01 Well Head Components

Quartz School for Well Site Supervisors Module – 5 Well Heads & BOPE

Section – 1 Well Head Components Components

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Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Contents

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•

Wellhead definition

•

Wellhead Components •

Flanges, ring gasket and outlets

•

Casing head housing

•

Casing head spool

•

Casing hanger

•

Primary and secondary seals

•

Tubing head spool

•

Wellhead Specification as per API 6A

•

Wellhead Running procedure

•

Wellheads for special application


Contents

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•

Wellhead definition

•

Wellhead Components •

Flanges, ring gasket and outlets

•

Casing head housing

•

Casing head spool

•

Casing hanger

•

Primary and secondary seals

•

Tubing head spool

•

Wellhead Specification as per API 6A

•

Wellhead Running procedure

•

Wellheads for special application


Wellheads Objectives •

•

•

•

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Be familiar with Wellhead components Be able to select an appropriate type of Wellhead system for a standard land / jack-up operation Be familiar with API Specification 6A Be aware of a some of the issues with installation and use of surface wellheads


Well Head Components

Flow Control Equipment ( 3/4/5 )

Tubing Suspension Equipment ( 2 )

Xmas Tree

C Section

B Section

Casing Suspension Equipment ( 1 ) 4/46


A Section

Well Head - Definition

The wellhead is the surface foundation on which the well is built up during the drilling operations and is the base for the x-mas tree for production operations.

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Functions of wellhead: 

Withstand tensile loads of suspended tubular



Provide a pressure sealing capability 

ISOLATE the well from the external environment



ISOLATE between casings and downhole formations





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MAINTAIN PRESSURE during well control operations, well testing or shut in periods.

Those functionalities must be achieved during the life of the well (Drilling, Production, Workover, Suspension and Abandonment)


The “Christmas Tree”, XT It comprises a series of valves, a choke and connections. It provides a means of controlling the effluents, ensuring the safety of the facilities and given measurement tools and instruments access to the well.

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Main components of surface installation

Xmas Tree

Tubing Head Spool Wellhead

Casing Head Spool Casing Head Housing

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Flanged Connection – API Classification A protruding rim with holes to accept bolts and having a sealing mechanism used to join pressure containing equipment. There are two types of API flanges: API 6B API 6BX

- 2,000, 3000, 5,000 psi (up to 11”) - 5,000 (from 13 5/8”) to 20,000 psi

What does a 3-1/16 , 10 000 flange means? 9/46

Working pressure of 10000 psi and 3 1/16 bore


Ring Gaskets Ring gaskets are made of a softer material than the flange body; therefore, they deform after being placed and tightened with the flange bolts. This results in a better seal. FLANGES

RING GASKETS Type R (oval or octagon shape)

TYPE 6B Type RX (octagon asymmetrical shape)

TYPE 6BX Notes:

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Type BX (square cross section with tapered edges)

BX and RX rings are pressure energized, meaning that pressure, in case of leaking, helps to improve the sealing. RX rings from sizes 82 through 91have pressure equalizing hole. Ring gasket shall not be reused. Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Flanges and Ring Gaskets

type R & RX

type BX

Standoff

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No Standoff

Standard Sizes of API Flanges What are the common flange sizes used in wellhead equipment ? inches

millimeters

1 13/16

46

2 1/16

52

2 9/16

65

3 1/16 or 3 1/8

78 or 79

4 1/16

103

5 1/8

130

7 1/16

179

9

228

11

279

13 5/8

346

16 ¾

425

18 ¾

476

20 ¾

527

21 ¼

540

26 ¾

680

30

762

Notes: When converting to millimeters they are rounded to the nearest millimeter. For flanges, the nominal flange size is equal to the bore size of the flange, but for wellhead sections the bore size is slightly smaller. Bore sizes for wellheads can be found in Table 10.34 of API Spec 6A. 12/46


Casing head Housing It is the lowest part of the wellhead assembly and almost always connected to surface casing. It support subsequent drilling wellhead and completion string. Its main functions are: Provides for attachment to surface casing string  Supports BOP during drilling operation  Provides for suspending and packing of the next casing string  Provides outlets for annular access  Provides for testing BOP while drilling 

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Types of Casing Head Housing (CHH)

Threaded

Slip on

Slip lock

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Although safer, threaded CHH requires to have the uppermost casing thread at precise depth. If the surface casing has to be set off depth (fill on bottom, stuck casing), slip-on CHH has to used. The welding must be tested through “Test port” located between the two welding. Not that the plug needs to be removed before the welding. They can be installed faster than a slip-on weld type. They can be re-installed or removed. This allows to use it as a temporary tool while drilling the intermediate hole. Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Casing Head Housing - Description Top connection flanged (standard) Ring groove

Landing area for Casing Hanger

Side outlets threaded or studded

Test port Slip-on weld or threaded bottom connection 15/46


CHH - Type of Outlets Threaded outlet*

Studded flange

*Usually low pressure and cost

Flanged

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Clamp hub


Base Plate The load acting on the the Casing Head Housing might be high (in case of deep well for instance). In this case a base plate is used to distribute the load and to increase the stability of the wellhead. The base plate sets at the bottom of the cellar.

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Casing hanger The objectives of the casing hangers are to: 

Suspends intermediate or production casing string



Centers the casing string in the head (or spool)



Seals off the casing annulus (It is the primary seal )

There are many types of hangers. Two major types of casing hangers : slip type hanger (wraparound casing slips) and mandrel type hanger. Wraparound casing can be set without removing BOP under certain conditions.

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Wraparound casing hanger Mandrel casing hanger Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Slip type hanger (examples) Wrap around casing slips with sealing capability provided by casing load

Dual slips distribute casing load to reduce casing deflection at high loads.

Use to obtain seal independent of the casing load (when no casing load available to energize the seal). Elastomer seal are mechanically activated by cap screws Casing hanger has an independent slip and seal assembly. The seal is installed when the casing cut off. 19/46


Casing head Spool It has a top bowl to accommodate the next casing hanger. It has a bottom bowl with a pack-off seal (or bushing) and a flange for mounting it up on the top of the casing head housing or previous casing head spool. Multiple casings spools can be stacked to hang intermediate or production casing strings. Its main functions are:  Seals off (packs off) previous string  Provides for suspending and packing of the next casing string  Provides support for well control equipment (BOP Stack)  Provides outlets for annular access  Provides for testing BOP while drilling

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Casing Head Spools - Description The top flange has a different size and rating than the bottom flange.

Landing area for Casing Hanger

The bottom flange is compatible with the previous casing head or casing spool flange. Side outlets can be threaded/ studded / flanged (threaded not common). Pack Off (or Secondary Seal) is designed to fit around OD of current casing.

The bottom flange includes a test port (with a non-return valve) allowing to test between the ring gasket, primary and secondary seal. Some CHS seal includes a port that allows injection of sealant in order to energize or re-energize the secondary seal (this feature is not include in this picture). 21/46


Test port

Primary and Secondary Seal Therefore, there are two separate barriers which prevent pressure from communicating with the environment outside the wellhead and up with the subsequent annulus.

Secondary Seals

Primary Seals

This figure illustrates packoff type secondary seals. Some of these secondary seals require plastic injection to re-energize or energize them.

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Spacer Spool & Adapter Spool The DSA (Double Studded Adapter) or the adapter spool. They are usually used to adapt between different flange end connections that would otherwise not connect. Usually the two sides are different in size and/or pressure rating.

Spacer Spool or also called Mud Cross. It is a unit of equipment used with Blowout Preventer to space pieces of equipment apart and provide outlets to attach lines extending to Choke and Kill Manifolds.

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Tubing head Spool It is the top spool on a surface wellhead assembly. It is installed after the last casing string to provide shoulder to support the tubing string and a seal bore for the tubing hanger or production . When the well is completed, the tree is installed on top of the tubing head. Its main functions are: Seals off (packs off) the production casing  Provides for suspending and packing of the completion string  Provides support for well control equipment (BOP Stack)  Provides outlets for annular access 

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Tubing Head Spool (THS) - Description The top flange has a different size and rating than the bottom flange. A tubing hanger lock down bolts system is included. Side outlets can be threaded/ studded / flanged (threaded not common). The top bowl provides support for the tubing hanger. The bottom flange is compatible with the previous casing spool flange. Pack Off is designed to fit around OD of the production casing. The bottom flange includes a test port (with a nonreturn valve) allowing to test between the ring gasket, primary and secondary seal. Some THS seal includes a port that allows injection of sealant in order to energize or re-energize the secondary seal (this feature is not include in this picture). 25/46


TEST PORT

Tubing Hangers There are many type of the tubing hanger. Most of the tubing hanger are mandrel type. The top thread allows the connection when setting or removing the completion string. The bottom thread allow the connection with the completion string. Most of them have a primary and secondary seals. The internal body is threaded to accommodate a back pressure valve (BPV). The BPV allows to shut-in the well when removing or installing the BOPs / X-Mas tree. 26/46

BPV


Wear Bushing •

Run and set into top bowl to protect wellhead from wear during drilling operation.

•

Lock screws tightened to contact wear bushing can be used if casing head has this feature.

•

Most wellhead from major manufacturers incorporate the wear bushing lock assembly into the body of the spool using a “J” slot system.

•

When wear bushing is not used

It needs to be remove before running the next casing string. Combination running tool

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Wear bushing running tool Wear bushing Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Wellhead Standards: API 6A •

Covers Wellhead and Xmas Tree equipment •

Mainly manufacture and specification.

•

Does not really cover, application, installation or operational aspects.

•

•

Temperature and Pressure Ratings

•

Materials •

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Guidelines on selection of equipment and quality assurance ( Product Specification Levels – PSL).

Standard & H2S / CO2 Conditions (NACE standard)

•

Requirements for welding on wellhead equipment

•

Quality control, marking of equipment, storing and shipping.

•

Details specific requirements for the different components. Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Pressure Ratings of Equipment Equipment shall be designed to operate in only the following maximum rated working pressure:

Psi

Mpa

2000 3000 5000 10,000 15,000 20,000

13.8 20.7 34.5 69.0 103.5 138.0

Note: The MPa readings are rounded off to preserve the same ratio of pressure ratings.

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Temperature Rating Table 4.2 of API Spec. 6A illustrates the temperature ratings classification for wellhead components.

Note: Temperatures listed in table refer to surface temperatures and not BHST. Minimum temperature is the lowest ambient temperature. Maximum temperature is the highest temperature of the fluid. Room temperature: Any temperature between 40 deg F and 10 deg F) 30/46


Material Specifications The material specification is dependent on the concentration of H2S and CO2 in the produced fluid.

NACE standard MR0175 is only concerned with metallic material requirements to prevent sulfide stress cracking and not with resistance to corrosion. 31/46


Materials Definitions Carbon steel: An alloy of carbon and iron containing a maximum of 2% carbon, 1.67% manganese, and residual quantities of other elements. Low alloy steel Steel containing less than 5% total allowing elements, but more than specified for carbon steel. Although not generally considered a low alloy steel, steels with less than 11% chromium shall be included in this category. Corrosion resistant Alloys (CRA) Non-ferrous alloys, where any one or the sum of the specified amount of the following alloy element exceeds 50%: titanium, nickel, cobalt, chromium, and molybdenum. Stainless Steel: Steel containing chromium (more than 11%) to render the steel corrosion resistant. Other elements may be added to secure special proprieties. 32/46


Corrosion from API 6A

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Product Specification Level (PSL) The PSL indicates the service conditions for which the wellhead may be used. API has defined four PSLs for wellhead equipment (PSL1-4). The four PSL designations define different levels of technical requirements. It defines also specification for quality control of equipment. The more critical the application (pressure, fluid composition and close proximity) of the wellhead the higher the PSL level is. A higher PSL level requires a greater level of testing and the traceability of the materials. Appendix A of the specification has a flow chart which helps define the PSL level required.

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API Spec 6A flow chart to determine PSL level.

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CHH, CHS & THS Identification – API 6A Each casing head is identified by : 1.

nominal size (nominal top flange).

5.

Type of material.

2.

Outlets size and type

6.

Temperature rating designation.

3.

Bottom connection for CHH

7.

PSL level.

4.

pressure rating (working pressure).

21 1/4" x 2000 psi Two x 2 1/8” threaded side outlets Slip on Weld Material: AA Temperature: S

13 5/8 " x 5M psi Top - 21 1/4 " x 2M psi Bottom Two x 2” 5M psi Flanged side outlets Material: “AA” Temperature: “S” PSL 1

11" x 5M psi Top - 13 5/8 " x 5M psi Btm Two x 2 1/8” 5Mpsi Studded Side outlets Temperature: T Material:AA PSL 1

PSL 1

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Information needed to order a “Casing Hanger” Casing hangers are ordered together with the wellhead sections since not all hangers are suitable for all sections. The following details of the application should be discussed in the planning phase with the supplier to obtain the proper hanger: • • • • •

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Casing size, weight and grade. Casing setting depth. Expected tension of the top joint. Surface temperature. Composition of fluids to which it will be exposed.


Well Head for Special Applications 1. Compact spool systems 2. Subsea wellheads 3. Splitter wellheads where conductor slots are limited 4. Dual Completions 5. Proximity Well Heads

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Compact Wellheads Advantages (Vs conventional Wellhead): 

The BOP Stack can be left in place until the installation of Xmas tree.



It saves rig time.



Reduction of flanged connections.

Disadvantages (Vs conventional wellhead):   

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Cost Support service is required Require contingency equipment


Subsea Wellheads

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•

Build on single unit. Concept of compact wellheads was derived from subsea wellheads.

•

Each casing string is landed on top of the previous one.


Splitter Wellheads

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Dual tubing hanger

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Well Head - Exercises

Find the following for a 21 ¼” x 2000 psi CHH: a) b) c)

Type of flange. Ring gasket type and number. Size, length and number of studs required for the flange.

Find how many combinations of flanges could you have for a 13 5/8” x 5000 psi by 21 ¼” x 2000 psi CHS: a) b) c) 43/46

Type of flanges. Ring gasket types and number. Sizes, lengths and number of studs required for the flanges. Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Group Exercise 1 Discussion Groups 1) Design a basic wellhead and Tree for the following development well.

5 ½” Production Tubing

Conductor 30” X 2 jts J55 – 94# Big Omega

Surface - 20” – 1500 ft. Expected LOT = 14.5 ppg The formation between 1500 and 5000 ft is a plastic clay. The mud weight for this section will start at 9.0 ppg and will be increased progressively to 10.5 ppg.

P110 – 72# BTC

Intermediate – 13 3/8” 5000 ft – Expected LOT = 17.5 ppg The formation between 5000 and 9000 ft is a highly compacted shale with sand stringers between 7000 and 8000 ft. These stringers could contain pockets of gas. The mud weight for this section will start at 14.0 ppg and will be increased progressively to 15.5 ppg.

C95 – 58.4# New Vam

Production Casing 9 5/8” – 9000 ft.

ABC Productive Sands – from 9300 to 1000 ft. Estimated formation pressure = 7500 7” Liner – 8500 - 10,000 ft. psi. H2S content = 0 ppm. BHT = 180oF. C95 44/46 38# New Vam Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

Group Exercise 2 Discussion Groups 1) Design a basic wellhead and Tree for the following development well.

3 ½” Production Tubing

Conductor 20” X 2 jts K55 – 68# BTC

Surface – 13 3/8” – 1500 ft. Expected LOT = 14.5 ppg The formation between 1500 and 5000 ft is a plastic clay. The mud weight for this section will start at 9.0 ppg and will be increased progressively to 10.5 ppg.

P110 – 47 # BTC

Intermediate – 9 5/8” 5000 ft – Expected LOT = 17.5 ppg The formation between 5000 and 9000 ft is a highly compacted shale with sand stringers between 7000 and 8000 ft. These stringers could contain pockets of gas. The mud weight for this section will start at 14.0 ppg and will be increased progressively to 15.5 ppg.

C95 – 35# New Vam

Production Casing 7” – 9000 ft.

ABC Productive Sands – from 9300 to 1000 ft. Estimated formation pressure = 7500 4 1/2” Liner – 8500 - 10,000 psi. H2S content = 0 ppm. BHT = 180oF. ft. P110 15.1# New Vam 45/46 Quartz School. Module 5: WH & Well Control Equipment / Section 1: Well Head Components

01 Well Head Components

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