ABSTRACT: The Hydrocarbon Potential of the Northern East China Sea Basin

OKAMOTO, S., and S. YOSHIDA,* Nippon Oil Exploration Limited, Tokyo, Japan

The northwestern half of the Japan/Korea Joint Development Zone (JDZ) occupies the northern part of the East China Sea basin. The basin is located between Taiwan-Sinzi Fold Belt to the east and Fukien-Reinan Massif to the west, and it elongates from north-northeast to south-southwest parallel to these major structural trends. The East China Sea basin is a back-arc basin, and the maximum sediment thickness may exceed 7 km in the JDZ portion of the basin.

Rifting may have initiated in Paleogene, and thick continental sediments mainly of Oligocene and Miocene age deposited on the Cretaceous basement. Sediments of Oligocene and Miocene age may have been deposited in lacustrine, fluvial, paludal environments and restricted shallow marine environment such as lagoon or embayment. This basin was initially developed under extensional tectonic regime, then underwent inversion tectonics and uplifts. The basin is characterized by block faulting trending northeast-southwest, and southeastern half of the basin underwent strong inversion. Miocene sediments are overlain by Plio-Pleistocene sediments of shallow marine origin, and they are separated by extensive regional unconformity.

Six wells were drilled in the JDZ portion of the basin. Potential sandstone reservoirs and mature source rocks were found in Miocene and Oligocene section. Seismic sections show structural traps including tilted fault blocks and anticlines, and stratigraphic traps such as sub-unconformity traps.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)