A Spool valve can be found in almost every industry you can imagine performing a wide range of tasks, but what is a spool valve and how does it work?

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Spool valves can be used in both hydraulics (where the oil is the energy source) or Pneumatics (where the air is the energy source) and their job is to control the flow direction of the energy source by combining or switching the paths through which the oil or air can travel.

What is a Spool Valve Exactly?

Essentially a spool valve is a cylinder inside a sealed outer case.

There are several chambers drilled through the case from one side to the other, these are commonly known as &#;ports&#;.

The function of the spool is to move within the sealed case and provide the function of either blocking or opening these ports depending on the position of the spool.

What are the Spool Valve Actuators?

The spool can be moved in many different ways;

&#; Manually using a button or a lever

&#; As part of a larger control system using a solenoid actuator

Whatever the method is chosen to control the valve, all that we are doing is simply pushing the spool to move within the housing, and by doing this we are allowing or blocking the path between the ports.

In some cases, there may be a solenoid at each end of the valve, whereas in others there is a spring return so when the solenoid is no longer pushing the actuator, the spring will return the spool to its &#;normal&#; or rest position.

How does a Spool Valve Work?

Imagine the example of extending a pneumatic cylinder using a spool valve.

The Pneumatic air supply is connected to the inlet port 1.

Port 2 is connected to the pneumatic cylinder extend connection.

Port 3 is unconnected as it is the exhaust port.

In the normal state without the actuator being operated nothing will happen as the spool is physically blocking the airflow at port 1 and the cylinder is retraced because ports 2 and 3 are connected due to the spool position.

So any air already within the system would escape to the atmosphere through the exhaust port.

Let&#;s consider this the &#;normal&#; or &#;rest position&#;.

Now imagine we operate the actuator.

We would see the spool position changes and the cylinder extends.

This is because the spool has moved position unblocking port 1 and simultaneously blocking port 3 resulting in allowing air flow from port 1 to port 2 while blocking the exhaust.

This is known as our &#;working position&#;.

The cylinder will remain extended until the spool is moved back to the normal position, either by way of another actuator at the opposite end of the valve or by an internal spring return.

In our example, this type of valve would be known as a 3/2 (three by two) valve because we have 3 ports and 2 spool positions.

What are the different Types of Spool Valves?

Spool valves come in a wide variety of different types and configurations, some having more ports and able to control multiple items of equipment at once.

Imagine how a 4/2 (four by two) or even a 5/3 (five by three) spool valve might be used.

It is also entirely possible to have a standard outer casing with the ports in the same configuration and fit a spool inside of this which have different profiles.

The blocking parts of the spool are known as &#;lands&#;, which are raised above the spool core; if these are made different in configurations they can change the way the port pathways interconnect.

Summery

In this article, we have learned that spool valves are a common way of controlling hydraulic or pneumatic components by allowing, restricting or blocking the flow of the energy source by way of a simple spool mounted within an outer casing.

We have learned that energy sources and components are connected to the spool valve using ports which are the chambers drilled through the outer casing of the valve.

A spool valve can be operated in a number of ways; we could use:

&#; Button

&#; Lever

&#; Solenoid

Spool valves are usually referred to by the nomenclature 3/2 or 5/3 etc., where the first number relates to the number of ports and the second to the number of different spool positions.

We hope you enjoyed this short introduction to pneumatic and hydraulic spool valves.

Here at RealPars, our team of experts is on hand to answer your questions and respond to your feedback. We&#;d love to hear your suggestions for topics you want our team to cover.

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The RealPars Team

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Completion Operation - Best Practices

1 Objectives

• No harm to people or damage to the environment or equipment.
• Make up and run production tubing along with all down hole equipment first time and with full pressure integrity.
• Correctly space out of the completion and ensure the tubing hanger can be run, landed, locked and tested on first attempt.
• Ensure that safety valve lines are terminated successfully at tubing hanger at first attempt.
• Production packer to be set and tested on first attempt.
• Suspend the completion in a safe manner meeting barrier policy.

Ensure Company two barriers policy is always in place during the entire completion running operations.

All depth measurements to be referenced to RKB through the first flange of the well head.

Contact us to discuss your requirements of Casing Spool Assembly. Our experienced sales team can help you identify the options that best suit your needs.

Make sure that COMPANY procedures on storage, handling, running and pulling for low alloy steel premium connection for both tubing and casing are followed.

Note: X-Tree to be installed after the rig move

2 Completion Preparation Checklist

• Confirm that all completion sub-assemblies, tubings and tubing hanger equipment with a back-up assembly is on site and suitable for use and has appropriate certification. (All downhole completion equipment shall be made up as sub-assemblies and pressure tested as per COMPANY pre-assembly procedure before sending to Rig site).
• Ensure a back up control line is on the rig site.
• Ensure that sub-assembly records also have been delivered with the sub-assemblies and are correct.
• Drift and measure all tubings and sub assemblies with appropriate drift and tally tape.
• Function test the safety valve assembly at the well site. COMPAY representative should witness.
• Ensure that all well control x-over subs for each type of tubing connection are available at the rig floor.
• Ensure that all tubing handling and running equipment (slips, elevators etc.) and the circulating head are available.
• Ensure that the BOP ram configuration is correct for the tubular to be run.
• Ensure that enough quantity of brine or water is available into the mud pits (150% of hole volume)
• Ensure that enough quantity of Glycol is available at rig site. Consider excess volume according to the amount of losses.
• Tubing preparation and running will be performed as per COMPANY procedure.
• Prepare tubing running tally for running the completion string. A copy of the tally should be available on the rig floor during running. The tally shall be cross checked by the Rig supervisor and Toolpusher.
• Make sure that the correct torque data is entered in the software and scale of the graph is agreed with COMPANY representative onsite.
• Tubular manufacturer representative will be at rig site to supervise the running of tubing, inspect, accept and sign off the graphs.
• Slickline service should be called and equipment required should be prepared as per completion program. The lubricator and X-over assembly should have been prepared in advance at the location before the slickline operations.
• Make sure that all the required slickline equipment including all x-overs is available at the rig site.
• Always monitor composition and weight of completion fluid at regular intervals and maintain the required levels in the tubing and annulus.

3 Sequence of Operations

1. Hold rig site pre-job meeting prior to starting completion operations.

2. Pick up clean up BHA and RIH to bottom; scrape packer setting depth. Ref appendices.

3. Clean out wellbore. POOH.

4. RIH completion as per tally to the packer setting depth.

a. Run Tail Pipe & Packer assembly

• Detailed Running list of completion string should have been prepared and all attached to the specific well completion program before running. It shall contain the cumulative depth as running in hole for &#;slick line tubing drift runs&#;.
• Ensure crossovers for well control are available during running completion.
• During the &#;tool-box&#; talk highlight that Driller needs to check if the sub-assy top Pup Joint is free to rotate from the elevator, before making up any sub-assembly.
• During RIH of sub-assemblies, get confirmation from the Driller that the sub-assembly is free to rotate from Elevator.
• The running speed of the completion string shall be one minute per joint (once in 7&#; liner reduce the speed to 1.5 minutes per joint).
• Use collar clamps for the first 10 joints until enough string weight is obtained.

b. Slickline Drift Run

c. Run Tubing & Downhole Equipment

• Make sure that prior to making up the x-over assembly all left over tubing has been counted and cross checked against the running tally.

d. Run 5 ½&#; Tubing

• Extra care is required when entering the liner hanger since it might hang up during passing.
• Reduce the speed to 1.5 minutes per joint.
• The driller has to pick up out of slips and RIH smoothly and gently to avoiding shocking wall cake.

e. Run & Function Test Safety Valve

• Ensure that a hole cover is used all the time while working over the rotary table.
• Flush line with supplied Hydraulic Fluid and test the connection to psi for 10 minutes
• Two cycles of Opening & Closing shall be performed in order to have a reference test. The same thing will be repeated immediately the tubing hanger lands and after cutting the control line. The final test will be reported on the proper &#;Installation Report for TR-SCSSSV&#; and added to EOWR.
• Care shall be taken while setting the slips as possibility exists to damage the control line.
• Whilst fitting and securing the cross coupling clamp ensure the control line is in the correct groove and is not crushed between the clamp and the tubing.
• ake sure that prior to making up the tubing hanger sub assembly all left over tubing has been counted and cross checked against the running tally.
• Before continuing with the program, COMPANY Well Completion Engineer or Halliburton Completion Engineer with Tenaris representative, must verify that the final recording graphs for the entire tubing string make-up torque are within the manufacturers tolerance.
• Flush and clean the hanger seal area.

5. Land the tubing hanger assembly.

• Confirm rig alignment.
• Ensure tubing spool side outlets are open.
• Keep the TR-SSSCV in open position and to avoid contaminating the control line fluid install at the extremity of the control line the proper needle valve, retaining psi.
• All the test charts will be signed by COMPANY representative and copies will be sent to Completion Engineer.
• Keep in consideration that the packer has not yet been set. When the tubing hanger has been landed there is no longer any hydraulic continuity through the BOP kill/choke lines and the bell nipple, for this reason need to make sure that the annulus is always topped up through the annulus valves.
• Prepare l. of 50% glycol mixture.

6. RIH and set RPT plug and prong in the 3.562&#; RPT nipple below the packer

• The following relation shall be considered in order to keep the Safety Valve open especially when the slickline cable is in the well.
  Pressure control line = Opening Press + Tubing Pressure + 500 psi (safety margin)
  For Halliburton SP, the Opening pressure @ zero Tubing Pressure is psi.

7. Pressure up tubing to psi and set the packer as per manufacturer&#;s recommended procedures.

8. Increase tubing pressure to psi for 30 minutes to test string

9. Pressure test annulus with psi for 30 minutes in order to test packer

• In tight formations (if in static condition we have 0 m3/h fluid losses), always pull prong before to pressurize the annulus to psi and check for any return from the tubing. Then reset prong and pressure test tubing to psi.

10. Remove Landing Joint

• Particular attention is required in order not to damage the Control Line at this stage. KIOS must witness this.

11. Install TWCV.

Two independent barriers (policy) must be in place.

The first "mechanical" barrier is the plug used to pressure test the completion.

The second barrier can be either "mechanical" (a second plug in the tubing hanger) or "hydraulic". For a "hydraulic" barrier to be considered an acceptable independent barrier, it must meet the following criteria:

• The fluid density is sufficient to kill the well if the 1st barrier fails,
• A pumping system and sufficient amount of kill fluid is available to maintain the hydraulic barrier for the duration of the operation in case of losses.
• This is a temporary barrier used during the BOP/ Tree operation only (i.e. this is not a long term solution).

On the annular side the 2 barriers are provided by the packer and the tubing hanger.

12. Nipple down BOP&#;s.

• Particular attention is required in order not to damage the Control Line at this stage. KIOS must witness this.

13. Install and test tubing head adapter as per KIOS instructions.

• If the TRSV is not open at the first attempt (pressurizing the control line), bleed off annulus pressure from 300 psi to zero and repeat the function test.
• Being the 3.562&#; RPT plug still set in the nipple, particular attention is required to open TRSV since there should be pressure trapped below the flapper. Pressure-up CL as for manufacture&#;s instruction, then pressure up tubing till there would be an indication that TRSV is open.

14. Nipple-up the Integral Lower Master Valve. The X-tree to be installed after rig move.

• Be sure that the gearbox of the lower master valve is rotated 180 degrees with respect to all the other WH and X-tree valves.

15. Clear rig floor and cellar area and release rig.

4 Appendices

Casing Scraper Run

1. M/U BHA (see table above)

2. Put Bakerlok on top dress mill face to act as indicator when mill is retrieved

3. RIH and space out mill with 7&#; tie back and top dress mill

4. Take up/down/rotating weights prior to entering 7&#; liner

5. Across 7&#; scab liner tie-back work with taper mill and string mill with 20 rpm in order to clean the tie back area

6. RIH and Work 7&#; scraper three times across packer setting depth +/-50m

7. Continue RIH to position Top Dress Mill at PBR and Taper Mill ~90 m above 7&#; liner shoe.

8. Polish top of PBR with 15 rpm and 1-2 klb WOB

9. Pull back 10m

10. Pump high viscous clean-up pill and displace OBM to inhibited brine

11. Circulate until wellbore is clean as for mud engineer instruction

12. POOH

Note: Environment and safety requires toolbox talk and HS&E meeting with the crew.
Ensure all tanks are line up with to take returns and catch pills, spacers,etc.
Detailed program is as per dedicated Mud Program.

13. Retrieve wear bushing.

14. Pick up well head jetting tool assembly, RIH and jet all BOP area in particular all cavities and also function rams while jetting. POOH, inspect junk basket if full repeat jetting run till clear of junk from BOP area.

15. Confirm rig alignment.

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