Response of Well Logging and "Sweet Spot" Rapid Evaluation Technology for Shale Oil in the Lucaogou Formation of Jimsar Sag

doi:10.3969/j.issn.1006-6535.2023.04.005

Abstract

Abstract: The hybrid sedimentary shale oil is complex in lithology, with many mineral types and rapid lateral changes in the "sweet spot".The conventional logging is not sensitive to the lithology, physical properties and oil-bearing properties response, while the NMR logging requires petro-physical experimental calibration and long interpretation period, so there is a lack of effective on-site "sweet spot" rapid evaluation technology. To address the above problems, the shale oil reser-voir in the Lucaogou Formation of the Jimsar Sag of the Junggar Basin is taken as an example to study the response characteristics of gas logging, carbonate minerals, drilling time and other logs to the lithology, physical properties and oil-bearing properties of hybrid sedimentary shale oil based on the interpretation of NMR logging, so that the internal connection is clarified and sensi-tive parameters are selected to achieve the rapid evaluation of parameters and "sweet spots" of shale oil reservoir. The study shows that the lithology, physical properties and oil saturation of the hybrid sedimentary shale oil all have obvious responses on the logging data, among which, carbo-nate content and dolomite percentage can effectively reflect the main lithologies such as siltstone, dolomitic siltstone, psammitic dolomite, dolomicrite and dolomitic limestone, the carbonate con-tent and total hydrocarbon/drilling time are sensitive to the porosity, and the carbonate content, humidity ratio and total hydrocarbon are sensitive to the oil saturation. Based on the interpretation model of logging sensitive parameters such as porosity and oil saturation, the accuracy can reach 71.0%.Compared with the NMR logging, the identification rate of "sweet spot" of Class I oil formation is over 90%, thus achieving rapid and accurate evaluation of "sweet spot" of shale oil in the process of drilling. The results of the study are useful for improving the drilling catching rate of the "sweet spot" in horizontal wells of hybrid sedimentary shale oil and for reducing costs and increasing efficiency.

Key words: mud logging response characteristics, NMR logging, "sweet spot"in horizontal well, hybrid sedimentary shale oil, Lucaogou Formation, Jimsar

CLC Number:

TE122

Xiong Xiong, Xiao Dianshi, Lei Xianghui, Li Yingyan, Lu Shuangfang, Wang Meng, Peng Yue, Guo Xueyi. Response of Well Logging and "Sweet Spot" Rapid Evaluation Technology for Shale Oil in the Lucaogou Formation of Jimsar Sag[J]. Special Oil & Gas Reservoirs, 2023, 30(4): 35-43.

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