DOWNHOLE TUBING DETAILS
6. GRAVEL PACKING PROCEDURES
6.5. OPEN HOLE GRAVEL PACK PROCEDURE
The procedure described herein is based on Baker’s gravel pack systems. 1) Pick up the hole opener and trip to the bottom of the production casing.
2) Establish circulating rates and pressures, then drop the activating ball to open the hole opener.
3) Drill the open hole length with the hole opener. 4) Pull out of the hole.
5) Conduct any stimulation treatment that may be necessary for the particular formation (this may be done post gravel pack, if desired).
6) Ensure the fluid in the hole has been properly filtered and cleaned before running the gravel pack (Refer to section 6.3.2 above).
7) Drift all BHA tubulars including GP equipment and wash pipe.
8) Pick up and assemble the gravel pack assembly in the rotary table as follows, from bottom up, running at a slow speed to prevent damage to the packing element and to prevent prematurely setting the packer.
• Blank bull nosed plug
• Sand screens
• Blank pipe.
9) Run flush joint washpipe inside, and to the bottom of, the screen and blank pipe. The assembly consisting of the following items is then picked up and made up onto the screen assembly.
• Knock Out Isolation Valve
• Blank pipe
• Shear Out Safety Joint
• Indicating Sub
• Crossover Sub
• Gravel Pack Extension with Sliding Sleeve
• Gravel Pack Packer.
10) The gravel pack service toolstring assembly is then made up to the previous assembly:
• Shifting Tool
• Gravel Pack Crossover Tool
• Hydraulic Setting Tool.
Note: Apply thread compound sparingly to the pin ends of the connections only. 11) Run in the hole slowly with the completion assembly (90sec per 90ft stand). Set down
into, and pick up gently out of, the slips.
12) Record the pick-up and slack-off weights when reaching the packer setting depth. 13) Once the assembly is positioned on depth, rig up the gravel infuser pumping
equipment, manifold and lines. Test to 5,000psi.
14) Establish circulation, record circulating pressure and drop the packer setting ball. Allow time for ball to gravitate to the ball seat in the crossover tool, roughly 5min/1,000ft.
1) Set the packer by slowly pressuring up the workstring according to the steps and pressures stated in the well programme.
2) Verify slip anchoring of the packer by alternately setting down and picking up 10,000- 15,000lbs weight.
3) Slack off to the neutral position and test the packer by pressuring the casing to 1,000psi. for 5min.
4) Since 1,000psi annular pressure releases the crossover tool from the packer, the crossover tool may now be snapped out of the packer. Alternatively, the crossover tool may be released from the packer by turning 15 rotations to the right at the packer depth holding a slight upstrain.
5) Raise the crossover tool to the reverse circulating position. Apply the appropriate workstring pressure to shear the ball seat in the crossover tool. Break circulation in the reverse direction at 3bpm and record the pump pressure.
6) Pickle the workstring by circulating the pickling agent to the end of the workstring. Reverse circulate 11/2 workstring volumes of filtered completion fluid until returns are clean.
7) Lower the crossover tool and set down 10,000lbs on the packer. This is the squeeze position, mark the pipe at the rotary table level. Establish injection pressures at 3, 2, 1, and 1/2bpm. Do not exceed the formation fracture pressure.
Note: If injectivity is low, an acid stimulation treatment may be conducted prior to performing the gravel pack.
22) Raise the crossover tool to neutral weight plus an additional 2ft. This is the circulating position, mark the pipe at the rotary table level. Establish circulating pressures at 3, 2, 1, and 1/2bpm. Monitor the return rate with a flowmeter to determine the leak-off rate to the zone. If full returns are observed, partially close the annular BOP to hold back- pressure and induce leak-off. Do not exceed the formation fracture pressure. 23) Raise the crossover tool to the reverse circulating position. Infuse gravel pack sand
into completion fluid at the desired mix ratio and pump a circulating rate of 3bpm. A pump rate of 3bpm must be maintained to achieve a fluid velocity of 500ft/min in 31/2” workstring.
24) When the sand is 5-10bbls above the packer, lower the crossover tool into the circulating position. Continue displacing the gravel with filtered completion brine until an initial pressure increase is observed due to gravel covering the screens. While pumping, allow the pressure to build to 1,500-2,500psi. over the initial circulating pressure at a given rate. Maintain this sandout pressure while slowing the pump rate to 2, 1, and 1/2bpm. Allow the pressure to bleed off to the formation. Calculate the gravel height above the screen top using the linear flow equation.
25) Do not re-stress the pack. Close the annular BOP and apply 500psi to the annulus. Raise the crossover tool to the reversing position. Reverse out excess gravel plus two workstring volumes. Divert the gravel returns to the slurry dehydration tank and determine the volume of gravel reversed out. The volume of gravel placed can then be calculated by subtracting the volume reversed out and the screen/open hole, blank pipe/open hole and blank pipe/casing annular volumes from the total volume of gravel pumped.
1) To test the gravel pack, lower the crossover tool into the circulating position and attempt to circulate at the same rate and pressure achieved earlier. If sandout pressure cannot be achieved, mix and pump another batch of gravel. Reverse out excess gravel. Repeat this step until final sandout occurs.
2) Pull out of the hole with the service toolstring.
3) Revert to the completion procedures in the completion programme. 6.6. CASED HOLE GRAVEL PACK PROCEDURE
The procedure described herein is based on Baker’s gravel pack systems. 1) Prepare the hole as per section 6.3.2.
2) Run in hole with the sump packer on electric line. Correlate with the GR/CCL to the reference log and set the packer at approx. 6ft below the planned depth of the bottom perforation. Pull out of the hole and rig down the electric line.
3) Pick up the perforating assembly and run in the hole (Refer to section 5).
Note: Use a Tubing Conveyed Perforating system with the highest possible shot density (typically 12spf), with Gravel Pack or ‘Big Hole’ charges.
4) Establish the desired underbalance.
Note: This operation should be performed with the underbalance stated in the well programme (normally 500-1,000psi depending on the formation strength.
5) Verify the proper positioning of the perforating guns by tagging the sump packer and space out the string at the correct depth.
6) Set the packer.
7) Rig up the control head and surface lines (if on a floater this will be done before step 6 above).
8) Detonate the perforating guns by appropriate procedure.
9) Flow the well to sufficiently remove all debris from the perforations.
10) Reverse circulate two workstring volumes with filtered completion fluid to stabilise the well. Continue circulating and filtering until returns are clean.
11) Monitor the well to determine if it has stabilised. Record any fluid losses or gains. If necessary to control fluid loss, spot a fluid loss control pill.
12) Unseat the packer and reciprocate the string to fully release the packer and repeat one more complete circulation.
13) Pull out of the hole with the TCP assembly, monitoring for fluid losses.
14) If there is evidence of formation sand in the returns, pick up and run a scraper with a tailpipe to enter and wash down to the sump packer.
1) Pick up and assemble the gravel pack assembly in the rotary table as follows, from bottom up, running at a slow speed to prevent damage to the packing element and to prevent prematurely setting the packer.
• Snap Latch Seal Assembly
• Sand screens
• Blank pipe
2) Run flush joint washpipe inside, and to the bottom of, the screen through the blank pipe. The assembly consisting of the following items is then picked up and made up onto the screen assembly.
• Knock Out Isolation Valve
• Shear Out Safety Joint
• Crossover Sub
• Gravel Pack Extension with Sliding Sleeve
• Gravel Pack Packer.
3) The gravel pack service toolstring assembly is then made up to the previous assembly:
• Shifting Tool
• Gravel Pack Crossover Tool
• Hydraulic Setting Tool.
Note: Apply thread compound sparingly to the pin ends of the connections only. 18) Run in hole slowly with the completion assembly (90sec per 90ft stand). Set down
into, and pick up gently out of, the slips.
19) Record the pick-up and slack-off weights when reaching the packer setting depth. 20) Record pick-up and slack-off weights one stand above the sump packer. Tag the
sump packer and set down sufficient weight to force the latch of the snap latch to engage the packer. If desired, the latch may be snapped out of the packer with pull to verify correct operation.
21) Once the assembly is positioned on depth, rig up the gravel infuser pumping equipment, manifold and lines. Test to 5,000psi. Establish circulation, record circulating pressure and drop the packer setting ball. Allow time for ball to gravitate to the ball seat in the crossover tool, roughly 5min/1,000ft.
22) Set the packer by slowly pressuring up the workstring according to the steps and pressures stated in the well programme.
23) Verify slip anchoring of the packer by alternately setting down and picking up 10,000- 15,000lbs weight.
24) Slack off to the neutral position and test the packer by pressuring the casing to 1,000psi for 5min.
25) Since 1,000psi annular pressure releases the crossover tool from the packer, the crossover tool may now be snapped out of the packer. Alternatively, the crossover tool may be released from the packer by turning 15 rotations to the right at the packer depth with a slight upstrain.
1) Raise the crossover tool to the reverse circulating position. Apply the appropriate workstring pressure to shear the ball seat in the crossover tool. Break circulation in the reverse direction at 3bpm and record the pump pressure.
2) Pickle the workstring by circulating the pickling agent to the end of the workstring. Reverse circulate 11/2 workstring volumes of filtered completion fluid until returns are clean.
3) Lower the crossover tool and set down 10,000lbs on the packer. This is the squeeze position, mark the pipe at the rotary table level. Establish injection pressures at 3, 2, 1, and 1/2bpm. Do not exceed the formation fracture pressure.
Note: If injectivity is low an acid stimulation treatment may be desired prior to performing the gravel pack.
29) Raise the crossover tool to neutral weight plus an additional 2ft. This is the circulating position, mark the pipe at the rotary table level. Establish circulating pressures at 3, 2, 1, and 1/2bpm. Monitor the return rates with a flowmeter to determine the leak-off rate to the zone. If full returns are observed, partially close the annular BOP to hold back- pressure and induce leak-off. Do not exceed the formation fracture pressure. 30) Raise the crossover tool to the reverse circulating position. Infuse gravel pack sand
into completion fluid at the desired mix ratio and at a circulating rate of 3bpm. A pump rate of 3bpm must be maintained to achieve a fluid velocity of 500ft/min in 31/2” workstring.
31) When the sand is 5-10bbls above the packer, lower the crossover tool into the circulating position. Continue displacing the gravel with filtered completion brine until an initial pressure increase is observed due to gravel covering the screens. While pumping, allow the pressure to build to 1,500-2,500psi over the initial circulating pressure at a given rate. Maintain this sandout pressure while slowing the pump rate to 2, 1, and 1/2bpm. Allow the pressure to bleed off to the formation. Calculate the gravel height above the screen top using the linear flow equation.
32) Do not re-stress the pack. Close the annular BOP and apply 500psi to the annulus. Raise the crossover tool to the reversing position. Reverse out excess gravel plus two workstring volumes. Divert the gravel returns to the slurry dehydration tank and determine the volume of gravel reversed out. The volume of gravel placed behind the casing can then be calculated by subtracting the volume reversed out and the screen/casing and blank pipe/casing annular volumes from the total volume of gravel pumped.
33) To test the gravel pack, lower the crossover tool into circulating position and attempt to circulate at the same rate and pressure achieved earlier. If sandout pressure cannot be achieved, mix and pump another batch of gravel. Reverse out any excess gravel. Repeat this step until final sandout occurs. Pull out of the hole with the service toolstring.
Figure 6.A - Typical Open Hole Gravel Pack Installation
Service
Seal Unit
With X-Over
Open
Automatic
J-Latch
Shear Pins
Tying Seal
Unit to Packer
Permanent-
Retrievable
Packer
Gravel Pack
Sand Screen
Swivel
Saftey
Joint
Production
Seal Unit
Figure 6.B - Typical Cased Hole Gravel Pack Installation Service Seal Unit With X-Over Open Automatic J-Latch Shear Pins Tying Seal Unit to Packer Permanent- Retrievable Packer Gravel Pack Sand Screen Swivel Saftey Joint Production Seal Unit