The Mahu Fengcheng Formation shale oil reservoir features deep burial depths，complex pressure systems and strong formation heterogeneity，and such complex geological conditions severely restrain the drilling efficiency of horizontal wells，highlighting the urgency of research on technologies enhancing rate of penetration（ROP）. Based on rock mechanical tests，whole-rock mineral composition analyses and geological characteristics of the Mahu Fengcheng Formation，the technical challenges of drilling were systematically investigated，and two technical routes for ROP enhancement were proposed，namely the optimized casing program and high-efficiency rock breaking with high weight on bit （WOB）. The proposed technologies were applied to six horizontal wells drilled in 2025 and delivered remarkable ROP enhancement performance. Specifically，based on characterization of the four pressure profiles （pore pressure，breakdown pressure，collapse pressure，and leak-off pressure），the surface casing set depth was optimized to precisely isolate low-pressure and fluid-loss-prone zones. A combined borehole profile and a potassium-calcium-based polyamine organic salt drilling fluid system were adopted to maintain a borehole enlargement ratio within 5%. Rock mechanics tests determined that efficient rock breaking in the Fengcheng Formation requires a WOB greater than 111.1 kN. A differentiated polycrystalline diamond compact （PDC） bit matching technology based on high WOB and an optimization technology for Ф139.7 mm high-stiffness bottom hole assembly （BHA） were developed to perform layer-specific optimization of drill bit parameters and operational parameters. Laboratory analyses and field applications demonstrated that this technology package can effectively resolve the ROP improvement challenges of the Mahu Fengcheng Formation shale oil and provide technical support and references for the efficient development of deep and ultra-deep hydrocarbon resources.

To address the challenges of high compressive strength，low drillability，and extended drilling time in the deep tight shale of the Mabei Fengcheng Formation，an experimental study on drilling parameter optimization for axial-torsional coupled percussive drilling was conducted. This study intended to identify the dominant factors affecting rock-breaking efficiency and to establish a parameter matching method suitable for this layer. Using a composite percussive rock-breaking efficiency testing device，drilling experiments were performed on core samples from the target layer under fixed conditions of weight-on-bit and rotational speeds with different combinations of axial and torsional impact frequencies. The effects of impact frequency on rate of penetration （ROP），torque，and mechanical specific energy （MSE） were evaluated. The results show that axial-torsional coupled impact can significantly increase the ROP while reducing torque and MSE. High-frequency torsional impact plays a dominant role in torque reduction and energy saving，and a synergistic rock-breaking mechanism was identified in which axial impact promotes crack propagation，whereas torsional impact alleviates bit sticking. This study confirms that axial-torsional coupled impact technology provides significant benefits in improving drilling efficiency，reducing torque，and lowering energy consumption in this shale formation. The obtained parameter optimization method provides a theoretical basis for field drilling design and offers important engineering guidance for accelerating drilling in deep hard strata.