Hydrocarbon Detection for High Temperature and High Pressure Undercompacted Formation:A Case Study of Dongfang X District in Yinggehai Basin

The high temperature and high pressure gas reservoirs are developed in the mid-deep strata of Yinggehai Basin,where the undercompacted formation is formed by rapid subsidence which caused huge undercompacted shale belt.Because of the influence of high temperature and high pressure reservoirs,the seismic reflection features are very complicated for the Dongfang X district located at the southwest of central mud diapir structure of Yinggehai Basin.Because of the undercompacted shale,the seismic bright spot information is invalid.Thus,the conventional hydrocarbon detection methods are not so effective in this district.To resolve this problem,we first conducted the rock physics analysis,and found that the undercompacted shale results in the difficulty of the gas detection technology in this area.Then,we use the prestack inversion for the undercompacted condition and frequency division imaging method to conduct the gas identification for the Dongfang X district.The results show that the methods proposed in this paper can identify and predict the gas target effectively,which is important for the following exploration and development to some extent.