Fracture Characteristics And Structural Control Factors Of The Xujiahe Formation In The Puguang East Syncline

Through core observation, experiment of field joint statistics and indoor identification of thin sections, scanning electron microscope (SEM), high-pressure mercury injection experiment, X-ray diffraction experiments, combined with XRMI imaging logging explanation, to study the fracture characteristics of structural control of Puguang East syncline Upper Triassic shall Xujiahe formation.The rock types of Xujiahe sandstone reservoir are mainly lithic sandstone and feldspathic lithic sandstone, belonging to low permeability or tight sandstone reservoir. Through the core observation of PLA and PLB, combined with EMI imaging logging interpretation data analysis shows that the development must home river group in the horizontal cracks,Based on the systematic observation of the PLA and PLB, the macro fracture of sandstone in Xujiahe formation is very developed. The fracture types are mainly horizontal fractures and diagonal fractures, and less in the nearly vertical fractures.Based on the core logging and combined with the EMI image logging interpretation data, advantage fractures occurrence of well PLA and PLB are respectively 50-90°∠ 10-20°、∠ 190-220°∠ 10-20°and 10-20°∠ 40-50°、 220-240°∠10-20°, which are the result of the Himalayan tectonic movement. The joint density near fault region was significantly greater than the joint far away from, and the tectonic movement both from the dominant joint development direction, the joint density, opening and filling plays key role. Tectonic position of the joint and distance from the fault and tectonic movement intensity have close relationship., To the reservoir of tight sandstone layer of Xujiahe Formation in the study area,a large number of cracks in the development promotes the efficient natural gas enrichment reservoir formation.