Logging-based identification and prediction of diagenetic facies in shale oil reservoirs in the Western Ordos Basin
Author of the article:DONG Yue1, LU Wei2, CHEN Hua2, WANG Zhenyu1, JI Chengwei3, LI Yanrong4, ZHU Yushuang4
Author's Workplace：1. Yanchang Oilfield Co., Yan'an, Shaanxi, 716099, China; 2. No.5 Oil Production Plant, Changqing Oilfield Company, CNPC, Xi'an, Shaanxi, 710200, China; 3. No.9 Oil Production Plant, Changqing Oilfield Company, CNPC, Xi'an, Shaanxi, 717600, China; 4. Department of Geology, Northwest University, Xi'an, Shaanxi, 710069, China
Key Words：Western Ordos Basin; Jiyuan area; Chang 7 shale oil; Diagenetic facies identification through well logging
Abstract：
Different diagenetic combinations control the
development of reservoir pores and the different characteristics of reservoirs.
In order to predict the diagenetic facies of unknown diagenetic facies well sections
in the Jiyuan area, this paper applies experimental techniques such as core
analysis, casting thin sections, cathodoluminescence, and scanning electron
microscopy to classify the Chang 7 shale oil reservoir in the Jiyuan area of
the Ordos Basin into six types of diagenetic facies based on the types of
diagenesis and mineral assemblages. Using SPSS software and Fisher's dimensionality reduction approach, the main and
secondary factors for identifying diagenetic facies were established, and
corresponding graphs were created. At the same time, discriminant functions for
different diagenetic facies were developed to predict the diagenetic facies of
unknown well sections. Compared with the conventional intersection plot method,
the Fisher discriminant method improves the accuracy of diagenetic facies
identification through well logging, achieving a correct identification rate of
91.4%, which improves the identification accuracy considerably and provides a
foundation for further oil and gas exploration and development in the Chang 7
shale oil reservoir of the study area.