Analysis Of The Evolution Of Fluid In Putaohua Oil Layer Of Gulong Sag Of Songliao Basin

Putaohua oil layer of Gulong sag of Songliao basin is low-ultra low permeable reservoir. In order to understand the process of the formation of low-ultra low permeable reservoir and the relationship between the development of reservoir physical property (including surface wettability) and the time of fluid filling, this paper analysis the character of fluid action which is discussed in terms of fluid flow regime, action time and palaeotemperature. Besides, this paper analysis the migration direction and discuss the process of oil reservoir accumulation in Gulong sag. The homogenization temperature of saline inclusion and syngenetic oil inclusion are tested by using polarizing microscope, fluorescent microscope, scanning electron microscope, and oil inclusion is sum up by MGOIPLUS. The results indicate that the time of organic-inorganic fluid action are divided into three periods. The fluid action experienced the full evolution from inorganic to organic during all the three periods. The inorganic fluid power of hydrogen transformed from acidity to alkalinity in the process, which produced abundant dissolution pores and cement. Because of intense compaction and cementation, the porosity decreased to 10% during second stage of fluid action, and sandstones became low permeable reservoir. In the process of oil filling, diagenesis is repressed. Oil flowed to high position because of the good reservoir physical property in the first filling period. Carbon-bearing bitumen of pores in deep sag and bituminous membrane adhere to the mineral surface made the reservoir wettability hydrophobic, which is benefiticial to postchronous migration and retention of oil. Therefore the important affecting factors include: the relationship between low-ultra low permeable reservoir and the matching of time-space during filling, changes of reservoir surface wettability, the flow model of inorganic fluid and crude oil density.