Glossary
Browse the IADC Lexicon alphabetically or by category. Get comprehensive definitions of drilling industry terms.
Integrated Pipeline Umbilical
Definition(s)
Integrated pipeline umbilical
Another form of umbilical is an IPU, consisting of a combination of one or more production and/or injection lines and/or various service lines, hydraulic lines, electrical and/or fibre optic cables, etc. An IPU differs from a traditional multicore umbilical in that it incorporates a relatively large-bore service or production line. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsMCU
Definition(s)
MCU
Multicore umbilical. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsMulticore Umbilical
Definition(s)
Multicore umbilical
An MCU is a combination of two or more lines (often of different functional types), including hydraulic lines, electrical cables, fibre optic cables and sometimes small-bore service lines (e.g. chemical injection lines). An MCU is typically armoured with steel wire, but is still sufficiently flexible to be deployed from a reel or a carousel on an installation vessel. Depending on manufacturing and/or transport constraints, an MCU may have dry splices in it at various points along its length, which are typically made prior to loadout of the umbilical onto the installation vessel. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsMultiphase Flowmeters
Definition(s)
Multiphase flowmeters (MPFM)
MPFMs are in-line meters designed to measure the relative flows of gas, oil and water in a flowline, without requiring prior separation of the phases. However, some MPFMs do require some form of flow conditioning upstream of the meter. Measurements of the flowstream are made by two or more sensors, and the resultant data are processed to yield the individual phase flowrates. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsPCSs
Definition(s)
Production control systems (PCSs)
A PCS provides the means to control and monitor the operation of a subsea production or injection facility from a remote location. The PCS consists of both surface and subsea equipment, see Figure A.23. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsProduction Control Systems
Definition(s)
Production control systems (PCSs)
A PCS provides the means to control and monitor the operation of a subsea production or injection facility from a remote location. The PCS consists of both surface and subsea equipment, see Figure A.23. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsSubmersible Pump
Definition(s)
Submersible pump
Downhole submersible pumps are basically multistage progressing cavity pumps driven either by an electric motor or a hydraulic turbine. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsHydrocarbon/water Separation
Definition(s)
Hydrocarbon/water separation
Hydrocarbon/water separation involves removing most or all of the produced water from the well fluids. The produced water can then either be discharged subsea or re-injected into a suitable formation. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsManifold Template
Definition(s)
Manifold template
A manifold template is a template used to support a centrally located manifold for gathering of produced fluids and/or distribution of injected fluids (see Figure A.21). In this arrangement, individual satellite wells are clustered around the manifold and tied back (to the manifold) using either flexible or rigid pipe. This type of template also includes connection point(s) for tie-in of flowlines or production risers to/from the manifold to the host facility. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsRiser Support Template
Definition(s)
Riser support template
A riser support template is a simple template which supports a production riser or loading terminal, and which serves to react to loads on the riser throughout its service life (see Figure A.20). This type of template can be integrated with other types of template, e.g. a manifold template or a multiwell manifold template. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsWell Spacer/tie-back Template
Definition(s)
Well spacer/tie-back template
A well spacer/tie-back template is a multiwell template used as a drilling guide to predrill wells at a single seabed location. Often this type of template is used prior to installing a surface facility above the template to which the wells are subsequently tied back (see Figure A.19). The wells can also be completed using subsea trees and individual production risers from each subsea tree, tied back to a floating or fixed host facility located above the template. Alternatively, a manifold may be subsequently landed on the template, thus effectively converting this system into a multiwell manifold template, as described further below. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsMudline Casing Suspension Systems
Definition(s)
Mudline casing suspension systems
Mudline casing suspension systems were originally designed to be installed by bottom supported drilling rigs (jack-ups) in shallow water applications with surface wellheads, although they are now also often used in deepwater applications with tension leg platforms. These systems provide a suspension point near the mudline to support the mass of casing strings within the wellbore. Typically the conductor and casing strings with their respective annuli are tied back to the surface, where they are terminated using conventional surface wellhead equipment. However, wells drilled with conventional mudline casing suspension systems can also be completed with a subsea tree, provided proper adaptation for the subsea completion is made. In general, subsea completions based on conventional mudline suspension equipment are best suited to shallow-water applications, where structural strength/robustness is not a major issue. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsHorizontal Tree
Definition(s)
Horizontal tree
In horizontal subsea tree systems, the tree is installed on the wellhead and then the tubing hanger is installed inside the tree. The tubing hanger forms the connection between the production/injection tubing and the tree. Figure A.14 shows a typical configuration with a production guidebase as part of the stack-up. This is to allow tree retrieval without disturbing the flowline and umbilical. Clearly, with the reduced likelihood of having to retrieve the tree, there is less need for a base and, in certain circumstances, the production guidebase may be integrated with the XT spool. This saves a running operation, but at the expense of reducing system flexibility, i.e.: restricts installation of the flowline and umbilical until after the XT is installed; disturbs the flowline and umbilicals if the XT ever has to be recovered. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsHorizontal tree
Subsea tree with production and annulus bore valves located external to the tree, where the tubing hanger or dummy tubing hanger is installed after the tree. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global StandardsHorizontal tree
A system of valves installed on a subsea wellhead that has a master valve in the horizontal outlet from the vertical bore rather than in the vertical bore. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global StandardsHorizontal tree
Tree that does not have a production master valve in the vertical bore but in the horizontal outlets to the side. 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 StandardsVertical Tree
Definition(s)
Vertical Tree
Vertical trees (VXT) typically have one or two production bores and one annulus bore running vertically through their entire length (as shown in Figure A.3). These bores permit the passage of plugs and tools down through the XT and into the TH or completion string. The vertical bores pass through a series of gate valves (production valves) used to isolate the vertical bores at differing levels. Two or more horizontal bores intersect the vertical bores to permit the passage of fluids into or out of the well, and each has an isolation gate valve (wing valves) to allow flow shut-off. Cross-over valves are usually incorporated to allow communication between the production and annulus bores. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsVertical Tree
Subsea tree with either multiple or concentric bores and production valves located in the vertical bore of the tree, where the tubing hanger is installed before the tree. Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global StandardsVertical Tree
Subsea tree with the master valve in the vertical bore of the tree below the side outlet. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global StandardsVertical Tree
Tree with the master valve in the vertical bore of the tree below the side outlet. 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 StandardsConcentric Trees
Definition(s)
Concentric trees
Concentric trees are configured with their valves very much like those of the VXT design, but with the distinct difference being that the production bore is located concentrically within the tree and the annulus located off-centre (see Figure A.11). The inherent feature of the design allows access only through the centrally located production bore for TH plug setting, and consequently other means are used for accessing the annulus, such as a flexible pipe run along the side of the completion/workover riser. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsExternal Load
Definition(s)
External Load
Includes global load effects like axial loads, bending moment, torque, and shear.
Source: API Technical Report 17TR7, Verification and Validation of Subsea Connectors, First Edition, April 2017. Global StandardsExternal Load
There are two types of primary external load, other than environmental load, to which a subsea tree and its upper and lower connectors can be subjected. The first type is installation, which includes riser loads and flowline connection loads. The second type of external load occurs during workover and, depending on the type of tree, can be due to attachment of a C/WO riser system or marine drilling riser system. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsSubsea System Engineering
Definition(s)
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 StandardsFlow Assurance
Definition(s)
Flow assurance
Flow assurance is a term commonly used to cover a wide range of flow-related issues. These issues typically include: hydrate formation, wax formation, asphaltene formation, emulsions, foaming, scale formation, sand production, slugging, materials-related issues. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsFlow assurance
Flow assurance is the control or mitigation of the deposition/formation of hydrates, wax, asphaltenes, and scale in the production flow path. Many factors affect flow assurance such as fluid composition, pressure, flow rate and temperature. Fluids in the wellbore can experience significant temperature changes, and plugs can form as a result. Flow assurance is provided by chemical and/or thermal management. Design of the total system should consider the wellhead and tree, which have the highest heat loss. Some methods of prevention used in industry are as follows: VIT; tubing coating or finish; gas-filled “A” annulus near/above the mudline; low heat transfer fluid in the annulus; injection of fluids to minimize/prevent the effects of hydrates, paraffin, scale through “control lines” strapped to the outside of the tubing; placement of SCSSVs below the top of hydrate/wax/asphaltene formation depth. Source: API RP 96, Deepwater Well Design and Construction, First Edition, March 2013. Global StandardsProduction Riser
Definition(s)
Production Riser
Casing strings rising from the seafloor to the wellhead (fixed platforms) or casing strings attached to the subsea wellhead rising from seafloor to a surface wellhead (hybrid wells). Source: ISO 16530-1:2017, Petroleum and natural gas industries — Well integrity – Part 1: Life cycle governance, First Edition, March 2017. Global StandardsProduction Riser
The portion of a pipeline extending from the seafloor to the surface is termed a riser. The function of a riser is to provide conduit(s) for the conveying of produced fluids and/or injection fluids between the seafloor equipment and the production host. Such risers are generally known as production risers in order to distinguish them from other types of risers such as marine drilling risers and completion/workover risers. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsProduction Riser
The casing string(s) rising from the seafloor to the wellhead on fixed platforms or the casing string(s) attached to the subsea wellhead rising from the seafloor to the surface wellhead on hybrid wells. Source: API RP 90, Annular Casing Pressure Management for Offshore Wells, Upstream Segment. First Edition, August 2006. Global Standards Source: API STD 65 – Part 2, Isolating Potential Flow Zones During Well Construction, Upstream Segment, Second Edition, December 2010. Global StandardsMultiphase Flow
Definition(s)
Multiphase flow
The simultaneous flow of gas and liquid, commonly referred to as multiphase flow, occurs in almost every aspect of the oil industry. Multiphase flow is typically present in the wellbore, flowlines and topsides processing facilties and is of particular importance in subsea production systems, where the feasibility and cost of the production facilities is directly linked to the fluid flow charateristics. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsReverse Emulsion
Definition(s)
Reverse emulsion
Emulsions can be water-in-oil, which are referred to as regular emulsions, as well as oil in-water, which are called reverse emulsions. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsRegular Emulsion
Definition(s)
Regular emulsion
Emulsions can be water-in-oil, which are referred to as regular emulsions, as well as oil in-water, which are called reverse emulsions. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsEmulsion
Definition(s)
Emulsion
Emulsions are heterogeneous systems consisting of at least one immiscible liquid dispersed in another in the form of small droplets of diameter usually greater than 0,1 μm. Such systems are thermodynamically unstable but they can be persistent if stabilized by surface-active components. Emulsions can be water-in-oil, which are referred to as regular emulsions, as well as oil in-water, which are called reverse emulsions. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsSignal on Power
Definition(s)
Signal on power
Separate electrical cables may also be required for transmission of control signals/data in an electrohydraulic PCS. Alternatively, the control signals/data may be superimposed on the power output, commonly referred to as “signal on power”. Source: API RP 17A, Design and Operation of Subsea Production Systems—General Requirements and Recommendations, Fourth Edition, Reaffirmed 2011. Global StandardsControl Pod
Definition(s)
Control pod
Assembly of valves and regulators (either hydraulically or electrically operated) that when activated directs hydraulic fluid through special apertures to operate the BOP equipment.
Source: API Specification 16Q, Design, Selection, Operation, and Maintenance of Marine Drilling Riser Systems, Second Edition, April 2017. Global Standards