--> --> Abstract: The Characteristics and Prospect of Giant Oil and Gas Fields in Marine Carbonate Sequence in China, by Zhijun Jin; #90082 (2008)

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The Characteristics and Prospect of Giant Oil and Gas Fields in Marine Carbonate Sequence in China

Zhijun Jin
Exploration & Production Research Institute, SINOPEC, Beijing, China

The recent discoveries of Puguang gas field in the Sichuan basin, southwestern part of China and Tahe oil field in the Tarim basin, northwestern part of China indicates the great hydrocarbon potential of the marine carbonate sequence in China. The most promising exploitation and exploration prospects are the Ordos, the Tarim, and the Sichuan basins and adjacent regions.
The characteristics of the giant oil and gas fields in marine carbonate sequence in China are as following:
1.Under the Paleozoic extention scenario, the sediments developed in the cratonic basins, rifting basins and margins in the North China, the Yangtze and the Tarim blocks, have provided good source rocks for hydrocarbon generation;
2.The paleo-uplifts and marginal slopes of the cratonic basins are enriched hydrocarbon zones. They are favorable traps for hydrocarbon accumulation. This types of the oil and gas fields have been found in the Sichuan, the Ordos, and the Tarim basins;
3.Reef, shoal sediments and pore-vuggy-fractured carbonate sequence are favorable reservoirs in marine carbonate sequence. The 480m Ordovician karstic carbonate sequence is the major reservoir in Tahe oil field in the Tarim basin, in addition the 329m Triassic vuggy dolomite provides good reservoir in Puguang gas field, in Sichuan basin;
4.Thick dark mudstone, shale and evaporates formed good seals and caprocks for hydrocarbon preservation, i.e. the Mid-Lower Triassic evaporates in the Puguang gas field and the Carboniferous evaporate-mudstone in the Tahe oil field are very effective seals.
5.In the Tahe oil field, the plays were formed in multiple phases. Some of them were formed in early-Hercynian time, late-Hercynian time and Indosinian--early-Yanshanian time, and the major play was formed in the late-Yanshanian time and Himalayan time. In the Puguang gas field, the gas play was formed during the Himalayan orogeny.

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