency using Schumberger Petrel E&P Software Platform and Midland Valley Move. Independent research, academic writing and presentation skills.

Tags: Structural geology, carbon capture and storage, seismic interpretation, fault analysis, back-stripping/restoration, North Sea geology
Published Nov. 12, 2018 11:21 AM - Last modified Nov. 12, 2018 11:21 AM

Scope (credits)