Reef Reservoir Prediction Of Changxing Formation In HLC Structure In Sichuan Basin

For the advantages of considerable reserve, high yield, good porosity, the reefreservoir proves to be one of the most important reservoir in marine carbonate rocksworth studying. However, the reef gas reservoir is subtle reservoir which is hard tobe exploited.Sichuan Basin has the largest verified marine gas reserve. As the exploration forthe marine carbonate gas progresses, the Changxing Formation, as one of the mainreservoir, becomes a major focus of the resent research.Aiming at the problem in predicting the reef reservoir of the ChangxingFormation in the northeast area of Sichuan province, this paper takes the predictionof reef reservoir in HLC areas as the study content. Starting from the analysis ofreservoir features of biogenic reef and instructed by the thoughts of controlling thedistribution and size of the biogenic reef with the sedimentary facies, this paperworks on the sedimentary facies and modes in the work area, confirms that the targetarea can be divided into three facieses, namely the basin, carbonate shelf and theshelf rim. As the transitional zone between the carbonate ramp and the downfold ofthe east Sichuan is at the down sloping of the ramp edge, it is favorable site for thedevelopment of margin reef. According to the characteristics of considerabledevelopment scale of the margin reef and the apparent asymmetry of the section ofthe reef, it comes to a conclusion that the reef is a product of discrete barrier reef,thus a main type of biogenic reef.Then, this paper also distinguishes different facieses of the target area, namelythe downfold facies, the shelf facies and shelf rim facies, the three seismic faciesescorresponding to the sedimentary facieses. Meanwhile, it also studies the respondingfeatures of the reef reservoir to the logging and earthquake, and analyzes the featuresof the reef reservoir. Through combining the features of the reservoir and the seismicfacies, this paper studies the favorable zone for the development of reef flat in the target area.At last, this paper takes seismic inversion as a tool to work out the biohermalsuite and the reef reservoir of the target area.