A trapdoor-style drilling mud screen system, comprising a first body having a first portion, a second portion and a third portion, a first drilling mud inlet at a first end of the first portion of the first body, a first drilling mud outlet at a second end of the third portion of the first body, a rotating trapdoor subassembly, wherein the rotating trapdoor subassembly is disposed within the second portion of the first body, wherein the first portion of the first body is fluidly connected to a first end of the rotating subassembly, and wherein a second end of the rotating subassembly is fluidly connected to the third portion of the first body, a pivot subassembly, wherein the pivot subassembly is disposed through the rotating trapdoor subassembly and through the second portion of the first body; and a drilling mud screen, wherein the drilling mud screen is disposed within the rotating trapdoor subassembly between the first drilling mud inlet and the first drilling mud outlet. Methods of installing and using the drilling mud screen system are also disclosed.

A trapdoor-style drilling mud screen system, comprising a first body having a first portion, a second portion and a third portion, a first drilling mud inlet at a first end of the first portion of the first body, a first drilling mud outlet at a second end of the third portion of the first body, a rotating trapdoor subassembly, wherein the rotating trapdoor subassembly is disposed within the second portion of the first body, wherein the first portion of the first body is fluidly connected to a first end of the rotating subassembly, and wherein a second end of the rotating subassembly is fluidly connected to the third portion of the first body, a pivot subassembly, wherein the pivot subassembly is disposed through the rotating trapdoor subassembly and through the second portion of the first body; and a drilling mud screen, wherein the drilling mud screen is disposed within the rotating trapdoor subassembly between the first drilling mud inlet and the first drilling mud outlet. Methods of installing and using the drilling mud screen system are also disclosed.

The invention relates to variation of concentrations of abrasive particles in a stream of drilling fluid mixed with abrasive particles, passed as an abrasive jet through abrasive nozzle(s) of a drill bit along rotations thereof, to vary the erosive power of the stream along angular sections of the borehole for directional drilling. During subsequent time periods majorities of abrasive particles are alternately deflected into two parallel channels with a different flow resistance. A resulting velocity difference between said majorities makes that the subsequently deflected majorities recombine downstream of the channels, so that high concentration stream portions of the combined majorities are formed which alternate low concentration stream portions. Synchronising the frequency of the stream portions with the rotational velocity of the drill bit results in a consistently higher erosive power of the abrasive jet within a selected angular section of the borehole than outside thereof.

The invention relates to variation of concentrations of abrasive particles in a stream of drilling fluid mixed with abrasive particles, passed as an abrasive jet through abrasive nozzle(s) of a drill bit along rotations thereof, to vary the erosive power of the stream along angular sections of the borehole for directional drilling. During subsequent time periods majorities of abrasive particles are alternately deflected into two parallel channels with a different flow resistance. A resulting velocity difference between said majorities makes that the subsequently deflected majorities recombine downstream of the channels, so that high concentration stream portions of the combined majorities are formed which alternate low concentration stream portions. Synchronising the frequency of the stream portions with the rotational velocity of the drill bit results in a consistently higher erosive power of the abrasive jet within a selected angular section of the borehole than outside thereof.

Geologic material in a borehole is weakened by accelerating a projectile into contact with the material. A drill bit is then used to bore through the weakened material. To accelerate the projectile, an endcap is placed in a conduit using a source of gas. The endcap isolates the conduit from the external environment. A projectile is then positioned in the conduit above the endcap. Movable members within the conduit are operated in sequence to enable single endcaps and projectiles to be moved into the conduit. Gas from the conduit is evacuated into an annulus between the conduit and a surrounding conduit, and a propellant material is provided into the conduit. The propellant material applies a force to the projectile to accelerate the projectile into contact with the geologic material. A fluid is circulated down a second annulus outside of the surrounding conduit to contact the drill bit and remove debris.

The invention relates to a drill head and to a method for producing a substantially vertical borehole in the ground, in particular for producing a shaft, having a body (11) which is able to be connected to a rotary drive of a drilling device, having drilling tools (12) which for loosening the ground at a face (100) of the borehole are disposed on the body (11), having a discharge device which for discharging the loosened ground on the face (100) is able to be connected to a suction unit for suctioning a conveying medium (90) by way of a conveying line (31), wherein the discharge device has an opening region (22) which is disposed on the body (11) and has at least one opening (23) in the region of the drilling tools (12) at the face. It is provided here that the at least one opening (23) of the opening region (22) is connected to a suction box (20) which as a component part of the discharge device has, at an end opposite the opening (23), a connector opening (29) for connecting to the conveying line (31), that at least one element which exerts an acceleration on the loosened ground in the region of the suction box (20) is provided, by way of which acceleration the ground loosened by the drilling tools (12) is able to be moved into the opening region (22) and/or through the opening (23) into the suction box (25), wherein the loosened ground (110) is acquired by the conveying medium (90) in the opening (23) and/or in the suction box (25) and is able to be discharged by way of the conveying line (31) by the suction unit.

A flow splitting device for gas reverse circulation drilling, including: an upper joint for connecting with a double-wall drill pipe; an inner tube which is arranged in the upper joint and defines a first passageway in communication with an inner chamber of the double-wall drill pipe, a second passageway in communication with an annular space in the double-wall drill pipe formed between the inner tube and the upper joint; a lower joint, having an upper end fixedly connected with the upper joint and a lower end for connecting with a drill tool; and a flow guiding member provided between the upper joint and the lower joint. A flexible sealing mechanism is provided outside the upper joint. The flexible sealing mechanism extends radially outward relative to the upper joint and the lower joint to form a sealing contact with a wellbore wall.

A flow splitting device for gas reverse circulation drilling, including: an upper joint for connecting with a double-wall drill pipe; an inner tube which is arranged in the upper joint and defines a first passageway in communication with an inner chamber of the double-wall drill pipe, a second passageway in communication with an annular space in the double-wall drill pipe formed between the inner tube and the upper joint; a lower joint, having an upper end fixedly connected with the upper joint and a lower end for connecting with a drill tool; and a flow guiding member provided between the upper joint and the lower joint. A flexible sealing mechanism is provided outside the upper joint. The flexible sealing mechanism extends radially outward relative to the upper joint and the lower joint to form a sealing contact with a wellbore wall.

A downhole system includes a drill string having a drilling fluid flow channel and at least one turbine alternator deployed in the flow channel. The turbine alternator is configured to convert flowing drilling fluid to electrical power. A voltage bus is configured to receive electrical power from the turbine alternator and at least one electrical motor is configured to receive electrical power from the voltage bus. An electronic controller is configured to provide active control of the turbine alternator via processing a desired speed of the electrical motor to generate a desired torque current and feeding the desired torque current forward to the turbine alternator. The turbine alternator is responsive to the desired torque current such that it modifies the electrical power provided to the voltage bus in response to the desired torque.

A downhole system includes a drill string having a drilling fluid flow channel and at least one turbine alternator deployed in the flow channel. The turbine alternator is configured to convert flowing drilling fluid to electrical power. A voltage bus is configured to receive electrical power from the turbine alternator and at least one electrical motor is configured to receive electrical power from the voltage bus. An electronic controller is configured to provide active control of the turbine alternator via processing a desired speed of the electrical motor to generate a desired torque current and feeding the desired torque current forward to the turbine alternator. The turbine alternator is responsive to the desired torque current such that it modifies the electrical power provided to the voltage bus in response to the desired torque.