摘要
Through measuring the displacement pressure of mudstone cap rock in member 2 of Yinggehai Formation of Yinggehai Basin, the linear relation between displacement pressure of cap rock and acoustic time was demonstrated, and the method to calculate the displacement pressure with acoustic time and seismic velocity data was put forward to. Then, based on acoustic time and seismic velocity data,the overpressure distribution of mudstone cap rock in the lower of member 2 of Yinggehai Formation was determined by means of equivalent depth method. Finally, the comprehensive index to evaluate the sealing ability of cap rock was put forward to, and was applied in member 2 of Yinggehai Formation. The results showed that the area with the best sealing ability of cap rock included most part of Ledong District, southern part of Lingao District and the region between eastern part of Dongfang District and No.1 fracture.