Study On The Characteristic Of Hydrocarbon Accumulation Mesozoic Formation In Zhenjing Block, Ordos Basin

Mesozoic Formation has rich oil and gas resources, according to the existing exploration achievements in Zhenjing area, Ordos Basin. Accumulation characteristics, the reservoir is born, laying on the reservoir characteristics of reservoir accumulation.Previous studies were focused on the area, reservoir, seal and other basic conditions of accumulation, on the lack of a systematic accumulation of knowledge rules. In In order to further clarify Mesozoic Formation distribution and accumulation of oil in Zhenjing area,Ordos Basin.This study by mudstone compaction, To study the characteristics of the excess pressure and the relationship between excess pressure and oil, Analyze typical reservoir, Combination of the basic study area forming a comprehensive analysis of geological conditions,understanding of the Mesozoic oil and gas accumulation characteristics and objective understanding of the law, Further search for oil and gas distribution in the region to provide a solid geological foundation.Mudstone compaction research shows that Uncompacted shale section at the bottom of the Chang- 7 member of yanchang formation in Daijiaping and Chuankou area ,but in Hejiaping area ,uncompacted shale section at the bottom of the Chang- 7 member of yanchang formation.In general, uncompacted paragraph rather scattered in Zhenjing region, and to extend the group of Xifeng Oilfield segment undercompaction significant difference.Excess pressure in the main study area and the gradual development of mutations in two pressure-type structure, thick layer of mud where a continuous development of mainly mutant mainly mudstone continuous development of the space is not graded based.Hydrocarbon source rocks in the area was developed, the Chang- 7 member of yanchang formation main source rock in the main kerogen typeâ…¡2, contains a small amount of typeâ…¡1.Outcrops, core data and logging data show that the Chang- 7 and chang -8 member of yanchang formation mainly develope delta front deposits , Sand comes from underwater distributary channel,the Chang- 7 member of yanchang formation mainly deposits lacustrine in the development of a block west delta, founding turbidite deposition in study areas. In a large number of slices and based on the combination of burial history, the Mesozoic Sandstone is divided into three types: Continuous buried type of diagenetic system (the Chang- 8 member of yanchang formation and part of the Chang- 6 member of yanchang formation), Intermediate open diagenetic system type (part of the Chang- 6 member of yanchang formation), and Long-term open-type shallow diagenetic system (Yan'an formation). Formed under different reservoir diagenesis, have different reservoir properties and oil and gas secondary migration of power is also different.The Chang- 8 member of yanchang formation close to high-quality long as source rocks, in the abnormal pressure driven down oil and gas directly into the reservoir, oil and gas into the reservoir high displacement pressure as no significant lateral migration.As long Chang- 6 member of yanchang reservoirs, source rocks generated oil and gas under pressure in the abnormal upward through cracks into the reservoir;For good reservoir properties, lateral migration may occur in the structure and reservoir property suitable accumulation conditions,most of the dense reservoir and no long-distance lateral migration,Yan'an Formation Reservoir mainly secondary reservoir, oil and gas in sandstone in the buoyancy-driven by long-distance lateral migration occurs, structural high position in the accumulation.According Zhenjing overpressure distribution in stratigraphy, diagenesis, reservoir formation conditions and the system closed, will extend the group - Yan'an Formation Reservoir accumulation mechanism is divided into 3 types:Closed high-pressure source petroleum migration and accumulation dynamic subsystem,High Pressure-Pressure reservoir closed mixed source petroleum migration and accumulation dynamic subsystem, Pressure from the source closed - semi-closed petroleum migration and accumulation dynamic subsystem, Pressure is open source - a semi-enclosed reservoir petroleum migration and accumulation dynamic subsystem. Closed high-pressure source petroleum migration and accumulation dynamic subsystem, due to tight reservoirs, oil and gas migration motivation enough for the typical diagenetic trap, reservoir formation is mainly controlled by the reservoir, the focus of exploration and the search for efficient reservoir cracks Development zone;For the high pressure from the source closed - semi-closed reservoir by atmospheric reservoir of fresh water leaching transformation is the focus of exploration, this part of the Jurassic reservoirs are developed in the former slopes Office of ancient landscapes, ancient landscape of slopes is the focus of exploration;Pressure is open source - a semi-enclosed reservoir exploration focus trap problem, or a river bend in the ancient sandstone landform development office, vulnerable to the formation of trap differential compaction.