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DMaC: System Overview
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DMaC System Overview
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The DMaC Diverless Connection System is designed to complement the DMaC field development philosophy by providing the means to pull-in and connect flowlines, lightweight control umbilicals and armoured control umbilicals thus providing the links between subsea field development hardware such as Christmas Trees, Manifolds, Pipeline End Terminations and Riser Bases. Using tooling powered by a workclass ROV, DMaC is capable of pulling in and connecting single or multiple bore connections in a single operation.
The system is designed to be deployed from a drill rig as well as from a wide variety of construction vessels. This flexibility creates the opportunity for connections to be made within a cluster of wells, in parallel with drilling operations, without the need to move the drill rig off station.
The system can also be used for connections outside the well cluster; such as risers and long jumpers to satellite wells and export lines, and it can be deployed from a variety of vessels ranging from large semi-submersibles through to small monohull offshore support vessels.
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DMaC is designed to have the absolute minimum of impact on its host structure. Hence DMaC flowline and umbilical inboard connections can be, and have been, located on many designs and makes of subsea tree, manifold, pipeline, riser and ancillary subsea structures.
A DMaC inboard flowline connection porch is a standard design whatever its host structure. Within given size ranges, whatever the services that pass through the connector, whether they be single, or multi-bore the connector and the connection process remain the same.
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The DMaC umbilical inboard connector is similarly a standard design accommodating a wide variety of hydraulic and electrical couplings.
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Primary uses to date have been for pull-in and connection operations as shown below.
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Jumper pulled into 1st End Porch and connection made
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Tool taken and docked to tree
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Jumper deployed on seabed
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Tool docked, paid back and landed on pullhead
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Tool pays back and lands on 2nd End pullhead
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Tool winches pullhead & jumper towards tree
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2nd End pulled in and connection made
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Tool retrieved and connection complete
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The pull-in and connection operation comprises a series of short interruptible steps giving the installer unparalleled opportunities for optimisation when planning and executing the offshore operation. Options for run to place and rigid jumpers are also available.
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FTP connect operations are shown below.
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Basket containing umbilical jumper deployed to seabed
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ROV tool docks with 1st End connector
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Tool flies 1st End out of basket
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Tool docks onto manifold & makes-up 1st End
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Tool docks to 2nd End and flies out of basket
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Tool flies 2nd End towards Tree removing jumper from basket
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Tool docks onto tree & makes-up 2nd End
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Connection complete ROV & basket can be retrieved
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Interface Management
DMaC interfaces are clear, pre-defined, and available from the start of FEED or detailed design. The interfaces between DMaC and other equipment are simple, surface made, physical, welded, or bolted interfaces. DMaC can be utilised to interface different contractors equipment. For example different makes of Subsea Tree can be interconnected with DMaC.
Commercial Independence
Inherent in the design of DMaC is that choice of DMaC connection equipment leaves the client free to select any subsea hardware supplier for trees manifolds, flowlines, etc. Similarly DMaC tools can be operated by any ROV with sufficient thruster performance, power and control capacity. This includes most workclass ROV’s. Choice of DMaC does not impact any other commercial decisions the client wishes to make.
Retrievability
All DMaC equipment and processes are designed with overrides such that any one failure subsea can be managed by retrieving and repairing the failed part. All moving or fallible parts within DMaC are retrievable from the host structure, including flowline clamps.
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