Command and control of subsea well completions by means of acoustic communications

Conventional approaches for controlling the equipment required for completion of deep ocean wells involves the use either of ROVs or wired connectivity between the surface and the subsea systems. The ROV is costly and slow, while the electrical wiring is (frequently) subject to breakage or tangling. A program is described which provides command and control via acoustic communications (acomms) for well completions, including both conventional and horizontal "Xmas Trees," to depths in excess of 3000 meters. Both conventional in-water acomms and unique acomms through steel pipe are components of the sytem. The vertical and rotational location of the modem inside the pipe is subject to uncertainties which may adversely impact signaling through the pipe. An examination of the through-pipe signaling requirements, especially extremely long ringing (reverberation) leads to the selection of frequency hopped modulation with non-coherent demodulation as the preferred signaling scheme. Because of the potential structural blockage of the signals among various in-water modems, multiple devices are geometrically distributed to enhance connectivity. This in turn requires intelligent routing of data and commands among the several in-water and the several through-pipe modems.