A wellhead is a critical piece of equipment in oil and gas extraction, comprising several components that ensure safe and efficient operations. The main components include the casing head, which supports the casing strings and contains seals for pressure control; the casing hanger, providing a seal between the casing and the wellhead while supporting the weight of the casing strings; the tubing head, supporting the tubing string and facilitating fluid production; the tubing hanger, suspending the tubing string within the wellbore and providing a pressure-tight seal; and the tubing adapter, which connects the tubing string to the wellhead assembly, ensuring proper sealing and load transfer.
Casing Head
Casing Head is the uppermost part of the wellhead, located just below the surface of the ground, and serves several important functions:
Support for Casing: The casing head provides support for the casing strings that run into the well. The casing is a series of steel pipes that are inserted into the well to stabilize the borehole, prevent it from collapsing, and isolate various formations to prevent the flow of fluids between them.
Pressure Containment: It helps contain the pressure within the wellbore. The casing head typically includes a series of seals and valves designed to prevent the escape of fluids from the well and to control the flow of fluids during drilling, completion, and production operations.
Connection Point: The casing head also serves as the connection point for various pieces of equipment used during drilling, such as blowout preventers (BOPs), drilling spools, and other well control equipment.
Injection/Production Wells: In some cases, the casing head may also serve as a connection point for injection or production tubing, allowing fluids to be injected into the well for secondary recovery operations or extracted from the well during production.
Casing Hanger
Casing Hanger supports the weight of the casing strings and provides a seal between the casing and the wellhead. It’s typically located within the wellhead housing and is designed to suspend the casing strings at the desired depth within the wellbore. Here’s a breakdown of its functions and features:
Supporting the Casing String: The casing hanger serves as a mechanical support for the casing strings that are run into the well. It holds the weight of the casing and ensures that it remains in place within the wellbore.
Sealing Function: The casing hanger incorporates seals or packing elements that create a pressure-tight barrier between the casing and the wellhead. This prevents the escape of fluids from the wellbore and maintains well integrity during drilling, completion, and production operations.
Adjustability: In some designs, the casing hanger may be adjustable, allowing for variations in casing size or accommodating deviations in wellbore geometry. This adaptability is essential for ensuring a secure fit and proper sealing between the casing and the wellhead.
Connection Point: The casing hanger often serves as a connection point for other components of the wellhead assembly, such as casing heads, tubing heads, or blowout preventers. It provides a secure interface for attaching additional equipment and facilitating well-control operations.
Load Transfer: The casing hanger also helps transfer the load from the casing to the wellhead housing and subsequently to the surface equipment. This ensures that the weight of the casing is distributed evenly and does not overload any individual component of the wellhead assembly.
Casing Spool
Casing Spool provides a transition between the casing and the surface equipment, such as the blowout preventer (BOP) stack or the Christmas tree. It is typically installed on top of the casing head and below the BOP or Christmas tree. The casing spool serves several important functions:
Sealing: The casing spool contains sealing elements, such as rubber seals or metal gaskets, which provide a pressure-tight seal between the casing and the BOP or Christmas tree. This prevents the escape of fluids from the wellbore and maintains pressure integrity during drilling, completion, and production operations.
Support: The casing spool supports the weight of the casing strings and provides a stable platform for the BOP or Christmas tree. It ensures that the weight of the casing is properly transferred to the surface equipment without overstressing any individual component.
Connection Point: The casing spool serves as a connection point for the BOP or Christmas tree, allowing them to be installed and secured to the wellhead assembly. It provides a secure interface for attaching these critical components and facilitates well control operations.
Adjustability: In some designs, the casing spool may be adjustable to accommodate variations in casing size or deviations in wellbore geometry. This adaptability allows for a secure fit between the casing and the surface equipment, ensuring proper sealing and load transfer.
Annulus Seals
Annulus seals are employed to isolate the annular space between casing strings or between the casing and the wellbore wall. The annulus is the space between two concentric tubes or between the casing and the wellbore wall, and it plays a crucial role in well integrity and safety. Annulus seals serve several important functions:
Pressure Containment: One of the primary functions of annulus seals is to prevent the escape of fluids from the annular space. This helps maintain pressure integrity within the wellbore and ensures safe drilling, completion, and production operations.
Fluid Isolation: Annulus seals isolate different fluid zones within the wellbore. For example, in multi-zone reservoirs, annulus seals prevent fluid migration between different formations, which is essential for maintaining reservoir productivity and preventing contamination.
Environmental Protection: Properly functioning annulus seals help protect the environment by preventing the release of fluids, such as oil or gas, into the surrounding soil and groundwater. This is particularly important for preventing environmental damage and complying with regulatory requirements.
Corrosion Prevention: Annulus seals help prevent corrosion of the casing and other wellbore components by isolating the annular space from corrosive fluids or gases that may be present in the formation fluids.
Thermal Isolation: In some cases, annulus seals may also provide thermal insulation, helping to maintain the temperature of the wellbore fluids and equipment within a desired range.
Tubing Head Spool
Tubing Head Spool is located above the casing head and provides a transition between the casing and the tubing string. The tubing head spool serves several important functions:
Support for Tubing: The primary function of the tubing head spool is to support the tubing string, which is a smaller-diameter pipe that is run into the well after drilling and casing operations are completed. The tubing is used to convey production fluids from the reservoir to the surface and may also house other equipment such as downhole pumps or sensors.
Sealing: The tubing head spool contains sealing elements, such as elastomer seals or metal-to-metal seals, that provide a pressure-tight barrier between the tubing and the wellhead assembly. These seals prevent the escape of fluids from the wellbore and maintain pressure integrity during production operations.
Connection Point: The tubing head spool serves as a connection point for the tubing string and other wellhead equipment, such as the Christmas tree or production control equipment. It provides a secure interface for attaching and securing these components to the wellhead assembly.
Pressure Control: The tubing head spool may incorporate valves or other pressure control equipment that allows operators to control the flow of fluids from the reservoir to the surface. This can include features such as adjustable chokes or hydraulic valves that regulate production rates and pressures.
Injection Wells: In some cases, the tubing head spool may also be used in injection wells, where fluids are injected into the reservoir for secondary recovery operations. In this application, the tubing head spool provides a connection point for injection tubing and may incorporate features such as injection valves or packers.
Tubing Hanger
Tubing hanger suspends the tubing string within the wellbore and provides a pressure-tight seal between the tubing and the wellhead. Here are the key functions and features of a tubing hanger:
Supporting the Tubing String: The primary function of the tubing hanger is to support the tubing string within the wellbore. The tubing is a smaller diameter pipe that is run into the well after drilling and casing operations are completed. It is used to convey production fluids from the reservoir to the surface. The tubing hanger ensures that the tubing string is properly suspended at the desired depth within the wellbore.
Sealing Function: The tubing hanger incorporates sealing elements, such as elastomer seals or metal-to-metal seals, that provide a pressure-tight barrier between the tubing and the wellhead. These seals prevent the escape of fluids from the wellbore and maintain pressure integrity during production operations.
Connection Point: The tubing hanger serves as a connection point for the tubing string and other production equipment, such as the Christmas tree or production control equipment. It provides a secure interface for attaching and securing these components to the wellhead assembly.
Load Transfer: The tubing hanger helps transfer the weight of the tubing string to the wellhead housing and subsequently to the surface equipment. This ensures that the weight of the tubing is properly distributed and does not overload any individual component of the wellhead assembly.
Adjustability: In some designs, the tubing hanger may be adjustable to accommodate variations in tubing size or deviations in wellbore geometry. This adaptability allows for a secure fit between the tubing and the wellhead, ensuring proper sealing and load transfer.
Gulfwell provides complete Wellhead solutions including casing heads, casing spools, casing hangers, tubing heads, tubing spools, tubing hangers, tubing adapters etc.
Gulfwell’s casing heads accept Automatic Casing Hanger (PCHA), Unitised Casing Hanger (PCHU), S-Slips (PS) & S-Pack off (PSPO) assembly and can be furnished with female thread or slip-on weld lower connection. Guflwell can provide casing heads of different measurements as per customers’ requirements. For example, our products can support flange sizes from 11” to 21.25”; casing size from 8” to 20”. It can work till 5000 PSI working pressure
Gulfwell’s tubing spools are designed for the popular split hanger suspensions for dual completions. It has welded wedges for hanger alignment and an open-face top flange. The tubing spool is provided with a wedge to position the hanger. The standard outlets are 2 1/16 2000-10000 PSI WP studded. The outlets are threaded for the valve removal plug to allow for the removal of the valve. The bottom of the flange is designed for installing the type PBP-1 Bottom pack off (PP Seal for high pressure over 5000 PSI WP) and is provided with a plastic packing injection port and a test port. The top of the spool is provided with hold-down screws to secure the tubing hanger.
Gulfwell’s Tubing Head Adaptors are designed for tubing suspension and can be used with extended neck threaded hanger PTHSE for a max WP of 15000 PSI. These can be provided with studded up connections and a recessed lower flange with test and bleed ports. Tubing Head Adaptors can also be used with wrap wrap-around tubing hanger (PTHSW) for a max. WP of 10000 PSI and are threaded female for tubing suspension. It can be threaded according to the customer’s specifications.
For more information on Gulfwell’s solution for wellheads please write us at sales@gulfwell.ae