The Reservoir Analysis And Trctonic Evolution Of Wunan Sub-depression In Hailar Basin

The data of field, exploration wells and massive seismic, with the newest theory of Structural geology, Sedimentary petrography, seismic stratigraphy and the method of seismic, logging, well logging and core, are used in this paper to analysis the stratigraphic sequence, structure characteristic, tectonic evolution and the control action of structure on hydrocarbon reservoirs formation.According to the method and principle of sequence stratigraphy, mutually using seismic- stratigraphic technology, as well as the contact of seismic and logging, we make sequence division and correlation on 52 wells in the area, definite five complete third-order sequences in area and establish the stratum framework of Wunan sub- depression.Through the explanation and analysis on seismic cross-section, Wunan sub- depression had three break distortions: early break distortion, intermediate stage break distortion, lately break distortion, and formed extensional structure style, shearing structure style and reversal structure style followed by many phase of structure evolutions.According to the study of seismic cross-section and structure, Wunan sub- depression has the characteristic of north-south segmentation and west-east belt. The main is controlled by western fault which is north-south, and form tensional rift lake nearly north-south. It has the characteristic of western fault, eastern onlap, single fault and dustpan shape. The faults are mainly western faults and a series of north-south normal faults and by the composition of flower-like structure in the depression. There are four tectonic zones from west to east: West off -order band, the central depression tectonic, the eastern fault nose tectonic belt and the eastern slope, they active a long term and control the formation and evolution of depression.Through the study of fracture characteristics and tectonic style in depression and the analysis on tectonic evolution by using of balanced cross-section, the tectonic evolution of depression is divided into three developmental stages: early depression, medium-term depression and late depression. At the same time the stretch volume analysis on the depression show that the level of stretch of the depression becomes larger from shallow to deep, which shows the tectonic evolution characteristics of the depression; because of stages of tectonic movement, regional unconformity surface formed control the vertical distribution of oil and gas reservoirs.