S

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S_ubs

Shear strength intercept at the clay layer’s surface in strong overlying soft soil.

Source: ABS Guidance Notes on Geotechnical Performance of Spudcan Foundations, January 2017. Global Standards

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Subsea BOP

Blowout preventer stack designed for use on subsea wellhead and wellhead assemblies, complete with redundant controls. Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards  

Subsea Blowout Preventer

A series of ram blowout preventers and annular blowout preventers designed to be installed as a unit on a subsea wellhead, tubing head, or subsea tree. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global Standards  

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Subsea BOP

Blowout preventer designed for use on subsea wellheads, tubing heads or trees. Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards  

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Subsea Buoy

Concentrated buoyancy system. NOTE This system generally consists of steel or syntactic foam tanks, as used in S-type riser configurations (4.4.5). See also buoyancy module (3.1.5). Source: API RP 17B, Recommended Practice for Flexible Pipe, Fourth Edition, July 2008. Global Standards

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Subsea buoy clamps

Subsea buoy clamps are used to secure flexible pipes to subsea buoys. They typically consist of a split steel assembly that is bolted onto the flexible pipe. Source: API RP 17L2, Recommended Practice for Flexible Pipe Ancillary Equipment, First Edition, March 2013. Global Standards  

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Subsea buoy frame

Structural part of a subsea buoy. Includes the gutters, housings for clamps and buoyancy tanks or buoyancy elements and connection points for tether connection hardware. Source: API RP 17L2, Recommended Practice for Flexible Pipe Ancillary Equipment, First Edition, March 2013. Global Standards  

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Subsea buoy systems

Subsea buoy systems are used to achieve S-shaped riser configurations, including lazy (Figure 19), steep (Figure 20) and reverse configurations (note that in the reverse configuration the lower catenary of the riser passes back underneath the buoy). The objective of the subsea buoy is to provide upthrust, longitudinal fixture and guidance to the supported risers. The subsea buoy typically consists of buoyancy tanks or elements, supported by a metallic structure, over which lie individual gutters for each flexible pipe. Source: API RP 17L2, Recommended Practice for Flexible Pipe Ancillary Equipment, First Edition, March 2013. Global Standards  

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Subsea Casing Hanger

Device that supports a casing string in the wellhead at the mudline. Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards  

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Subsea Completion Equipment

Specialized tree and wellhead equipment used to complete a well below the surface of a body of water. Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards  

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Subsea control module or control pod

A subsea control module (colloquially referred to as a “control pod”) is normally mounted directly on the facility to be controlled, such as a subsea tree/manifold, on a base from which it can be removed for maintenance if necessary. The control pod is the interface between the control lines, supplying hydraulic and electric power and signals from the host facility, and the subsea equipment to be monitored and controlled. The control pod contains pilot valves powered by hydraulic fluid, electric power or both, that is supplied from the host facility. The pod also contains electronic components that are used for control, communications and data-gathering. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards  

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Subsea Fillup Valve

A special riser joint having a valve means to allow the riser annulus to be opened to the sea. To prevent riser pipe collapse, the valve may be opened by an automatic actuator controlled by a differential-pressure sensor. Source: API RP 16Q, Recommended Practice for Design, Selection, Operation and Maintenance of Marine Drilling Riser Systems, First Edition, November 1993 (Reaffirmed August 2001). Global Standards  

Subsea Fill-Up Valve

Special riser joint having a valve means to allow the riser annulus to be opened to the sea. NOTE To prevent riser pipe collapse, the valve can be opened by an automatic actuator controlled by a differential pressure sensor. Source: ISO 13624-1:2009, Petroleum and natural gas industries – Drilling and production equipment – Part 1:Design and operation of marine drilling riser equipment. Global Standards  

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Subsea Isolation Valve

SSIV SIV valve which closes within a defined time limit derived from the risk assessment in order to reduce consequences of pipeline/riser leak or rupture Note 1 to entry: The SSIV can be an actuated valve (e.g. remotely controlled subsea valve) or a non-activated valve (subsea check valve). An activated valve is normally designed as fail safe (i.e. closes and remains closed on all failures external to the valve and actuator themselves). Note 2 to entry: Where the flexible risers are connected directly to the subsea wellhead, the master and wing valve may be considered to represent the SSIV function. [SOURCE: ISO 14723] Source: ISO/TR 12489:2013(E) Reliability modelling and calculation of safety systems. Global Standards

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Subsea Mud Lift

A form of MPD utilizing pumps located on the sea floor to pump the mud and cuttings returns back to the surface. This system may also employ a rotating seal above the BOPs and can create or reduce back-pressure on the wellbore by varying the pump operating speed and RCD configuration.

Source: ABS Guide for Classification and Certification of Managed Pressure Drilling Systems, September 2017. Global Standards

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Subsea processing (SSP) systems

In general, SSP encompasses all separation and pressure-boosting operations that are performed subsea, whether downhole or on the seabed. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards  

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Subsea Production Control System

Control system operating a subsea production system during production operations. Source: API SPEC 17F, Specification for Subsea Production Control Systems, Second Edition, December 2006 (Reaffirmed April 2011). Global Standards

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Subsea reeled-tubing systems

Subsea coiled/reeled-tubing systems are similar to subsea wireline systems in that they also involve the use of subsea pressure-control equipment (including a lubricator), attached directly to the top of the subsea tree, while the reel is mounted on the intervention vessel. The configuration of a subsea reeled-tubing system is very similar to that for a subsea wireline system, and in fact one system could be configured to be able to handle both reeled tubing and wireline operations. A typical subsea reeled-tubing system consists of the following major components: a tree connector; a lower lubricator assembly, consisting of a series of various blind/shear and pipe BOPs for pressure control of the well in the event of an emergency disconnect; an upper lubricator assembly, consisting of a connector, crossover spool (to accommodate the length of the various downhole tools), tubing ram BOP, tubing stuffing box (to retain well pressure), injector assembly (to control movement of the tubing in and out of the well), tubing stripper (to prevent seawater entering the injector assembly), tubing cutter/crimper (to cut and crimp the tubing in an emergency disconnect situation) and a flexible tubing guide (to ensure the tubing is not accidentally crimped at the point where it enters the injection assembly); a surface-mounted tubing reel; a control system, similar to a WOCS as described in A.11.2.3, for controlling the subsea tree and downhole safety valves as well as all the valves and functions contained within the subsea reeled-tubing equipment; a handling system, for deployment and retrieval of the subsea equipment (usually with guidewires); a supporting ROV spread, for observation and operation manual overrides, etc., as required. Unlike a subsea wireline system, which requires motion compensation of the wire in order to maintain accurate depth control of the downhole tools, the reeled-tubing system controls the depth of the tools using the subsea injector assembly and therefore this control is decoupled from the motion of the intervention vessel, i.e. motion compensation of the tubing is not required. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards  

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Subsea Service

Descriptive term used to apply to any item intentionally used in a wet condition below the sea water level. Subsea service requires multiple design features for that purpose, depending on each piece of equipment.

Source: ABS Guide for Classification and Certification of Managed Pressure Drilling Systems, September 2017. Global Standards

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Subsea system engineering

Subsea system engineering is an interdisciplinary approach which covers the complete system, from the reservoir to the processing facilities on the host (inclusive), with consideration of the requirements of all phases of the development, including engineering, procurement, construction, testing, installation, commissioning, operation, workover/maintenance and abandonment. The system engineering process consists of a management part and a technical part. An evaluation of the need for application of the various system engineering processes should be performed for each specific field development, based upon the characteristics of the development. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards  

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Subsea Termination Interface

Mechanism that forms the transition between the umbilical and the subsea termination. NOTE The interface is comprised typically of an umbilical armour termination and/or a mechanical anchoring device for the tubes, bend stiffener/limiter, and tube or hose-end fittings. If the umbilical contains electric cables/fibre optics, then penetrator(s) and/or connectors may also be incorporated. Source: API SPEC 17E, Specification for Subsea Umbilicals, Upstream Segment, Fourth Edition, October 2010. Global Standards

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Subsea Test Tree

Assembly of valves positioned above the tubing hanger running tool located inside the subsea BOP and equivalent to the lower workover riser package. NOTE It is used to secure the well and provides a disconnect point for the C/WO riser. The subsea test tree can be configured for operation on horizontal or vertical trees. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards

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Subsea Tree

A system of valves placed on the subsea wellhead designed to control the flow into or out of the completed well. NOTE The subsea tree may provide numerous additional functions [e.g. chemical injection points, well intervention means, pressure relief means (annulus vent), etc.]. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global Standards  

Subsea Tree

Assembly of valves attached to the uppermost connection of the subsea wellhead and used to control well production. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

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Subsea tree system

The equipment required to complete a subsea well for production or injection purposes includes a tubing hanger and a tree, often referred to in combination as the “subsea tree system”. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards  

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Subsea Umbilical Termination

Mechanism for mechanically, electrically, optically and/or hydraulically connecting an umbilical or jumper bundle to a subsea system. Source: API SPEC 17E, Specification for Subsea Umbilicals, Upstream Segment, Fourth Edition, October 2010. Global Standards

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Subsea Wellhead

Wellhead that is installed at or near the seabed. Source: ISO 16530-1:2017, Petroleum and natural gas industries — Well integrity – Part 1: Life cycle governance, First Edition, March 2017. Global Standards

Subsea Wellhead

Assembly used during drilling, completion and production operations that has provisions to lock and seal to a subsea BOP stack, to a subsea tree, to a high pressure drilling riser or to a top-tensioned production riser. Source: API Standard 2RD, Dynamic Risers for Floating Production Systems, Second Edition, September 2013. Global Standards

Subsea Wellhead

Wells drilled and completed with a subsea wellhead located near the seafloor. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global Standards  

Subsea Wellhead

Wellhead assembly used during drilling and completion operations that has provisions to lock and seal to a subsea BOP stack and to the subsea tree. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards  

Subsea Wellhead

A wellhead that is used with a floating drilling rig that uses a subsea BOP stack for well control. The subsea wellhead is usually connected to the surface casing string and all subsequent casing strings are installed, landed, and sealed inside the subsea wellhead’s high pressure housing, immediately below the BOP. The well can be completed in one of two methods: 1. Using a subsea tree (subsea well). 2. Using one or two production risers leading back to a surface casing head, tubing head/tubing hanger, and christmas tree (hybrid well). Source: API RP 90, Annular Casing Pressure Management for Offshore Wells, Upstream Segment. First Edition, August 2006. Global Standards

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Subsea Wellhead Housing

Pressure-containing housing that provides a means for suspending and sealing the well casing strings. Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards  

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Subsea Wells

Wells drilled and completed with a subsea wellhead located near the seafloor. Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global Standards  

Subsea Well

Wells completed with a subsea wellhead and a subsea tree. Source: ISO 16530-1:2017, Petroleum and natural gas industries — Well integrity – Part 1: Life cycle governance, First Edition, March 2017. Global Standards Source: API RP 90, Annular Casing Pressure Management for Offshore Wells, Upstream Segment. First Edition, August 2006. Global Standards

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Subsea wireline systems

Subsea wireline systems involve the use of subsea pressure control equipment (including a lubricator), attached directly to the top of the subsea tree. Typical subsea wireline systems use a surface-mounted wireline winch/reel on the intervention vessel. Designs also exist for systems involving deployment of the winch at the subsea tree, thus decoupling the vertical movement of the wire from the vessel motion, however such systems have the corresponding features of some loss of “feel” for the wireline operator, as well as additional potential leakpaths and more complex subsea machinery. A key design feature of subsea wireline systems is whether or not hydrocarbon fluids are returned to the intervention vessel during the operations. If hydrocarbons are/can potentially be returned to surface, then the classification requirements for the vessel are much more onerous than for a vessel using a system in which hydrocarbons are not/cannot be returned to the surface. A typical subsea wireline system (i.e. using a surface-mounted wireline winch/reel) consists of the following major components: a tree connector; a lower lubricator assembly consisting of a wireline cutting valve and wireline BOPs, for pressure control of the well in the event of an emergency disconnect; an upper lubricator assembly consisting of a connector, tool trap, lubricator sections, wireline BOPs, stuffing box (for slickline) and a grease injection system (for monoconductor line), for loading and unloading of wireline tools; a surface-mounted wireline winch/reel (fitted with a motion compensation system); a control system, similar to a WOCS as described in A.11.2.3, for controlling the subsea tree and downhole safety valves as well as all the valves and functions contained within the subsea wireline equipment; a handling system for deployment and retrieval of the subsea equipment (usually with guidewires); a supporting ROV spread for observation and operation manual overrides, etc., as required. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global Standards  

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Subsea Wireline/Coiled Tubing BOP

Subsea BOP that attaches to the top of a subsea tree to facilitate wireline or coiled tubing intervention. Source: API SPEC 17D, Design and Operation of Subsea Production Systems—Subsea Wellhead and Tree Equipment, Upstream Segment, Second Edition May 2011 (Errata September 2011). Global Standards