Abstract: A surface mud pipeline system is described with a mechanical acoustic filter (1245) tuned to a predetermined frequency band so as to attenuate pump noise (132) within this band. The filter can be combined with a Venturi constriction to provide enhanced attenuation and is used to improve signal transmission of a mud pulse telemetry system (113-2).

Abstract: There is provided an apparatus for measuring flow rates of multi-phase flows in metal pipes, the apparatus comprising a transceiver generating a pulsed Doppler signal in the range 100 KHz to 10 microHz and an impedance device adapted to be coupled to a pipe so as to reduce or prevent reflections occurring from a pipe wall in response to the pulsed signal. The apparatus includes signal processor for analysing reflected signals received by the transceiver and for calculating the energy contained in a received signal. The pulsed signal is a shear wave which assists analysis of the reflected signals. The impedance device comprises a sound absorbing block made from plastics material with tungsten particles embedded therein. Different embodiments using various arrangements of transceivers are described, and also a related method of using the apparatus.

Abstract: Methods and apparatus are described that characterize flows within a conduit by generating acoustic waves, and receiving acoustic energy representing at least one in-wall leaky acoustic wave mode. Attenuation of acoustic energy that has entirely propagated within the wall of the conduit is measured and evaluated in order to derive parameters relating to the fluid or fluids flowing in the conduit. The wave modes described include bulk waves and lamb waves and propagate in axial and circumferential directions.

Abstract: There is provided apparatus for measuring flow rates of multi-phase flows in metal pipes, the apparatus comprising transceiver means (30) generating a pulsed narrow band ultrasonic signal in the range 100 KHz to 10 MHz and an impedance matching device (50) adapted to be coupled to a pipe so as to reduce or prevent reflections occurring from a pipe wall in response to the pulsed signal. The apparatus includes signal processing means (80, 84, 86) for analysing reflected signals received by the transceiver means (30) and for calculating the energy contained in a received signal. The pulsed signal generates an ultrasonic shear wave in the pipe wall which assists analysis of the reflected signals. The impedance device (50) comprises a sound absorbing block made from plastics material with tungsten particles embedded therein. Different embodiments using various arrangements of transceivers are described, and also a related method of using the apparatus.

Abstract: A cross correlation fluid flow meter including a body having first and second sensor devices positioned such that in use they are spaced apart a known distance in the direction of fluid flow, each sensor device having a signal transmitter and a signal receiver. According to one embodiment of the flow meter, the signal transmitter of the first sensor device is operable to transmit signals at a first frequency and the signal receiver of the first sensor device is arranged to receive signals at the first frequency. The signal transmitter of the second sensor device is operable to transmit a second signal at a second frequency and the signal receiver of the second device is operable to receive signals at the second frequency, the first and second frequencies being different from one another. The first sensor is non-responsive to the second frequency and the second sensor is non-responsive to the first frequency. Cross correlation of the received signals provides an indication of the fluid flow rate.

Abstract: A cross correlation fluid flow meter including a body having first and second sensor devices positioned such that in use they are spaced apart a known distance in the direction of fluid flow, each sensor device having a signal transmitter and a signal receiver. According to one embodiment of the flow meter, the signal transmitter of the first sensor device is operable to transmit signals at first phase of a first frequency and the signal receiver of the first sensor device is arranged to receive signals at the first phase of the first frequency. The signal transmitter of the second sensor device is operable to transmit a second signal at a second phase of the first frequency and the signal receiver of the second device is operable to receive signals at the second phase of the first frequency, the first and second phases being out of phase with one another. The first sensor is non-responsive to the second phase and the second sensor is non-responsive to the first phase.