SpoolTree Subsea Christmas Trees

SpoolTree™ SubseaChristmas Trees

Certified System ComponentsTMA C C E S S

When Cameron invented the horizontaltree in 1992, it was a revolutionary con-cept. Now the patented SpoolTree™

Christmas tree is one of the most widelyused (and often imitated) trees in theworld’s offshore fields. Subsea field devel-opment has changed fundamentally as aresult of this technology.

Cameron created a tree with significantoperational advantages by re-engineeringfield-proven components. It featuresCameron FLS Gate Valves and CameronWillis subsea chokes, for example, theindustry’s most trusted brands. SpoolTreetubing hangers and running tools areproven in numerous wells.

SpoolTree Christmas trees have work-ing-pressure ratings of up to 15,000 psi.They mate to any of Cameron’s STM andSTC wellhead connection profiles — hub,mandrel or deepwater high capacity —and can be adapted to other wellheadprofiles. SpoolTree Christmas trees are

integrated with Cameron’s MOSAIC™

subsea production systems, which pro-vide options for current and future fielddevelopment unavailable anywhere else.

How SpoolTree Christmas trees aredifferent from ordinary treesSpoolTree technology turns conventionalChristmas tree technology upside down.Instead of the typical wellhead-hanger-

tree stackup, the SpoolTree design has awellhead-tree-hanger stackup. In thisconfiguration, the Christmas tree con-sists of a concentric bore spool with awellhead connector below and a well-head connector profile on top. The tub-ing hanger is hung off inside the spool

SpoolTree™ subsea Christmas trees from Cameron: completions and workoverswith full BOP protection and full-bore vertical access without removing the tree.

SpoolTree operational andcost advantages

• Wells can be completed and worked

over with full BOP protection at all

times;

• Downhole completions can be

retrieved without removing the tree,

leaving the tree connector gasket,

flowline connection and production

control umbilical undisturbed;

• Completions and workovers can be

performed with a standard drilling

riser and BOP. The need for a special-

ized completion/workover riser system

is eliminated;

• Wireline tools are not run through the

tree valves, greatly reducing the risk of

damage;

• The amount of equipment required for

handling offshore is reduced;

• Installation is performed with familiar

equipment and routine rig procedures;

• Overall height of the completion is

substantially lower;

• SpoolTree Christmas trees are fully

integrated with Cameron’s modular,

high-performance MOSAIC production

systems.

• SpoolTree systems reduce rig time,

not only during workovers, but also

during initial completion operations.

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Cameron introduces theSpoolTree Christmas tree

Cameron SpoolTree receives approvalfrom Health Safety Executive (HSE) andMinerals Management Service (MMS)

Cameron installs the world’s first SpoolTreeChristmas tree in 350 ft of water in the

North Sea. Fourteen 5,000 psi WP trees wereinstalled in a system of subsea satellite wells

tied back to a floating production facility.Well types included oil producers, water

injectors, gas supply and gas injectors

First Gulf of Mexico SpoolTree is installed in 650 ft of water.Two 3 x 2” 10,000 psi WP treeswere used on a two-well subseatemplate with production manifold.

First mudline SpoolTree is installed in150 ft of water in the North Sea. Three5 x 2” 5,000 psi WP trees were used in a diver-assisted satellite completion ondrill-through mudline wellheads.

SpoolTree Christmas trees deliverunique performance benefits in everytype of offshore well

Subsea – oil or gas production

Subsea – gas or water injection

Subsea – aquifer

Platform – tie-back*

Mudline – completion*

*See page 7 for more information.

Unique wellhead-tree-hanger stackup is the key differencebetween SpoolTree Christmas trees and conventional trees.

1992 1993 1994

on a dedicated load shoulder, and thevalves are situated on the side of thespool. No valves are in the vertical boreof the wellhead/tree system. The com-pletion is run after the tree is installed,and the completion can be pulled withthe tree in place and flowline connec-tions undisturbed.

Reduced costs, increased safetyIn re-thinking traditional Christmastrees, Cameron’s goals were to shortenrig time, reduce capital equipment costsand increase safety. Eliminating the needto remove the tree to pull productiontubing saves rig time (see chart below),especially for completions that requirefrequent retrieval of downhole equip-ment. Eliminating the need for anexpensive, dual-bore workover andcompletion riser system cuts equipmentcosts.

And SpoolTree Christmas trees aresafer than ordinary trees. All completionand workover activities can be per-formed under full BOP control using astandard drilling riser and blowout preventer, which connects to an 18-3/4”profile on top of the SpoolTree body.Because tubing is installed after the treeis in place and the BOP connected, thereis uninterrupted BOP protection fromthe moment the well is perforated. Withconventional equipment, the tubingmust be installed before removing theBOP and installing the tree.

The SpoolTree design has earned theapproval of major regulatory bodiesgoverning its use including the MineralsManagement Service for the Gulf ofMexico and the Health and SafetyExecutive for the North Sea.

Modular Subsea AndIntegrated Completion systems: The MOSAIC™concept

MOSAIC systems are the result of a design

philosophy that eliminates the usual tradeoffs

you expect with a pre-engineered, modular

system. With MOSAIC systems, you gain

simplified installation procedures, reduced

personnel training and faster delivery.

Unlike ordinary systems, you don’t have

to give up flexibility, expandability and

desirable product features and benefits.

The ordinary approach to modularity

is fixed assemblies run progressively to large

structures, which are not appropriate for

many applications. MOSAIC systems are

modular at the component level, standard-

ized to work together in many combinations.

The result is a cost-effective system that can

be adapted to virtually any subsea job. The

MOSAIC system is more easily expanded as

field development needs evolve, and its

components contain the technology that

provides the performance you need.

Cameron’s SpoolTree Christmas trees

are an integral part of the MOSAIC system.

They’re the perfect fit for today’s subsea

economics.

First deepwater SpoolTree is installed in 2150 ft of water inthe Gulf of Mexico. Three 3 x 2”

10,000 psi WP trees were tiedback to a 24-slot subsea template,producing to a floating production

facility through a free-standingproduction riser system.

First platform SpoolTree is installed in theNorth Sea. A total of twenty-nine 5 x 2” 5,000psi WP SpoolTrees were installed using 13-5/8”10,000 psi WP compact wellheads. SpoolTreeswere used on every well type.

Christmas Tree Rig Time Comparison

WaterDepth

Rig Time (Hours)

100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600

SpoolTree Completion SpoolTree Workover

Conventional Tree Completion Conventional Tree Workover1000 ft(305 m)

2000 ft(610 m)

3000 ft(914 m)

4000 ft(1219 m)

5000 ft(1525 m)

1995 1996 1997 1998

SpoolTree is awardedpatent in U.S.

First Australian SpoolTreetrees are built by Cameronfor the Timor Sea area.

First guidelineless SpoolTreerun in 3,638 ft of water,Campos Basin, Brazil

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Modular SpoolTree Christmas trees: The foundation of a production system with endless possibilities.

4

Spool bodyThe Spool body provides outlets to attach production, annulus and isolation valves for downhole functions andthe electrical penetrator bonnet assembly. The tubing hanger landing shoulder is specially ported to accept controlstabs and provides hydraulic continuity between the production control system and downhole hydraulics.

Flowline and pipeline connections

Vertical, horizontal, diver assist and ROV-driven connections are available. Common interfaces allow a variety of different types ofconnection systems to be used.

Valve assembliesValves are contained both as an integral part of the spoolbody, and in mini-blocks externalto the vertical bore of the tree. A typical valve cluster includesproduction and annulus mastervalve, production and annuluswing valve, crossover valve,workover valve and isolationvalves for SCSSV, CIV and otherrequirements. Assemblies areavailable for 3” – 7” completions.

Tree connectorThe tree connector is capable of providing approximately 3 million pounds of preload whenoperated by the Tree Running Tool (TRT). Tree installation is diverless. The TRT contains allhydraulic tree connector functions, leaving the tree connector with no hydraulics exposed tothe subsea environment.

SpoolTree Christmas trees can be configured with a wide array of component choices. The benefits ofCameron’s MOSAIC concept — modularity at the component level — can be seen here in sharp focus.The possible combinations of component choices, available pressure ratings and sizes are virtually endless. Which means you get equipment precisely suited to your current requirements and flexibleexpansion options as your development plans evolve.

Control moduleWithin the advanced CAMTROL™ control pod, the controls circuitry and hydraulicsare also modular. Up to 32 hydraulic control points, in multiples of four, can beincluded in the pod. These control points can be used not only for traditional treevalves but also for functions such as manifold valve control, choke adjustment,position indication/feedback and accommodating smart well technology.

Basic Chemical Injection Annulus Crossover

Gas Lift ChokeProduction Choke

5

Tubing hangerThe modular design allows up to six hydraulic andtwo electrical penetrations. Available for 3” – 7”

completions, the tubinghanger has a concentricbore and side productionoutlet. During installation,the hanger orients, landsand locks to the bore ofthe SpoolTree spool body.At the bottom of the

hanger, an orientation sleeve with a helix engages akey in the tree, which provides 180º of passive ori-entation to positively align the hanger outlet withthe spool body. This design makes precise orienta-tion simple, sure and automatic. Tubing hanger sealsare either metal-to-metal or Cameron’s CAMLASTMetal End-Cap (MEC) seal. The SpoolTree tubinghanger allows multiple penetrations for SCSSV, CIV,DHPTS, smart well, etc..

GuidebasesSpoolTree Christmas trees can be easily configured for template or satellite installation.They can be run with guidelines on drilling guidebases or guidelineless. Completionguidebases for satellite installations can be customized with a variety of connectiontypes and other features to fit field development requirements.

Retrievable subsea chokesRetrievable subsea chokes from Cameron Willis provideflexibility to replace worn trim or change it out basedon the well production profile. Plug-and-cage and external-sleeve trim types are available. Chokes areoffered for diver-assist and diverless installation andretrieval. Retrievable subsea chokes can be specifiedwith crown or clamp connectors.

Internal tree cap and wireline plugsThe SpoolTree design follows Cameron’s dual pressure barrier philosophy.The primary pressure barrier is a plug in the tubing hanger. The Internal TreeCap (ITC) provides a secondary barrier above the tubing hanger. The ITC isrun and retrieved through the BOP stack using the tubing hanger tools. Thecap seals and locks into the tree using the same mechanism as the tubinghanger. Two versions of the ITC are available: either solid or bored for a wireline plug. The plug option allows access to the tubing ID usingwireline tools. The ITC plug is metal sealing with an elastomer backup.

Debris capThe debris cap covers and protects the spool top, and need not contain pressure.The cap is mechanically weight set and is run and retrieved with drillpipe. Whenlanded, the cap latches to the external profile on to the top of the SpoolTreebody. The design allows the top of the spool and the inside of the cap to befilled with corrosion inhibitor.

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SpoolTree Christmas trees outperformed ordinary trees in these projects.Imagine how they’ll perform in yours.

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Campos Basin, BrazilWater Depth: 1,109 meters (3,638 ft)

Problem: Using electrical submersiblepumps (ESP) in deepwater subsea wellsand reducing intervention costs.Solution: In the world’s deepest commercial application of electrical submersible pumps in subsea wells,SpoolTree Christmas trees were chosenbecause their modular design andunique wellhead/tree/hanger stackupprovided the right combination of fea-tures to make interventions faster andeasier than with ordinary trees.

Subsea trees were installed in waterdepths up to 1150 meters, but the opera-tor wanted the flexibility to locate theproduction platform in shallow water.This called for the use of ESPs becauselong horizontal flowlines made reservoirpressure and gas lift insufficient. TheESP can also withstand high flow rates.

Although the ESPs have proven reliable, their presence almost alwaysmeans that more interventions will berequired. The operator chose the

SpoolTree design because it dramaticallysimplifies interventions. And it providesfull-bore access to accommodate electri-cal connections. SpoolTree’s monoboredesign also allows more penetrationsthan conventional types.

SpoolTree modularity allows an easy

conversion from gas lift to ESP. Another bene-fit: a custom flowline connector designed bythe operator was a simple retrofit. TheSpoolTrees used here were the first with eccen-tric tubing hangers. This was also the firstguidelineless SpoolTree installation.

Gryphon Field, North SeaWater Depth: 112 meters (370 ft)

Problem: Economically develop a marginalfield with four types of wells. The water injection wells used in this project required ahigh volume of water production. In addition,the operator did not want to acquire an expen-sive, dual-bore riser system. Solution: SpoolTree modularity gave the oper-ator the flexibility to control eight productionwells, four water injection wells, one gas injec-tion/production well and one water produc-tion well with only one basic tree type. Theoperator was able to reduce costs substantiallyby drilling only one water production well.Using ordinary trees, more water productionwells would be required to match the flowrates of the water injectors. Because theSpoolTree Christmas tree’s design allowedwater production from a 9-5/8” concentricbore, no additional water producers wererequired. The oil and gas wells were tied to apurpose-built, permanently moored FPSO inthe North Sea.

Gryphon Field, North Sea

Campos Basin, Offshore Brazil

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SpoolTree modularity and operationaladvantages had a dramatic impact ondelivery and installation times. The firsttree was delivered only nine months fromreceipt of the purchase order. And instal-lation time was considerably reduced,which allowed earlier production and alsorepresented a significant cost savings forthe operator.

Because SpoolTree Christmas trees allowall completion and workover activitiesunder the control of a conventional BOP, anexpensive completion/workover riser sys-tem was not necessary. Such a system cancost as much as three Christmas treeassemblies.

Cauvery Basin, Offshore IndiaWater Depth: 90 meters (295 ft)

Problem: Re-enter and complete two wellsthat had been drilled with Cameron WS-1Lo-Torque subsea wellheads and aban-doned 10 years earlier. Drill and completetwo additional wells in the field for a total

of four wells producing to an FPSO off theeast coast of India. Favorable developmenteconomics and a fast schedule where crucial for the success of this project.

Since the condition of the sealing surfaces of the two old wellheads wasunknown, it was important to minimize theeffects of seal surfaces that may have beencorroded, damaged or covered with marine

growth. In addition, the permanent guide-bases on the old wells were not recoverableand not designed to provide productionflowline support.Solution: The conventional approach insuch a situation is to utilize a tubing spoolassembly to provide new seal surfaces forthe BOP and for the tubing hanger system.The dual bore tree can then be run on topof the spool. This spool assembly can alsoprovide a structure for the flowline supportbase. But this solution was impracticalbecause in addition to the cost of a separatetubing spool, it would have required alarge capital expenditure for a dual borecompletion riser just to complete four wells.

The SpoolTree Christmas tree alleviatedall these problems. The spool part of theSpoolTree allowed the establishment ofnew seal surfaces for the BOP and tubinghanger system, in essence combining thespool and the tree into one assembly. TheSpoolTree did not require an expensive

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Platform and mudlineSpoolTree configurations

All the advantages and versatility of

subsea SpoolTree Christmas trees are

also present in platform and mudline

versions. On platforms, SpoolTree valve

arrangements, low height and compact

overall size allow tighter spacing. Because

mudline SpoolTrees are compact and sit

close to the seabed, damage from fishing

trawl boards and nets can be minimized.

Both versions retain easy access to the

completion with full BOP protection.

Cauvery Basin, Offshore India

Mudline SpoolTree

Platform SpoolTree

completion riser system. Cameron engi-neers designed a simple flowline supportstructure that interfaced with the existingguidebase, without requiring a spoolassembly for only that purpose. The resultwas an economical solution to a problemthat would have been far more expensiveto solve with conventional equipment.

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© Cooper Cameron Corporation, Cameron Division, Printed in USA, 3/99, HG/7.5M, WR6565/TC1265

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MOSAIC, SpoolTree, Cameron, CAMLAST, STM, STC, CAMTROL and Cameron Willis are trademarks of the Cooper Cameron Corporation, Cameron Division.