The document provides an overview of Christmas trees in petroleum engineering, describing their purpose, components, and types, including vertical and horizontal configurations. It details their functionality in controlling wellbore fluid flow, including various safety features and specifications pertaining to industry standards. Additionally, it discusses the advantages and limitations of each type concerning well completion, intervention needs, and costs associated with installation.

1. Submitted by
"Mr . AMAR M.GAIKWAD"
Under the guidance of
" Prof. S.A. Joshi "
DEPARTMENT OF PETROLEUM ENGINEERING
MAEER'S
MAHARASTRA INSTITUTE OF TECHNOLOGY,PUNE
UNIVERSITY OF PUNE
2015-2016

2.  What is Christmas tree?
 The set of valves, spools & fittings connected
to the top of the well to isolate, direct and
control the flow wellbore fluids.
 The control valves, pressure gauges and
chokes assembled at the top of the well to
control the flow of oil and gas after the well
has been drilled and completed.
 The purpose of a production
Christmas Tree:
 The purpose of an injection
Christmas Tree: Fig. Schematic of Wellhead & Christmas Tree

3.  Tubing Hanger
 Tubing Head Spool
 Tree piping
 Flow line connector
 Wellhead connector
 Valves and fittings
 Choke

4.  Safety barrier
 Safely stop produced or injected fluid
 Injection of chemicals to well or flow line
 Allow for control of down hole valves
 Allow for electrical signals to down hole gauges
 To bleed of excessive pressure from annulus
 Regulate fluid flow through a choke
 Allow for well intervention

5.  API 6A: Specification for Wellhead and Christmas Tree
Equipment.
 API 17D: Design and Operation of Subsea Production
Systems-Subsea Wellhead and Tree Equipment.
 ISO 13628-4: Petroleum and natural gas industries –
Design and operation of subsea production systems.
 ISO 10423:2009: Petroleum and natural gas industries -
Drilling and production equipment - Wellhead and
Christmas tree equipment.

6. 1. Vertical Christmas Tree
2. Horizontal Christmas Tree
l Christmas Tree
Vertical Christmas Tree Horizontal Christmas Tree

7. Horizontal tree Vertical tree
 Production master valve (PMV) in
horizontal bore
 Single, concentric bore
 Must pull the production tubing to retrieve
the tree
 Both barriers fail if the tree is accidentally
removed
 Designed to take the load from a BOP
(increased weight)
 Batch-wise completion possible
 Tubing hanger is installed in the tree body
instead of the wellhead.
 The Horizontal tree concept can be further
defined as –
1.“Partial Drilling HT”
2.“Full Drilling HT”
 Production master valve (PMV) in vertical
bore
 Dual bore (production + annulus)
 Must pull the tree to retrieve the production
tubing
 Requires landing string to secure well before
work over
 Primary barrier is maintained if the tree is
accidentally removed
 Not designed to take the load from a BOP
 The vertical tree concept can be further defined
as –
1.“Eccentric” production flow is routed
eccentrically (dual bore configuration)
2.“Concentric” concentrically (single bore
configuration) through the tubing hanger.

8.  The valves are mounted on the lateral sides, allowing for simple
well intervention and tubing recovery.
 This concept is especially beneficial for wells that need a high
number of interventions.
 Swab valves are not used in the HXT since they have electrical
submersible pumps applications.
 The key feature of the HXT is that the tubing hanger is installed
in the tree body instead of the wellhead.
 This arrangement requires the tree to be installed onto the
wellhead before completion of the well.

9. Fig. Partial Drilling HT Fig. Full Drilling HT

10.  Partial Drilling HT:
 Diana, Marshall, Madison
(ExxonMobil GOM)
 Mica (ExxonMobil GOM)
 Kizomba (ExxonMobil
Angola)
 Full Drilling HT:
 Dalia (Total Fina Elf –
Block 17 Offshore Angola)
 Ross (Talisman Energy –
North Sea UK)

11.  The master valves are configured above the tubing hanger in the
vertical Xmas tree (VXT).
 VXT are applied commonly and widely in subsea fields due to
their flexibility of installation and operation.
 The vertical tree concept can be further defined as –
 “Eccentric” production flow is routed eccentrically (dual bore
configuration)
 “Concentric” concentrically (single bore configuration) through
the tubing hanger.

12. Fig. Concentric Mono-bore VTFig. Eccentric Dual Bore VT

13.  Eccentric VT:-
 Zinc (ExxonMobil – GOM)
 Girossol (Total Fina Elf -
Block 17 Offshore Angola)
 Balder (ExxonMobil –
North Sea Norway)
 Blackback (ExxonMobil –
Austraila)
 Concentric VT:-
 Bongo (Shell – Nigeria)
 Mensa (BP – GOM)
 Crazy Horse (BP – GOM)
 Macaroni (Shell – GOM)

14.  The cost of an HXT is much higher than that of a VXT; typically the purchase
price of an HXT is five to seven times more.
 A VXT is larger and heavier, which should be considered if the installation area
of the rig is limited.
 Completion of the well is another factor in selecting an HXT or VXT. If the
well is completed but the tree has not yet been prepared, a VXT is needed. Or if
an HXT is desired, then the well must be completed after installation of the tree.
 An HXT is not recommended for use in a gas field because interventions are
rarely needed.

15.  For the last 20 years the Horizontal Christmas tree has been the preferred
design for deepwater fields, while in recent years the focus in the industry
is returning to the conventional Vertical Christmas tree system.
 An HXT is applied in complex reservoirs or those needing frequent
workovers that require tubing retrieval, whereas a VXT is often chosen for
simple reservoirs or when the frequency of tubing retrieval workovers is
low.
 A tree often provides numerous additional functions including chemical
injection points, well intervention means, pressure relief means, monitoring
points such as pressure, temperature, corrosion, erosion, sand detection,
flow rate, flow composition, valve and choke position feedback, and
connection points for devices such as down hole pressure and temperature
transducers.

16. 1.Towns, T. K., Deeken, D. G., Derby, L. M., Exxon Mobil Development
Company, “Diana Subsea Tree Selection and Installation Results in
4,653 Feet of Water” Deep Offshore Technology held in Rio de Janeiro,
Brazil, October 17-19, 2001.
2. Moyer, M.C., Barry, M.D., Tears, N.C., "Hoover-Diana Deepwater
Drilling and Completions", OTC 13081, Offshore Technology
Conference, Houston,, May 2001.
3. Havard Devold," Oil And Gas Production Handbook", An Introduction
to Oil And Production, ABB Oil And Gas, May (2009), Edition 2.0
Oslo,29-32.
4. Oda Ingeborg Stendebakken, NTNU Trondheim, "A reliability study of
a Deepwater Vertical Christmas Tree with attention to XT retrieval
rate", June (2014),11-32.
5. Randy J. Wester and Eric P. Ringle / FMC Energy Systems," Installation
and Work over Time Savings: Key Drivers for Deepwater Tree
Selection" ,OCT 12943, Offshore Technology Conference, May (2001).