Provided are systems and methods for drilling a horizontally-oriented well having a sigmoid-shaped wellbore including an upper sigmoid portion having a downward curving wellbore trajectory and a lower sigmoid portion having an upward curving wellbore trajectory. The upper sigmoid portion having a first trajectory having a generally horizontal gradient at an entry point of the wellbore and that increases in downward gradient to a vertical gradient at an inflection point. The lower sigmoid portion having a second trajectory that includes the vertical gradient at the inflection point and that decreases in downward gradient to a generally horizontal gradient at a horizontal transition point of the wellbore.

The present application relates to a weight-on-bit self-adjusting drill bit, namely a pulsed jet type weight-on-bit self-adjusting drill bit, comprising a reaming bit, a WOB adjusting element, a transmission mechanism and a pilot bit and a pulsating impact generating mechanism; the pulsating impact generating mechanism comprises a centralizing element, a driving element, a rotating element and a throttling element which are placed and connected successively, the centralizing element, the driving element and the rotating element are connected successively, the throttling element is in clearance fit with the rotating element, both of the centralizing element and the throttling element are respectively provided with a flow-through passage for the drilling fluid to flow through, the driving element drives the rotating element to rotate, the rotating element rotates relative to the flow-through passage on the throttling element. Compared with the prior art, the present application can realize the rotary percussion drilling of the pilot bit, reduce the chip hold down effect of the pilot bit and the reaming bit, and realize the automatic and reasonable distribution of the weight on bit, thus to protect the bit, improve the bit service life and rate of penetration, and improve the drilling effect.

A rock drilling shank adaptor has at least one flush hole extending radially through the body of the adaptor in communication with an axially extending internal bore. The flush hole in a direction from an external side to an internal side includes a surface at a rearward region that is curved at least at a radially inner portion to extend in an axial direction towards a forwardmost end of the adaptor to increase the resistance of the adaptor to stress concentrations whilst achieving a desired flow rate of flushing fluid flow into the internal bore.

A rock drilling shank adaptor has at least one flush hole extending radially through the body of the adaptor in communication with an axially extending internal bore. The flush hole in a direction from an external side to an internal side includes a surface at a rearward region that is curved at least at a radially inner portion to extend in an axial direction towards a forwardmost end of the adaptor to increase the resistance of the adaptor to stress concentrations whilst achieving a desired flow rate of flushing fluid flow into the internal bore.

A percussion device that includes: an input side; an output side; at least one drive transmitter; a drive transmitter pathway; a percussion impactor; and a percussion anvil; where: the drive transmitter pathway is a circumferential pathway around a longitudinal axis of the percussion device; the drive transmitter pathway includes at least one tooth section including a lift section and a lead section; the at least one tooth section is essentially one wavelength of a sawtooth wave; the lift section is inclined away from a base of the drive transmitter pathway; the lead section is a section of the tooth section which abruptly returns to the base of the drive transmitter pathway; the input side is rotationally isolated from the percussion impactor; the percussion anvil is attached to, or forms part of, the output side; the percussion impactor includes an impact end and a force input end which are longitudinally opposite terminal ends of the percussion impactor; and the impact end faces the percussion anvil; such that: when in use, and the output section is free to rotate, the at least one drive transmitter and the drive transmitter pathway are configured to act co? operatively to transfer the rotational motion of the input side to the output side; and when in use and limited or no rotation of the output side is possible, the at least one drive transmitter and the drive transmitter pathway are configured to act co-operatively to increase, maintain or decrease the distance between the percussion impactor and the percussion anvil; wherein the at least one drive transmitter and the drive transmitter pathway are configured to act co-operatively to accept rotational motion from the input side and transmit a percussive and/or rotational motion to the output side.

A percussion device that includes: an input side; an output side; at least one drive transmitter; a drive transmitter pathway; a percussion impactor; and a percussion anvil; where: the drive transmitter pathway is a circumferential pathway around a longitudinal axis of the percussion device; the drive transmitter pathway includes at least one tooth section including a lift section and a lead section; the at least one tooth section is essentially one wavelength of a sawtooth wave; the lift section is inclined away from a base of the drive transmitter pathway; the lead section is a section of the tooth section which abruptly returns to the base of the drive transmitter pathway; the input side is rotationally isolated from the percussion impactor; the percussion anvil is attached to, or forms part of, the output side; the percussion impactor includes an impact end and a force input end which are longitudinally opposite terminal ends of the percussion impactor; and the impact end faces the percussion anvil; such that: when in use, and the output section is free to rotate, the at least one drive transmitter and the drive transmitter pathway are configured to act co? operatively to transfer the rotational motion of the input side to the output side; and when in use and limited or no rotation of the output side is possible, the at least one drive transmitter and the drive transmitter pathway are configured to act co-operatively to increase, maintain or decrease the distance between the percussion impactor and the percussion anvil; wherein the at least one drive transmitter and the drive transmitter pathway are configured to act co-operatively to accept rotational motion from the input side and transmit a percussive and/or rotational motion to the output side.

A multi-fluid drilling system (10) drilling is disclosed for drilling a hole or well (11). The system (10) is coupled to a dual wall drill string (12). The drill string (12) is configured to enable separate flow of a first fluid (14) and a second fluid (16). The system (10) has a hammer (22) and a downhole motor (24). Both the hammer (22) and the motor (24) are supported by and are coupled to the drill string (12). The motor (24) is uphole of the hammer (22). The hammer (22) is arranged so that when supported by the drill string (12) the first fluid (14) when flowing through the drill string (12) is able to flow to and power the hammer (22). As the motor (24) is disposed between the hammer (22) and the drill string (2) the first fluid (14) is also able to flow through the motor (24). To this end the motor (24) has a channel (25) to enable the first fluid to flow from the drill sting (12) to the hammer (22). The channel (25) acts as a part of a flow path or conduit for the first fluid (14).

A multi-fluid drilling system (10) drilling is disclosed for drilling a hole or well (11). The system (10) is coupled to a dual wall drill string (12). The drill string (12) is configured to enable separate flow of a first fluid (14) and a second fluid (16). The system (10) has a hammer (22) and a downhole motor (24). Both the hammer (22) and the motor (24) are supported by and are coupled to the drill string (12). The motor (24) is uphole of the hammer (22). The hammer (22) is arranged so that when supported by the drill string (12) the first fluid (14) when flowing through the drill string (12) is able to flow to and power the hammer (22). As the motor (24) is disposed between the hammer (22) and the drill string (2) the first fluid (14) is also able to flow through the motor (24). To this end the motor (24) has a channel (25) to enable the first fluid to flow from the drill sting (12) to the hammer (22). The channel (25) acts as a part of a flow path or conduit for the first fluid (14).

A hybrid bit includes an earth-boring element and a percussion element. The earth-boring element and the percussion element are coaxially arranged, with the earth-boring element surrounding the percussion element. A reciprocating member of the percussion element may oscillate in a manner that enables a bottom end of the reciprocating member to repeatedly protrude from a bottom end of the earth-boring element and to be repeatedly withdrawn. A configuration of the earth-boring element may enable it to drill into and remove some materials from an earth formation, while the percussion element may enable the hybrid bit to drill into and remove difficult-to-drill materials, including abrasive materials and/or materials with high compressive forces, such as chert.

Provided are systems and methods for drilling a horizontally-oriented well having a sigmoid-shaped wellbore including an upper sigmoid portion having a downward curving wellbore trajectory and a lower sigmoid portion having an upward curving wellbore trajectory. The upper sigmoid portion having a first trajectory having a generally horizontal gradient at an entry point of the wellbore and that increases in downward gradient to a vertical gradient at an inflection point. The lower sigmoid portion having a second trajectory that includes the vertical gradient at the inflection point and that decreases in downward gradient to a generally horizontal gradient at a horizontal transition point of the wellbore.