Reservoir Characteristics And Fluid Mobility Of The Lucaogou Formation Mixed Rock In The Jimusar Sag,Junggar Basin

The exploration of continental shale oil in China is still in the initial stage.The research degree is low while the resource potential is huge.To realize the rapid development of shale oil scale will be of great significance to improve the domestic oil production capacity and guarantee the national energy security.This paper takes the Lucaogou Formation in the Jimusar Sag,Junggar Basin,China’s first state-level continental shale oil demonstration area,as the research object.Using X-ray fluorescence spectroscopy(XRF)scanning,Quantitative Evaluation of Minerals by Scanning electron microscopy(QEMSCAN),scanning electron microscopy(SEM),nano CT,and other observation methods,The analysis methods of rock pyrolysis,total organic carbon(TOC)determination,X-ray diffraction(XRD)mineral analysis,diagenetic physical simulation,physical property determination,low temperature liquid nitrogen adsorption,high pressure mercury injection,nuclear magnetic resonance,formation water ion determination,etc.,reconstructed the sedimentary palaeo-environment of Lucaogou Formation,and defined the petrology,mineralogy and reservoir properties.The characteristics of pore evolution of Lucaogou Formation under formation conditions are explored,the difference of fluid flow performance in different types of reservoirs is identified,and the favorable reservoir development areas are predicted.The main results are as follows:1.The sedimentary environment of the Lucaogou Formation mixed sedimentary rocks in the Jimusar sag of Junggar Basin is relatively complex,which can be divided into three sedimentary units.In the reservoir,wavy laminated structure,parallel laminated structure,horizontal laminated structure and uniform massive structure are developed.Different laminated structure corresponds to different mineral composition,among which wavy laminated structure and felicitic-dolomite-calcite clay-rock combination have the best reservoir correspondence.2.The porosity of the mixed sedimentary rocks reservoir in Lucaogou Formation is mainly distributed in the range of 0.64%-20.15%,and the permeability is mainly distributed in the range of 0.001-0.01 m D.The shale pore evolution in the study area is affected by the evolution of non-clay minerals,the transformation of clay minerals and the generation of hydrocarbon by the thermal evolution of organic matter,and the pore growth is in a "three-stage" pattern.3.For the samples with different physical properties,the better the physical properties,the higher the saturation of the corresponding movable fluid.The movable water in the study area was mainly concentrated in the range of 0.05μm-0.23μm,and the movable oil was mainly concentrated in the range of >0.05μm.4.Combined with the study area peperite reservoir physical property and oil content characteristics is divided three kinds of reservoir.Based on this,the study area is divided into three types of favorable zones.The upper sweet spot of the study area is Ⅰ type zone and the stratum zone,which are mainly distributed in the middle and southeast of the study area.The lower desserts are mainly in Ⅱ category,mainly distributed in the central,southern and southeastern regions of the study area.The relevant understanding obtained in this paper has clarified the geological conditions and exploration potential of the mixed-rock reservoir development of the Lucaogou Formation in the Jimusar Depression,and provided scientific guidance and technical support for the evaluation and optimization of "sweet spot area" and industrial exploration and development in the study area.