Classification of Shale Oil Horizontal Well Production: A Case Study of the Chang-7 Interval in the Ordos Basin

Abstract

This study analyzes 70 shale-oil horizontal wells in the Chang-7 interval of the Qingcheng Oilfield, Ordos Basin, using the K-means clustering algorithm to evaluate production capacity. The objective is to provide a foundation for differentiated development and refined management. First-year cumulative oil production was selected as the primary classification metric. The silhouette coefficient and elbow methods were used to determine the optimal cluster number. Results indicate that a three-class division is most appropriate: Class I wells (> 4,300 t, 21.7%), Class II wells (2,900-4,300 t, 40.8%), and Class III wells (< 2,900 t, 37.5%). Correlation analysis revealed distinct controlling factors for each well type. Class I wells are jointly influenced by engineering and geological conditions, with key parameters including drilled lateral length, proppant volume, and log-interpreted Class I intervals. Class II wells are primarily affected by engineering parameters and production practices, notably injected fluid volume, cluster number, pump rate, and shut-in duration. Class III wells are mainly governed by geological factors, with permeability, porosity, and average total organic carbon content being the most critical. The findings suggest that fracture-design and production strategies should be tailored to the specific controlling factors of each well type to enhance shale-oil development efficiency and achieve targeted exploitation. This approach offers a practical technical pathway and theoretical reference for classification management and optimization of shale-oil horizontal wells in the region.