| Organic reef belongs to a kind of special carbonate structure. It is made of various reef-building organism with strong vitality which can resist wave impact. In the growth process of organic reef, the succession of reef-forming organism and the evolution of the ancient geographical environment have an influence on the organic reef, meanwhile controlling the shape, the structure, the size and the distribution of the organic reef. And its growth environment is in the place which has strong water power, so it has good porosity and permeability. And it has good reservoir space. Organic reef is a good place which is advantageous to store oil and gas. What's more, organic reef has the characteristic of great abundance and high capacity, so it has the exceptional advantage of oil and gas storage. The research to organic reef is of important geological significance to many respects, such as divide and compare strata accurately, study how to restore the ancient geographical environment and cyclicity event and so on.This article takes the Changxing Formation organic reef in TLP area of east Sichuan from Sichuan Basin as the object of study. The organic reef gas reservoir belongs to carbonatite's lithologic trap gas reservoir. Although it has good porosity and permeability, its reservoir has strong anisotropy, and its vertical and horizontal difference is very obvious. What's worse, its buried depth is very big. Through the analysis on geophysical significance, its lineup is discontinuous in the seismic section. And the resolution of seismic data is low. In addition, its internal structure is very complex, so we can't track the horizon well. In conclusion, its multiplicity of solution is very strong.In order to solve the difficulty of the organic reef reservoir recognition, we consult the area's geological information, well information and seismic data, using seismic facies analysis, sedimentary facies analysis, attribute analysis and ancient landform analysis techniques at the same time. We have tried many methods of reservoir prediction in order to divide the boundary of organic reef. Then we conduct the prediction of organic reef's favorable facies belt distribution, consequently, we set up the response model of Changxing Formation reservoir in TLP area. Based on the experiment effect of prediction methods, we predict the distribution range and thickness of the reservoir from Upper Permian series' Changxing Formation by the techniques of bright spot analysis, trace integration analysis and velocity inversion analysis. Finally we use the frequency attribute analysis method for the exploratory study of reservoir fluid's identification.Research shows that the platform-edge facies reservoir from TLP area's middle part and east part is the largest reservoir in the region that exists effective thickness. Its amplitude attribute is weak amplitude or trough. Thus it is suitable to the organic reef's development best. The velocity of Changxing Formation reservoir is low velocity under the background of high velocity relatively. And the velocity range of beneficial reservoir is in 5200 ~ 6150 m/s, the time window is among the range of 50 ms that lies in the Feixianguan Formation's bottom. By analyzing the frequency attribute of the Z5-well profile, the attenuation value of energy is bigger in the frequency attribute profile of gas reservoir. And the log response characteristic of reservoir is: low velocity relatively, low gamma, high CNL, low density relatively, high resistivity. In consequence, the application effect of fluid identification method which combines well logging interpretation with seismic interpretation is obvious in TLP area. |
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