IWCF Glossary

A completion component designed to accommodate tubing movement.

Pressure-containing environmental barrier installed above production swab valve (PSV) in a vertical tree or tubing hanger in a horizontal tree.

Source: API SPEC 17D

Remotely controlled subsea tool that it latched to the top of a subsea Xmas Tree. The TRT may be used for running or pulling a subsea Xmas Tree, or used in an OWIRS system for subsea intervention. It may be described as the lower part of the LRP or WCP, or as a separate component below the LRP or WCP.

An exercise to ensure the rig floor crew reacts correctly to potentially dangerous surface well flow situations initiated when tripping pipe into or out of a wellbore.

An accumulation of gas which enters the well during tripping. This can be caused by swabbing or gas diffusion. This will be detected in the drilling fluid when circulating bottoms-up after a round trip.

An increase in drilling fluid density to provide additional overbalance to compensate for effects of swabbing.

Source: API RP 59

A table containing predicted (calculated) and actual volumes displaced from or pumped into the well during tripping. It is used to confirm if the well is static as well as the position of the toolstring during tripping.

Low-volume (100 barrels [15.9 m3] or less) calibrated tank that can be isolated from the remainder of the surface drilling fluid system and used to accurately monitor the amount of fluid going into or coming from the well.

Source: API STD 53

The act of removing tubulars from a wellbore, partially or fully, (pulling out of hole) and then returning the tubulars back into the well (running in hole). Also known as a ‘tripping process’, ‘tripping operation’.

The vertical distance between two points within a well. This measurement is used for calculating well pressures.

Pipe placed within a well and serving as a conduit for produced well fluids or to inject fluids.

Source: API RP 5A5

A device attached to the top most tubing joint that isolates the completion from the ‘A’ annulus at surface and supports the completion string in the wellhead.

Used in the horizontal Xmas Tree (HXT), the tubing hanger crown plug is a wireline-installed plug located in the top of the tubing hanger providing a primary well barrier element.

Primary barrier plug used in vertical Xmas Trees (VXTs), set in a landing profile inside the tubing hanger. For subsea vertical Xmas Trees, the plug is run and pulled with slickline.

Remotely controlled subsea tool that is latched to the tubing hanger in TBIRS systems.

Used in some monobore vertical subsea Xmas Tree systems, the THS is a spool connected to the subsea wellhead to provide a landing location for the tubing hanger. The monobore vertical tree is then installed onto the THS rather than onto the subsea wellhead.

A wireline tool designed to make a hole in the wall of tubing.

A system of seals arranged on the lower end of a component that engages in a seal bore to isolate the production tubing from the annulus.

A condition where the pressure in the wellbore is less than the formation pressure. For a downhole well barrier, underbalance refers to a lower pressure above the barrier.

The second (middle) inline valve on an Xmas Tree. Sometimes this valve is an actuated valve and is designed to cut wire.

The upper master valve in the production bore of the vertical Xmas Tree.

The upper set of rams that provide the primary barrier element when running or retrieving a workstring using the ‘ram to ram’ deployment method. Used during a snubbing / hydraulic workover operation.

A vessel that removes gas entrained in the drilling fluid by expanding the size of the gas bubbles through a reduction in pressure. This is placed downstream of the shale shakers, recirculating drilling fluid in the sand traps.

Closing and sealing component in a ram BOP that is capable of sealing on a range of tubular sizes.

Source: API STD 16AR

An open-ended conduit designed to carry and relieve excess pressure within a system to the atmosphere or another containment vessel.

A Xmas Tree design configured with master valves and swab valve in the vertical bore(s). The tubing hanger is landed inside the wellhead or THS. The vertical tree is then installed after well barriers are set and the drilling BOPs and marine riser are pulled. The completion is installed before the VXT is installed. After setting well barriers, the VXT is pulled before running drilling BOP allowing the completion to be pulled using a TBIRS.

A non-circulating well control method that allows gas to migrate to the surface of a well while maintaining a relatively constant bottomhole pressure.

A one-circulation well kill method that is delayed at the beginning while kill weight fluid is mixed (wait and weight). The influx is circulated out of the well as the kill weight fluid is displaced into the well.

Erosion caused by abrasive flow of fluids or gas. This often occurs across the choke (choke washout) or at tubular connections (string washout).

Typically located above the secondary seal assembly of a ram shaft. The weep hole serves as an indicator of potential seal failure by allowing small amounts of fluid to escape the BOP. Generally clean fluid is operating fluid and dirty fluid is from the wellbore.

A device that measures the weight of tools being deployed into the well.

High specific-gravity solids used to increase the density of drilling fluids. This material is commonly barite or haematite, and in special applications may be limestone.

Source: API RP 13C

The collective physical system, composed of well barrier elements, that prevent fluids from flowing unintentionally from the formation into another formation or to the external environment.

Procedures and processes to prevent or mitigate an unintentional release of formation fluids and gases from the well to its surroundings.

An exercise conducted to test the work crew react correctly to simulated emergency situations.

Portion of OWIRS that extends from the tree running tool (TRT) (bottom) to the emergency disconnect package (EDP) connector (top); purpose is to provide well and pressure control at the mudline directly above the wellhead.

Source: API STD 17G

The containment and prevention of the escape of well fluids to the surface or subsurface zones.

Source: ISO 16530:1

Applying technical, operational and organisational solutions to reduce risk of uncontrolled release of formation fluids throughout the life cycle of a well.

Source: API RP 90

Maintaining pressure integrity when working on live wells.

Each stage of the life of the well, including the basis of design, design, construction, operational, intervention and abandonment phases.

The borehole or cased hole sections in a well.

Source: API STD 65:2

An annular BOP that allows pressure within a well to act on the bottom surface area of the operating piston while in the closed position. The wellbore pressure attempts to lift the piston, which adds upward force to assist the accumulator-supplied closing pressure to maintain the seal created by the elastomeric sealing element.

One or more spools at the top of the well that contain the casing hangers and tubing hanger. It is installed on top of the surface casing and is a base for a BOP stack or Xmas Tree.

Hydraulically-operated connector that joins the BOP stack to the subsea wellhead.

Source: API SPEC 16D

Tripping in and out of the well during drilling operations to assess wellbore cleaning efficiency and confirm wellbore conditions.

A gate valve in a Xmas Tree that is capable of cutting wire and still being able to provide a seal/barrier from the well. Also known as ‘wirecutting upper master gate valve’.

A valve designed to cut wire and continue to provide a seal. Also known as ‘shear/seal valve’.

Cable for deploying tools in and out of the well. There are several types of wireline, including braided line, digital slickline, slickline, and electric line (e-line).

An operation where a wireline tool called a ‘drift’ is run into the well to ensure it is free of obstructions. The outside diameter and length should ideally replicate the dimensions of tools that will be run next.

Completion accessory used at the end of tubing to assist re-entry into the tubing for well intervention tools.

The working area or platform at the top of a snubbing unit where the snubbing personnel work. Also known as a ‘snubbing basket’.

The difference between maximum and minimum allowable values. In well control, it generally refers to pressure values, which represent the limits for safe operations.

Changing the profile of the well for repair or to enhance production.

A hoisting rig used for operations such as well deepening, plugging back, running and pulling completions.

A series of valves at the top of a production well that allow or prevent well flow and access depending on their position.