Accurate data from undamaged core is key to evaluating the substantial reserves of moderate to highly viscous oil held in Arctic unconsolidated formations.

This paper describes a laboratory technique which can be used to design trip schedules to reduce gas-in-viscous-oil expansion core damage. This technique, based on X-ray CT core structure visualisation, indicates the majority of core dilation due to retrieval occurs during the last 500 psi (3.45 MPa) of decompression. Reducing the trip rate over the latter stages of the trip will therefore result in better quality core.

Improved fibretube core processing systems compact enough for Arctic enclosed rigs; and methods of preserving core structure through the rigours of Arctic transportation are also described in this paper.

Keywords:
dry ice, freezing, fibretube, disturbance, transportation, viscosity, unconsolidated core, retrieval, core dilation, sediment
Subjects:
Drilling Operations, Formation Evaluation & Management, Coring, fishing
Copyright 1991, Society of Petroleum Engineers
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