Origin Analysis of the Intermediate-deep High Quality Reservoir in XX29-2 Oil Field,Bohai Sea

The reservoir characteristics and physical properties of medium-deep Paleogene Shahejie Fm in XX29-2 oil field have been studied by using thin sections observation,physical properties analysis,scanning electron microscope and core description.The study results showed that the reservoir sandstones are dominated by conglomeratic mesograin-macrograin lithic arkose and feldspathic lithic sandstone.The main pore types are intergranular pores in this area.The reservoir physical properties are good,with middle porosity and high permeability.According to the general theory,the physical property of mid-depth reservoirs is low-middle porosity and permeability due to the influence of diagenesis.To understand the origins of this kind of excellent mid-depth reservoir,analysis has been conducted on the seven factors influencing the high-quality reservoir.Through analysis,it is concluded that the main control factors for high-quality reservoirs are CO₂ hot fluid and gritstone.The study results provide a scientific foundation for looking for high-quality reservoirs in Bohai bay.