Study Of Remaining Oil Distribution Rules In PⅠ Oil Bearing Group On The West Section Of Central Saertu Oil Field

This paper basing on detailed geologic research of Pâ… oil bearing group on the west section of central Saertu Oil Field, finding out the underground geological conditions, determine the remaining oil distribution to lay the foundation for stable oil field.This study used core, analysis assay data, logging in the region, as well as other early geological research, and other information, according to sedimentary cycles, and from top to bottom divides PI group of the study area into Pâ… 1 to 4 and Pâ… 5 to 7 two sandstone groups and seven small layers.The top structures of every small layer within the Pâ… reservoir are irregulary and complex nose structures cased by faults, and there are six faults, These faults are located on both sides of the east and west borders, the occurrence and development of fractures play an important role in controlling the formation of traps and the distribution of oil and gas. According to sedimentary facies analysis and sediment background, the basic model of the study area is the large shallow lake branched inland river and delta deposition formed by tectonic uplift and the whole lake retreat, Pâ… group belongs to branched delta front Asia facies. Lithology of Pâ… group of the study area is mainly fine-grained sandstone, siltstone, mudstone and siltstone, mudstone. the types of sand in the study area are distributary channel sand, and underwater natural levee sand, and underwater sand crevasse fan sand, as well as distributary channel inter-thin sand. When the sedimentary of PI group in the study area, water frequent changes, the distributary channel changes frequently and flow intensity frequent changes, so there are obvious sedimentary cycles. Sand is mostly single-layer, positive rhythm or complex rhythmic layers, reservoir interbedded , in-layer reservoir and layers on the plane have shown a complex heterogeneity and can be divided into five flow units from top to bottom in the vertical.Analysis shows that there are eight types of remaining oil in this area. They are respectively caused by incomplete water driving and productive system, microfacies, microstructure, semi\|communicated sandbody, sandstone nip, upper part of the sick distributary channel sandbody, fault and useless reservoir. Remaining oil is mainly distributed in the underwater natural levee, crevasse fan in the sand of the first, third and fifth mobile unit on the main vertical distribution and distributary channel sand body with a semi-quintana parts, sand in the upper part of the deterioration of physical property as well as underwater natural levee, crevasse fan of the sand in the second and third mobile unit.