The Seismic Forecasting Of The Deep Strata In YuXi Region Of Xujiaweizi Fault Depression

Guided by the theory of Structural Geology, Seismic stratigraphy, Reservoir Sedimentology and Volcanics Petrology, based on carefully analyzing and referring the research fruits of the predecessors, sufficiently using the data of seismic, well logging and well drilling, adopting several methods of seismic, the thesis has studied the stratigraphic framework of the strata in yuxi region of Xujiaweizi fault depression and this paper forecasts and researches the volcanic reservoir at the objective of Yingcheng formation of Xujiaweizi fault depression.The strata is divided according to the contact relations of the strata which are reflected from seismic section, drilling data and log data. Accordingly the stratigraphic framework is set up in the yuxi region of Xujiaweizi fault depression.The tectonic characteristics of the critical boundaries of stratigraphic framework and structure evolution are studied through the establishment of structure map and structural history profile. The strata in yuxi region were controlled by xuxi, yuxi ,songxi faults, These 3 breaks constructs the evolution and the stratum deposition .they have obvious control action, they are the important transportation channels, with volcanic rock and gas pool's formation close related. The structure evolution process experienced 4 stages: faulting period, the period transformed from fault depression to sag, depression period and structure reverse period.Through the research of the lithology, lithofacies and the relations with the accumulate room of volcanic reservoir, and combinded with the well drilling data of Xujiaweizi fault depression, In view of YingchengI formation, beginning with the seismic identify of the volcanic reservoir, using the technique of 3D visualization and coherence, 41 volcanic bodys in the target stratum are forecasted, using the technique of the seismic attribute analyzing and using the technique of the seismic inversion to forecast the volcanic lithofacies and the volcanic reservoir. Based on these, taking analysis of the section and the plane, it can be found that: the volcanic of YingchengI formation is destributed widely in the region of interest; The growing of the volcanic reservoir is affected largely by the volcanic edifice, the volcanic facies belt, the fault and the depth of burial, it is usually that the burst facies and the effusion facies are main, and the area near the fault is vegetal, the physical property is favorable and the thickness is high.At last, through analyzing the diagenesis condition of the deep gas reservoir of Xujiaweizi fault depression, combinding with the forecast fruit of the volcanic reservoir and the test gas fruit of multiwell, the distribution of the beneficial areas are pointed out in YingchengI formation.