Rapid vertical lithological variations and well-developed laminae are exhibited in the shale oil reservoir of the Chang 7 Member in the Ordos Basin, leading to strong heterogeneity. As a result, great challenges are posed to the accurate evaluation of engineering sweet spots in target layers. To address these problems, a novel evaluation model for engineering sweet spots in laminated shale oil reservoirs was proposed. By introducing the laminae weakness opening index and weakness density index to characterize the influence of laminae on the spatial distribution of complex hydraulic fractures, a multi-scale computational model for the engineering sweet spot index was established. This model integrated the laminae weakness opening index, weakness density index, mineral brittleness index, core brittleness index, and horizontal stress difference coefficient to assess the reservoir fracturability. Validation of the engineering sweet spot index model was performed using fracture morphology inversion and microseismic monitoring data. Finally, engineering sweet spot evaluation was carried out for wells in the A well area of the Chang 7 Member of the Yanchang Formation in the Ordos Basin. The results indicate that in the engineering sweet spot index model, the weights assigned to the laminae weakness opening index, weakness density index, mineral brittleness index, core brittleness index, and horizontal stress difference coefficient are 0.24, 0.22, 0.19, 0.18, and 0.17, respectively. The predicted engineering sweet spot index achieves a match rate of over 90% with the inverted fracture geometry and microseismic monitoring data. Based on the engineering sweet spot index, rational optimization of perforation locations for production wells can be realized. The results provide valuable guidance for the design of perforation cluster placement and the optimization of operational parameters in laminated shale oil reservoirs.
CHEN Wen-bin, MA Bing, CAO Wei, XU Chuang-chao, ZHU Hai-yan, ZHANG Zhao-peng, JI Peng-cheng.
Engineering Sweet Spot Evaluation of Laminated Shale Oil in Chang 7 Member of Ordos Basin[J].
Science Technology and Engineering, 2026, 26(23): 9866-9873 DOI:10.12404/j.issn.1671-1815.2506121
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