A well drilling bit for drilling bedrocks includes a columnar bit body, and a drilling fluid flow path formed in the bit body to wash away drilled cuttings from a bottomhole and/or a periphery of the bit body. The flow path is provided with a venturi mechanism including a venturi tube having a reduced-diameter portion where a cross sectional area is reduced and capable of generating a decompression region around a tip of the bit body, the decompression region being more decompressed than a surrounding by the Venturi effect.

An open drill bid and system for using is disclosed. The open drill bit has an upstream end and a downstream end. A downstream face is located on the downstream end. A single central opening located on a downstream face of a drill bit extends through to the upstream end. The drill bit has at least two blades attached to the drill bit. At least a portion of the blades are located downstream of the downstream face. The central opening allows for the drill bit to be used at lower pressures without plugging. Thus, the drill bit can be used for water well drilling which is typically at a lower pressure.

A rotary steerable drill string (16) employs a drill bit (10) selected to positively contribute to underpressure in a preselected azimuthal segment of the borehole relative to an opposing azimuthal section. Generally, a high flow velocity of drilling fluid in the selected azimuthal segment relative to in other segments will result in a more pronounced underpressure in the selected azimuthal segment. Drill bit designs which locally enhance the drilling fluid flow velocity are proposed to be employed in the present rotary steerable drill string.

A nozzle for distributing drilling fluid from a drill bit has a central axis and includes a first end, a second end, and a radially inner surface extending axially from the first end to the second end. The radially inner surface defines a flow passage extending from the first end to the second end. The flow passage has a central axis, an inlet at the first end, an outlet at the second end, a first section extending from the inlet, and a second section extending from the outlet to the first section. In addition, the nozzle includes a side outlet extending radially from the radially outer surface to the radially inner surface. The side outlet extends axially from the second end and is contiguous with the outlet. The second section of the flow passage at least partially overlaps with the side outlet. The first section of the flow passage is curved as viewed in a cross-section of the nozzle taken in a reference plane containing the central axis of the nozzle and bisecting the side outlet. The second section of the flow passage is curved as viewed in the cross-section of the nozzle taken in the reference plane. The second section of the flow passage is configured to direct at least a portion of the drilling fluid flowing through the flow passage toward the side outlet.

A cutting element may include a fluid passage passing through the cutting element. The cutting element may further include a cutting edge and an aperture proximate the cutting edge. The aperture may be coupled to the fluid passage.

Systems and methods for drilling a subterranean well with a drill bit include a drill bit body with a central bore. A plurality of ports extend through the nose end of the drill bit body from the central bore to an outside of the drill bit body. A blocked nozzle is located within one of the plurality of ports. The blocked nozzle has a nozzle bore end and a nozzle nose end opposite the nozzle bore end. A bore end disk is located at the nozzle bore end of the blocked nozzle, preventing a flow of fluids through the blocked nozzle past the bore end disk. A nose end disk is located at the nozzle nose end of the blocked nozzle, preventing the flow of fluids through the blocked nozzle past the nose end disk. The nose end disk and the bore end disk are removable.

A wellbore drill bit includes a body that defines an inner volume and includes a top sub-assembly, and a plurality of cutting cones along a longitudinal axis of the body. The wellbore drill bit includes a chamber positioned in the inner volume of the body to form an annulus between the chamber and the body; a first set of nozzles positioned in the plurality of cutting cones, each nozzle of the first set of nozzles including a fluid entry that is fluidly coupled to a primary drilling fluid flow path, and a fluid exit oriented toward the second longitudinal end of the body; and a second set of nozzles positioned in the body. Each nozzle of the second set of nozzles includes a fluid entry that is fluidly coupled to the annulus, and a fluid exit oriented toward the first longitudinal end of the body.

A downhole cutting tool has a body that includes a cutting end, a connection end, a longitudinal axis extending axially through the body, and a gradient composition having one or more gradients. Each gradient extends a distance in a respective direction through the body. Each gradient has changing amounts of a first material in the gradient composition along the respective direction in which the gradient extends.

A drill bit includes a bit body with high and low fluid pressure bodies. The low-pressure bit body includes a fixed cutting structure, and the high-pressure bit body includes at least one high-pressure fluid channel and nozzle capable of withstanding fluid pressures greater than 40 kpsi (276 MPa). A bottomhole assembly includes a drill bit with a bit body having fixed cutter and fluid jetting portions. Low and high-pressure channels in the bit body exit in the fixed cutter and fluid jetting portions. A high-pressure nozzle is coupled to the fluid jetting portion and the high-pressure fluid channel, and a plurality of fixed cutting elements are coupled to the fixed cutter portion. A pressure intensifier is coupled to the drill bit and is configured to increase a pressure of a fluid supplied to the high-pressure fluid channel in the bit body.

A drill bit performs pilot rock-breaking using an outer annular drill bit and breaks a central rock pillar using a central drill bit mounted in the middle of the annular drill bit and located inside a drill bit body to induce unloading of a bottom hole stress. A method mixes rock debris produced by rock breaking of the central drill bit as abrasive with the drilling fluid flowing into the entire drill bit as abrasive jet liquid phase to form an abrasive jet. The method includes obtaining an annular borehole by braking, and breaking the rock pillar at the inner side of the annular borehole to induce unloading of the bottom hole stress, mixing the rock debris produced by breaking the rock pillar at the inner side of the annular borehole as abrasive with the drilling fluid entering the drill bit to form an abrasive jet.