--> Abstract: Characteristics and Geologic Controls of Petroleum Systems in Rift Basins of Eastern China, by J. Qiang, R. T. Ryder, and P. J. McCabe; #90937 (1998).

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Abstract: Characteristics and Geologic Controls of Petroleum Systems in Rift Basins of Eastern China

JIN, QIANG, University of Petroleum, China; ROBERT T. RYDER and PETER J. MCCABE, U.S. Geological Survey.

Summary

Most oil-bearing basins in eastern China are Mesozoic-Cenozoic continental rifts, which include the Songliao, Bohaiwan and Pearl River Mouth basins. They play a significant role in oil and gas exploration and production in China, as 65% of the proved reserves (in place) and 80% of the annual yield have been discovered and produced from these basins. Also 60% or more of the estimated undiscovered resources in China are in these basins. Investigations of petroleum systems may provides a better understanding of oil and gas habitat and resources in the rift basins.

Among the essential elements of a petroleum system, the high-quality source rock that has high TOC and hydrogen-rich kerogen is the most important. However, the character and distribution of source rock and other essential elements in a petroleum system are closely controlled by rift tectonics. A five-stage model is suggested here for the evolution of the rift basins. Each rift basin may consist of extensional fault-bounded sub-basins, depressions, sub-depressions; and major, moderate, and minor uplifts. Moreover, each depression or sub-depression has its own deposition center (mainly occupied by source rocks) and adjoining lacustrine sediments, thus, has all the essential elements era petroleum system. Only a depression or sub-depression in which contains high quality source rocks serves as an oil source center or even forms a petroleum system. Immature oil generation, another characteristic, complicates the identification of petroleum systems in the rift basins.

Three types of oil and gas habitats are recognized in the 26 largest hydrocarbon accumulations discovered in the rift basins in eastern China: uplifts between flanking oil source centers are the most prospective places for oil and gas accumulation; slopes connecting oil source centers and uplifts are the second most prospective places; and the subtle traps in the oil source center are third.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah