--> Abstract: Structural and Stratigraphic Settings of Oil and Gas Fields in the Greater Bohai Bay Basin, by G. Murray, Z. Baoming, and C. Wu; #90937 (1998).

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Abstract: Structural and Stratigraphic Settings of Oil and Gas Fields in the Greater Bohai Bay Basin

MURRAY, GENE and ZHENG BAOMING, Kerr-McGee China Petroleum Ltd., Beijing, China; CHANGLIN WU, International Exploration of Kerr-McGee Corporation, USA

The greater Bohai Bay basin of northeastern China covers an area of 73,000 sq km and contains more than 15 oil and gas fields. The total annual production in the basin is 1 billion bbl. The total reserves are about 20 BBOR.

The basin is underlain by granite and metamorphic rocks of the Sino-Korean Platform. Initial sedimentation commenced in the early Paleozoic with the deposition of a cyclic sequence of carbonate under open marine conditions. The marine conditions terminated in the mid-Ordovician due to the collision of the Sino-Korean Platform and the Tarim Platform. This resulted in a 200 MMY hiatus during which the Upper Paleozoic red beds were deposited and significant karsting of Ordovician carbonates occurred. The subduction of the Pacific Plate under the Eurasian Plate created an intense period of crustal doming and rifting during which numerous half-grabens and “buried-hills” were created. The final stage of basin development in the early Tertiary with syn-rift deposition of the Shahejie Formation under deep lacustrine conditions. Post-rift sedimentation began in the Oligocene with the deposition of the Dongying Formation under progressively more fluvial-deltaic conditions. The basin has gradually filled in to its current marine conditions with the deposition of the Pingyuan Formation.

Production in the basin encompasses the entire stratigraphic succession. Early discoveries naturally focused on the shallower fluvial deltaic Guantao and Dongying Formations and the lacustrine Shahejie Formation. In recent years discoveries have been extended into the pre-Tertiary “buried-hills”. The best of these discoveries are the Ordovician carbonates but the Mesozoic and granitic basement discoveries are also represented. The primary source rocks in the basin are the lacustrine shales with TOC of 1.5-5% in the Eocene Shahejie Formation.