A cross hole deburring tool which performs rotary cutting on a cross hole burr occurring on a cross ridgeline part between a through path and an inner circumferential surface of a spherically-shaped hollow part. A tool main body includes a tip part and a shank, and the tip part has a shape obtained by setting a diameter axis of a circle, setting an eccentric axis parallel to the diameter axis and away therefrom by a predetermined eccentric distance, setting a closed region in a bow shape formed of a line segment obtained by cutting the eccentric axis by the circle and a minor arc on the circle by defining this line segment as a chord, setting an outer surface shape of a bow-shaped solid of revolution formed by rotating this bow shape about the eccentric axis, and taking this outer surface shape as the shape of the tip part.

A hybrid rotary drill bit having at least one fixed blade and at least one rolling cutter assembly is configured for reverse fluid flow from an annulus, through junk slots and into a fluid pathway system located substantially centrally to a bit body. The fluid pathway system may be located underneath a portion of the at least one fixed blade.

A hybrid rotary drill bit having at least one fixed blade and at least one rolling cutter assembly is configured for reverse fluid flow from an annulus, through junk slots and into a fluid pathway system located substantially centrally to a bit body. The fluid pathway system may be located underneath a portion of the at least one fixed blade.

A system includes at least one processing unit and a bottomhole assembly (BHA) that includes or communicates with the at least one processing unit. The BHA includes at least one drilling component and at least one acoustic transducer to convert drilling noise into one or more electrical signals. The at least one processing unit analyzes the one or more electrical signals or related data to categorize different components of the drilling noise as rock contact noise and mechanical noise. The at least one processing unit derives a data log, a plan, or a control signal based on the categorized drilling noise components.

A system includes at least one processing unit and a bottomhole assembly (BHA) that includes or communicates with the at least one processing unit. The BHA includes at least one drilling component and at least one acoustic transducer to convert drilling noise into one or more electrical signals. The at least one processing unit analyzes the one or more electrical signals or related data to categorize different components of the drilling noise as rock contact noise and mechanical noise. The at least one processing unit derives a data log, a plan, or a control signal based on the categorized drilling noise components.

A metal matrix composite tool includes a body having hard composite portion that includes reinforcing particles dispersed in a binder material. At least some of the reinforcing particles comprise a monolithic particle structure including a core having irregular outer surface features integral with the core.

A wellbore fluid may include an oleaginous fluid forming a continuous phase; a non-oleaginous fluid forming a discontinuous phase; at least one emulsifier stabilizing an emulsion of the non-oleaginous continuous phase within the oleaginous continuous phase; and at least one viscosifier dispersed into the oleaginous continuous phase in a concentration of at least 4 ppb; wherein upon subjecting the wellbore fluid to shear rate of at least 10,000 s.sup.−1, the emulsion is disrupted and the non-oleaginous fluid contacts the at least one viscosifier, thereby solidifying the wellbore fluid.

A wellbore fluid may include an oleaginous fluid forming a continuous phase; a non-oleaginous fluid forming a discontinuous phase; at least one emulsifier stabilizing an emulsion of the non-oleaginous continuous phase within the oleaginous continuous phase; and at least one viscosifier dispersed into the oleaginous continuous phase in a concentration of at least 4 ppb; wherein upon subjecting the wellbore fluid to shear rate of at least 10,000 s.sup.−1, the emulsion is disrupted and the non-oleaginous fluid contacts the at least one viscosifier, thereby solidifying the wellbore fluid.

A rotary drill bit for directional drilling operations, in which a rotating bit with cutters advances a borehole in the earth invention, provides a smaller radius of curvature to increase drilling efficiency. The rotary drill bit comprises a box connection for connecting the bit to the drill string. The drill bit receives a pin connection that seats adjacent the plenum of the bit to shorten the distance between the bit face and steering tools behind the bit so the drill string can be steered more efficiently.

A rotary drill bit for directional drilling operations, in which a rotating bit with cutters advances a borehole in the earth invention, provides a smaller radius of curvature to increase drilling efficiency. The rotary drill bit comprises a box connection for connecting the bit to the drill string. The drill bit receives a pin connection that seats adjacent the plenum of the bit to shorten the distance between the bit face and steering tools behind the bit so the drill string can be steered more efficiently.