Apex

Surface Test Tree

Apex , Well Testing has developed its own set of fabrication specifications to ensure that equipment used by Apex Petroleum Services, Well Testing meets or exceeds all local requirements. Apex Petroleum Services, Well Testing specifications are primarily based on the following worldwide recognised specifications:

Equipment Design and Fabrication Specifications

  • API Spec 6A – Specification for Valves and Wellhead Equipment
  • ASME VIII For construction of pressure vessels , Div 1&2
  • API RP 14C – Recommended Practice for Analysis, Design, Installation, and Testing of Basic Surface Safety Systems on Offshore Production Platforms
  • NACE MR-01-75
  • Product Specification Level (PSL) 3
  • Material Class DD
  • Temperature Class P&X (-20° F to +350° F)
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Surface Test Tree

The Surface Test Tree (STT), also known as the Flowhead, is located directly on top of the well and serves as the first piece of equipment that well fluid passes through. Its primary function is to control the flow of fluid into and out of the well.

Equipment and Configuration

The size and number of components in the Surface Test Tree depend on the type of test being performed and the rig used. The minimum required equipment includes:

  • Lift sub
  • Surface test tree block
  • Swivel
  • Crossover to the test string
  • Test lines

The STT incorporates a central body that contains the following components:

  • Four Gate Valves:
    • A master valve
    • A swab valve
    • A kill valve
    • A hydraulically actuated (normally closed) flow valve
  • A Swivel situated below the central body, allowing tubing rotation for manipulating downhole equipment without turning the test tree.
  • A Lifting Sub for rig elevators to raise and lower the tree in the derrick.

Additionally, each tree is supplied with wing blocks that are attached to enable flexible flow lines to be connected to the surface tree.

The Surface Test Tree can be adapted to various sizes of tubing or drill pipe through the use of a crossover sub.

Pressure and Specifications

The test trees are available in models with 10,000 psi and 15,000 psi working pressure. The configuration has a variable tensile rating, dependent on connection type, size, pressure, and temperature.

Additional Components

To complement the standard configuration, several additional components are available to enhance flexibility:

  • Actuators for manual gate valves as required
  • Lower master valve fitted below the swivel for complete STT isolation
  • Chemical injection subs for the injection of hydrate inhibitors, foam, or emulsion breakers
  • Stiff joints allowing the STT to be freestanding above the rig floor if necessary

Features and Benefits

  • Meets applicable industry standards for added safety.
  • Additional components can be added for flexibility.
  • Can be third-party certified according to required standards.
  • A flapper or check valve is set at the inlet of the killing line.
  • The swivel enables rotation of the test string for packer setting and disconnect operations.

Operation

The flow wing valve is controlled by a hydraulic actuator, which can be integrated with an Emergency Shutdown System (ESD). A manual wing valve is typically used for kill line connection, circulating procedures, or stimulation.

Slickline, coiled tubing, or electric line operations can be performed through the STT swab valve by connecting BOP’s and a lubricator to the top connection of the STT.

The swivel, an integral part of the STT assembly, is installed between the STT block and the work string or tubing. Its primary function is to allow the rotation of the work string or tubing for manipulation of downhole equipment without turning the STT and the flexible flowlines attached to it.

A check valve can be installed on the kill side of the STT, preventing well effluent from flowing back through the kill line into the kill pumps, which allows the kill valve to remain open for emergency purposes during testing operations.

The lower master valve adds an additional layer of safety. In the event of a leak occurring above the valve, it can be closed to allow for repairs. It also helps pressure test the installation above the rotary table and prevents test fluid and pressure from entering the test string.

The lower master valve can be used when multiple valve isolation of the work string or tubing is needed.

Surface Test Tree Specifications
Size and DescriptionWorking Pressure (Psi)Working Temp.FEnd Connections Flanges Crossovers Design CodeHandling Sub Tensile Rating (lb)
 3 -1/16″  10,000  -50 to 250 5 3/4″ – 4Stub Acme Box 3 1/16″ API 6A, Bx 15410,000 psi 3 1/16″ API6A, Bx 154x Fig 1502 hammer union API 6A, ANSI B31.3, NACEMR-01-75, PSL 3 5 3/4″ – 4Stub Acme Box x Pin660,000 @ MAWP@ 250° F570,000 @ MAWP@ 350° F
  3 -1/16″  10,000 -50 to 350 5 3/4″ – 4Stub Acme Box 3 1/16″ API 6A, Bx 15410,000 psi 3 1/16″ API6A, Bx 154x Fig 1502 hammer union API 6A, ANSI B31.3, NACEMR-01-75,  5 3/4″ – 4Stub Acme Box x Pin660,000 @ MAWP@ 250° F570,000 @ MAWP@ 350° F
      PSL 3 
  3- 1/16″  15,000  -50 to 350 5 3/4″ – 4Stub Acme Box3 1/16″ API 6A, Bx 15415,000 psi 3 1/16″ API6A, Bx 154x Fig 2202 hammer unionAPI 6A, ANSI B31.3, NACEMR-01-75, PSL 3 5 3/4″ – 4Stub Acme Box x Pin450,000 @ MAWP@ 250° F480,000 @ 12,500 psi@ 350° F
   5 -1/8″  10,000   -50 to 250 Top: 8¼” – 4SA (F)Bottom: 8¼” 4SA (F) 3 1/16″ API 6A,- Bx 15410,000 psi5-1/8″ API6A, flange x/overx Fig 1502 hammer unionAPI 6A, ANSI B31.3, NACEMR-01-75, PSL 3  8 -1/4″ – 4Stub Acme Box x Pin 580,000 @ MAWP@ 250° F460,000 @ 9,700 psi@ 350° F
Surface Test Tree
TypeDescription
Check ValveCheck Valve – 3 1/16″ 10K, API 6A, Bx 154 Flange, w/Lockout Pin, NACE Service
Check ValveCheck Valve – 3 1/16″ 15K, API 6A, Bx 154 Flange, w/Lockout Pin, NACE Service
Swivel3 1/16″ ID 10K Swivel Assembly, 5 3/4″ – 4 Stub Acme Pin x Pin, NACE Service
Swivel3 1/16″ ID 15K Swivel Assembly, 5 3/4″ – 4 Stub Acme Pin x Pin, NACE Service
Swivel5 1/8″ ID 10K Swivel Assembly, 7 1/2″ – 4 Stub Acme Box x Pin, NACE Service
Lower Master Valve3 1/16″ 10K Lower Master Valve w/Actuator, 5 3/4″ – 4 Stub Acme Box x Pin, NACE Service
Lower Master Valve3 1/16″ 15K Lower Master Valve w/Actuator, 5 3/4″ – 4 Stub Acme Box x Pin, NACE Service
Stiff JointStiff Joint – 3″ ID 10K, 5 3/4″ – 4 Stub Acme Box x Pin, NACE Service, Various Lengths
Stiff JointStiff Joint – 3″ ID 15K, 5 3/4″ – 4 Stub Acme Box x Pin, NACE Service, Various Lengths

Meets requirements of NACE MR0175. Transportation skid included.

Other sizes, configurations, and pressure ratings are available to meet most applications. For more information, please contact your local Apex Petroleum Services representative.

Surface Test Equipment

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