High Quality Reservoir Development Controlling Factors Of Chang2in Zhiluo Oil Field

Zhiluo oil field is a typical extra-low Permeable oil field, and Chang2are main oil bearing series in Late Triassic. According to its drilling, logging and experimental analysis data, and through these experimental methods such as the X-ray diffraction, physical property test, scanning electron microscope, intrusive mercury experiment etc. The paper analyzed sedimentary facies, lithology, pores structure, diagenesis, physical property of Chang2reservoirs, which provides geological basis for development adjustment of the area.By researching,the following results are received:Chang2reservoir of Yanchang formation is divided into three oil sub-groups:Chang21, Chang22, Chang23. Chang21oil-bearing bed are the major oil Producing formations in the study area.The study area of Chang2is situated in Yan’an delta. Micro-facies are mainly occurred in the submerge distributary channel and distributary interchannel, the channel is a distribution of NE-SW tending and a stable channel development, moreover, its sandbodies are fundamentally together.Chang2reservoirs is mainly fine arkose feldspar sandstone. Compositional Maturity is low but textural maturity is high. Grain size sorting is better and the grain shape is mostly subangnlar. We draw the conclusion that the reservoir space of the Chang2oil-bearing is dominated by inter-granular Pore, and secondary dissolution Pore, main microthroat caused by low Permeability, average permeability is0.40×10-3μm2and porosity is between14%and19%, which formed extra-low permeable reservoir. Pore throat type is mainly medium pore-micro throat. Dominant diagenesis types are compaction, cementation, replacement and dissolution. Horizontally the reservoir physical properties are mainly influenced and controlled by the sedimentary environment, While vertically impacted by the diagenesis. The reservoirs are divided into four categories according to the lithology, porosity and permeability. It is mainly I and II in study area. According to the sedimentary facies zones, sand-body distribution law, pore structures, diagenetically regional features etc. Some favorable exploration zones are predicted comprehensively by through evaluation.