Oil-bearing Characteristics and"Sweet Spots"Evaluation of Medium-low Maturity Shale Oil Reservoirs in Ludong Sag
To address the issues of unclear distribution characteristics and enrichment control factors of medium-low maturity shale oil reservoirs in the Jiaolige Sag,Ludong Depression,a study on the oil-bearing characteristics of shale oil reservoirs was conducted through methods such as 2D NMR analysis,nano-CT scanning,and identification of kerogen microscopic components.A comprehensive evaluation standard for identifying shale oil sweet spots was established based on factors such as shale lithofacies,reservoircapabilities,oil-bearing characteristics,andmobility.The results show that the degree of development,density,lithology,and other structural characteristics of shale lami-nation and bedding are the primary influencing factors on the oil-bearing characteristics and distribution.The lay-ered siltstone,composed of coarse grained clastics and laminated felsic shale,exhibits excellent pore microstructure and connectivity.The specific surface area is less than 15 m2/g,and the average pore size of nitrogen adsorption is greater than 8 nm,which is a highly favorable reservoir.The total organic carbon(TOC)content of class Ⅰ+Ⅱ"sweet spot"exceeds 1％,with the reservoir exhibiting medium and large pores accounting for over 25％.The pore size within the reservoir space is greater than 8 nm,indicating a medium to good oil bearing potential and mobility,leading to relatively enriched oil and gas.These findings offer valuable technical support for identifying favorable tar-gets for shale oil development in the study area,as well as for deploying and evaluating test areas.
"sweet spot"evaluationoccurrence characteristicsmicroscopic distributionmedium-low maturityshale oilJiaolige SagLudong Sag
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