Pushing Limits: Innovative Solutions for High Bandwidth, Long Distance Subsea Data Transmission

Feature Story - Page 10

Deepwater Power Point Provides a PowerPoint and Fibre Optics to the Seabed

Feature Story - Page 20

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EDITORIAL FOCUS

Single ConduitsWhen electrical and/or fiber optic lines are run in a single

conduit Flying Lead, Pressure Balanced Oil Filled (PBOF)hoses are required, giving way to Electric, Optical, andElectrical Optical (Hybrid) Flying Leads (EFL, OFL, EOFL,respectively). A key feature of PBOF hoses is that all lines arehoused within a single hose, making it the sole protective barrierfor these lines (See Figure 1) via its Kevlar properties, forexample. Conversely, bundled conduits contain and house mul-tiple independent steel tubes or thermoplastic hoses (forhydraulics, chemicals) within an outer jacket/sleeve.

In spite of PBOF hoses having protective qualities, it is notdifficult for a technician to bend/kink a hose by hand; this is fur-ther compounded when a Remotely Operated Vehicles(ROVs) manipulator incorrectly handles a hose (handling sen-sitivity increases when an OFL is engaged due to the fragility offibers). For this reason, ROV connectors with grab handles are

terminated at each end (see Figure 2). However, when a hoseitself needs to be handled/maneuvered independent of theconnectors handles monkey fists attached on surface areemployed (Figure 3). Moreover, single conduits differ frombundle conduits on two additional fronts. Firstly, PBOFhoses with multiple fiber and electric lines weigh substantial-ly less. Secondly, ROV tools are not utilized for their han-dling and installation.

Mating Sequence: Single ConduitsOnce a single conduit is landed on the mudline by way of

a Figure 8 deployment frame (Figure 4), the most commonmethod, an ROVs foremost task is to create slack byunspooling the lead one end at a time as engaging both endssimultaneously can lead to entanglement. Failing to createsufficient slack can have severe consequences, should theleads unspooled distance fall short of the installation point,causing it to be tugged on and adversely impacting the hoseand its internals.

Conversely, excessive spooling can cause a single conduit tobecome snagged on an asset as the ROV travels to its destina-tion point, splitting the hose open and flooding it. Moreover, inan obstruction-free scenario, it is imperative that the connectorsmating face not fall onto the mud line. Should this occur, themuds removal is critical (Figure 5 illustrates an ROV attempt-ing to remove lodged mud; topside cleansing is the preferredoption) failing to do so can cause the connector and the mat-ing point on asset to become damaged when mated. Should anasset not have backup/redundant ports, it can force an operatorto recover said asset, a cost-intensive task.

FLYING LEADS: The Howhe previous article Flying Leads and Production Schemes served as a starting point for oiland gas professionals to further understand the manner by which lying leads provide anddistribute power and communication to a subsea production scheme. In short, said articleanswered the what of Flying Leads what they are and what they do when bridginga path of continuity in open water. The intent of this follow up article is to expand on theprevious article by intimately detailing the less-covered facet of Flying Leads, the how which applies to their deployment, handling, and mating via specific tools and methodsand, more importantly, how formidable obstacles are addressed and countered during

their installation. But to further understand the how of this technology, single conduit and bundled con-duit Flying Leads must be defined and comparatively analyzed.

Figure 1: (Left) Running of fiber within a PBOF hose. (Right)Fiber prior to being run within hose, thinness/fragility shown.

By: Fernando Hernandez, Reaching Ultra

Figure 2: (Right) ROV engaging hybrid connector. (Left) Differenthandles on different styled connectors on an asset, with PBOF hosesshown (Source: Connect Subsea).

Figure 3: Monkey fist on a PBOF being engaged to strategicallymove hose

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Bundled ConduitsBundled conduits, when employed, are specifically used

for the running of hydraulic and chemical lines, giving way toHydraulic Flying Leads (HFL) and Chemical Flying Leads(CFL). Bundled conduits can also be outfitted with electricaland fiber optic lines. A jump out panel is typically utilized toconnect a PBOF hose and connector to its designated point inthis backdrop.

Termination wise, each end of a bundled conduit has amechanical mating plate and an ROV bucket; both are key formating and unmating an HFL and CFLs couplings onto anassets receiving plate (said couplings facilitate the indepen-dent routing of chemicals and hydraulics) by way of a stemlocated in the buckets center (Figure 6). Because bundled

conduits run multiple mediums, this greatly increases theirweight, requiring a crane to offset their weight via lift pointson the leads termination points. These points are of benefitfor two reasons: they assist an ROV in unspooling a lead andensure that the vehicles buoyancy is not impacted, affect-ing/preventing it from handling and installing a bundled lead.

With regard to a bundles unspooling, because of theirweight, the following methods are typically employed (andall require ROV and crane to work in unison, as shown inFigure 7): the use of a Figure 8 subsea deployment framewhere an ROV undoes a lead in an overlapping manner, atopside carrousel that overboards a single end of a lead at atime, or by way of a subsea helical frame here the FlyingLead is unspooled upward and in a helical fashion from asubsea deployment frame.

Installation wise, here too, only one end of the lead is han-dled at a time. However, once the Flying Lead is at a goodstopping point, an ROV will engage the leads ROV bucketvia ROV tooling consisting of an ROV Torque Tool (RTT)and a Flying Lead Orientation Tool (FLOT). Both tools per-form distinct functions when employed independently but areused singularly and installed on an ROVs porch for bundledlead installation (Figure 9). Functionally, RTTs methodicallyrotate the buckets stem via the RTTs end-effector/socket,but for this to occur this requires that both the socket andstem be of the same class class denotes the stem size andsocket to be used and the torque to be applied, as detailed inthe American Petroleum Institutes 17H document.

Figure 4: (Left) Hybrid Flying Lead configured in Figure 8 posi-tion. (Right) Figure 8 Flying Lead deployment landed on seafloor.

Figure 5: ROV attempting to remove mud from a connectorsfaceplate.

Figure 6: ROV bucket with stem at center.

Figure 7: ROV maneuvering Flying Lead via strap attached tocrane wire.

Figure 8: (Left) Flying Lead spooled on carrousel frame. (Right)Flying Lead unspooled from carrousel and being pressure tested.

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Should the classes not match when subsea, an ROV willhave trip to surface in the absence of a universal end effec-tor to adjust the RTTs socket, resulting in downtime.However, when both components properly interface, latcheson an RTT secure the bundle to an ROV via a FLOT, creatinga stationary point for the lead. This, in turn, prevents the fol-lowing: dropping a lead onto an asset and damaging it andfrom the lead being dropped on the mud line, lodging mud onthe mating plate. The muds removal is imperative; the intro-duction of mud particulates is detrimental to a control systemwhen mating an HFL.

Mating Sequence: Bundled ConduitsBecause bundled leads are typically installed at a nominal

90 angle on an asset, FLOTs are equipped with two specificmechanical devices consisting of cylinders, rotary devices,etc. Said devices are critical as they properly orientate andcenter a bundled conduits mating plate at the required angle;the inability to orientate a bundle conduit via ROV toolingcan prevent its installation.

The first of these devices allows the pitching of the lead,offsetting an ROVs tilt. The second device a rollingapparatus is used when an ROV is not centered on its lon-gitudinal axis; both devices ensure the lead successfully inter-faces with the receiving end on an asset. Next, the RTT willbegin rotating its end effector to mate a bundle (the RTT willcontinue to remain latched to the lead until installation iscompleted). It is at this juncture that two important featuresof RTTs must be diligently monitored: the turns and torqueapplied to the stem. Neglecting either can negatively impact

both mating ends (depending on the extent of damage, theasset may have to be recovered). Because of this, deck testingand calibration is imperative to verifying an RTT is fit for ser-vice, ensuring the successful installation of a bundled conduit.

ConclusionAs subsea production continues to see an uptick, so will

the need to continue installing Flying Leads both singleand bundled. For this reason, familiarization and the under-standing of the how of Flying Lead technology is key.Furthermore, the technological insights shared herein equallyserve as a refresher for field personnel and as a data resourcefor the oil and gas community at large.

EDITORIAL FOCUS

Figure 9: ROV and FLOT attached to ROVs porch; end effectorshown on RTT on left side of image.

Figure 10: ROV without any tooling attached to porch

Figure 11: RTT being tested and calibrated on ROV deck.

Figure 12: ROV positioning itself with FLOT and RTT to inter-face with an asset.