Reservoir Prediction In The Wunan Slope Zone Of The Qaidam Basin

Wunan slope located Wunan-Lvcaotan structural belt in the southwest of Qaidam Basin, closing to Qiekelike Sag in the south, separated by ? faults. The tectonic belt is interpreted to control by structure and source rock, the main production is interpreted to come from high point of structure. Overall, the main reservoir is upper Youshashan formation and lower Ganchaigou formation in deeper and there are an plentiful source and deposition facies variations. The formation consists of siltstone. shale siltstone and the reservoirs are characterized by poor properties, thickness of 0.5 to 3m. The vague Seismic is difficult to identify. Over oilfield, it has produced oil and gas in industry, while oil generated from Lv 10. Wu 26, Which is attributed to a very high overpressure.Based on sedimentary and reservoirs characteristics analysis, the paper integrate with seismic multi-attribute analysis, seismic inversion techniques, to do reservoir prediction on gas segment of lower Youshashan ??? group. and further to predict the favoriable reservoir by using wavelet decomposition and fluid mobility techniques.The present of sedimentary analysis, lower Youshashan formation was deposited in delta fringe deposit environment shoreward of lake facies sand bank at a slope anticline, and with delta front dip to Wunan structure, sand bank an eastward gradually reduced to distribution range. The characteristics of reservoir formation indicates the low-energy water limnetic environment, with restricted transform to sand body; the predominant factor of physical properties is compaction. The secondary factor is cementation and original source.Using the regression analysis, optimizing the seismic attributes sensitive to reservoir, and combined with multi-attribute analysis, dimension reduction, to get the relationship between the attributes and properties. From the result of attribute analysis, the reservoirs are mainly distributed in the body of Wunan and the central of Lvcaotan, The most developed area of group ? oil sand is in between Wu 7 and Wu8 well area, the perimeter of it and Lv 9 block and Wunan body is the secondary developed area.According to the CSSI and StatMod inversion results analysis, for ? formation, the most profitable reservoir is located between the area Lv3 and Lv 13,then the secondary profitable reservoir is located in the northeast of the project area, with wide distribution; for ? formation, the best reservoir is located Lv 2 well, Lv 13 well block in the south.With the wavelet decomposition and prediction of fluid flow, we draw a range of favorable reservoirs:? oil group favorable reservoir zones are mainly located in the northeast corner of the work area, ? oil group is distributed in the area between Wu 7, Wu8.