SHALE OIL RESOURCES ASSESSMENT FOR THE MEMBER CHANG 7 IN ANSAI AREA OF ORDOS BASIN

The oil shale of the Chang 7 Member of the Triassic Yanchang Formation in the Ordos Basin mainly occur in the southwest Ansai area, with a thickness of more than 10 meters. The average content of chloroform asphalt "A"reaches 0.87%, that found the basis for shale oil formation. CT SEM, NMR and other techniques have been used to quantitatively characterize the storage space and storage performance of the oil shale. It's revealed that the nano-sized clay granules flake pores are the main types of pores for shale oil storage. The average effective porosity approaches 4.86% and the average oil saturation 44.63%. The Chang 7 Member of the Ansai area has provided excellent material basis for shale oil accumulation. There are great amount of and widely distributed black oil shale, sufficient hydrocarbon, low viscosity of crude oil, excellent high-angle fracture system and reservoir space, all of which are beneficial to the oil flowing through the nano-scale pore throat. Resource assessment suggests that a resource potential of 4.42×10⁸ m³ is expected. Using horizontal well and volume fracturing, single-well production will be improved.