Abstract：The prospect of natural gas exploration in Paleogene, Bonan sag is very promising. The study on the gas reservoir forming conditions will help to understand the forming process and the mechanism of the gas reservoirs, and to provide a theoretical basis for future gas exploration. It is carried out in this paper, based on geological, seismic and logging data in this area. It is shown that the main gas generating bed is the upper Sha4, with high thermal evolution degree, as a late accumulation, and with advantageous gas source conditions. All kinds of fans and secondary pores create favorable reservoir conditions of Eogene. Mudstone in middle and lower Sha3, together with salt bed and mudstone in upper Sha4, form a favorable regional cap bed and reservoir bed. The effective configuration of reservoir-forming and geologic conditions is the key factor of the natural gas accumulation. Deep Bonan sag correspondingly forms an inter and below salt bed natural gas reservoir-forming system. The gas generation center and the areas surrounding all kinds of fans are the next exploration targets.
2010, Vol. 28 
