--> Abstract: Jurassic-Cretaceous Basaltoid Magmatism and Formation of Giant Hydrocarbon Accumulation in the East-Barents Basin, by Eduard Shipilov; #90177 (2013)

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Jurassic-Cretaceous Basaltoid Magmatism and Formation of Giant Hydrocarbon Accumulation in the East-Barents Basin

Eduard Shipilov

Numerous sills in Triassic sediments are also observable in seismic records across the Shtokman–Lunin Upliftl, where they underlie the local hydrocarbon structures: Shtokman, Ledovoe and Ludlovskoe . Under these anticline structures, the thickness of sill packets increases on account of the increased number of individual bodies. Judging from drilling data from the Franz Josef Land and Spitsbergen archipelagoes, the thicknesses of sills range from several to tens of meters. The wells drilled on the Ludlovsdkoe field penetrated the two uppermost gabbro–dolerite bodies among Middle Triassic sediments. The geochronological study of these rocks by the K–Ar method revealed they belong to two different generations: the upper and lower sills are 131–139 and 159 Ma in age, respectively. The recent dating of samples from the trappe formation of Franz Josef Land by the 40Ar/39Ar method yielded wider scatter of age values: from 125 to 189 Ma. Thus, the seismostratigraphic analysis and geochronological study of basaltoid bodies indicate with a high degree of confidence that the formation and growth of local structures in the hydrocarbon fields under consideration were practically synchronous with intrusive activity. It is conceivable that heterogeneities observed in the sedimentary cover as well as the Shtokman–Lunin Uplift proper could be formed under the influence of the inertial thrust formation front of the Novaya Zemlya belt and were subsequently intruded, as mature structures, by sills. The presented data allow the statement that the Jurassic–Cretaceous tectonomagmatic stage was of principal significance for the formation of prerequisites for hydrocarbon accumulations and, consequently, the hydrocarbon potential of the Shtokman–Lunin Uplift. Conclusions: - The tectonomagmatic factor, i.e., intrusion of sills, was responsible for the formation of the anticlinal structures under consideration, which host giant gas condensate accumulations. - Dissimilar to other petroliferous structures of the Barents Sea, the prevalent phase composition of fluids in the fields under consideration was to a significant extent determined by the influence of basaltoid magmatism on the gas generation properties of host Upper Permian–Triassic and older rocks. - Magmatic conductive channels and faults could serve as active channels for hydrocarbon fluids, which stimulated their migration to fill structural traps. - Wide lateral and vertical development of basaltic bodies implies that they could serve as intermediate confining beds for hydrocarbon fluids, although discovery of satellite hydrocarbon fields. References Shipilov, E.V., 2010. Role of tectonomagmatic factor in formation of giant hydrocarbon accumulation in the East-Barents basin. Doklady Earth Sciences, 434, 2, 1298-1302. Shipilov E. V. and Yunov A. Yu., 1995. Genesis of Anticlines Oil and Gas Fields of the Eastern Barents Sea. Dokl. Akad. Nauk. 342(1), 87–88.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013