| The Junggar Basin is one of the large superimposed petroliferous basins of western in China.The research area is located in the east of the Junggar Basin including two positive elements that is Dinan Arch and Baijiahai Arch to Fubei Slope. and there is Dongdaohaizi sunken and Wucaiwan sunken between them,which is south to Fukang sunken and southeast to the Shaqi Arch and west to the Mobei Arch.Baijiahai Arch is located in eastern of central uplift belt in Junggar Basin, which is an old apophysis and a favor area to capture hydrocarbon. It has superior hydrocarbon accumulation condition. While, there are severel hydrocarbon depressions and source rocks in Baijiahai Arch which leads to complex oil-source. In recent years, exploration is mainly Lower-Middle Jurassic formation, but the study is less to Middle-Upper Jurassic formation. Oil-source, horizontal distribution, hydrocarbon migration and accumulation of Middle-Upper Jurassic formation not have studied systematicly. With the deepening of the oil and gas exploration, this issue study in-depth.Researching the logging data, testing data, the various analytical laboratory data and collecting the sedimentary structure and the evaluation of the source rock, taking advantage of the various parameter to analysis the oil-source rock correlation which cnfirm the oil resource of Middle-Upper Jurassic in area. Based on the the distribution of oil and gas and the sedimentary structure which could confirm the hydrocarbon migration by the physical property and geochemical behavior of the oil including the orientation and the drdging system.Basing the above researching,we could analysis the mode of the hydrocarbon accumulation and cncluse the method of the hydrocarbon accumulation.This is nessisary for the next exploration of the hydrocarbon accumulation.The research area is chipping by four north-East faulted zone which are nearly parallel for each other.They are the fault which alongs the Ful6-Fu4-Shaxi,is the north of Dongdaohaizi fault, alongs C47-C36-CS2-C10-C8-C24of the south Baijiahai arch.There are Toutunhe group, Qigu group,Cretaceous formation from the bottom to top.The main sedimentary system includes meandering river and the meandering river delta deposit.The Permian and Jurassic source rock are main source rocks of the study area. The more favorable oil-generating sag of Permian Source rocks is the Dongdaohaizi sag and Fukang sag. Pingdiquan formation’s source rock of Dongdaohaizi sag began to enter the hydrocarbon generation threshold in the Early Jurassic, and began a number of hydrocarbon in Cretaceous period. Mudstone with the seam is the main hydrocarbon source rocks of Lower-Middle Jurassic; The largest source rocks of Badaowan Formation deposited in the Fukang sag, it has a certain extent thinning in Baijiahai Arch; Source rocks of Lower-Middle Jurassic in Dongdaohaizi sag enter into low-mature stage in the early Cretaceous, and it enter into the hydrocarbon peak period in Tertiary; Source rocks in Fukang sag enter into the hydrocarbon generation threshold in the early Cretaceous Period, and it is in a large amount of hydrocarbon in the Late Cretaceous.Vertically, the oil and gas distribute in the natural levee,crevasse,distrbutary channel of delta plain of Toutunhe group.There is a little oil and gas distribute in channel sand of Qigu group in Baijiahai Arch.The oil and gas centralized in Bajiahai Arch,seldom in Fubei Slope.Totally,there are three type oil in Middle-Upper Jurassic.The A type oil comes from the source rock of Permian System which distribute in Baijiahai Arch and Dinan Arch,such as C44,C42,C31,C36and so on.The B type oil comes from the source rock of Jurassic System which distribute in C36,C45,C401of Baijiahai Arch and Fu7,Ful6,Full of Dinan Arch.The C type oil is confused Permian System and Jurassic System which distribute in C45,C43,C501of Bajiahai Arch.There are seldom sapropelic gas which comes from the source rock of Permian System in Dinan Arch,such as Dixi22and Dixi9.Most humic gas comes from source rock of Carboniferous System,such as C501,C43,Dixi13,D201.As a whole,there was a trend of the migration of oil and gas from the low point of structrue to the higher,and the pathway of oil and gas migration mainly is the fault and the unconformity. It is fault mainly in Baijiahai Arch and sand body in Fubei slope and unconformity in Dinan Arch.Combined the result aboving,there are three kinds of accumulation models.lt is the multi-source filling^unconformity-fualt-sandbody multiple transports and multiple times hydrocarbon accumulation mode which is in Baijiahai Arch.In Fubei Slope that is the single-source filling and sandbody transport hydrocarbon accumulation.In Dinan Arch that is the single-source filling and fualt-sandbody multiple transports hydrocarbon accumulation. Since the respective factors play its own role in the accumulation of oil and gas,the hydrocarhon reservoirs in disternct layers have their own characteristics. |
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