The Research On Characteristics And Reservoir Of Foreland Basin Of Western Margin Of Ordos Basin

The research foundation on collecting the predecessor materials, combining the field observing and office work, by means of the technologies of petroleum geology and tectonics as method, unifying other disciplines, and correlation among Chinese and foreign basins, and integrated analysis of the features of evolution of the basin, tectonic transformation, sedimentology and analysis typical oil and gas pools, the paper focused on the reservoir forming features of the foreland basin, probed into the characteristics of enrichment, distribution and pool-forming of oil and gas, and forecasted the favorable areas or belts of exploration. The following were attained:This article focuses on the North-South Thrust Fault districts. Based on studies on features in present geomorphography, surface geology, sedimentary environment and structural distributed direction and seismic, gravity and magmatic data, the author proposes a new explanation that there exists evident structural difference between south and north in western margin of Ordos basin. The western margin can be divided into two structural units by Qingtongxia-Mjiatan transition belt. The author firstly presents that the west margin of Ordos was connected with the main basin body, opening westward in the late Triassic for sediments. Meanwhile, no foreland basin developed during late Triassic.Through this synthetic study, conducted earnestly on analyzing structure deposition and evolutionary process, the author believes that this foreland basin isn't classical foreland basin, but an interior continent foreland basin.The analogy with other mid-west foreland basins, thrust belts, depression belts, slope belts and lifting belts reveal different characteristics of reservoir. This synthetic study indicates that, western margin of Ordos basin has effective conditions to form the large and middle oil-gas fields. Plenty of faults formed by thrusting constitute the ideal channel for migration of oil and gas. Therefore, the foreland basin becomes the favorable place for reservoir.