Apparatus and method for monitoring fluid flow in a wellbore using acoustic signals

An electro-acoustic telemetry system for monitoring fluid flow in a wellbore, comprising:

• a tubular body disposed in a wellbore;
• a topside communications node placed proximate a surface of the wellbore;
• one or more sensors along the wellbore for at least one of sensing, monitoring, and measuring a parameter indicative of fluid flow within the wellbore and generating a sensor signal representative of fluid flow data;
• one or more sensor communications nodes associated with and in communication with at least one of the one or more sensors, each of the one or more sensor communications nodes configured to (i) receive a sensor signal from an associated sensor and (ii) transmit an acoustic signal indicative of the sensor signal to at least one of a plurality of subsurface communications nodes;
• the plurality of subsurface communications nodes spaced along the wellbore and attached to a wall of the tubular body, each of the plurality of subsurface communications nodes configured to receive and transmit acoustic communications signals indicative of the sensor signal from node-to-node up the wellbore within the tubular body and to the topside communications node;
• and
• a receiver at the surface configured to receive signals from the topside communications node;
• wherein each of the plurality of subsurface communications nodes comprises:
• an electro-acoustic transducer and associated transceiver in acoustic communication with the wall of the tubular body, with the transceiver being designed to relay the acoustic communications signals from node-to-node up the wellbore using the tubular body as an acoustic transmission medium, with each of the acoustic communications signals representing a packet of information that comprises an identifier for the sensor communications node that originally transmitted the signal, and the fluid flow data;
• and
• an independent power source providing electrical power to the transceiver;
• wherein adjacent nodes selected from the plurality of subsurface communications nodes represent pairs of nodes;
• wherein a receiving node in the pair of nodes is configured to detect amplitude and/or reverberation time for each tone received in a packet from a transmitting node in the pair of nodes, and then return the packet to the transmitting node;
• and
• wherein the transmitting node is configured to
• adjust its transmitting energy or its frequency band so that a weakest tone in the packet as returned by the receiving node will be received at a weakest signal amplitude for which communication remains robust,
• reduce a waiting time between tones to a smallest time required for the reverberation to substantially subside, and
• instruct the receiving node that it has made any changes in the transmitting energy, the waiting time, or the frequency band.