Whipstock Operations Procedures

Casing exit training manual

Whipback™ Hydraulic Set Whipstock Operations Procedures

Prepared by Technical Publications 515 Post Oak Blvd. Suite 1100 Houston, TX 77027

REV.#

DATE

PREPARED

©1998 Weatherford International, Inc. All Rights Reserved 07/27/99

PREPARED

CHECKED

APPROVED

Contents SCOPE ................................................................................................................. 3 EQUIPMENT REQUIRED .................................................................................... 3 PRE-OPERATIONAL PROCEDURES................................................................. 4 Hole Preparation Run ...................................................................................... 4 Collar Log......................................................................................................... 4 Solids Control .................................................................................................. 4 BHA Overview.................................................................................................. 4 Equipment Inspection Procedure .................................................................. 5 Starting Mill........................................................................................................... 5 Setting Device ...................................................................................................... 5 Whipstock Concave and Anchor........................................................................... 6 Bit Sub .................................................................................................................. 8 Fill Sub (optional).................................................................................................. 8 Making Up the Milling Equipment .................................................................. 8 RUNNING PROCEDURE ................................................................................... 10 Running and Orienting the Whipstock ........................................................ 10 Setting the Whipstock ................................................................................... 11 Milling with the Starting Mill ......................................................................... 12 Running the Window Mill .............................................................................. 14 Making the Elongation Run .......................................................................... 16 Final Procedures ........................................................................................... 18


SCOPE The following procedures are intended to provide concise but definitive steps to follow in operations involving the milling of lateral hole sections from a parent well, using the hydraulic whipstock window milling system.

EQUIPMENT REQUIRED (see also BHA configuration on page 3 for specific equipment required) •

Whipstock with hydraulic anchor (whipstock)

•

Starting Mill

•

Setting Device (for the Starting Mill)

•

Bit Sub

•

Drill pipe joint

•

Fill Sub (optional)

•

Universal Bottom Hole Orientation Sub (UBHO sub)

•

Pup joints (for space-out if necessary)

•

Tool kit consisting of the following items:


PRE-OPERATIONAL PROCEDURES Hole Preparation Run Weatherford strongly recommends that a Window Mill/smooth-OD Watermelon Mill/casing scraper assembly be run immediately prior to running the hydraulic whipstock, in order to ensure that the wellbore is clean and free of debris. Collar Log Weatherford strongly recommends that a collar log be run, prior to running any whipstock. The whipstock should be positioned so that the window is milled through the wall of the casing joint, and not across a casing collar/connection. This milling practice will help avoid the possibility of the casing string parting, in case the cement behind the casing is poorly set and unconsolidated. Solids Control Good solids control is mandatory for the successful operation of the hydraulic whipstock, particularly if auto-fill is desired or a drilled float valve is not in use (or both). At the very minimum, the operator must be willing to circulate “bottoms up” across a shale shaker (80 mesh screens or finer recommended). The shale shaker must also remain in operation until the whipstock is set. Sweeps or pills with high solids of any type must be avoided while the whipstock is being run and prior to setting the anchor. If circulation is required, as an additional precaution, a drill pipe screen (such as the type used by MWD operators) may be placed at the top of the drill pipe string at all times after the whipstock is picked up, and prior to setting the whipstock. BHA Overview Weatherford is aware that variations will exist from one milling operation to the next, and complying with the client’s particular requests is fundamental. However, Weatherford will make recommendations as to the proven criteria involved in continuing to execute successful milling operations. In order to meet this objective, Weatherford recommends that the hydraulic whipstock milling assembly be comprised of the following sample arrangement of components, listed in order, from the bottom-most component and proceeding upward (see Figure 1). •

Starting Mill

•

Bit Sub (24 inches long maximum)

•

Drill pipe joint (must be installed directly above the Bit Sub)


•

Fill Sub (optional)

•

Universal Bottom Hole Orientation Sub (UBHO sub)

•

Drill pipe and drill collars above milling assembly to surface as required (size, type, and quantity at the operator’s discretion)

Other surface and space-out equipment required: •

Pump-in sub

•

Side-entry valve and union (when using gyro)

•

Crossovers as required

Equipment Inspection Procedure Starting Mill 1.

Record the part number and serial number of the Starting Mill for the well file (see Figure 2).

2.

Inspect the threads on the pin-end connection of the Starting Mill for damage. Repair if necessary.

3.

Ensure that the shear stud hole will accept the shear stud.

4.

Using a gauge ring, record the dimensions of the milling material on the OD of the Starting Mill.

5.

Inspect the ID of the Starting Mill to ensure that it is free of dirt or debris. The setting device will have to be installed in the ID of the Starting Mill, prior to running the whipstock downhole.

Setting Device 1.

Ensure that the setting device is complete and intact (see Figure 3).

2.

Verify that the shear screws are installed in the setting device.

3.

Ensure that the o-ring is installed on the OD of the setting device.


4.

Ensure that the proper shear configuration is installed in setting device (i.e. the shear plug or the ball and seat configuration - see BHA configuration options at beginning of procedure).

5.

If the Bit Sub to be used has a bore-back box connection, the keeper must be added to the Setting Device. To remove the keeper, back out the set screws directly below it and remove the keeper.

6.

Lightly grease and install the Setting Device into the Starting Mill (see Figure 4).

Whipstock Concave and Anchor 1.

Record the part number and serial number of the whipstock assembly for the well file (see Figure 5, next page).

2.

Ensure that the hoisting swivel ring is the appropriate load rating for the particular whipstock being inspected (see Figure 5 and Figure 6, next page).

3.

Inspect the pilot lug at the top of the concave to verify that it is not damaged, including the threaded hole in the pilot lug. The threaded hole will later accept the shear stud that secures the Starting Mill to the whipstock concave.

4.

Inspect the whipstock retrieval slot. Ensure that the slot is free of any damage which could prevent the whipstock retrieving tool from engaging the slot, if the whipstock is retrieved later.

5.

Inspect the stainless steel tubing and fittings for the hydraulic system on the whipstock. Ensure that the fittings are tightened properly and are not damaged, and that the tubing is not crimped or smashed.

6.

Lay the whipstock assembly in a position to connect the Starting Mill to it.

7.

With the Setting Device already inserted into the Starting Mill, make up a test-sub (with a test port) to the top of the Starting Mill in preparation for a 500-psi pressure test.

8.

Install the Starting Mill on the whipstock, and secure it with a shear stud and lock nut.

9.

If not done previously, cut and fit the stainless steel hydraulic tubing that connects the 9/16-inch o-ring boss port in the Starting Mill to the 1/4-inch NPT port in the concave face of the whipstock (see Figure 7, next page). Do not tighten any of the Swagelok fittings at this time.

10.

Install the Swagelok fittings onto the ends of the tubing as follows:


a) Insert the tubing into the Swagelok tubing fitting, making sure that the tubing rests firmly on the shoulder of the fitting. b) Tighten the nut on the fitting finger-tight. c) Using a back-up wrench on the fitting, tighten the nut exactly 1-1/4 turns past the fingertight position. This action will crimp the ferrule under the nut onto the tubing end. d) Back the nut off of the fitting, thereby releasing the portion of the fitting that will screw into the Starting Mill and the whipstock concave. 11.

Tighten the 9/16-inch o-ring boss fitting on the Starting Mill as follows:

a) Lubricate the o-ring on the straight-thread end with grease. b) Thread the straight-thread end into the 9/16-inch port in the Starting Mill until the metal back-up washer on the fitting contacts the Starting Mill. c) Back the fitting out of the Starting Mill until the Swagelok end is oriented in the proper direction (facing the whipstock). Do not back the straight-thread end out of the Starting Mill any more than one full turn. d) Holding the elbow portion of the fitting with a back-up wrench, tighten the lock nut on the straight-thread end of the fitting against the Starting Mill. 12.

Remove the 1/4-inch NPT plug from the port in the concave face.

13.

Using two wraps of teflon tape only, tighten the 90° NPT fitting into the 1/4-inch port in the whipstock concave face.

14.

Assemble the tubing section and tighten the Swagelok fittings.

15.

Connect a test-pump to the test-sub on the top of the Starting Mill.

16.

Remove the 1/4-inch NPT plug from the bottom of the whipstock.

17.

Raise the bottom end of the whipstock.

18.

Fill the fluid passageway of the entire assembly with 50/50 water and antifreeze mix (or water and soluble oil).

19.

When all the air has been purged from the hydraulic passageway, replace the plug at the bottom of the whipstock.

20.

Begin pumping until 500 psi is reached, holding the test pressure for approximately 5 minutes. Observe all the connections for any visible leakage, and tighten or adjust fittings as necessary.


21.

When the tubing integrity has been verified, vent the test pressure and remove the test pump.

22.

Disconnect the tubing from between the whipstock concave and the Starting Mill.

23.

Remove the Starting Mill and shear stud from the whipstock.

24.

Remove the test-sub from the top of the Starting Mill.

25.

Reinstall and tighten the 1/4-inch NPT plug in the bottom of the whipstock anchor and the concave face.

26.

Remove the steel set screws in the anchor and replace them with the brass shear screws that are taped on the anchor body.

27.

Ensure that the cap screws which secure the bow springs on the anchor are tightened properly.

28.

Ensure that the ½-in. cap screw which is installed directly above the modified slip is tightened properly. This screw will prevent the modified slip from traveling too far up the body of the whipstock during the setting operation.

Bit Sub 1.

Record the part number and serial number of the Bit Sub for the well file.

2.

Inspect the threads on the box-end connections for damage. Repair if necessary.

Fill Sub (optional) 1.

Record the part number and serial number of the Fill Sub for the well file.

2.

Inspect the threads on the pin- and box-end connections for damage. Repair if necessary.

3.

Check the fit of the vented float valve in the box end of the Fill Sub to ensure compatibility.

Making Up the Milling Equipment 1.

Latch onto and suspend a drill pipe joint in the elevators.


2.

Make up the Fill Sub (if applicable) to the top of the drill pipe joint.

3.

Make up the UBHO to the top of the Fill Sub according to the torque specifications of the UBHO supplier.

4.

Make up the Bit Sub to the bottom of the drill pipe joint.

5.

Make-up the Starting Mill to the bottom of the Bit Sub.

6.

Ensure that the wear bushing is either removed from the wellhead or that the ID of the wear bushing is compatible with the OD of the milling assembly.

7.

Run the milling assembly down through the wellhead to ensure that the milling assembly will pass through without encountering any obstructions.

8.

After this verification, pull the milling assembly out of the hole, washing it off while it is being retrieved.

9.

Temporarily install the shear stud and locking nut in the hole at the bottom of the Starting Mill.

10.

Scribe a straight orientation line from the shortest flat side at the bottom of the Starting Mill to the top of the UBHO Sub.

11.

Have the survey company representative align the UBHO sub with the scribed orientation line.

12.

Pull the entire assembly off to the side and secure it temporarily, in order to clear the rotary table area for the placement of the whipstock.

13.

Lay the whipstock on the catwalk, with the top of the whipstock facing the rig floor.

14.

Install a safety clamp onto the whipstock, with the safety clamp positioned and tightened approximately halfway down the face of the whipstock concave.

15.

Pick up the whipstock with an air hoist line attached to the hoisting swivel ring on the whipstock.

16.

Place the whipstock in the mouse hole or rotary table, whichever is appropriate for the whipstock size. Leave the air hoist attached to the hoisting swivel ring, with all slack removed from the air hoist line.


17.

Putting a light amount of thread compound on the shear stud, thread the shear stud into the pilot lug until the stop flange makes contact with the pilot lug.

18.

Slightly tighten the shear stud into the pilot lug using pliers or vise grips only.

19.

Release the Starting Mill assembly from its tied-back position.

20.

Align the shear bolt hole on the Starting Mill with the corresponding hole in the pilot lug of the whipstock.

21.

Push the Starting Mill assembly into position on the whipstock / pilot lug (see Figure 8).

22.

Install and tighten the locking nut onto the shear stud, using a 12-inch adjustable wrench.

23.

Center punch the threads of the shear stud immediately behind the nut with a hammer and punch to keep the nut from backing off.

24.

Re-connect the hydraulic tubing from the Starting Mill to the whipstock concave and tighten.

25.

Pick the entire whipstock assembly up out of the rotary table.

26.

Install the rotary table cover.

27.

Remove the hoisting swivel ring and safety clamp from the concave.

28.

Remove the rotary table cover.

29.

Lower the whipstock assembly slowly through the rotary table, verifying that the scribed orientation line from the Starting Mill to the UBHO sub is properly positioned relative to the whipstock concave. Consult with the UBHO representative to achieve mutual consent that the UBHO sub is properly adjusted.

30.

Land the drill pipe joint above the whipstock assembly in the rotary table, and prepare to make up the drill pipe and drill collars as required to complete the milling string.

RUNNING PROCEDURE Running and Orienting the Whipstock


1.

Make up and run the drill pipe and drill collars above the whipstock assembly as required.

2.

Run the whipstock assembly into the hole at a rate of approximately 2 to 3 minutes/stand. Fill the drill pipe string every 10 stands if the BHA is not self-filling.

3.

Run the whipstock assembly until it has reached the final setting depth.

4.

Space out and make up the side-entry pump-in sub and kelly or top drive as necessary.

5.

Record the pick-up and slack-off weights after making up the space-out assembly, finishing the process with the traveling slip on the whipstock approximately 5 feet above a casing collar.

6.

With the whipstock assembly in the desired location, run in the hole with the gyro survey tool and seat into the UBHO sub for an orientation reading.

7.

Pick up and re-seat the gyro until a consistent azimuth is achieved, using a minimum of two readings.

8.

Determine the direction (if any) that the whipstock assembly needs to be rotated to orient it to the correct azimuth.

9.

Rotate the milling string no more than ½-revolution to the right to orient the whipstock to the final desired azimuth. If the whipstock needs to be rotated more than ½-revolution, after the first ½-revolution, the milling string needs to be picked up and set down approximately 10 feet to eliminate any torque that is being held in the milling string at the whipstock assembly.

10.

Reseat the gyro survey tool into the UBHO for an orientation reading. Determine if the whipstock assembly still needs to be rotated to be oriented to the correct azimuth.

11.

Repeat the gyro seating and string rotating steps as necessary until the whipstock is oriented properly. It may be difficult to set the whipstock assembly exactly to the desired azimuth. Maintain communication with the customer and survey representative to determine an acceptable margin of direction. When an acceptable orientation has been achieved and verified by the client, driller, and survey personnel, continue with the remainder of the whipstock setting procedure.

Setting the Whipstock


1.

Slowly apply pressure down the drill pipe through the side-entry sub to approximately 500 psi, while monitoring the orientation.

2.

If the orientation is still correct, vent the drill pipe pressure and pull out of the hole with the gyro.

3.

Apply approximately 2,320 psi of pressure down the drill pipe to shear the shear screws in the whipstock anchor assembly (see Figure 9). The shearing of the screws will allow the anchor sleeve to travel upward, driving the modified slip up and into its setting position between the casing wall and the whipstock.

4.

Continue to increase the pressure to approximately 3,000 psi to shear the shear screws in the Starting Mill setting device.

5.

When the setting device has sheared, slowly lower the whipstock assembly until the shear stud on the Starting Mill shears (see Figure 10 for shear value/whipstock size relationship).

6.

Pick up the Starting Mill five feet above the top of the whipstock.

7.

Lower the Starting Mill three feet. If the Starting Mill travels three feet without encountering a major weight loss, this travel confirms that the Starting Mill has sheared loose from the whipstock.

8.

Using the measurements of the equipment in the hole, record the depth of the top of whipstock.

9.

Proceed to the next section for instructions on the milling operation.

Milling with the Starting Mill The milling process will vary from project to project, depending upon such matters as the type of equipment being used, the formation, and special hole conditions. The optimum rotary speeds and the weight applied to the mills are best determined on location by the Weatherford Service Technician. However, Weatherford recommends the following procedure when milling with the Starting Mill assembly. 1.

In preparation for milling, bring the mud pumps on line.

2.

Build the flow rate and begin rotating the string at 20 to 40 RPMs.


3.

After the rotary has stabilized, slowly increase the rotary speed to between 50 and 75 RPMs (depending on the mill size). Record the “free” rotating torque at this time.

4.

With the milling assembly rotating approximately 2 feet above the top of the whipstock, and the rotation stabilized, record the string weight.

5.

Slowly lower the Starting Mill until an immediate and substantial torque increase occurs, combined with a weight loss. This torque increase and weight loss are indications that the pilot lug has been contacted by the Starting Mill.

6.

Mark the kelly with the milling starting point and ending point for the Starting Mill size being used.

7.

Mill down past the top of the concave of the whipstock, applying a maximum of 1,000 lb. down on the Starting Mill for the first foot. The mill weight can then be increased incrementally according to the mill size (see Technical Data portion of the Reference section for details).

8.

When the proper mill run length has been achieved for the mill size being used (see Technical Data portion of the Reference section for details), pull the milling assembly out of the hole without rotating the string.

9.

Upon retrieval of the milling assembly to the surface, inspect the Starting Mill immediately. The bottom tapered section of the Starting Mill should be shiny (paint removed) up to the base of the milling blades (see Figure 11). Any paint remaining below the base of the milling blades is an indication that the pilot lug was not completely milled off in the initial milling operation.

10.

Re-run the Starting Mill as necessary to achieve the appropriate milling run length and proper pilot lug removal.


Running the Window Mill 1.

Assemble the Window Milling components (see Figure 12). The Window Mill run will consist of (from the top): •

Balance of Drillstring

•

One Joint of Drill Pipe

•

Bit Sub (minimum length, bored for float assembly)

•

Watermelon Mill (rough-OD)

•

Window Mill (CPE Design with carbide inserts or standard, whichever is applicable)

2.

Using a gauge ring (OD +1/32"), measure all mills for their full OD. Record all measurements for each assembly component.

3.

Lower the Window Mill assembly into the hole, stopping 5 to 10 feet above the top of the whipstock.

4.

Make up the kelly to the drill pipe string.

5.

Engage the pumps and slowly increase to the appropriate circulation rate.

6.

Engage the rotary and slowly increase to between 50 and 75 RPM's (depending on the mill size).

7.

Record the following information: •

Free rotary torque

•

Pump pressure

•

Pump rate

•

Free weight – up and down (string weight with zero weight on mill)

8.

While rotating, slowly lower the drill string and ream back into the window.

9.

As the torque increases, increase the rotary speed to the recommended RPM (based on the mill size).


10.

Continue milling with a constant rotary torque and weight (1,000 to 3,000 lb) on the mill. Additional weight may be required if the rate of penetration (ROP) begins to slow.

The type of window mill being used will dictate the weight that must be applied in the milling process. • CPE Mill - It is designed specifically to eliminate any decline in ROP that is normally associated with core point; therefore, it is not necessary to add additional weight as the CPE Mill approaches core point. Core point is attained when the mill is centered directly over the wall of the casing (see Figure 14). •

Standard Window Mill - At core point, rotary torque and ROP will drop considerably with the standard Window Mill. It is recommended that additional weight (3,000 to 4,000 lb) be added approximately one foot above core point and maintained through core point to minimize any drop in ROP. Return to the previous weight on the mill after passing core point.

11.

Monitor returns for cuttings during milling operations and pump high viscosity sweeps as needed to remove cuttings from the well. This practice is especially important if the window is being milled in a lateral section.

12.

The Window Mill run is completed after milling down the concave’s face into the formation AND when the Watermelon Mill is centered at the bottom of the window (see Figure 15).

13.

Ream back and forth through the window until no signs of additional torque or drag are indicated.

14.

Stop the rotary and slide the Window Mill assembly through the window several times. If any weight or drag is indicated, start the rotary and ream back and forth through the window until weight or drag is eliminated.

15.

Stop the rotary and check for weight or drag again. Repeat this process as necessary.

16.

Once the window is complete, stop the rotary, clean the hole of cuttings with high viscosity sweeps, and pull out of the hole without rotating.

17.

Closely inspect and gauge all mills for wear using a gauge ring of OD + 1/32".

18.

Determine the estimated size of the window.

19.

Review the window requirements with the customer to determine if the Elongation Run is required.


Making the Elongation Run 1.

Assemble the Elongation run components (see Figure 16): •

Balance of drill string

•

One or more drill collars or heavy weight

•

Bit Sub (minimum length, bored for float assembly)

•

Watermelon Mill – rough-OD

•

Watermelon Mill – rough-OD

•

Window Mill (CPE design with carbide inserts or Standard Window Mill) If a PDC bit will be used through the window for additional drilling, use a newly dressed, full gauge window mill in the Elongation run.)

2.

Lower the Elongation run assembly into the hole, stopping 5 to 10 feet above the whipstock.

3.

Make up the kelly to the drill string.

4.

Engage the pumps and slowly increase to the desired circulation rate.

5.

Engage the rotary and slowly increase to between 50 and 75 RPM (depending on the mill size).

6.

Record the following information: •

Free rotary torque

•

Free weight – up and down (string weight with zero weight on mill)

•

Pump pressure

•

Pump rate

7.

While rotating, slowly lower the drill pipe string and ream back into the window.

8.

As the torque increases, increase the rotary speed to the recommended RPM (based on the mill size).

9.

Continue milling with a constant rotary torque and weight on the mill.


While milling down the concave, if the ROP decreases rapidly, and additional weight does not increase ROP, pull out of the hole, make up a new Window Mill, and re-enter the well. 10.

Monitor returns for cuttings during milling operations. Pump high viscosity sweeps as needed to remove cuttings from the well.

11.

Continue milling down the concave face, elongating the milled window at the top with the two Watermelon Mills.

12.

The Elongation run is complete (unless directed otherwise by the customer) when the TOP Watermelon Mill is centered at the bottom of the window (see Figure 17).

13.

While rotating, ream back and forth through the window until no additional weight or drag is indicated.


14.

Stop the rotary and slide the Window Mill assembly through the window several times. If any weight or drag is indicated, start the rotary and ream back and forth through the window until weight or drag is eliminated.

15.

Circulate the hole clean with one or more high viscosity sweeps to remove all cuttings from the well.

16.

When circulation is complete, stop the rotary and pull out of the hole without rotating.

17.

Inspect and gauge all mills using a gauge ring of OD + 1/32", to determine wear to the mill and to estimate window/hole size. Review signs of wear with the customer. Repeat Run #3 if the hole appears to be undersized.

18.

Lay down the Elongation Run assembly.

Final Procedures 1.

Personally meet with the customer and the driller and give them the following cautions regarding the whipstock and the milled window.

2.

When the window is complete, ask the customer if he would prefer you to stay on location until the next BHA is run through the window. Stay if required.

3.

Complete one copy of the Approximate Window Location form for the Customer’s well files (see Figure 18). (Make sure all dimensions, approximate location, and orientation of the milled window are shown.)

4.

Account for all mills and other accessory items that are to be returned and contact the Weatherford store to make arrangements for the mills to be picked up.

5.

Fax one copy of the Whipstock Post Job Report form to the appropriate Weatherford supervisor for entry into the whipstock database.

6.

The whipstock window milling job is now complete.


Whipstock Operations Procedures

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