Identification and Evaluation of Fracturing Advantageous Lithofacies in the Main Structural Zone of Yingxiongling, Qaidam Basin

The Yingxiongling structural zone in the Qaidam Basin is a critical yet challenging target for shale oil exploration due to strong reservoir heterogeneity and complex sedimentary cycles. This study employs an integrated methodology combining laboratory rock mechanical tests, field fracturing diagnostics, and tracer data to evaluate the fracturing performance of dominant lithofacies. Results indicate that: (1) Laminated dolomitic limestone exhibits higher mechanical strength and requires elevated fracturing pressure compared to laminated shale, but contains inferior hydrocarbon content. In contrast, laminated shale develops more uniform and complex fracture networks post-fracturing. (2) A lower microseismic b-value in laminated dolomitic limestone suggests shear-dominated failure along bedding planes, enhancing micro-fracture development. (3) Pressure decline analysis and microseismic monitoring confirm that laminated shale facilitates higher fracture network complexity. In conclusion, laminated shale is identified as the preferred lithofacies in the Yingxiongling area, as it possesses a superior potential for generating complex fracture networks that meet the technical requirements for effective volume stimulation.