Special Oil & Gas Reservoirs ›› 2024, Vol. 31 ›› Issue (4): 27-35.DOI: 10.3969/j.issn.1006-6535.2024.04.004

• Geologic Exploration • Previous Articles     Next Articles

Oil-bearing Characteristics and "Sweet Spots" Evaluation of Medium-low Maturity Shale Oil Reservoirs in Ludong Sag

Zhou Liguo   

  1. PetroChina Liaohe Oilfield Company, Panjin,Liaoning 124010,China
  • Received:2024-05-16 Revised:2024-06-04 Online:2024-08-25 Published:2024-09-20

Abstract: 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 lamination and bedding are the primary influencing factors on the oil-bearing characteristics and distribution.The layered 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 targets for shale oil development in the study area,as well as for deploying and evaluating test areas.

Key words: "sweet spot" evaluation, occurrence characteristics, microscopic distribution, medium-low maturity, shale oil, Jiaolige Sag, Ludong Sag

CLC Number: