Page 86: of Offshore Engineer Magazine (May/Jun 2013)

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Industry takes steps shutdown systems including BOPs and HIPPS (high-integrity pressure to monitor, control protection systems) are critical.

subsea processing

Subsea

Wired vs. Wireless

Choosing between wired and wire- less subsea communication is a matter of great importance, but the decision is not straightforward. Long-distance “ocean bottom cable systems” are wired solutions that can be pneumatic or hydraulic.

The challenge with these technolo- gies is that they can be limited by

Milton Korn of ABS explains how industry is monitoring the great distances and depths. Other well conditions and fuids for effcient and safe production.

wired solutions include copper and fber-optic systems, which use sea foor level, and stimulation and proven technologies that are frmly

The task of monitoring and control- re-injection wells have their own established in the scientifc commu- ling operations is diffcult onshore, subsea piping network. nity and are likely better choices.

T and when subsea drilling and The extensive geographic cover- The great bandwidth, immunity production are taking place in ultra- age of modern ultra-deepwater felds to interference and noise, and the deep water, the complexity and mag- and the large number of systems and ability to carry information over nitude of this task is compounded equipment being deployed to the long distances with minimal attenu- several-fold. Monitoring and control sea foor is increasing the volume of ation make fber optics a preferred concerns are moving to the forefront monitoring and control information choice for communications. One of now that previously unreachable that must be exchanged. Monitored the challenges to the full deploy- reserves are being recovered and information can include tempera- ment of fber-optic communication particularly when the percentage of tures, pressures, fow rates, well fuid in the production environment is the recovery is increasing toward 50%. viscosity, etc. both down hole as well development of wet-mate, fber-optic as at various points in the subsea connectors for use at depth that

Expanding needs collection network, risers, tie backs can be readily manipulated by an

With the discovery of deepwater and processing equipment. Control ROV. Allied technology is regularly reservoirs, operators are expending information and signals might ex- covered at the bi-annual IEEE Sympo- great effort planning the develop- tend to the position of valves to shut sium on the Scientifc Use of Subma- ment of their felds to do more with in a particular well, valve position rine Cables and Related Technologies. less, to maximize the amount of oil control to direct fow, valve position Manufacturers that have established recovered from each feld as well as modulation to control fow rates, the solutions for scientifc applications the rate of recovery from individual starting/stopping and speed control are transferring the technologies to reservoirs. Fields can include mul- of pumps and compressors, pipeline the offshore production environment. tiple reservoirs that can be spaced heating, and the control of subsea Long-distance copper-based elec- over an area as large as 100sq km or processing and separation equipment. trical communication is possible; more with multiple production wells The proliferation of subsea however, it is susceptible to more and additional wells for stimulation monitoring and control information interference and noise and exhibits and re-injection. manifests itself in several ways. The greater signal attenuation than is

Production wells are connected repetitive sample rate of select indi- encountered with fber-optic com- to a subsea collection network that vidual channels is increasing along munication. Copper-based electri- spans the feld. Operation of valves with the overall bandwidth require- cal systems possibly could require and pumps, etc., controls the move- ment as the number of individual additional repeaters (amplifers) ment and manipulation of well fuids channels of information dramatically along the length of the communica- as they are processed as necessary to grows. The ability to reliably ex- tions line than would be needed in a facilitate transport to the surface or change information and transmit and fber-optic system and consequently tieback to shore. Each of these wells receive control commands without would be more power intensive. In while in production requires moni- corruption over the great distances many cases, the communication line toring for effective control. Some envisioned in felds with tiebacks can be included as part of a subsea wells include electric submersible extending hundreds of kilometers is power cable from shore, integrated pumps to help lift well fuids to the of paramount importance; safety and into a fow tieback or umbilical.

OE | May 2013 oedigital.com 88 subsea1_abs.indd 88 4/22/13 5:57 PM