Impact of Diagenesis on the Reservoir Quality of Tight Oil Sandstones: the Case of Lower Jurassic Badaowan Formation in

Tight oil and gas reservoirs which defined in Chinese literature as those reservoirs with porosity less than 12% and air permeability less than 1mD, have been a hot spot in oil and gas exploration for their large favorable exploration area and recoverable resources in China. Previous studies have shown that the reservoir quality of tight oil sandstones are controlled by initial sediment composition and subsequent diagenetic modification. Because diagenesis can modify reservoir properties and exert a strong control on hydrocarbon production, it is crucial to understand the diagenetic evolution and controls of reservoir quality in tight sandstone reservoirs. The Jurassic Badaowan formation in hinterland of Junggar basin is a tight oil sandstones reservoir characterized by low porosity and low permeability. Badaowan formation has such intervals that still remain high porosity and permeability at temperature >100 °C,and at a depth >4000m. However, the diagenesis and its effect on reservoir quality of Badaowan tight oil reservoir has not been well explored. The objectives of this studies are to: (1) Describe the texture and composition of Badaowan sandstones; (2) Investigate diagenesis type and degree and reconstruct the diagenetic history of the Badaowan sandstones; (3) Unravel the impact of diagenesis on reservoir quality.