Abstract: Method and apparatus to allow continuous recovery and broadcast of data and commands to and from a tubular string (32) through all phases of drilling and completion running in a wellbore. A RF transceiver (76/74) is located on the tubular string, the transceiver being adapted to receive signals and broadcast the signals, and a RF transceiver (88/90) is located remote from the tubular string and adapted to receive the broadcasted signal by virtue of an antenna (92) arranged within a fluid filled annulus (60) around the tubular string. RF transmission through the wellbore using distributed RF transceivers providing data and command transmission up and down the tubing string.

Abstract: Method and apparatus to allow continuous recovery and broadcast of data and commands to and from a tubular string (32) through all phases of drilling and completion running in a wellbore. A RF transceiver (76/74) is located on the tubular string, the transceiver being adapted to receive signals and broadcast the signals, and a RF transceiver (88/90) is located remote from the tubular string and adapted to receive the broadcasted signal by virtue of an antenna (92) arranged within a fluid filled annulus (60) around the tubular string. RF transmission through the wellbore using distributed RF transceivers providing data and command transmission up and down the tubing string.

Abstract: A high pressure pump for use in the injection of liquid chemicals into subsea oil or gas wells, and intended to be positioned in the subsea environment adjacent to the wellhead, comprises a piezoelectric actuator (19) for reciprocating a plunger (22) which acts to compress and expand the effective volume of a pumping chamber (29) having a valved inlet (15) connected to a source of the liquid and a valved outlet (16) to lead the liquid to the well. The device has a minimum of moving parts and in particular avoids the need for any rotating parts and attendant high performance bearings and seals.

Abstract: A high pressure pump for use in the injection of liquid chemicals into subsea oil or gas wells, and intended to be positioned in the subsea environment adjacent to the wellhead, comprises a piezoelectric actuator (19) for reciprocating a plunger (22) which acts to compress and expand the effective volume of a pumping chamber (29) having a valved inlet (15) connected to a source of the liquid and a valved outlet (16) to lead the liquid to the well. The device has a minimum of moving parts and in particular avoids the need for any rotating parts and attendant high performance bearings and seals.

Abstract: A stress or magnetic field sensor comprising a generally elongate magnetically soft amorphous or nanocrystalline electrically resistive element and biasing means for applying to the element a bias magnetic field of which the component directed along the length of the sensor has an amplitude variation pattern along the element. A periodically varying pattern has the effect of reducing the sensitivity of a stress sensor to external ambient fields (FIG. 3 shows that with a sawtooth bias field the sensitive portions a of a sensor move to positions b in the presence of an ambient field, but their number remains the same). A ramped bias field enables the position of the sensitive region of the sensor to be controlled, for measuring local stress, or for mapping an external magnetic field. Control of the regions where the sensor is active may include selective conductive coating of portions of its length.

Abstract: A stress or magnetic field sensor comprises a generally elongate magnetically soft amorphous or nanocrystalline electrically resistive element and biasing means for applying to the element a bias magnetic field of which the component directed along the length of the sensor has an amplitude variation pattern along the element. A periodically varying pattern has the effect of reducing the sensitivity of a stress sensor to external ambient fields (FIG. 3 shows that with a sawtooth bias field the sensitive portions a of a sensor move to positions b in the presence of an ambient field, but their number remains the same). A ramped bias field enables the position of the sensitive region of the sensor to be controlled, for measuring local stress, or for mapping an external magnetic field. Control of the regions where the sensor is active may include selective conductive coating of portions of its length.