Measure while drilling system

A retrievable well-logging tool that is of elongate form and is adapted to be lowered through the interior of a drill string to a desired location to transmit signals therefrom to the surface through the drilling fluid, said tool having at the upper end thereof a spear point arrangement enabling lowering of the tool to a predetermined location in the drill string by a soft-releasing tool engaging therewith, said well-logging tool being subsequently retrievable by engagement of said spear point assembly by an overshot tool, said tool including a pressure modulator adapted to transmit signals indicative of selected parameters existing at said location, such signals being in the form of positive pressure pulses transmitted through the drilling fluid to a remote receiver on the surface, said pressure modulator comprising:

• a stator co-axially arranged in said tool and having angularly spaced channels therein that extend from an upstream end of the stator to a downstream end thereof to define passage means through which at least a portion of said fluid flow is to be directed;
• a rotor element rotatably mounted in the path of drilling fluid flow adjacent said stator and movable angularly between an inoperative condition wherein it is positioned in non-restrictive relationship with respect to said channels and an operative condition wherein it effects rapid, temporary, at least partial restriction of said passage means to generate said positive pressure pulses, said rotor element having angularly spaced radially projecting ribs thereon that pass alternately between said operative condition wherein they occlude said passage means, and the inoperative condition;
• impeller means interacting with the fluid flow to apply a driving torque to said rotor, said impeller means having angled blades projecting into the path of the fluid flow to interact therewith so that the impeller is urged to rotate thereby, said impeller being directly coupled to said rotor;
• latching means effective to retain said rotor in the inoperative condition against said driving torque;
• and
• electrical actuator means for said latching means said actuator means being selectively energizable to release said latching means and free said rotor to undergo incremental angular movements away from the inoperative condition to the operative condition and again to said inoperative condition under the influence of said driving torque.

A method of pressure pulse telemetry, comprising

• positioning a signalling tool in a conduit through which fluid is flowing, said tool comprising a stator that partially blocks the conduit while leaving at least one passage to conduct fluid from upstream to downstream of the stator, and a rotor that is angularly movable in the conduit adjacent the stator, said rotor having at least one channel therethrough positioned to be moved, upon angular movement of the rotor, between an operative position in which the rotor substantially restricts flow through the stator passage, thereby creating a positive pressure pulse, and an inoperative position in which the rotor causes substantially less restriction of flow through the stator passage,
• utilizing the force of the flow of the fluid through the conduit to continuously urge the rotor to move angularly,
• repeatedly at controlled intervals releasing the rotor for angular movement between the inoperative and operative positions and stopping the rotor at each occasion it reaches the inoperative position to create a coded series of positive pressure pulses for transmission through said fluid, and
• receiving and interpreting said positive pressure pulses at a location remote from said signalling tool.

A method of well-logging, comprising

• positioning a signalling tool in the bore of a drill string through which drilling fluid is flowing, said tool comprising a stator that partially blocks the bore while leaving at least one passage to conduct fluid from upstream to downstream of the stator, and a rotor that is angularly movable in the bore adjacent the stator, said rotor having at least one channel therethrough positioned to be moved, upon angular movement of the rotor, between an operative position in which the rotor substantially restricts flow through the stator passage, thereby creating a positive pressure pulse, and an inoperative position in which the rotor causes substantially less restriction of flow through the stator passage,
• utilizing the force of the flow of the fluid through the drill string bore to continuously urge the rotor to move angularly,
• repeatedly at controlled intervals releasing the rotor for angular movement between the inoperative and operative positions and stopping the rotor at each occasion it reaches the inoperative position to create a coded series of positive pressure pulses for transmission through said fluid, and
• receiving and interpreting said positive pressure pulses at a location remote from said signalling tool.

A remote sensing system comprising a tool for positioning at a predetermined location in a conduit through which a flow of fluid is circulated, said tool including a pressure modulator adapted to transmit signals indicative of selected parameters existing at said location, such signals being in the form of positive pressure pulses transmitted through the fluid to a remote receiver, said pressure modulator comprising:

• a stator co-axially arranged in said tool and having at least one channel therein that extends from an upstream end of the stator to a downstream end thereof to define passage means through which at least a portion of said fluid flow is to be directed;
• rotor means adjacent said stator and rotatable from an operative condition wherein it effects rapid, temporary, at least partial restriction of said passage means to generate a positive pressure pulse, an inoperative condition wherein it is positioned in restrictive relationship relative to said passage means;
• impeller means for interacting with the fluid flow to apply a driving torque to said rotor, said impeller means being directly coupled to said rotor so that the rotor is urged to follow angular movement of the impeller means;
• latching means effective to retain said rotor in the inoperative condition against the driving torque of the impeller means;
• and
• electrical actuator means for said latching means, said actuator means being selectively energizable to release said latching means and free said rotor to undergo incremental angular movements away from the inoperative condition to the operative condition and again to said inoperative condition under the influence of said driving torque.

A retrievable well-logging tool that is of elongate form and is adapted to be lowered through the interior of a drill string to a desired location to transmit signals therefrom to the surface through the drilling fluid, said tool having at the upper end thereof a spear point arrangement enabling lowering of the tool to a predetermined location in the drill string by a soft-releasing tool engaging therewith, said well-logging tool being subsequently retrievable by engagement of said spear point assembly by an overshot tool, said well-logging tool including a pressure modulator adapted to transmit signals indicative of selected parameters existing at said location, such signals being in the form of positive pressure pulses transmitted through the drilling fluid to a remote receiver on the surface, said pressure modulator comprising:

• a stator co-axially arranged in said tool and having at least one channel therein that extends from an upstream end of the stator to a downstream end thereof to define a passage means through which at least a portion of said fluid flow is to be directed;
• rotor means adjacent said stator and rotatable from an operative condition wherein it effects rapid, temporary, at least partial restriction of said passage means to generate a positive pressure pulse, and an inoperative condition wherein it is positioned in restrictive relationship relative to said passage means;
• impeller means for interacting with the fluid flow to apply a driving torque to said rotor, said impeller means being directly coupled to said rotor so that the rotor is urged to follow angular movement of the impeller means;
• latching means effective to retain said rotor in the inoperative condition against the driving torque of the impeller means;
• and
• electrical actuator means for said latching means, said actuator means being selectively energizable to release said latching means and free said rotor to undergo incremental angular movements away from the inoperative condition to the operative condition and again to said inoperative condition under the influence of said driving torque.