X-mass tree & wellhead operations we.pdf

X-mass tree & wellhead operations maintance and testing

1. X-MAS TREE & WELLHEAD
OPERATIONS, MAINTENANCE
AND TESTING
By Engineer: Jamal Amer

2. Course Introduction
•Wellhead and Xmas tree is the main equipment for oil
production, water injection and down hole operation.
•It is installed on the casing head to seal the annular space
between casing and tubing, control wellhead pressure,
adjust well flow rate and transport oil to pipeline.
•This course is designed to provide an up-to date overview
of x-mas tree, wellhead equipment, mechanical barriers,
safety valves and wellhead operating control system.
•Participants will develop a better understanding of wellhead
operating procedures and working under safe conditions.

3. Course Objectives:
Upon successful completion of this course, the delegates will
be able to:
➢Apply and gain an in-depth knowledge on x-mas tree &
wellhead operations, maintenance and testing
➢Discuss the various wellhead equipment as well as x-mas
tree, tubing hanger, production packers & landing nipples
Practice barriers principles & well safety on hydraulic
barriers and mechanical barriers as well as subsurface
control valve packer setting and testing
➢Demonstrate flanging of the wellhead, wellhead safety
valves and control system
➢Apply the proper procedures of x-mas tree and wellhead
operations to work under safe conditions

4. Xmas Tree
General
➢TheXmastreeisanitemofsafetyequipmentthatisplaced
ontopofthewellhead.Itconsistsofasystemofvalves
whichmaybeeitheropenorclosedaccordingtothestateof
thewell(ordinaryoperation,well-toolintervention,pumping,
testing,repairs).
➢ThepurposeoftheXmastreeistocontroltheflowof
hydrocarbonsfromthewellandtoallowaccesstothewell
duringtheoperationalphase.WecalltheXmastreeasafety
barrier.

5. Xmas Tree Components
Not normally used: always fully
open. Close in emergency
Normally used
All above valves are gate valves
Upper Master Valve (UMV)
•The Upper Master Valve is used
on moderate to high pressure
wells as an emergency shut-in
system
•Valve should be capable of
cutting braided wireline and
slick line
•Valve can be actuated
pneumatically or hydraulically.
•The UMV valve is normally
connected to an emergency shut-
down (ESD) system.
•The UMV can be considered as
a primary barrier

6. Crown Or Swab Valve
▪Topmost valve on a Christmas tree
▪Swab valve is used to
a.control access to, and
b.isolation of the wellbore when
performing well-intervention
operations such as slickline,
electric wireline or coiled
tubing.
▪Valve is usually a manual valve.
Wing Valve
▪Used for production.
▪Usually a hydraulic valve
▪Tree cap: it allow entry of tools
into the well
Xmas Tree Components

7. Summary of Well Construction
Hole Size Casing SizeCasing Name
30” 26” Conductor
23” 20” or 18 5/8”Surface
17 ½” 13 3/8 Intermediate
12 ¼” 9 5/8” Production
8 ½” 7” Production
Liner
wel
d
Wellh
ead
7

8. Summary of Well Construction
wel
d
▪Well construction based on
a repeated set of processes.
▪Drill a hole, run and cement
steel casing
▪Install a wellhead section
and nipple up BOPS.
▪Drill a hole, run and cement
steel casing and run another
wellhead section
▪Process is repeated several
times until the hole total
depth ( TD) is reached.
▪The table belwoshowssthe
sequence of hole and casing
sizes in common use
8

9. Well Head Assembly
•A wellhead is part of an oil/gas well that terminates at
the surface, whether on land or offshore.
•The primary role of the wellhead is pressure
containment and to hold the casings and the
production tubing.
•Every oil or gas well has some type of wellhead.
•Conventional wellhead assemblies include the casing
head Housing , casing hangers, spool sections,
tubing head, tubing hanger, valves and fittings.
•The assembly of valves and fittings that sit on top of
the wellhead are also known as the Christmas tree.
9

10. Production Tubing
Surface Casing
Intermediate Casing
Production Casing
0
200
0 3000
500
0
4000
100
0
Conductor Pipe Section D
Production
Tree
Section C
Tubing Spool
Section
B
Casing
Spool
Section A
Casing Head with
Landing Base
Conventional Wellhead and Christmas Tree Assembly

11. 11

12. Wellhead Main Functions
•Casing/Tubing suspension.
•Pressure sealing and isolation between casing at surface
when many casing strings are used.
•Provides a means of attaching a blowout preventer during
drilling.
•Provides a means of attaching a Christmas tree for
production operations.
•Provides a reliable means of well access. (Tubing Head)
•Provides a mean of attaching a well pump. (Artificial Lift)
•Provides pressure monitoring and pumping access to
annuli between the different casing/tubing strings.
12

13. Casing Head (Housing)
13

14. Casing Head Components
14

15. •Casing head is the primary interface for the surface pressure
control equipment, for example blowout preventers (for well
drilling) or the Christmas tree (for well production).
•Casing Head has a straight bore bowl with 45°landing
shoulder design which avoids damage to sealing areas by
drilling tools and prevents test plug and bowl protector.
•Most casing heads allow for the pressure readings to be
taken on the annulus and provide the means to pump out or
into if necessary. The top of the casing string and annulus is
usually sealed.
•Casing Head provided are normally furnished with threaded
outlets and studded outlets and also can be manufactured
by request.
•Bottom connections can be furnished threaded or slip-on for
welding.
Casing Head (Housing)
15

16. Pressure testing:
•A pressure test must be carried out using hydraulic
oil after cooling of the base flange.
•Do not exceed 70% of API casing collapse pressure
rating.
•During this test, no sweating should occur. Upon
completion of the test, install a wellhead protection
cap to prevent objects accidentally falling into the
wellbore.
•Re-install the 3/4” NPT plug in the test port.
Casing Head (Housing)
16

17. 20”
casing
13 3/8”
casing
Casing
head
Casin
g
Hang
er
Casing Hangers
▪A casing hanger is a retainer /
packer mechanism which
supports, centers, and seals a
string of casing in a casing head
,casing spool or tubing head bowl.
Slips
Bowl
Elastomer
Seal element
Landing
profile
Casing hanger
17

18. Casing Hanger Types
There are two types of casing hanger in common use. Wellheads can be
designed to accept both types of hanger.
Mandrel (boll weevil) Type Casing Hangers:
•This type of hanger is screwed onto the top of
the casing string so that it lands in the casing
housing when the casing shoe reaches the
required depth.
•Short lengths of casing, known as pup joints
may have to be added to the string so that the
casing shoe is at the correct depth when the
hanger lands in the wellhead.
•The calculation which determines the length of
pup joints required to achieve this positioning is
known as spacing out the string.
•Although this is the most common type of
hanger it cannot be used if there is a risk that
the casing will not reach bottom and therefore
that the hanger will not land in the wellhead.
18

19. Casing Hanger Types
Slip Type Casing Hangers:
•This type of hanger is wrapped
around the casing and then
lowered until it sits inside the
casing spool.
•The slips are automatically set
when the casing is lowered (in a
similar fashion to drillpipe slips)
•This type of hanger can be used if
the casing stands up on a ledge
and cannot reach its required
setting depth.
•These types of hanger are also
used when tension has to be
applied in order to avoid casing
buckling when the well is brought
into production.
19

20. Casing Hanger
20

21. Casing Hanger
21

22. 22
Casing Spools
The casing spool in a conventional wellhead
system is the component that allows for an
additional string of casing to be set in the well.
Depending on the casing program for the well,
there can be one or more casing spools and they
perform the following functions:
•Allows for suspending the next casing string in the
well
•Provides outlets for fluid returns
•Provides a means to test the blowout preventers
while drilling
•Has flanges on both the top and bottom of the
assembly
•Has a seal area in the bottom flange for a
secondary seal between the casing annulus and
the flanged connection
•Utilize a test port in the bottom flange that allows
for seal and the flanged connection to be pressure
teste

23. 23
Casing Spool Components

24. Casing Head Housing -Description
24

25. Threaded
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.
25
Types of Casing Head Housing (CHH):

26. Composite Trees
•This type of tree
should only be
used for low
pressure and low
risk applications.
Christmas Tree Type
26

27. Normal (Convention)Wellhead & Christmas Tree
Electric submersible pumps
•Used in oil production to provide
a relatively efficient form of
"artificial lift“.
•Able to operate across a broad
range of flow rates and depths.
•By decreasing the pressure at the
bottom of the well (by lowering
bottom hole flowing pressure, or
increasing drawdown),
significantly more oil can be
produced from the well when
compared with natural production.
•The pumps are typically
electrically powered.
27

28. ▪DHSV: are used to close the well in an
emergency
▪Potential situations include:
▪serious damage to the wellhead
▪failure of surface equipment, and
▪fire at surface.
Tubing Hanger
Flow Coupling
SCSSV Landing Nipple
SPM
Top Packer
Producing Zone 2
Producing Zone 1
WL Entry Guide
Top No-Go Nipple
Bottom No-Go Nipple
Top No-Go Nipple
Perforated Joint
SSD
SSD
PRODUCER COMPLETION SCHEMATIC
Blast Joint
Control Line
Btm Packer
Function Of Sub-Surface SafetyValves
▪Set below the depth where they can be
damaged by surface impact explosion

29. Downhole safety valves (DHSVs) are installed in the well in order to prevent
blowouts if:
➢The topside Xmas tree becomes damaged (e.g. by collision with a crane lift)
➢surface equipment is sabotaged
➢A neighboring well suffers a blow-out (in order to prevent a domino effect)
➢drilling collision from nabouring well (the valve must be located so deep that
drilling-in will most probably be above the valve).
Such valves are of the “Fail-safe Closed” type. If hydraulic pressure to the
valve is lost, it will immediately close.
These valves can also be pumped through from the surface even when they
are closed.
Such valves exist in two versions:
✓Flapper valves
✓Ball-valves.
Function Of Sub-Surface SafetyValves

30. ▪In offshore wells, at least one safety valve is
placed in every well at a depth from 200 ft to
2,000 ft below the seabed.
▪Depth of safety valve depends on:
▪well environment (onshore, offshore)
▪below depth where damage to the safety
valve can occur from surface related
hazards such as impacts, explosions,fires
etc
▪production characteristics (wax or hydrate
deposition depth)
▪characteristics of the safety valve.
(maximum and minimum setting depths)
Setting Depth of Safety Valves
Tubing Hanger
Flow Coupling
SCSSV Landing Nipple
SPM
Top Packer
Producing Zone 2
Producing Zone 1
WL Entry Guide
Top No-Go Nipple
Bottom No-Go Nipple
Top No-Go Nipple
Perforated Joint
SSD
SSD
PRODUCER COMPLETION SCHEMATIC
Blast Joint
Control Line
Btm Packer

31. TRSVWRSV
SVLN
CL Port
Profile
Seal Bore
Lock
Mandrel
Packing
Packing
Piston
Spring
Flow Tube
Flapper
WRSV Set In SVLN
Nipple Profile
Control Line
Lock-Out
Mechanism
Piston
Flow Tube
Spring
Flapper
Function Of Sub-Surface SafetyValves

32. Control line installationWire line SCSSSV Nipple
SCSSV
Function of Sub-Surface SafetyValves

33. They can be divided into two categories :
1-S. S. C.S.S.S.V.
2 -S. C .S.S.S.V.
1. ( Down Hole ) Sub Surface Controlled Sub SurfaceSafety Valves
▪often called velocity valves or Storm® chokes) are wireline retrievable
▪installed in standard profile seating nipples in the tubing string below the
surface tubing hanger.
▪A subsurface safety valve requires a change in the operating conditions at the
valve to activate the closure mechanism.
▪The velocity valve contains an internal orifice that is specifically sized to the flow
characteristics of the well.
▪The valve is normally open and is closed by an increase in flow rate across the
orifice.
▪This creates a pressure drop, or differential pressure, across the valve that causes it
to close.
▪The velocity valve reopens when the pressure is equalized across the valve.
Types of Down Hole Safety Valves

34. ▪Often called velocity valves or Storm® chokes are wireline retrievable
▪installed in standard profile seating nipples in the tubing string below the
surface tubing hanger.
▪A subsurface safety valve requires a change in the operating conditions at the
valve to activate the closure mechanism.
✓The velocity valve contains an internal orifice that is specifically sized to
the flow characteristics of the well.
✓The valve is normally open and is closed by an increase in flow rate across
the orifice.
✓This creates a pressure drop, or differential pressure, across the valve that
causes it to close.
✓The velocity valve reopens when the pressure is equalized across the
valve.
Differential pressure controlled
velocity valves
Subsurface-controlled safety valves SSCSSV

35. ▪Subsurface Controlled Safety valves are
restrictions in the flow path held open by a
spring.
▪When the flow rate through the valve
becomes so high that the resistance force
collapses the spring and the force of the
reservoir holds the valve shut.
▪The well can be reopened by pumping into
the well.
▪This valve has to be reset every few weeks
as reservoir pressure falls to ensure that
▪“wide open flow” would still be
adequate to collapse the spring and
close the valve.
Activated by maximum flow of the well
Sub Surface Controlled Sub SurfaceSafety Valves
▪Once closed, the valve can be re-opened by applying tubing pressure above it,
or by means of an equalisingvalve run on wireline.

36. Function Of Sub-Surface SafetyValves

37. Ambient pressure controlled
▪This type of valve is normally closed.
▪The well pressure (hydrostatic or
flowing) keeps the valve open.
▪If the well starts to produce at an
increase flow rate
▪the tubing pressure drops and
▪valve is closed by a spring and
pre-charged nitrogen chamber.
▪Once closed, the valve can be re-
opened by applying tubing pressure
above it, or
▪by means of an equalisingvalve, run
on wireline .
Sub Surface Controlled Sub SurfaceSafety Valves

38. TRSVWRSV
SCSSV
-WRSV
-TRSV
Surface-controlled subsurface safety valves (SCSSVs)

39. WELL INTERVENTIONS COURSE HANDOUTSWell Intervention Course Handouts
W/L SCSSSV
TRSV
WRSV
SVLN
CL Port
Profile
Seal Bore
Lock
Mandrel
Packing
Packing
Piston
Spring
Flow Tube
Flapper
WRSV Set In SVLN
Nipple Profile
Control Line
Lock-Out
Mechanism
Piston
Flow Tube
Spring
Flapper

40. ▪Surface controlled wire line retrievable
DHSV is
▪run in the open position with a prong on a
wire line running tool
▪Closure mechanism is either
•ball or
•flapper type
▪Held open by hydraulic pressure applied to the
valve via control line
▪Retrieval is much easier compared to tubing
retrievable valves
▪Have to be pulled prior to wire line operations
due to restricted bore
▪The valve is re-opened by applying equal
pressures above and below the valve
Wireline Retrievable SCSSV

41. ▪In gas lift systems where large amounts
of pressurized gas exists in the tubing-
casing annulus.
▪Annulus Safety Valves may be
incorporated to contain this gas
inventory in the annulus in the event
that the wellhead becomes damaged.
Annulus Safety Valve
Why is an annulus safety valve installed ?
▪Annulus safety valve is run part of
completion string
▪Us in gas lift wells

42. Annular Safety Valve -Gas Lift
❑The ASV contains large
amounts of pressurised
gas in the tubing-casing
annulus –should the
well-head become
damaged
❑Provides annular by-pass
via a hydraulically
operated valve array
Lift Gas

43. Corrosion & Erosion
43

44. Barrier Concept
Barrier element: A barrier element is any device,
substance or fluid that prevents the flow of formation
fluids into the wellbore.
Primary
Barrier
Secondary
Barrier
Formation
Pressure
Formation
Pressure
➢A barrier is in effect a defence system to avoid
or reduce the consequences of accidental well
control events.
➢Barrier(s) may be located downhole
(mechanical plugs, columns of fluid), or topside
(valves, plugs, BOPs).
➢Even if a barrier element is designed to
prevent well flow on it own, it must always be
accompanied by other barrier elements.
➢In other words two barriers must exist at all
times

45. Types of Barriers
•Mechanical
•Fluid:
▪designed to stop flow by providing a hydrostatic pressure greater than the formation pressure
▪but must have another barrier such as BOPs as a back up
The principles of different barrier types
1.Primary
2.Secondary
3.Tertiary
Classes of Barriers
Barrier Definition:
Barrier is any device, fluid or substance that prevents flow of wellbore
fluids.

46. ▪Barrier elements include:
▪Mud hydrostatic pressure: designed to stop flow but must have another barrier
such as BOPs as a back up
Formation Pressure
Mud Hydrostatic Pressure
Mud Hydrostatic Pressure
Mechanical Barriers
2
Mechanical barriers
✓Casing and Cement.
✓Drill string.
✓Drilling, Wireline, Coil Tubing, Workover BOP’s.
✓Wellhead .
✓Deep set tubing plug.
✓Production Packer.
✓Stab-in Safety Valves.
✓Completion String
✓Tubing Hanger
The principles of different barrier types

47. Barrier Envelope
Barrier Envelope is an envelope consisting of one or several
dependent well-barrier elements designed to prevent fluids or gases
from flowing unintentionally from the formation, into another
formation or to surface.
▪Pressure control requires a minimum of two independent and
tested barriers at all times.
▪If either of the barrier fail then attempts must be made to re-
establish the existence of two barriers before normal operation can
continue
▪A barrier envelop refers to a barrier containing a system of
barriers made up of hydrostatic and mechanical barriers or a
combination of various mechanical barriers.
▪The systems within the barrier envelope must be independent
of each other so if a barrier fails it will not affect the other
barriers.

48. Packer/Tubing Envelope
Barrier elements include:
▪Casing below Packer
▪Packer
▪Tubing
▪Tubing Accessories
▪Tubing Hanger
▪Xmas Tree
Example of Barrier Envelope
Tubing Spool
Outlet Valves
Packer Fluid
Tubing
Production
casing
Packer
Surface casing
Cement
Perforations
DHSV

49. PACKER/TUBING ENVELOPE
Barrier elements include:
▪Casing below Packer
▪Packer
▪Tubing
▪Tubing Accessories
▪Tubing Hanger
▪Xmas Tree
Example of Barrier Envelope

50. Production Casing Envelope ( Annulus Flow)
Barrier elements include:
•Production Casing
•Side Outlets Valves
•Tubing Hanger
•Tubing Head
•Casing Head Housing
50
Example of Barrier Envelope
Tubing
Hanger/Hanger
Spool

51. Tubing Spool
Outlet Valves
Packer Fluid
Tubing
Production
casing
Packer
Surface casing
Cement
Perforations
DHSV
Which Barriers Prevent Annulus Flow
Follow Red Arrows
1.Packer
2.Production casing below packer
3.Tubing Hanger/Hanger Spool ( Tubing Head)
4.Tubing spool outlet valves
5.Production tubing
In the production well schematic in figure identify the main barrier
elements (envelope) that prevent annulus flow?
Well Fluids

52. API connections
On all BOPs flanges, three different types of connections are used both as end
connections and side outlet connections:
1.Studded connection
2.Clamped hub connection
3.Flanged connection
Flanged connection
Studded
connection