Kevin P. Corbett¹, Werner Leu², Janell D. Edman³, Anne-Marie Jepsen⁴

(1) The Anschutz Overseas Corp, Denver, CO
(2) Geoform AG, Winterthur, Switzerland
(3) Marathon Oil Company, Littleton, CO
(4) DONG E&P, Hørsholm, Denmark

ABSTRACT: Rotliegend in the northern Permian Basin, Danish North Sea: Identification of a new source rock oil system

Deep-water turbidite sandstones and conglomerates interbedded with organic-rich marine shales of the Rotliegend Formation have recently been identified from cores and cuttings in the Felicia 1A well in the Norwegian-Danish Basin. Deep-water marine rocks were previously unknown in the northern Permian Basin. These deep-water facies and their corresponding source potential indicate the presence of an unrecognized and under-exploited petroleum system. Specifically, the Felicia 1A well is located along the northern flank of the basin, and the total thickness of deep-water section intersected in this well is 205m, more than 100m of which is shale. Correlation of the deep-water section into a regional 2D seismic grid and mapping based on seismic facies indicates the deep-water section thickens to more than 400m along the basin axis. The Felicia 1A deep-water shale section is divided by a maximum flooding surface (MFS) that occurs at 5174m. The shales above the MFS generally have lower TOC contents and Hydrogen Index values and a greater terrestrial component than do the shales below the MFS. It is likely these shales are past peak oil generation, and, consequently, the measured organic parameters represent reduced, residual hydrocarbon generating potential rather than initial generative capacity. Still, TOC contents approach 2% in the lower shale, and Hydrogen Index values sometimes exceed 600. The basin reached maximum burial in the early Paleocene and has undergone modest uplift and cooling subsequently. Preliminary 2D maturation modeling demonstrates significant oil generation and migration into Oligocene and younger structural traps with Rotliegend fluvial-deltaic reservoir facies.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado