Abstract: A pressure pulse generator for use in transmitting pressure signals to surface in a fluid-based drilling system having a housing having an inlet to admit drilling fluid to the interior of housing, and an outlet to discharge fluid from the interior of the housing; a control element slidably mounted in the housing between an open and a closed position, the control element generating a pressure pulse in the supply of pressure fluid when the control element takes-up the closed position; a control passage extending through the control elements and closable by a pilot valve element exposed to the pressure of the fluid in the passage; and an actuator coupled with the valve element to generate a pressure signal, to move the valve element to a position closing said passage and thereby to cause movement of the control element towards the closed position; the coupling between the actuator and the valve element includes a yieldable biassing element which provides control of the amplitude of the pressure signals produces

Abstract: A data coupler for use in transmitting data between mechanical parts which have a common axis and which are in relatively close engagement. The parts are adjustable relative to the other along the common axis. The data coupler includes an elongate housing having a longitudinal axis extending parallel to the common axis of the parts and is slidable relative to the parts during adjustment of the parts. A data source A and a data receiver B are spaced apart lengthwise. An axially short solenoidal coil is provided at each of the data source A and the data receiver B.

Abstract: A pressure pulse generator to generate pressure signals in drilling fluid for transmission to surface includes an outer housing having an inlet and an outlet for supply to the drilling assembly; a control element slidably mounted in the housing for opening and closing said inlet, the element being operative to generate a pressure pulses when it closes; a control passage extending through the element and closable by a valve element arranged to be exposed to the pressure in the passage; and an actuator assembly connected to the control element. The control element moves upon activation relative to the inlet to generate a pulse. When deactivated, it blocks the flow through the passage so that all of the fluid bypasses via the inlet.

Abstract: An antenna assembly for an induction logging tool for use in a drilling operation. The assembly includes an outer pressure housing, a coil former within the pressure housing, magnetic cores mounted in the housing, a core carrier within the coil former and the pressure housing which carries the magnetic cores, and shock-absorbing mountings on the core carrier for the magnetic cores.

Abstract: A pressure pulse generator for use in transmitting pressure signals to surface in a fluid-based drilling system. The generator is arranged in use in the path of a pressurized fluid to operate a drilling assembly and is capable of being actuated to generate pressure signals in such fluid for transmission to surface pressure monitoring equipment. The pulse generator includes pulse height compensation to keep the pulse height within acceptable limits over a wide flow range.