Research On The Relationship Between Compaction Characteristics And Reservoir Developing Of The Mesozoic In Fuxian Area, Ordos Basin

This paper researched the rule of mudstone compaction through constructing mudstone compaction's curve. The equivalent depth method was used to calculate the overpressure. We established a model of hydrocarbon migration through describing the shape of overpressure detailedly and associating sandstone-mudstone relationship. Analyzed key controlling factors of oil accumulation and hydrocarbon distribution regularities, and established a model of hydrocarbon accumulation on the basis of sedimentation, structure, reservoir and hydrocarbon generation history and expulsion history. All of we do was in order to evaluate the favorable area.Results show that Yanchang formation develops un-compaction from chang9 to chang6. East of the Fuxian develops un-compaction from the roof of chang9 to the middle of chang7; and east of the Fuxian develops un-compaction from the roof of chang9 to the bottom of chang6. The degree of un-compaction in the west is higher than it in the east. We can classify the overpressure into 4 classes: typeâ… a nd typeâ…¡have one high overpressure band, and the pressure decrease from the bottom up. Chang8, chang7, and chang6 have good Oiliness in this area which have typeâ… and typeâ…¡overpressure. Typeâ…¢have two high overpressure bands, and the curve of overpressure looks like a letter"B". Chang8, chang6, chang3 in this area have good oiliness. Typeâ…£h ave one high overpressure band, and the pressure decrease upwards and down. Channg8 have good oiliness in this area.The main force of oil-gas migration is overpressure. Hydrocarbon fluid always migrates along the direction of pressure decline. At the same time, high overpressure band can be a capping layer, which can stop hydrocarbon fluid from migrating or dispersing. By research on the relationship between high overpressure and oiliness, we found that the normal pressure interval which between two high overpressure bands is the most favorable place for hydrocarbon accumulating, and the pressure transition zone which above or under a high over pressure zone is the second.Hydrocarbon accumulation mainly influenced by sedimentary environment, tectonic setting, reservoir and overpressure. Sedimentary environment controls the distribution of distributary channel sand body. Smooth settlement and Tectonic uplift make layers smoothly, and develop low -amplitude nosing structure and some anticline. Physical property of the reservoir controls oil saturation. Overpressure controls hydrocarbon migration and accumulation which is in the lower Yanchang formation, and influence oil accumulation the upper formation. Oil accumulation model has"three floors"in the vertical. The lower model close to the source rocks contains Chang8+9 and chang7, and chang7 is source rocks. The middle model also close to the source rocks contains chang7, chang6 and chang4+5, and chang7 is the source rocks. The upper model contains chang4+5, chang2+3 and chang1, is Away from the source rocks. By looking distributary channel sand body, higher pore and higher permeability area and low -amplitude nosing structure, combined with overpressure distribution and oil product characteristic, 5 advantageous blocks of oil are predicted of chang8,chang6 and chang3 of Yanchang formation, which provide the credibility geology gist for further exploration and exploitation in this area.