PREDICTION METHODS OF OIL AND GAS PREDICTION ABOUT THE COMPACT SANDSTONE OF T_3x~2 IN MIDDLE OF WEST SICHUAN DEPRESSION——TAKING THE FENGGU STRUCTURE AS EXAMPLE

The prediction of oil and gas in compact sandstone is a momentous puzzle of the petroleum exploration , both domestically and abroad. Beacuse of the compact characteristic of the T 3x 2 sandstone on the Longmen mountain leading edge in the middle of West Sichuan depression, the prediction methods of oil and gas prediction, giving priority to crack prediction, have been developed. But their actual effect is not ideal. The paper takes the Fenggu structure in the middle of West Sichuan depression as example to use structure recovery to analyze the characteristic of structure evolution and points out the place where the ancient oil and gas gather. On the basis of formation conditions of the reservoirs and principal factor analysis , with the history study of structure evolution, oil gas water, sedimentary, hydrocarbongenesis, thermal and pore evolution, the paper dissects the process of reservoir formation of the ancient structure when oil and gas gather and points out that the most effective exploration target of the T 3 x 2 compact sandstone is the inchoate trap which principal clue is the anticline in the course of oil and gas gathering. On the basis of the above, with the seismic recognition techniques of oil and gas reservoirs, such as seismic multi parameter prediction, pressure prediction, the paper predicts the zone of favorable reservoir and the place of wells. Its prediction result coincides with the actual result. And the payoff has been used in the disposition of development and exploration.