Research On The Structural Evolution And Fault Sealing Of Fuyu Reservoir In Chaochang Area, Songliao Basin

Fuyu Reservior is the intended exploration interval in Chaochang Area. This paper, which is aimed at the outsteping problems during the developing of Fuyu Reservior, focuses on the structural evolution and fault sealing, based on the geological and geophisical data, using related theory and reserching method of petroleum structural geology. The results obtained are listed as below.1. The top of Fuyu Reservoir developed a lot of faults, which distributed densely in the plane, and assembled as multiple“y”type, multiple graben-horst type in the section. The local structure was complicated and lots of fault nose structure, fault anticline structure and fault block structure were formed by the incising of faults. There are early stage fault, middle stage fault, late stage fault and long-term fault in Chaochang area, between which the middle stage ones and long-term ones cut off the Fuyu reservoir and have intimate relation to the reservoir forming.2. Fuyu reservoir was a unified downwarping region from the Qingshankou Formation to Nenjiang Formation depositional period. Then the Fuyu reservoir experienced three stages of tectonic movements, including the end of Nenjiang Formation, the end of Mingshui Formation, and the end of Paleogene. The structural miniature was formed in the end of Nenjiang Formation, developed till the end of Mingshui Formation, and shaped at the end of Paleogene. The structural deformation was more intense in east and south.3. Most of the faults were in an open state at the end of Nenjiang Formation and Mingshui Formation, which was favorable for oil-gas migration. Nowadays mostly were sealed, which was advantageous for oil-gas trap preservation. It shows good matching relation between the fault sealing and oil-gas migration because the main reservoir forming period was at the end of Nenjiang and Mingshui Formation.4. The relationship between tectonism and reservoir forming was manifestied by the controlling of structural evolution to hydrocarbon, the controlling of faults to the trap forming and the matching relation between tectonism and oil-gas migration.