When drilling wells on the Riphean deposits of Yurubcheno-Tokhomskoye field there occurs wear-out of the bits, that can be up to 10 bits for one well. However, there were examples when it was possible to drill a horizontal wellbore section in just 2-3 bits. The work performed on the bits selection didn’t allow finding a breakthrough solution, which would significantly reduce the wear-out of the bits on the study area. Alternative solution on reducing bit wear-out might be to predict zones with highly abrasive rocks in order to sink the operating wells outside of such zones, but not to the detriment of deposit development. The conducted comprehensive analysis of core data, well-logging, seismic data, well performance, geological and technological research and technical and technological support for well drilling made it possible to establish a connection between the seismic facies (chosen for geological drilling support) with the drill footage per one bit. It was found out that in low-amplitude seismic facies the average drill footage per bit is 48 % higher than in high- amplitude seismic facies (in average is 179 vs 121 m). The maximum average drill footage per bit values were achieved in the wells drilled in the zones of minor faults and fractures. The minimum average footage per bit was found in the zones of large disintegrations, cavernous porosity, leaching and cavern porosity, as well as in the zones of a relatively homogeneous dense section. The analysis of the average drill footage per bit according to the bit types showed that the best drilling results were achieved by PDC bits in the zones of minor faults, fractures and in the zones of large sections and paleo incisions developing along them. For these conditions multiple increase of drill footage is noted. In the zones of large disintegrations there is a slight advantage of roller-cone bits over PDC.
References
1. URL: https://www.rosneft.ru/press/news/item/202131/
2. SPE/IADC 16145. Application of the new IADC dull grading system for fixed cutter bits, 1987.
3. IADC/SPE 23939. First revision to the IADC fixed cutter dull grading system, 1992.
4. IADC/SPE 23940. Fixed-cutter drill bit classification system, 1992.
