The shelf to deep-water transition using analogues to understand the pressure regime in un-drilled Labrador basins

摘要

The Labrador Shelf extends from the Davis Strait in the north through the Saglek Basin and down to the Hopedale Basin in the south, along the NE margin of East Canada. The majority of wells have been drilled in the Hopedale Basin. The water depths of wells drilled to-date are typically 100-200m, with only rare wells such as Hopedale E-33 and South Labrador N-79 drilled in water depths > 500m. Mud-weights used in many of the Labrador wells are low; however, there are occurrences in wells such as Pothurst P-19 of very high kicks taken, implying under-balanced drilling and highly pressured shales at depth. These highly overpressured shales (and associated reservoirs) are likely a feature of the deep-water where they will present a drilling hazard, as in similar deep-water settings worldwide. To-date, all drilling has been therefore on the Shelf, whereas recent shooting of seismic in offshore Labrador has suggested new interest in the deep-water. Following the announcement on September 13, 2011 to shoot large-scale multi-client 2D seismic survey of offshore Newfoundland and Labrador into the deep water, understanding the shelf-to-deep water transition becomes even more crucial. In the absence of well penetrations in the deep-water, the use of analogues becomes vital.