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UDC (552.143:553.98):550.8(571.1) GENETIC FEATURES AND DEPOSITIONAL ENVIRONMENT OF THE UPPER POKUR FORMATION IN THE SOUTHEAST OF THE PUR-TAZ INTERSTREAM AREA
N. M. Nedolivko, T. G. Perevertaylo, A. M. Barkalova
The pay horizon PK1 was studied in the paper. It was identified within the Pokur Formation in the Cretaceous (Cenomanian) terrigenous gas-condensate play. The horizon was penetrated in the south-east of the Zapolyarnoye gas-condensate field confined to the Pur-Taz interstream area (Yamal-Nenets Autonomous District) with the aim to specify its structure and depositional features. The horizon was found to have a complex structure comprising repeated interbedding and alternation of poorly cemented sandy, silty, argillaceous, and rarer coaly rocks. There are five cycles of deposition and five reservoir beds, respectively, designated PK1 5, PK1 4, PK1 3, PK1 2, and PK1 1 bottom up and separated by coaly-argillaceous (in the base) and argillaceous interbeds. The genesis was found to be coastal-marine against general increasing sea transgression, which was derived from genetic features of rocks (interbedding and replacement pattern, textual-structural and material characteristics) and macrodescription of core, granulometric, petrographic, and X-ray phase analysis. Sandy deposits of beds PK1 5 and PK1 4, rarer PK1 3 (lower part of horizon PK1) accumulated at the coastal margins of a sea in the highly dynamic wave environment with waves rushing toward shallow areas. The sandstones in beds PK1 3, PK1 2 and PK1 1 accumulated in less dynamic but rather stable water environment within the rough water zone of a shallow-marine basin.
Key words: Pur-Taz interstream area, West Siberia, Cenomanian, Pokur Formation, horizon PK1, oil and gas accumulation terrigenous deposits, genetic features, depositional environment.
DOI 10.20403/2078-0575-2016-2-96-104 |
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