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Weatherford products and services are subject to Weatherford’s standard terms and conditions. Formore information concerning the full line of Weatherford products and services, please contact yourauthorised Weatherford representative. The Intellectual Property (including patents, trade marks,design rights and copyright) relating to the tools, devices and other material contained in thisliterature, is the exclusive property of Weatherford. Unauthorised use or reproduction of any of thematerial contained herein is strictly prohibited. Where patent numbers are declared, other patentapplications may be pending on the design

© 2001. Weatherford. All rights reserved. Brochure number 227.00

Norfolk House, Pitmedden Road, Dyce, Aberdeen AB21 0DPTel: +44 (0)1224 225200Fax: +44 (0)1224 225202www.weatherford.com

UNISET WELL SERVICING SYSTEMIn the mid 1980's a retrofit lock mandrel was developed for use in other manufacturers' landing nipple profiles.The lock was called Uniset and was designed to overcome the problems with contemporary systems. Incombination with a range of innovative flow control devices, this lock mandrel was the foundation of what hasbecome the Petroline Uniset Well Servicing System.

Today Uniset has grown to offer a suite of well completion and intervention equipment. The objectives of Unisetare:

• To optimise well completion designs

• To allow reliable life of field well servicing

• To provide innovative solutions

In short, Uniset aims to offer the operator a well which delivers maximum value from initial completion installationto final well abandonment. It is essential that flow control completion equipment does not compromise what canbe achieved at any stage of the well's life cycle. Indeed, the flow control equipment should only ever enhancethe wells performance.

Weatherford Completion Systems will manufacture Petroline Uniset equipment in whatever sizes optimise thewell design, irrespective of so-called "industry" standards. To this end, Uniset nipples and associated lockmandrels are available in ANY seal bore size. However, when specifying Uniset equipment Weatherford alwaysaims for standardisation across any single field or group of fields. This gives the Operator maximum flexibilityfrom minimum equipment inventory.

In many cases Weatherford aim to produce a "Uniset Working Monobore" flow control completion design. Thisresults in a well design which allows through-tubing retrievable mechanical bridge plugs to be run into the liner,yet still allows the use of landing nipples in the upper completion. The Uniset Working Monobore is a truly flexibledesign. It uses nipples for simple, reliable, low cost well completion and servicing, and bridge plugs for redundantwell plugging later in field life.

Uniset, used in conjunction with other elements of Weatherford's range of well servicing and completion products,offers innovative, low cost solutions to potentially expensive problems including:

• A system which provides insurance against workovers caused by wireline in reverse taper wells;

• A depth correlation system which removes the need for electric line to achieve depth control;

• A barrier system ensuring reliable operation in high debris potential HP/HT operations.

The following pages outline many of the items which comprise the Petroline Uniset Well Servicing System.Should you require more information or advice on its application within your completion, Weatherford'srepresentatives are available to assist you.

DETAILED TECHNICAL SPECIFICATIONThis Uniset Well Servicing System brochure has been designed to give an introductory overview of the rangeof equipment available. For each item illustrated here a Technical Specification Sheet is available, examplesof which are shown below. These documents give more in-depth information to assist in equipment evaluationand selection, including detailed specification tables. For further information on any of the equipment featuredplease contact a Weatherford representative.

UNISET CD-ROMA CD-Rom is available using multimediaanimation to further explain the operationof the Uniset Well Servicing System.Animated 3D models are utilised todescribe the detailed operation andassembly of the various Uniset flow controldevices. Please contact your localWeatherford representative for a copy ofthe uniset CD-Rom.

Featured equipment tool range

Equipment title

Features & benefits

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Equipmentillustration

QN NIPPLE PROFILEThe Petroline Uniset System was developed in response to Operating Companyrequests to produce an improved lock mandrel design to suit existing completionnipple profiles. After several years of field proving of retrofit Uniset lock mandrels,it became clear that the system could be optimised by the design of a new nippleprofile. Weatherford’s QN Nipple Profile is used to seat Uniset Lock Mandrels. Theprofile is widely used in Weatherford’s own Uniset landing nipples and third partymanufacture’s equipment including:

• Tubing Hangers

• Tubing Retrievable Safety Valves

• Downhole Flow Meters

• Sliding Sleeves

PrinciplesThe Uniset Nipple and Lock System utilises the no-go principle. This allows for theuse of simple equipment with minimal manipulation required downhole. The Unisetsystem uses the no-go only for location of the lock mandrel in the nipple. When thelock is set it lifts off the no-go, and load is taken on the mandrel keys. There areseveral advantages to this "lift-off the no-go" approach:

• Because the no-go is locational and not load bearing, the no-go dimension issmaller than in conventional nipple designs. This gives less taper effect to thecompletion and improves access to the reservoir.

• Pressure rating of the nipple is consistent for the life of the well because only thekey locking grooves see load.

• If some wear or erosion of the no-go occurs there is still no possibility of overpressuring the no-go shoulder and cold welding the lock into the nipple profile.

The nipple profile is machined with an entry angle of 15 degrees. This low angle isbeneficial in high deviation applications to provide easy entry for the lock mandrelto the nipple profile. The lead in also minimises entrance and exit pressure lossesand turbulent vortices.

Completion OptimisationThe Uniset nipple profile can be supplied in ANY seal bore size. This removes thelimitations imposed by other manufacturers’ size increments, allowing a truly optimisedwell design.

We recommend consultation with Weatherford Completion Systems when decidingupon completion configuration. The options can be reviewed to ensure that the wellarchitecture offers the best life-of-field solution.

ADDITIONAL EQUIPMENTPUMP OUT LOCKS & STANDING VALVESVariations of the Uniset QX Lock Mandrel and RNG Standing Valve can be supplied that can be set in aconventional landing nipple. Instead of being retrieved to surface on slickline these devices are designed to be‘pumped out’ and then fall to the bottom of the wellbore. This is typically of value in applications in which a pre-installed flow control barrier can not be retrieved to surface due to the presence of a completion restriction above.

INSERT LANDING NIPPLEUniset QN landing Nipples can be supplied to be run below Uniset Lock Mandrels. These are typically used inapplications such as long term well suspension when a large bore flow control device is to be installed, abovewhich a smaller bore tubing string will be run. It is then possible to run and retrieve Uniset plugs in the insertlanding nipple hung below the ‘parent’ lock mandrel. This ability can be of particular value when working wellsover to install smaller diameter tubing strings.

DROP-OFF SUBThe Uniset Drop Off Sub was originally developed as a suspension barrier to be run in heavy barite weightedHP/HT muds. A novel approach was required as large quantities of barite were expected to settle on anysuspension barrier in the well. It was known that this would make retrieving the barrier problematic.

The system consists of an adapted QN Nipple and QX Lock Mandrel. The Lock Mandrel is set at surface in anipple, typically positioned below a production packer. A length of tubing is run below the lock mandrel to createa bi-directional barrier. However, this length of tubing also acts as a large debris ‘sump’. The packer, insert nippleand drop off sub are run and set in the wellbore. Once the packer is set a bi-directional barrier is formed. Anydebris settling on the device is accommodated in the debris ‘sump’. This ensures that slickline access to thelock mandrel is maintained. A single slickline run releases the lock mandrel and allows it to fall to the bottomof the well when the barrier is to be removed.

HOLD OPEN & PROTECTION SLEEVESThe Uniset Hold Open Sleeve is set in a SSSV nipple profile and straddles across the entire length of the valve.The sleeve prevents damage to the valve sealing bores during wireline or coiled tubing operations. Uniset NippleProtector Sleeves are available to protect landing nipple seal bores. Both sleeve types are available to suit anynipple seal bore and feature positive lock-in or collet finger style mechanisms. Sleeve ID is optimised to maximisewell servicing access capability.

WIREFINDER TRIP SUBReverse taper, or bottleneck, completions are those in which the tubing string diameter increases with depthin the well (e.g. a 7” tubing string below a 5-1/2” section). Reverse taper completions present one major riskduring any wireline operations - breaking the wire in the large bore tubing. Should this occur, a conventionalwirefinder gives a high possibility of missing the top of the wire, becoming entangled, and causing a workover.

The solution is to use a Weatherford Expandable Wirefinder in conjunction with a Wirefinder Trip Sub (WFTS).The WFTS is used in place of a conventional crossover from the small bore to the large bore tubing. The WFTSfeatures a controlled taper profile which is designed to suit the trip keys on the Expandable Wirefinder. Thisminimises any bearing forces within the wirefinder mechanism and maximises its reliability.

Wirefinder Trip Subs can be supplied to suit any tubing crossover combination and any premium thread type.In combination with the Expandable Wirefinder, the WFTS represents a very low cost insurance against potentialworkovers in reverse taper completions.

QX LOCK MANDRELThe Uniset QX Lock Mandrel was designed specifically to overcome problems withexisting lock mandrel systems. It has undergone extensive field proving both as a retrofitdesign to suit Third Party nipple profiles, and in conjunction with Petroline's QN Nipple.The QX lock mandrel has established an outstanding service record in many applicationsthroughout the World.

Plugging ApplicationsThe QX lock mandrel is ideally suited for both routine and specialised plugging operations.The major features are:

• The rigid outer mandrel maximises the strength and impact resistance of the lock. Thisis borne out by Uniset's exceptional record for reliability and recovery.

• All jarring forces are transferred directly to the seal stack, minimising the effects ofseal friction. This feature is especially valuable when twin seal stacks are required fordevices such as wireline retrievable safety valves and isolation sleeves.

• Minimal downward jarring is required to set the lock mandrel which gives improvedperformance in very high angle wells. QX locks have been set at deviations in excessof 75 degrees in conjunction with Weatherford's Rolling Systems.

Flowing ApplicationsThe QX lock mandrel is especially suited to use in flowing applications such as hangingwireline-retrievable safety valves, injection valves, flowmeter assemblies, and downholegauges. Its major features are:

• The inner mandrel moves in the direction of flow to lock the keys out. There is no needfor a secondary lock-down mechanism to prevent flow-induced vibration from unseatingthe lock mandrel. This makes the Uniset lock design the leader in safety and reliabilityin flowing well service.

• The lock mandrel design can be customised to maximise its through-bore. Thisminimises the well fluids' velocity and hence the flowing pressure drop.

• The highly polished inner mandrel minimises frictional pressure loss, and the tendencyfor scale adhesion.

Technical DetailsThe QX lock mandrel is available with pressure ratings up to 15,000 psi, with 10,000 psias standard. Uniset lock mandrels can be supplied in ANY seal bore size, to suit Weatherfordor Third Party nipple profiles. Special clearance locks can be designed with reduced o.d.'sfor applications where running clearance is of particular importance.

DEPTH CORRELATION SUBThe Uniset Depth Correlation Sub (DCS) is designed to allow depth control without need forelectric line correlation. DCSs allow reservoir section interventions, such as zonal isolations andlogging surveys, to be carried out using conventional slickline or coiled tubing. DCSs are placedat strategic locations in the liner, such as above each major perforated interval. When the wellis completed, the precise location of each DCS can be determined using a Collar Log and tiedback to the base line Gamma Ray. The features of the DCS are:

• Offers no restriction below tubing drift.

• Selective and repeatable location.

• Does not impede passage of conventional cementing plugs.

• Allows upward ‘pull’ for location purposes.

• Can be used with wireline or coiled tubing.

For wireline operations, the DCS is used in combination with the Petroline Spring Roller Centraliser(SRC). The SRC rollers locate the profile in the DCS as the toolstring passes through. This givesa distinctive 'weight signature' at surface, allowing the operator to establish depth control.

For coiled tubing operations, the DCS is used in combination with the hydraulic DepthCorrelation Tool, as described below.

DEPTH CORRELATION TOOLThe Uniset Depth Correlation Tool (DCT) is a hydraulically activated device usedwith coiled tubing to locate Depth Correlation Subs (DCS) in the liner. The DCT allowsdepth correlation in the liner without resort to expensive “stiff-wire” operations.

The tool features a set of pressure-activated keys, which are expanded by eithercirculation or pressurisation of the coiled tubing. Once expanded these keys latch intothe DCS profile, allowing an overpull to remove any helix from the coiled tubing.Thereafter accurate depth control can be maintained at surface as the coil is pulledback through the well. When the coil is depressurised, the keys will relax back withinthe body OD.

Plugging of non-monobore wellsIf required, the lower bore of the DCS can be extended to provide a plugging point inthe liner. This is especially useful for non-monobore wells, where the size of the lineris such that through-tubing retrievable mechanical bridge plugs can not be set in theliner base pipe. In this form the DCS is known as a Slickplug Locator Joint (SLJ). SLJsare always sized such that they provide the least possible restriction in the liner, whilststill allowing Slickplugs to be set inside them. The SLJ retains all the depth controladvantages of the standard DCS.

ROLLING SYSTEMSThe Uniset Well Servicing System has anumber of features making it suited tohigh angle applications. Whether settingon slickline or coiled tubing, operationalperformance at high angle can be furtherenhanced by the application of RollingSystems technology. Please contact yourlocal Weatherford representative forfurther information.

QX RUNNING TOOLThe Uniset QX Lock Mandrel Running Tool has a number of features to ensure correctsetting of the lock. The running tool incorporates a positive tell tale device that indicateswhether or not the lock is correctly set once the running tool is retrieved to surface. Thisfeature is of particular significance because:

• If there are problems in setting the lock (e.g. due to sand or scale in the nipple) thenthe running tool is released from the lock mandrel and retrieved to surface. Thisallows the selection of alternative toolstring configurations or heavier wire to retrievethe lock. Many systems currently on the market do not allow for retrieval of therunning tool when problems are encountered; if the lock cannot be retrieved directlythen a difficult fishing job with wire in the hole is often the result.

• Unless the lock mandrel keys are fully expanded and the lock correctly set, the telltale will shear. There can be no doubt whether the lock is set correctly or not.

• The tell tale device is positive; the lock mandrel and running tool cannot be assembledtogether unless the tell tale is pinned in the running position. This means there canbe no confusion about the tell-tale once the running tool is retrieved to surface.

Hydraulically activated running tools are available for setting QX lock mandrels on coiledtubing in very high angle wells. The hydraulic running tool removes the need for jarringwhen setting the lock, and provides instantaneous indication at surface that the settingoperation is complete.

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ABC TUBING HANGER PLUGThe Uniset 'ABC' Tubing Hanger Plug was designed be set on wireline or polished rod,offering a much higher level of operations flexibility than conventional devices of this type.The tool consists of three sections each offering certain unique features and benefits:-

A. UNISET QXT LOCK MANDRELThis is a variant of the standard Uniset Lock Mandrel which offers all the benefits associatedwith this system but has a revised geometry more suited to wellhead applications. It useslow friction ST seals in place of conventional 'Chevron' or 'O' ring type devices.

B. UNISET ‘AB’ EQUALISING DEVICEOffers one run set / pull capability with a much greater degree of intrinsic safety than othermechanisms. In order to reduce reliance on operator ability the AB equalising assemblyincorporates a pressure sensing piston which, in the event of differential pressure beingpresent below the device, prevents the lock mandrel from being latched but permits equalisation.

"If it can't be latched, it can't be unlatched" describes the principle of operation and this isobviously an essential safety feature.

C. UNISET TYPE ‘C’ BACK PRESSURE VALVEThe Type 'C' Back Pressure Valve offers dual sealing with a primary metal to metalseal and back up elastomeric seal. In the event that it is necessary to pump throughthe device the spring loaded protector sleeve isolates the elastomeric back-up, givinga higher degree of integrity than similar devices without a secondary seal capability.

UNISET TUBING HANGER PLUGSIn addition to the range of Uniset WellServicing system equipment describedhere, a separate brochure specificallyaddresses tubing hanger pluggingapplications for land, platform and subseaapplications. Please contact your localWeatherford representative for furtherinformation.

DU PULLING TOOLThe Uniset DU Pulling Tool was designed to overcome the weaknesses of conventionalpulling tools used with internal fishing necks.

Bi-Directional JarringWhen retrieving many lock mandrel types it is necessary to jar both downwards, to free-offrelative key motion, and upwards, to overcome seal friction. Whilst Uniset locks do not requiresuch manipulation, with other devices this causes two problems:

• Downward jarring will shear a GS-type pulling tool.

• Upward jarring will shear the alternative GR-type pulling tool.

Consequently, 'one-run' devices can often require at least two runs to recover. The design ofthe DU Pulling Tool overcomes these problems by allowing bi-directional jarring:

• Initial downward jarring will not affect the DU, no matter how prolonged or severe.

• Subsequent upward jarring can also be applied indefinitely. This action merely shears screwsin the DU mechanism which moves the tool into a pre-release position.

• Final downward jarring will shear the release pin, allowing retrieval of the DU from the fishingneck.

RetrievabilityWith a GS-type pulling tool, debris inside a lock mandrel, or incorrect equalising prong spacing,may prevent the pulling tool from shouldering-out on the fishing neck. This means that the GSrelease pin will not shear and a fishing job is the likely result. However, the design of the DUPulling Tool is such that it can be released from the fishing neck even if the DU does notshoulder-out.

QX LOCK PULLING PROBEThe Uniset Pulling Probe is used in conjunction with a DU or GS Pulling Tool to retrieve QXLock Mandrels.

The probe depresses the inner mandrel of the lock to collapse the keys. The pulling tool thenengages the lock mandrel fishing neck, allowing the lock to be recovered to surface. The pullingprobe is also used in conjunction with a pinning handle to prepare the QX lock mandrel forrunning.

DUAL SEAL STANDING VALVEThe Uniset Dual Seal Standing Valve is a high integrity sealing valve using the sameretractable no-go technology as the Uniset RNG Standing Valve. The equalising mechanism(shown here), incorporates a dual seal device, which features a primary metal-to-metal sealwith an elastomeric back up. The major features are:

• All the benefits of retraceable no-go technology.

• Reliable sealing in horizontal wells.

• Ability to reseal in high debris environments.

A conventional standing valve equalising mechanism relies on gravity or flow rate to move aball on to its seat. This can make operation in horizontal wells problematic. However, the DualSeal device uses a power spring to re-seal the mechanism, allowing reliable service inhorizontal or even sub-horizontal wells.

When running in hole the power spring is compressed, allowing fluid bypass through the tool.In this open position the elastomeric seal is protected by a spring-activated wiper sleeve,avoiding contact with the well fluids at all times. This feature enhances the likelihood of sealintegrity being maintained even in high debris well conditions.

WIRELINE TOOLSTRING & FISHINGEQUIPMENTOperational success with the Uniset rangeof flow control equipment can be furtherenhanced by the use of the appropriatewireline toolstring equipment. TheWeatherford range of wireline toolstringis particularly applicable to fielddevelopments contemplating the use ofthe Uniset Well Servicing System. Pleasecontact your local Weatherfordrepresentative for further information.

UNISET RNG RETRACTABLE NO-GOSYSTEM SCHEMATICThis schematic depicts the Uniset RNGRetractable No-Go system in conjunctionwith the various flow control device optionsand associated running and pulling tools.Whilst not exhaustive in detail, the aim isto communicate graphically the fulloperational flexibility achievable with acomprehensive suite of Uniset equipment.

PT EQUALISING ASSEMBLYThe Uniset PT Equalising Assembly allows mechanical equalisation of 'one-run' pluggingassemblies. It is often used in conjunction with Pumpopen Plugs, Pumpout Subs andFormation Surge Tools.

In the running position the melon is held below the equalisation ports by a running prongattached to the QX Lock Mandrel Running Tool. This allows fluid by-pass through the plugbody.

When the lock mandrel running tool is retrieved from the lock, the melon is pulled upwardsby the running prong and the ports are sealed. The sealing O-rings are in a controlled boreat all times and are never fully exposed to the well fluids.

If the melon cannot move fully upwards for any reason, then a tell-tale collet on the runningprong will shear, indicating that the plug is incorrectly set. (Note that unlike similar designs,the running tool can always be recovered).

The plug is equalised by jarring down to push the PT melon off seat and open the ports.

PUMPOPEN PLUGThe Uniset Pumpopen Plug was designed to enable plugged wells to be brought backinto production more safely and economically than when using conventional wireline plugs.

Operated by applied differential pressure from above, the device can be 'pumped open'.The Pumpopen Plug is designed to have a high accuracy shear rating and to be reliableeven in severe debris conditions. There are recorded cases where these devices haveoperated with over 100 feet of debris above them. This capability is one reason why thePumpopen Plug should not be confused with equipment having similar names. The significantfeatures of the Pumpopen Plug are:

• Allows suspension and early production from wells.

• Minimises wireline operations - avoids requirement to bail.

• Provides positive equalisation in high debris environments.

• Designed to withstand long term, high rate flow through equalising ports.

Normally used in conjunction with an equalising assembly, Pumpopen Plugs can be suppliedto suit any make of lock mandrel.

Customised variants are available to suit specific operational requirements such as workovers,multiple tests, and high shear ratings.

RNG STANDING VALVEStanding valves are used to test the integrity of tubing strings and to set production packers.These devices are self-filling and hold pressure from above only. The prime criteria for thedevelopment of the Uniset Retractable No-Go Standing Valve was to significantly reduce thenumber of wireline runs required during the completion of a well.

The RNG Standing Valve uses a retractable no-go to locate the landing nipple. The standing valvecan be set, tested against and retrieved with a single wireline run. The major features are:

• Pressure ratings up to 15,000 psi, with 10,000 psi as standard

• Pressure loadings taken on lock-out keys (not on no-go)

• Single run to set, test and retrieve

• Can be set without downward jarring

The ability to set the standing valve hydraulically (no downward jarring) makes the tool ideal foruse in high angle wells. RNG Standing Valves have been successfully run in wells with up to 79degrees. In high angle wells it is recommended that the Dual Seal Equalising Assembly isinstalled.

All standing valves are supplied with a dummy rope socket top sub, which allows the insertionof extension bars for use in high debris conditions. Alternatively, this top sub can be replaced witha junk / valve catcher sub fitted with an internal fish neck.

RNG Standing Valves can be supplied in ANY seal bore size to suit Uniset QN or Third partynipple profiles.

PRESSURE CYCLE PLUGThe Uniset Pressure Cycle Plug has been designed for use in circumstances where a high-test pressure with a low operating pressure is required. The Cycle Plug is typically run belowa QX Lock Mandrel and PT Equalising Assembly although it can also be run below other flowcontrol devices such as bridge plugs. When set in a landing nipple the Cycle Plug forms a bi-directional barrier. Repeated pressure cycles applied from above will result in the tool openingto give a large bore flow area through the plug assembly. The Pressure Cycle plug is availableto suit operation in high overbalance or underbalance circumstances. Typical Cycle Plugapplications are:

• Temporary well suspension.

• Equalisation of plug assemblies in highly deviated wells.

• Rapid resumption of production flow without well intervention.

• Protection against production flow loss in the event of a stuck plug.

• Reduction in slickline runs to retrieve plug assemblies.

• High debris potential applications in which fill can be flowed or pumped away.

Features

• Cycles applied without exceeding tubing test pressures.

• Tool opens at the end of the bleed off phase avoiding surge pressure damage of the formation.

• Simple and rugged allowing easy field redress.

• Highly debris tolerant.

• Available in a range of sizes.

• Standard 6 pressure cycles to open with 12 cycle option.

• Unique protection system allows use in high debris potential applications.

FLOW SUBThe Uniset Flow Sub is typically run beneath a QX Lock Mandrel or bridgeplug. A ball and seat sealing arrangement allows pressure testing fromabove. The ball moves off seat to allow fluid bypass from below whenrunning in hole. Essentially the Flow Sub converts a QX Lock Mandrel orbridge plug into a standing valve. The primary application of the Flow Subis during completion installation pressure testing and production packersetting. The flow sub allows the tubing to self-fill if pre-installed in thecompletion.

When applied in high deviation applications a conversion kit is availablefor the Flow Sub. This consists of a Ball Retainer and Coil Spring, whichensures that the Ball reliably seats even at extreme high angles.

Flow Subs should always be run with an equalising device to allow pressureequalisation during retrieval. A separate Uniset PT Equalising Assemblycan be run between the Flow Sub and Uniset QX Lock Mandrel. As anoption, Flow Subs are available with an integral PT Equalising Assembly.

CL TYPE PLUGThe Uniset CL Type Plug was developed for use in the annular bores of dual tubing hangers. Themechanism is identical to that of the RNG Lock Mandrel system with the exception of the retractableno-go shoulder.

Generally used in 2" bores and smaller, the reduction in load seen by the no-go shoulder of theprofile allows the use of a solid no-go shoulder on the lock mandrel without any reduction in pressurerating.

Although normally supplied with a separate equalising sealing prong, CL Plugs have also beenused successfully in conjunction with the Uniset Pump Open Plug.

As with the Uniset QX Lock, the CL Lock Running Tool features a tell tale. This gives a positiveindication after running the lock to confirm correct setting. Should it not be possible to set the CLLock for any reason the running tool can always be released. This then allows selection of alternativetoolstring configurations or heavier wire to retrieve the lock. The CL Lock is retrieved with a GSType or Weatherford DU Pulling Tool.

The CL Lock mandrel is available with pressure ratings up to 15,000 psi, with 10,000 psi as standard.Uniset lock mandrels can be supplied in ANY seal bore size, to suit Uniset or Third Party nippleprofiles.

RNG LOCK MANDRELThe Uniset Retractable No-Go (RNG) Lock Mandrel was first developed for use in sub-seacorrosion cap and tubing hanger profiles. The remit for the design was to give a lock, which offeredpositive no-go location, with a 10,000 psi capability and the minimum restriction possible throughthe hanger profile. The length of the lock was also minimized to prevent protrusion above the tubinghanger. The use of retractable fingers in the main body, which act as a locating no-go until the lockis set, allows all pressure loading to be taken on the lock out keys. In summary, the major featuresare:

• 10,000 psi pressure rating as standard

• Positive tell-tale indication by running tool

• Short body length for use in sub-sea wellheads

As with the Uniset QX Lock, the RNG Lock Mandrel Running Tool features a tell tale. This givesa positive indication after running the lock to confirm correct setting. Should it not be possible toset the RNG Lock for any reason the running tool can always be released. This then allows selectionof alternative toolstring configurations or heavier wire to retrieve the lock. The RNG Lock is retrievedwith a GS Type or Weatherford DU Pulling Tool.

The RNG Lock mandrel is available with pressure ratings up to 15,000 psi, with 10,000 psi asstandard. Uniset lock mandrels can be supplied in ANY seal bore size, to suit Uniset or Third Partynipple profiles.

TYPE-H EQUALISING ASSEMBLYThe Uniset Type-H Equalising Assembly is a conventional two run equalising systemcomprising of a Housing, which fits below the lock mandrel, and an Equalising Prong.

The Equalising Prong incorporates dual centralisers, the upper is fixed permanently and thelower is shear pinned in place. This both assists centralization into the housing and protectsthe elastomeric seals from wear and damage as they are lowered into the wellbore. When theplug body is encountered, light downward jarring shears the lower retaining pin allowing thesealing prong to move downward, through the centraliser to the sealed position.

All sealing prongs are supplied with dummy Rope Socket top subs with Sucker Rod threads,which allows the insertion of spacer bars (stem) to extend the prongs when required for highdebris conditions. Alternatively this top sub can be replaced by a Junk / Valve Catcher subfitted with an internal fishing neck on request. To further assist in debris management the H-Bottom Housing can be extended on request. Large bore equalising ports can also be supplied.

TYPE AVH ANTI-VIBRATION PRONGThe Uniset Anti-Vibration Prong was developed for Type-H Equalising Assemblieswhich may be exposed to vibration, such as when installed in subsea corrosioncap plugs.

In this application there is potential for the sealing prong to move out of the sealingposition due to the vibration of the xmas tree during well production. The corrosioncap would not be plugged and no environmental barrier would be present.

The Anti-Vibration Prong is held in place by means of a locking collet which latchesinside the bottom housing. This ensures that the sealing prong cannot be removedother than by wireline methods, and plug integrity is maintained.

PT SHUT-IN TOOLThe Uniset PT Shut-In Tool allows downhole shut-in to remove the effects of wellbore storagefrom pressure build-up data. The device is designed to be run on a lock mandrel and set ina landing nipple using conventional wireline techniques. Memory gauges are installed belowthe tool.

When initially set the device is in the open position, allowing the well to produce through thelarge equalisation ports. The well is shut-in using an Activation Tool which latches inside thePT and pulls the melon on-seat. The Activation Tool is released by taking an overpull, leavingthe PT in the closed position.

The well is re-opened using an Equalisation Prong which jars the PT melon off-seat. Thisallows production to resume through the equalisation ports.

The PT Shut-In Tool allows multiple flow and build-up periods by repeating the Activation andEqualisation operations described above.

At the end of the test the equalised assembly is recovered to surface using conventional lockmandrel retrieval techniques.

Note: The Uniset QX lock mandrel is ideally suited to use with this device, owing to theexcellent performance of the lock in flowing applications.

INSTRUMENT HANGERThe Uniset Instrument Hanger allows downhole pressure / temperaturegauges to be suspended on a lock mandrel in the wellbore. The lock mandrelpacking stack is removed and the hanger sleeve section covers the packingbarrel protecting it from flow erosion and mechanical damage.

Typically the flow through area of the instrument hanger will be greater thanthat of the carrier lock mandrel to optimise flow. Hangers can be suppliedto suit any manufacturers' lock mandrels.

FORMATION SURGE TOOLFormation damage of the reservoir section, due either to the presence of perforatingdebris or to fines migration, can have a severe impact on well production.

The Uniset Formation Surge Tool (FST) provides an instantaneous draw-down acrossthe formation, assisting in the removal of mud filter cake and debris from perforationtunnels. The tool has been operated in a number of wells in various fields and significantimprovements in well performance have resulted.

The FST is set in a nipple profile using a lock mandrel and equalising assembly. Preciselyrated shear screws are used to activate the FST at a predetermined draw-down pressure.Varying the number of shear screws allows the draw-down pressure to be changed tothe desired value.

Activation of the tool is achieved in a number of ways:

• Bleeding off above the tool.

• Circulating out well contents to nitrogen above the tool.

• Pre-pressuring the formation and bleeding off above the tool.

The last method is carried out using the Uniset Type C Back Pressure Valve whichallows fluid to be pumped through the tool once the lock mandrel is set.

PUMPOUT SUBThe Uniset Pumpout Sub was developed primarily for sub-sea well suspension toallow reservoir access without the need for secondary intervention.

Consisting of a piston which is held in place by rated shear screws the Pumpout Suboffers full pressure rating from below and a shear value rating from above (determinedby quantity and size of shear screws).

In order to activate the device differential pressure is applied from above until the shearvalue of the pins is exceeded. The piston is then expelled into the sump allowingproduction to be resumed.

Pumpout Subs can be supplied as an integral part of production tubing or run on a lockmandrel by wireline. The mass of the piston is minimised to improve shear accuracyand the piston is designed to roll when expelled to maximise reliability.

UNISET QX LOCK SYSTEM SCHEMATIC

This schematic depicts the Uniset QX Lock system in conjunction with thevarious flow control device options and associated running and pulling tools.Whilst not exhaustive in detail, the aim is to communicate graphicallythe full operational flexibility achievable with a comprehensive suite of Unisetequipment.