Abstract: About 90% of oil and gas resources in Kuqa foreland basin are in deep and ultra-deep formations, but in this area with complex geological conditions, oil and gas reservoirs are big in burial depth (5000-8000m), high in temperature (100~178℃ ) , and pressure (100 ～ 140MPa). The upper formation with high-steep structures and thick gravel layers, pose great challenge to anti-deviation and ROP (Rate of Penetration) enhancement; the middle and lower sections consisting of salt and gypsum layers, ultra-high-pressure saline water layer (2.4 - 2.6g/cm³), and low pressure lost circulation formation, have variable pressure systems and thus high risks; abundant fractures, strong tectonic force, strong water sensitivity and high abrasion of the reservoir bring about a series of problems such as drill pipe sticking and low ROP etc. In order to solve the problem of increasing ROP in high -steep structural, Tarim Oilfield has introduced and improved the vertical drilling system and worked out the principle of bit selection, forming a corollary technique series for increasing ROP in high-steep structures. In view of the problem of salt and gypsum formation, Tarim Oilfield has introduced and improved the imported oil based drilling fluid, forming ultra-deep salt & gypsum formations drilling technology centering on oil base drilling fluid; aiming at the difficulty in enhancing ROP in reservoir formation, ROP enhancement tools have been introduced from abroad. With the combination of the above key technologies, the ultimate whole-well ROP enhancement technology has been formed.

Key words: Kuqa foreland basin, ultra-deep well, high-steep structure, ROP enhancement, vertical drilling, oil-base mud