Publications

Remobilised deposits – detached (e.g. slumps and debrites) and in-situ (e.g. load, flame, ball-and-pillow structures, and sand dyke) – were found within deep-to shallow-marine, Palaeocene successions in the HN Field. Unlike regional-scale remobilised deposits that can be easily recognised in seismic reflection data (e.g. mass-transport complexes), small-to-medium scale (cm to 10s of m) remobilised deposits are subseismic in scale and poorly documented. Thus, their importance, especially in reservoir description, is poorly understood. This study aims to evaluate the stratigraphic distribution of small-to-medium scale remobilised deposits and their impacts on reservoir geometry prediction, by utilising cores and image logs. There are two main parts of the study: (1) core description and interpretation (c. 331 feet), and (2) reevaluation of existing image logs interpretation. The core study shows that detached deposits (>1 feet) are thicker than in-situ deposits (<0.5 feet). Although the in-situ deposits appear to be insignificant, a potential injectite reservoir was identified in an interpreted channel axis, as evident by a 0.5 feet height sand dyke within a brecciated mudclasts sandstone. This smallscale feature might represent a larger injectite system. Analogues of injectite reservoirs in other fields, which had previously been interpreted as debrites, support this interpretation. The image logs study reveals the presence of a 70 feet thick, slumped sandstone succession. This slump is characterised by east-dipping beds (c. 50°) at the base and west-dipping beds (c. 40°) at the top. The scale and dip directions of this deformed deposit suggest a local, channel complex margin failure. This sub-seismic reservoir complexity could affect reservoir properties, geometry and connectivity, and it cannot be recognised by standard wireline logs (e.g. GR log). This study demonstrates the value of utilising cores and image logs for describing small-to-medium scale remobilised deposits. These deposits, although often neglected, can have significant impacts on reservoir geometry prediction, which ultimately affect reserves calculation.