Depositional environments and architecture in arid alluvial deposits from the Devonian in the Southern North Sea

The MSc project will focus on the reservoir characteristics of fluvial sands and conglomerates, aeolian sands, and the interplay between these reservoir facies and the interdune non-reservoir shales. Specifically, the project aims to enhance the understanding of how reservoir properties develop, are preserved, and are distributed within these sediments. There has been a heightened interest in Devonian rocks on the Norwegian Continental Shelf following the Edvard Grieg and Solveig discoveries in the Utsira High region. Similar opportunities are also present in the southern North Sea, in the Grensen Nose area, where the Devonian Embla Field, with reservoirs within Devonian rocks (Buchan Formation), is located.

The Buchan Formation is believed to have been deposited in a dry, alluvial plain setting comprising alluvial fans and braided rivers depositing sand and conglomerate, aeolian dunes, and interdune lakes (Figure 1) (Knight et al., 1993).

Somehow, the reservoir is functioning, but the reasons for this are not fully understood. The reservoir properties are considered poor to moderate at best; however, despite this, the Embla Field has been producing since 1993. Is this due to a fractured reservoir (parts of the Buchan Formation are heavily fractured), or is it facies-controlled with slightly better properties distributed within specific facies? A detailed study of available material from wells is designed to improve the understanding of this stratigraphic interval.

The study will be based on traditional core work, utilising sedimentological logs and petrographic (thin-section) descriptions, supported by petrophysical logs and seismic data. Data and material from wells in the study area (e.g. the Embla Field) will be made available, as well as seismic data; however, the imagery of the Devonian in this area has a somewhat limited resolution.

Complementary data from UK wells (e.g. the Alma Field, as published by Tang et al., 2017) can also be made available, in addition to onshore field analogues in the UK (Figure 2 & Figure 3).

Knowledge goals: 

The candidate will become familiar with the sedimentology and depositional architecture of arid alluvial and aeolian environments, as well as the factors that influence their reservoir behaviour. The primary focus will be on the Devonian of the southern North Sea.

Skill goals:

• The candidate will employ and become proficient in methods such as sedimentary logging of core material and the analysis of thin sections.
• The candidate will develop skills in conducting independent research to solve a problem by integrating methods, theory, and data to test a hypothesis.
• Additionally, the candidate will use conventional word processing and illustration-type software to compile the thesis.