Development of drill bit with eccentric matrix top used for drilling anisotropic rocks and its application in borehole inclination control

Abstract:

In drilling engineering， borehole inclination is often encountered. The borehole inclination depends on many factors， such as formation conditions， bit design， drilling parameters， operation level， management ability and so on. Among them， the formation conditions objectively exist and can not be changed by human will. In the formation conditions anisotropic rocks are encountered often. An important problem in drilling of the anisotropic rocks is production of overturning moment（produced from rock reaction force）， leading to deviation of bit matrix top and as a result to serious inclination of the borehole. To resolve the problem， Russian specialists have proposed designing the drill bit to resist （balance） of the overturning moment by using the bending moment produced by the eccentric matrix top while drilling and got patents and good results obtained. That deserves our attention.