Analysis on Anisotropic Rock Fragmentation Process and Research on the Drill Bit Design

Abstract:

Anisotropic rocks are often encountered in drilling engineering construction; while drilling, the anisotropic rocks strengths in different directions are not the same. The rocks that are vertical to the strata are broken easily, but those drilling in other directions have big fragmentation resistance, therefore the core part of rock is deformed into ellipsoidal shape by extrusion. Axial drilling load is mainly used for overcoming internal friction resistance in the rock and the reactions from the rock fragmentation. Under the action of vertical component of rock reaction, overturning moment is produced to the drill bit; under the action of the overturning moment, drill bit is deflected and borehole is deviated, which have direct influence on the penetration rate and hole quality. Doctor Скоромных В.В., who is a Russian professor, and some others have made a lot of studies in resolving the overturning moment, a new idea of drill bit design is proposed for drilling in the anisotropic rocks.