Research and Field Application of Drilling Acceleration Technologies for Deep Shale Gas in the Qiongzhusi Formation, Ziyang

To enhance the development efficiency of deep shale gas in the Qiongzhusi Formation of Ziyang, a series of drilling acceleration technologies were investigated, significantly improving drilling efficiency. Based on research on differentiated adjustment of mandatory casing-setting points according to drilling runs and the “1+N” principle, a dynamic casing program optimization technology was developed. The minimum curvature method was prioritized in trajectory design to reduce the total drilled footage, establishing a trajectory design approach conducive to drilling acceleration. In the vertical section, based on dynamic modeling, a pre-bent bottom hole assembly (BHA) was introduced to enhance deviation control, enabling both effective deviation control and rapid drilling. For difficult-to-drill formations, customized polycrystalline diamond compact (PDC) bits were developed based on drillability experiments and rock-breaking mechanism studies, achieving an 18.75% increase in rate of penetration (ROP). In the horizontal section, a “four-in-one” steering technology combined with oil-based drilling fluid was applied to balance collapse pressure and prolong the duration of wellbore stability, and the synergistic use of a rotary steerable system (RSS) and a motor enabled single-run drilling operations. Field application results demonstrated that the average ROP across16 wells increased from 5.78 m/h to 7.74 m/h, and the average drilling cycle decreased from 122.83 d to 101.33 d. Breakthroughs in this key technologies including dynamic casing program optimization, trajectory design for drilling acceleration, and development of bits enabling physical-limit rock cutting for difficult-to-drill formations effectively ensured the safety and efficiency of drilling operations, providing technical support for deep shale gas development.