Research On Distribution Of Hydrocarbon Reservoirs In Natun Formation Of Beizhong Subsag

The prime line of this thesis is clarifying structure character, sedimentary character, reservoir character, plane distribution and oil/water relationship. In this thesis, the sequence characters of the stratum, oil/water distribution relationship, reservoir types and distribution regularities of Nantun Formation are figured out, by sequence stratigraphy theory and method, seismology, geology, logging theory and so on. In this thesis, four critical technologies, including accurate 3D seismic interpretation technology of faulted basin, analytic technique of the sequence stratigraphy, recognition technique of the sedimentary microfaciesand, reservoir valuation and inversion forecasting techniques are used. Based on the available 3D seismics, well drilling, well logging, well testing data and so on and as the guide of the reservoir-forming theory of complicated faulted basin. there are six fruits and understandings, which enriched the regular recognition of the reservoir distribution in complicated faulted basin. The fruits and understandings are as follows:(1) the dark clay of Nantun 1 Member is the main hydrocarbon source rocks, which are middle to good level oil source rock in Beizhong sub sag and are also the material base of making the whole Beizhong sub sag bear oil; (2) Beizhong sub sag is a kind of duplex fault sag controlled by East and West faults, deferent structural units have different control of the oil and gas and the formation of different types of reservoir, and the favorable accumulation regions of oil and gas are early formed and inherited developed step-fault zone in west and embossed zone in center; (3) using sequence stratigraphy theory and method, Nantun formation is subdivided into two third sequences and five system tracts, underwater distributary channel sand of inner frontier of fan delta in low system tract of Nantun formation widely spread which are the main oil bearing formation, and the widespread clay of transgressive systems tract and high system tract of latchstring facies are the main hydrocarbon source rocks; (4) in low systems tract of Nantun 1 Member, there developed lot of sand zones, every single zone of which is thick, overlying and widespread, and provides advantages for the formation of lithologic oil pool; (5) for the tuffaceous lithologic characters, easy denuded, secondary pore developed, lot of clay mineral and silicide crystallization forming from the tuffaceous in the diagenetic evolution process and protectingthe primary pore, the saving conditions in Nantun formation are better; (6) there developed two set of play in vertical of Nantun formation in Beizhong sub sag, and on plane, the reservoir is zoned. The oil-gas distribution regulars of the rich-oil sag are system summed, the research clue and method of which will play an important part in the exploratory work in the similar area...