Logging Evaluation Of Geological "Sweet Spot" Of Shale Oil Of Lucaogou Formation In Jimusaer Sag

The Lucaogou Formation in Jimusaer Sag is a saline lacustrine basin with two relatively independent petroleum systems,which are integrated with source and reservoir and full of concave oil.It is an important shale oil exploration area.Shale oil geological"sweet spot"evaluation has great significance to the exploration and development.This paper takes"sweet spot"interval of Lucaogou Formation in Jimusaer Sag as the research object.The geological characteristics of“sweet spot”interval are elucidated based on the core observation,thin section identification,combining with the analysis of oil test data,conventional logs and image logs,nuclear magnetic resonance log.According to source rock quality,reservoir quality,and source and reservoir configuration relationships,a set of geological"sweet spot"evaluation criteria suitable for the shale oil of Lucaogou Formation in Jimusaer Sag is established and classified,and the distribution law of vertical geological"sweet spot"of the Lucaogou Formation is clarified.The results show that the source rocks of the"sweet spot"member of the Lucaogou Formation are in the mature stage,and the organic matter types are mainly typeⅠand typeⅡ₂,with high organic matter abundance and good hydrocarbon generation potential.The reservoir lithology is complex and changeable.The reservoir space is diverse and the physical properties and oil content are good.It is clear that the upper sweet spot（P2l2）of the Lucaogou Formation is mainly source-derived adjacent reservoir,and the lower sweet spot（P2l1）is mainly self-generated and self-stored reservoir.The logging evaluation model of source rock and reservoir characterization parameters is established,and the validity of the model is verified by core data and oil test.The parameters that can effectively reflect the quality of source rock are TOC and S1+S2,and the parameters that can effectively reflect the reservoir quality are porosity,permeability,and fracture development degree.On the basis of determining the lower limit of organic carbon content and physical property,the evaluation criteria of source rock quality and reservoir quality are established and classified.The geological"sweet spots"ofⅠ、ⅡandⅢare divided according to the source-reservoir configuration relationship.In addition,the distribution law of vertical geological"sweet spots"of shale oil in the Lucaogou Formation is clarified.The results provide references for the next step of shale oil exploration and development in Lucaogou Formation,Jimusaer Sag.