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ESP By-Pass
In a conventional completion the Electrical Submersible Pumps (ESP's) are run on the bottom of the completion string and it is therefore not possible to gain access below the ESP without first pulling the completion.

An ESP By-pass system allows the well bore below the ESP to be accessed by hanging the ESP from one side of the Y-Block. It is then possible to run past the ESP to carry out logging operations, set bridge plugs, perforate, run wireline and coiled tubing etc. without first pulling the completion thereby reducing workover costs and increasing flexibility.

NOV has designed and supplied its ESP By-pass Systems for use within highly deviated, extended reach wells and also manufactures a complete range of associated field proven wireline and coiled tubing running tools to complement the systems.

TYPICAL USES FOR A BY-PASS SYSTEM
  • Production Logging
  • Through tubing Perforating
  • Spotting fluids
  • Coiled Tubing operations
  • Wireline/Electricline operations
  • ESP pump Isolation
  • T.C.P.
  • Bridge Plug Setting
  • Acidizing/Stimulation
  • Reservoir Monitoring
  • Dual ESP completions (Redundancy or dual zones)

SIZING INFORMATION

NOV have supplied ESP By-pass systems for the following Casing sizes: 7", 7-5/8", 9-5/8", 11-3/4", 13-3/8". The standard By-pass system is run in 9-5/8", with 7" a less common though not unusual size. The sizing information in the table opposite will therefore concentrate on these two sizes.

When designing an ESP By-Pass System the first thing to look at is the fit of by-pass tubing and the ESP inside the casing. This will give us the maximum allowable ESP size and the maximum allowable by-pass tubing size. The rest of the system can then be designed around these figures.

Once the maximum permissible ESP diameter is determined the required ESP can be designed. The required overall length of by-pass tubing and quantity of clamps can then be specified.

Clamps should be placed on all the flange connections in the ESP assembly apart from the connection directly below the intake. This connection should be left clear so as not to interrupt flow into the intake.

The 6ft is to ensure a minimum stick-out at the bottom of the ESP string of 6ft of by-pass tubing. By-pass tubing can be supplied in any length but is generally supplied in 20ft lengths for the 2-7/8", 2-3/4" and 2-3/8" by-pass tubing and 15ft lengths for the 2-1/8" by-pass tubing.

In order to prevent re-circulation of well fluids during normal operations a blanking plug is set in the Telescopic Swivel Nipple. The maximum O.D. of the plug must be smaller than the minimum restriction in the tubing string above the Y-Tool. In selecting the nipple size, the maximum tool string size to pass through the by-pass tubing should also be considered.

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'BM' BLANKING PLUG

The main function of the Blanking Plug is to provide a seal to the By-pass tubing by sealing in the Telescopic swivel nipple located directly below the Y-tool. This prevents recycling of the well fluids through the aforementioned tubing, allowing the ESP to pump the fluids to surface as normal.

NOV have designed their Blanking Plug with extended field usage in mind. It uniquely offers the following three fundamental features in one design:
  • External fishneck profile to prevent sand intrusion. The fishneck is located directly below the Y-tool flow path to prevent fishneck erosion, however the turbulence created will prevent sand build up on the fishneck, assisting trouble free Plug retrieval.
  • Positive Dog-Locking mechanism to eliminate the possibility of upward movement during pump operation when set into the nipple profile.
  • Full integral equalization feature, this facility is achieved by upward movement of the retrieval neck, allowing the plug to be equalized and retrieved (and therefore run) in a single slickline operation.
NOTE: NOV can supply all appropriate running/pulling tools to complement the Blanking plug.
THE Y-TOOL

The Y-tool is an internally profiled one piece casting. Its main function is to offset the ESP away from the main production string, thereby allowing toolstrings free vertical access past the pump to carry out various operations as described in the applications section of this document.

The Y-tool profile has been carefully designed to minimise flow erosion. As the produced fluid leaves the ESP it flows through a pump sub and then joins the main production string through the Y-tool profile.

The Y-tool also clamps and protects the passing Motor Lead Extension Cable within slots on each side of the Y-tool block.

TELESCOPIC SWIVEL NIPPLE (TSN)

The TSN is located directly below the Y-tool on the By-pass (through bore) side.

Its main function is to provide a seal bore for the Blanking/Logging plugs and Isolation sleeve (Described later). The no-go and profile are carefully positioned to ensure the fishneck of the plugs are kept slightly below the production flow path to avoid erosion. This position also ensures that the turbulence created above keeps the plugs free from sand ingress.

NECK CLAMPS

The TSN also provides full rotation and up to 18 inches of linear movement in order to assist system make-up. (See running procedures).

The neck clamps are a high grade investment casting. Their main function is to securely hold the by-pass tubing to the ESP assembly, and maintain clearance between the assembly OD and the ID of the casing. The neck clamps take significant loads during tripping and are therefore robust by design.

They also perform the vital function of protecting the Motor Lead Extension Cable from damage. NOV maintain a large inventory of all cast components, ensuring we can respond rapidly to customer completion requirements.
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WIRELINE BY-PASS LOGGING PLUG

The Wireline By-Pass Logging Plug is landed in the seal bore of the telescopic swivel nipple and prevents circulation around the ESP during logging operations. The ESP can therefore continue to operate during logging operations, in static or dynamic conditions. Sealing is provided by Vee-packings.

The Wireline By-Pass Logging Plug has an external Fishneck to prevent sand intrusion whilst set in the nipple. It has a full equalization facility, and if required a lower tool catcher collet to prevent loss of the Logging string in the event of the logging cable breaking. The catcher can be designed to suit any common logging tool rope socket.

The Wireline By-Pass Logging Plug can be supplied to suit all common logging cable and slickline sizes.

COILED TUBING BY-PASS LOGGING PLUG

The CT By-Pass Logging Plug utilizes the seal bore of the Telescopic swivel nipple in the same way as the Wireline version, however can be run on CT.

The CT By-Pass Logging Plug is connected to the CT by means of a Dimple/Roll-On connector. When the plug reaches the no-go of the nipple, sit down weight is applied through the coil, which releases the connector latch profile, allowing the CT logging string to be run through the by-pass tubing to the desired logging depth. Sealing around the coil is provided by profiled brass casscade seals. The plug is retrieved simply by over-pulling the logging string through the nipple, allowing the plug collet latch to retract from the nipple profile.
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BY-PASS ISOLATION SLEEVE

NOV can also supply an Isolation Sleeve which seats in the blanking plug nipple and an additional upper nipple above the Y-tool. This effectively straddles the ESP, allowing free flowing of the well. It can also be used to protect the ESP in situations where the bullheading of fluids through the by-pass tubing is required.
MISCELLANEOUS By-PASS COMPONENTS

Handling Sub/X-over - Located directly above the Y-tool, this component incorporates an upset shoulder for handling the system during installation, and also acts as a crossover to the production tubing thread.

Pump Sub - Connects the ESP assembly to the Y-tool.

By-Pass Tubing - located below the Telescopic Swivel nipple, this tubing allows the passage of toolstrings past the ESP. The tubing Utilizes a flush joint connection to prevent coupling/ESP clashing at clamping points. Re-entry Guide - Located below the By-pass tubing, this component acts as guide for wireline, Logging or CT tool strings.

Motor Plug - Connected to the bottom of the ESP, this plug provides an additional clamping position, as well as protecting the ESP when running the completion.

NOTE: All NOV By-pass completion equipment is NACE MR-01-75 compliant. Material is Low Alloy Steel as standard, however 13% or 9% Chrome grade material equipment can also be supplied if required.

MISCELLANEOUS HANDLING EQUIPMENT

Stove Pipe - The stove pipe is used to raise the work platform to a comfortable working height.

Swivel Lift Sub - The Swivel Lift sub allows the by-pass tubing to be safely picked up when the elevator is in use.

Safety Clamp - The Safety Clamp is used to retain the by-pass tubing on the top of the Stove Pipe when adding additional lengths of tubing.
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