Key Technologies for ROP Improvement of Ultra-deep Wells in the Kuqa Piedmont Area

Aiming at the problems of complex geological conditions, long drilling cycles and high non-production time of ultra-deep wells in the Kuqa Piedmont Area, based on the characteristics of difficult-to-drill formations such as ultra-thick gravel layers, composite salt-gypsum layers and tight sandstone reservoirs, this paper adopts the integrated geology-engineering method to carry out technical research in different intervals, including bit optimization, bottom hole assembly (BHA) optimization, casing program and cementing design optimization, high-temperature resistant drilling fluid upgrading, logging process integration and fault prediction. Six categories of key ROP (Rate of Penetration) improvement technologies have been formed, including non-planar tooth PDC bits, "vertical drilling + high-torque screw + shock absorber" BHA, "slim" casing program, "package" cementing process, and rapid drilling fluid conversion. Field application shows that the drilling cycles in blocks such as Bozi, Dabei, Kela and Keshen are generally shortened by 15%～45%; the footage of non-planar tooth PDC bits is increased by more than 1.5 times; the single-well system conversion cycle is shortened by 11.5 days; and the proportion of cementing and intermediate completion operation time is reduced to less than 30%. The research indicates that the ROP improvement of ultra-deep well drilling in the Kuqa Piedmont Area should adhere to the technical route of "taking bit as the core, BHA integration as the support, design optimization as the source, and management innovation as the guarantee". Constructing a differentiated ROP improvement system by intervals can effectively solve the problem of low drilling efficiency of ultra-deep wells.