Xinjiang Petroleum Geology ›› 2026, Vol. 47 ›› Issue (2): 222-232.doi: 10.7657/XJPG20260211

• APPLICATION OF TECHNOLOGY • Previous Articles     Next Articles

Lithology Identification of Volcanic Rocks Based on Extra-Trees Classifier: A Case Study of the Huoshiling Formation in the Chaganhua Subsag, Changling Fault Depression, Songliao Basin

WANG Yelei1,2(), CI Xinghua1,2(), DU Huanfu1,2, HOU Wenhui1,2, WANG Zhifeng3, WANG Shunye4, WANG Chunwei1,2   

  1. 1 Geological Measurement and Steering Technology Research Institute, Sinopec Matrix Co., Ltd., Qingdao, Shandong 266000, China
    2 Sinopec Key Laboratory of Well Logging and Mud Logging, Qingdao, Shandong 266000, China
    3 Research Institute of Exploration and Development, Sinopec Northeast Oil and Gas Company, Changchun, Jilin 130062, China
    4 School of Electronic Information Engineering, Langfang Normal University, Langfang, Hebei 065000, China
  • Received:2025-02-20 Revised:2025-04-23 Online:2026-04-01 Published:2026-04-08

Abstract:

Volcanic rock reservoir is one of the key exploration targets in the Changling fault depression of the Songliao Basin in recent years. The logging responses of complex volcanic lithologies are crucial to clarifying the reservoir properties (lithology, physical property, electrical property, and oil-bearing property). Based on the microscopic analysis of complex volcanic lithology, the lithology of volcanic rocks in the Huoshiling formation of the Chaganhua subsag in the Changling fault depression was calibrated through thin-section examination, whole-rock X-ray diffraction (XRD) analysis, and quantitative analysis using the RoqScan mineral auto-identification system. The conventional logging data and elemental logging data of the calibrated interval were divided into training set and test set. The training set was used to fit the target lithology, and the test set was loaded into the model calculation for prediction. Moreover, the model was employed in blind well testing. The results show that the volcanic rocks in the Huoshiling formation of the Chaganhua subsag in the Changling fault depression can be categorized into 5 classes such as volcanic lava, pyroclastic lava, pyroclastic rock, sedimentary pyroclastic rock, and pyroclastic sedimentary rock, indicating complex and varying lithologies. Six algorithms, i.e. decision tree, LightGBM, random forest, neural network, K-nearest neighbor (KNN), and extra-trees classifier (ETC), were compared for distinguishing lithology, revealing the accuracy of above 77% for all algorithms. ETC exhibits the best performance, with an accuracy up to 90%. This model has a strong generalization ability and yields an accuracy of 89% in blind well testing while correcting the results of original cutting logging. It can accurately identify and predict the lithology of volcanic rocks in the study area and provide intelligent support for subsequent volcanic oil and gas exploration and development.

Key words: Songliao Basin, Changling fault depression, Huoshiling formation, volcanic rock, lithology, machine learning, extra-trees classifier

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