Freeze & Hot Tap Case Histories

Freeze and Hot Tap Case History #1

Objective: Replace 4 ½” Demco with broken stem.

Well Information: Sweet Gas Well Approximately 6000 KPA

Procedure: Hold JHA and safety meeting with all personnel. Rig up x/o nipple back to 2” Nitric in 2” x 5K ball valve. Fill valve cavity with fluid. Rig in Hot tap drill c/w ¾” drill bit. Pressure test equipment to 21 MPA. Hold 7 MPA on drill and valve. Rig in N2 drive to Drill. Drill through gate which is about 2 ½” thick. Once verified that bit hole is reamed clean, retract bit into drill and close 2” ball valve. Remove drill. Rig in pump line and start pumping fluid to kill well.

Time on location: 2 hours

Demco Freeze

Freeze and Hot Tap Case History #2

Objective: Freeze wellhead to remove damaged top section.

Well Information: 3,700kPa sweet gas well with damaged master valve not allowing access into tubing.

Procedure: Warm up wellhead to prevent gel from prematurely freezing. Install pumping equipment and pressure test. Inject gel into tubing. Install dry ice cribbing across tubing spool to produce plug in tubing hanger and tubing bellow hanger. Pressure test plug and replace damaged equipment.

Time on Location: 8.5 hours

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Freeze and Hot Tap Case History #3

Objective: Freeze wellhead to remove plunger lift equipment stuck across master valves.

Well Information: 8MPa sweet gas well with high LPG production with plunger lift mandrel stuck in top section.

Procedure: Remove piping downstream from wing valve. Install pumping equipment and pressure test. Inject gel into wellhead freeze gel and mandrel in top section. Pressure test plug, remove cap, and install wireline lubricator with line attached to mandrill. Pressure test lubricator, bleed down to well pressure and thaw plug. Retrieve mandrel.

Time on location: 17 hours

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Freeze and Hot Tap Case History #4

Objective: Freeze tubing to remove joint with plug.

Well Information: Tubing bridge plug set prematurely in tubing while being run for snubbing operations. 89 mm tubing, 18Mpa sweet gas well with high LPG production.

Procedure: Pull tubing through snubbing unit and position joint with plug above working floor. Install saddle clamp and hot-tap drill above tool joint, and pressure test. Drill 19mm hole into tubing and remove drill. Clean tubing by pumping solvent into clamp. Inject gel and freeze below tool joint, pressure test plug, remove top joint and install valve. Pressure up to well pressure and thaw plug.

Time on location: 8.5 hours

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Freeze and Hot Tap Case History #5

Objective: Freeze casing to replace damaged casing below orbit valve.

Well Information: Low pressure (2,000kPa) sweet gas well; 114mm mono-bore completion with the pipe below the bell nipple bent.

Procedure: fill surface casing will water. Install cribbing and dry ice around casing. Install pumping equipment and pressure test, inject gel into production tubing and maintain dry ice until freeze plug is generated. Pressure test plug, replace tubing and install new valve. Pressure test, maintain pressure above plug, and thaw.

Time on location: 14.5 hours

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Freeze and Hot Tap Case History #6

Objective: Hot tap damaged gate valve using 2 ½ “hole saw to enable slick line to set a plug in profile and change out gate valve.

Well Information: 8600Kpa sweet gas well with a depth of 1500m.

Procedure: Check for pressure, remove wellhead flow tee and install work valve. Assemble hot tap drill with ¾” bit and centralizer, fill with oil to the top of the work valve and rig in drill. Pressure test to 13000kpa then bleed off to 5000Kpa. Spin the bit using air drive w/ nitrogen and advance drill till through the gate. Retract the drill and close work valve, bleed off pressure in drill and remove. Install coupon catcher and 2 ½” hole saw, rig in drill. Pressure up to 8600Kpa and open work valve, spin the hole saw with air drive and advance the drill till through the gate. Retract the drill, close the work valve and bleed off pressure in the drill. Rig out the drill and remove the coupon from the hole saw and turn the well over to slick line.

Time on location: 3 hours

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Freeze and Hot Tap Case History #7

Objective: Freeze wellhead to replace malfunctioning top section valve.

Well Information: 5,000kPa sweet gas well with malfunctioning master valve.

Procedure: Install cribbing and dry ice. Install pumping equipment and pressure test. Inject gel into tubing and freeze across tubing hanger. Pressure test ice plug, replace top section. Pressure test top section, maintain pressure above plug, and thaw.

Time on location: 11 hours

Wellhead Freeze

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Freeze and Hot Tap Case History #8

Objective: Hot-tap tubing to ensure no pressure is present when breaking connections.

Well Information: 35MPa sour gas well. Rig pulling production tubing, annulus dead, but tubing plugged with sulfur precipitant.

Procedure: Pull to top of sulfur plug. Install safety valve, pull to next connection. Install saddle clamp and drill, pressure test, drill 12.5mm hole, check for pressure and presence on H2S. bleed off to testers as necessary. Process repeated 35 times until BHA out of hole.

Time on location: 21 hours

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Freeze and Hot Tap Case History #9

Objective: Hot tap 3 ½ tubing full of scale plugs to safely remove tubing from well.

Well information: 2600 Meter sour well pressure between shale plugs unknown. Casing pressure zero mPa.

Procedure: All operations performed masked up. Install 3 ½ inch tubing clamp, working ball valve and hot tap drill with ¾ inch bit. Pressure test with baker pump to 15 mPa based on well history. Leave 10 mPa on assembly drill ¾ inch hole, once hole drilled pressure dropped to zero. Rig out hot tap equipment and tie into testers, bleed off. Tie in to rig pump and attempt to pump fluid to determine if any more shale plugs in tubing. Unable to break circulation- bleed off pressure, rig out pumping equipment, confirm no pressure between hot tapped joint above collar of next joint. Break out joint and install a TIW valve in next joint in well. Continue above procedure until circulation obtained and tubing clear of shale plugs. In all 33 hot taps were performed with pressures of up to 3000 kPa and 16% sour gas to be found.

Time on location: 36 hours

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Freeze and Hot Tap Case History #10

Objective: Re-enter access to abandon wells’ wellbore.

Well Information: Well was abandon to Alberta E.U.B. standards. Re-entry is required.

Procedure: Well located, uncovered to visual with hydrovac, and then excavated with backhoe. Hot-tap equipment installed on surface casing, pressure tested and 19mm hole drilled into casing. Check for pressure or hydrocarbons. Bleed off and fill with water. Cut off surface casing to gain access to production casing. Install hot-tap equipment, pressure test and drill 19mm hole in casing. Check for pressure or hydrocarbons. Bleed off and fill with water to produce a safe situation for customer to cut off cap and install appropriate risers and wellhead equipment for re-entry.

Time on location: 4.5 hours

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Freeze and Hot Tap Case History #11

Objective: Re-enter access to abandon wells’ wellbore.

Well Information: Well was abandon to Alberta E.U.B. standards. Re-entry is required.

Procedure: Well located, uncovered to visual with hydro-vac, and then excavated with backhoe. Hot-tap equipment installed on surface casing, pressure tested and 19mm hole drilled into casing. Check for pressure or hydrocarbons. Bleed off and fill with water. Cut off surface casing to gain access to production casing. Install hot-tap equipment, pressure test and drill 19mm hole in casing. Check for pressure or hydrocarbons. Bleed off and fill with water to produce a safe situation for customer to cut off cap and install appropriate risers and wellhead equipment for re-entry.

Time on location: 4.5 hours

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Freeze and Hot Tap Case History #12

Objective: Remove malfunctioning orbit valve and install rig BOPs.

Well Information: 5,600kPa sweet gas well. After rigless fracture stimulation orbit valve does not open properly.

Procedure: Install cribbing and dry ice on casing. Rig up pumping equipment and pressure test. Inject gel into casing and produce a freeze plug. Pressure test plug, remove orbit valve and install BOPs. Pressure test BOPs, maintain well pressure above plug and thaw.

Time on location: 12 hours

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Freeze and Hot Tap Case History #13

Objective: Freeze tubing to remove obstruction in tubing during snubbing operations

Well Information: 27MPa sweet gas well. During snubbing operations, obstruction in 89mm tubing did not allow running a wireline plug to bottom. A bridge plug was set above obstruction and tubing was pulled to position first tool joint below obstruction at working height in snubbing basket.

Procedure: Hot-tap clamp and drill installed above tool joint, pressure tested and 19mm hole drilled in tubing. Drill removed, pumping equipment installed and pressure tested. Inject gel and provide dry ice contact to tubing below tool joint. Pressure test plug, break connection and install valve. Pressure test valve and maintain well pressure above plug during thaw. Flow gel to testers and rig up wireline to run plug to bottom of string.

Time on location: 8.5 hours

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Freeze and Hot Tap Case History #14

Objective: Hot tap 2 7/8” master valve to gain access in order to kill well and replace damaged valve.

Well information: 15 Mpa sour gas well.

Procedure: Erect scaffolding; confirm no pressure above seized master valve, rig out wellhead equipment. Install correct crossover flange, working valve and hot tap drill. Pressure test connections and hot tap equipment to 30 Mpa. Bleed pressure back to 17 Mpa and commence drilling through gate. Advance drills through both halves of gate and confirm based on measurements and pressure equalization as well as drill torque. Retract bit above working valve and close. Tie bleed off into testers and bleed off sour gas above work valve. Rig out hot tap drill, hand over well for kill operations.

Time on location: 3 hours

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Freeze and Hot Tap Case History #15

Objective: Remove malfunctioning slim-hole valve.

Well Information: 8,000kPa sweet gas well. Approximately 35m of sand was cleaned off a bridge plug after a fracture stimulation using a snubbing unit and slim-hole safety valves. The bridge plug was released. The first valve in the well bore was brought to working height and closed. Clean out package was removed hose connected to tubing above valve. Joint pulled and next valve positioned and closed. Top valve equalized but would not open.

Procedure: Hot-tap clamp and drill installed above lower valve and pressure tested. 12.5mm hole drilled in tubing, drill removed, and pressure vented to testers.

Time on location: 1 hour

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Freeze and Hot Tap Case History #16

Objective: Freeze tubing to replace damaged master valve to gain entrance into tubing.

Well Information: 12.4MPa sour gas well shut in for several years, master valve seized.

Procedure: Heat wellhead, expose surface casing install cribbing around surface casing and fill with dry ice. Inject gel into surface casing. While frost is transferring through gel in surface casing, scaffolding is built and hot-tap equipment is rigged up. Rig up pumping equipment to production casing, pressure test and inject gel. While frost is penetrating gel in production casing, the hot-tap drill is pressure tested and a 19mm hole is drilled in the seized master valve. The drill is removed and pumping equipment installed, pressure tested, and gel is injected to the production tubing. Due to the well conditions the dry ice maintained overnight. At daylight, the plug is pressure tested, the top section is dismantled, and the new valve is installed and pressure tested. Well pressure is applied above the ice plug and turned over to the thaw crew.

Time on location: 27.5 hours

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Freeze and Hot Tap Case History #17

Objective: Freeze well to remove top section and tubing hanger on well which was suspended.

Well Information: A low pressure gas well (3,000kPa) was suspended and left with no tubing in the hole, tubing hanger in the tubing spool and top section installed. Over time gas pressure developed in the casing. When our customer acquired the well, they wanted to re-complete the well to produce gas without introducing any more kill fluids.

Procedure: Expose surface casing and install cribbing and dry ice. Inject gel into surface and production casings. When freeze plug is achieved, the plug is pressure tested and the top section and tubing hanger is removed and BOPs are installed and pressure tested. Well pressure is applied to the top of the plug and turned over to the thaw crew.

Time on location: 15.5 hours

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Freeze and Hot Tap Case History #18

Objective: Freeze tubing to remove lost wireline tools in completion tubing.

Well Information: 16.5MPa sweet gas well. During wireline operations, tools became stuck approximately 300m from the bottom of the tubing. Subsequently, slickline fishing tools were lost. Total length of lost wire line tools is approximately 31m.

Procedure: A bridge plug was set in the tubing above the wireline tools; the tubing was snubbed out to the bridge plug. The tubing was capped. A crane was rigged up with the crown 20m above the crown of the rig. The winch was attached to the tubing and 4 joints were snubbed out. The tubing was hot-taped and gel injected into the tubing and froze. The 4 joints were removed, laid down and hot tapped to check for trapped pressure. A valve was installed into the tubing, pressure tested and thawed. The gel was blown out and wireline rigged up to set a plug on bottom.

Time on location: 11 hours

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Freeze and Hot Tap Case History #19

Objective: Hot tap Lower Master Valve To provide access to Tubing in order to freeze well and replace faulty valve.

Well Information: Sweet Gas Well Drilled in 1993. CSG is full of inhibited fluid with packer set 2334 meters from surface. Estimated SITP = 4000 KPA

Procedure: Perform JHA and Safety meeting with all personnel. Take measurements and ensure hot tap equipment is suitable for task. (Enough stroke to get through valve and can still retract back enough to get behind safety valve. Confirm valve is holding pressure. Remove all wellhead equipment above faulty valve. Install x/o flange onto valve, 2 9/16 x 2”, c/w 2 9/16”x 2” threaded nipple. Install 2” x 5K ball valve. Fill valve up with fluid. Install hot tap drill. Rig in pressure pump and pressure test all connections and drill to 21 MPA. Estimated SITP is 4 MPA. Bleed pressure back, maintaining 10 MPA. Start drilling through valve monitoring pressure above valve at all times. Pressure dropped to approximately 4.3MPA.Continue drilling until ¾” hole has been reamed clean, and the bit can pass through un hindered without rotating. Retract bit into drill housing and close 2” ball valve. Bleed off drill and remove. Hook up flow back line and flow tubing to ensure good access. Remove flow back line. Build Ice cribbing around surface casing and inject freeze gel into surface and production casings as well as tubing. Add dry ice and wait allotted time for gel to freeze. Pressure test freeze plug on the tubing side and when verified plug is holding, remove faulty master valve and install new valve and the rest of the well head components. Pressure test well head against freeze plug. Remove ice from well and let thaw.

Time on Location: 24 hours

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Freeze and Hot Tap Case History #20

Objective: Hot tap 2 7/8” gate valve to gain access to tubing in order to freeze and remove damaged gate valve.

Well information: 32 Mpa water injections well

Procedure: Confirm damaged valve is holding, remove all wellhead equipment above faulty valve, use appropriate crossover over flange and rig in hot tap drill. Pressure test equipment to 35 Mpa as restricted by wellhead rating. Bleed off drill to 30 Mpa drill ¾ inch hole completely through gate making sure to go through both halves-pressure equalizes at 32 Mpa when completed. Retract drill close working valve, bleed off drill assembly and rig out drill. Build cribbing, inject gel into surface casing and production casing to transfer freeze. Rig in gel injection equipment to tubing and inject gel into tubing, fill cribbing with dry ice and maintain through the night. Maintain and monitor freeze operation overnight. After sufficient freeze time, pressure test freeze plug, tested OK, bleed off pressure and replace damaged valve. Apply equal pressure above freeze plug and hand over well for thawing.

Time on location: 28 hours

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Freeze and Hot Tap Case History #21

Objective: Re abandonment

Well Information:
Well was previously abandoned but the bank where the well was located had eroded away leaving 8 meters of abandoned casing exposed in an environmentally sensitive area.

Procedure: Well was only accessible via helicopter. Crew and equipment were flown into location. Climbing crew prepared and shored bank with a wire mesh. Hot tap crew repelled down bank and inspected casing stump. A hole was discovered in casing stump already. Welding equipment was lowered down and an automatic feeder was installed below hole and casing was cut off. A new cap with ball valve was welded onto new casing stump.

Time on location: 8 hours

Freeze & Hot Tap Case History 21

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Freeze and Hot Tap Case History #22

Objective: Freeze casing to replace full opening 7” orbit valve

Well Information: While functioning gate valve the stem had been twisted off with the valve half closed. Well was secured with blind rams on the 70mPa BOP stack… Surface casing pressure was 42mPa.

Procedure: Hole volume of fluid was pumped down the casing to lower working pressure to 10 mPa. Gel was then injected by the freeze crew into the surface and production casings. Gel was then frozen using dry ice and freeze was held on for 24 hours. Freeze plug was then pressure tested to 84 mPa, tested OK. Pressure was then bleed off above freeze plug and monitored. Atmospheric test was good. A crane was then used to lift 70 mPa stack and malfunctioning orbit valve off of well. New orbit valve was then installed along with 70 mPa stack. New orbit valve and BOP stack was then pressure tested. Thawing operations were performed by rig crew.

Time on location: 24 hours

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Freeze and Hot Tap Case History #23

Objective: Hot tap 114.0mm gate valve.

Well information: 3500 Kpa sweet gas well

Procedure: Assemble hot tap drill with ¾” bit and centralizer. Fill wellhead with oil and tie on hot tap drill. Pressure test to 5500Kpa then bleed off to 2000Kpa. Start drilling gate valve while monitoring pressures and adjust to stay under 5500Kpa. Drill through both halves of the valve and the pressure drops downs to 3500Kpa once through. Retract drill and close the top valve, bleed off pressure from the drill and rig out equipment.

Time on location: 1.5 hours

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Freeze and Hot Tap Case History #24

Objective: Freeze casing to install primary seal on intermediate casing.

Well Information: 51 mPa Bottom hole pressure. Failed cement job was allowing pressure to surface on intermediate casing side where there was no primary seal installed. Invert mud was being pushed thru failed cement to surface.

Procedure: Fresh water was pumped to push invert down away from surface. One cube of drilling mud was then pumped to ensure area to be frozen was clear of invert. Freeze gel was then pumped down surface, intermediate and productions casing. Dry ice was applied and freeze was held for 24 hours and pressure tested. Freeze plug tested OK. Drilling rig was then rigged out. Freeze was then held for another 48 hours. Crane was then brought in and drilling rigs BOP stack was removed. Primary seals were then installed in casing. 7 1/16” Gate valve and 70 mPa stack were installed and pressure tested. Well was turned over to rig crew for thawing operations.

Time on location: 5 days of 24 hour operations.

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Freeze and Hot Tap Case History #25

Objective: Freeze well to install another 7 1/16” gate valve.

Well Information: 30 mPa BHP. Wire line tools were hydrated in the hole approximately 150 meters down and braided line was across existing gate valve. Wireline lubricator rated for 21mPa with a 14mPa equalize loop with leaking 35mPa ball valve.

Procedure: Attempted to inject gel thru casing valves but pressure ratings of wireline surface equipment limited pumping pressures and gel could not be injected. Hot tap was performed on 14mPa equalize loop and gel was injected thru leaking 35mPa valve. Gel sealed leaking 35mPa valve, equalize loop was rigged out and installed new 35mPa ball valve behind failing 35mPa valve. Gel was then injected into well thru lubricator valve and casing valve. Gel was also injected into surface casing. Freeze plug was then formed and freeze was held thru the night. Plug was pressure tested from above in the morning and held. Pressure was bleed off above freeze plug and monitored. Once freeze plug had been verified the wireline lubricator was broken apart and the braided line was cut and wireline equipment was rigged out and another orbit valve was installed and pressure tested. Well was turned over to steamer truck crew to thaw.

Time on location: 28 hours

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Freeze and Hot Tap Case History #26

Objective: Hot tap and Freeze tubing to replace damaged master valve to gain entrance into tubing.

Well Information: 12.4MPa sour gas well shut in for several years, master valve seized.

Procedure: Heat wellhead, expose surface casing install cribbing around surface casing and fill with dry ice. Inject gel into surface casing. While frost is transferring through gel in surface casing, scaffolding is built and hot-tap equipment is rigged up. Rig up pumping equipment to production casing, pressure test and inject gel. While frost is penetrating gel in production casing, the hot-tap drill is pressure tested and a 19mm hole is drilled thru the seized master valve. The hot tap drill is rigged out and pumping equipment installed, pressure tested, and gel is injected into the production tubing. Due to the well conditions the dry ice maintained overnight. At daylight, the plug is pressure tested, the top section is dismantled, and the new valve is installed and pressure tested. Well pressure is applied above the ice plug and turned over to the thaw crew.

Time on location: 27.5 hours

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Freeze and Hot Tap Case History #27

Objective: Hot tap and mill out a damaged gate valve 90% closed and freewheeling.

Well information: 4,200kpa sweet gas well on an offshore platform with damaged gate valve not allowing access into tubing. Top gate valve functioning.

Procedure: Assemble hot tap equipment and function. Bleed off gas pressure above top valve and remove wireline flange install hot tap equipment pressure test.Equalize pressure and open top operating gate valve hot tap a ¾ inch hole in bottom valve pull above top valve close bleed off well gas remove drill bit. Install mill and reconnect flange equalize with well gas and open top valve mill out damaged bottom valve pull above top valve and close bleed off well gas and remove mill. Install reamer to open bore to 3 1/8 reconnect flanges and equalize with well gas and open top valve ream bottom gate valve to full drift. Pull above top valve and bleed off well gas remove reamer. Install wire brush reconnect flange equalize with well gas open top valve clean tubing hanger threads with wire brush pull up above top valve and close. Bleed off well gas and remove hot tap equipment.

Time on off shore platform: 33 hrs over three days

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Freeze and Hot Tap Case History #28

Objective: Mill out gate to 3 1/8 diameter on top master valve that is seized closed and freewheeling to accommodate wireline tools and installation of back pressure valve in tubing hanger. Bottom master Valve previously milled out.

Well information: 3 Mpa water injection well

Procedure: Assemble hot tap equipment, start power pack and check all functions. Confirm no pressure above damaged valve, remove wireline cap and install crossover-work valve-Bop and hot tap equipment. Pressure test all components and connections to 7 Mpa. Bleed pressure back to 5 mPa drill ¾ inch pilot hole. Retract drill above work valve, close, bleed off pressure, and change out bit to 3 inch cone mill. Rig up new assembly, equalize above work valve and open valve. Advance mill to gate, record measurements and confirm depth is correct. Commence milling, noting time for advancement gained. After advancing 2 inches through 2 ½ inch gate advancement slowed considerably. Retract cone mill above work valve, close valve and bleed off. Change out cone mill to 2 7/8 outside-in aggressive mill. Rig up hot tap equipment, equalize above work valve and open valve. Advance drill to gate, check measurements and resume milling. Monitor torque and distance traveled, double check measurements to confirm through gate. Retract mill above working valve, close valve and bleed off. Change out mill to 3 1/8 reamer re-install hot tap equipment, equalize and open work valve. Ream out gate valve, retract above work valve, close and bleed off. Change out reamer to wire brush, re-install equipment, equalize above work valve and open. Advance brush to threads in tubing hanger, check measurements and clean threads in hanger. Retract brush above work valve and close valve, bleed off and rig out hot tap equipment. Hand over well to wireline.

Time on location: 27 hours over three days

Valve Drilling

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Freeze and Hot Tap Case History #29

Objective: Replace master valve on well. No vehicle access.

Well Information: 18mPa surface pressure with 2% H2S content.

Procedure: All personnel and equipment were flown into location from staging area. Portable lubricators filled with gel were flown into location. Wiper plug was installed in one end of lubricator and a portable 35mPa pressure washer was used to inject the freeze gel. Freeze plug was formed and pressure tested and master valve changed. Freeze plug was thawed by mother nature.

Time on location: 24 hours.

Remote Freeze Operation

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Freeze and Hot Tap Case History #30

Objective: Replace split 4 by 2 inch swedge below master valve on a coil tubing completion.

Well Information: Well gas blowing out of swedge that is split vertically from threads to top of the neck and split horizontally half way around neck. Shut in casing and tubing pressure is 7 mPa, flowing pressure of 3.5 mPa. Casing size of 4 ½ inches with 1800 meters of 2 inch coil tubing landed in coil tubing hanger above 4 ½ demco valve and below 4 by 2 inch swedge with 2 inch master valve. No vehicle access, temperatures ranging from minus 20 degrees centigrade to minus 30 degrees.

Procedure: All personnel and equipment were flown into location from staging area. A small shelter using scaffolding, tarps and Herman nelson heater erected for purpose of shelter and keeping lubricators of freeze gel, pumping equipment and water needed for pumping purposes thawed. Installed a dog collar around the vertical crack of the damaged swedge to keep from blowing out sideways and chained top of swedge to bottom of demco valve to keep from blowing off from the top. Cribbing for dry ice was built between demco valve and damaged swedge on the coil tubing hanger and connecting nipple. Casing was left flowing to compressor station to lessen stress on damaged swedge. A mixture of freeze gel and sealing material were pumped into the coil tubing through side wing valve on the flow line using portable lubricators with wiper plugs and gas powered pressure washer. Once flow of gas was sealed sufficient gel was pumped to ensure that freeze plug would form where cribbing was built. Maintained dry ice and monitored pressures through evening. Intrinsically safe heat tape powered by portable gen-set was used to keep pumping areas and equipment to be changed from freezing. In a.m. pressure test revealed freeze plug was not holding. Flowed out failed freeze plug, swedge remained sealed. Moved cribbing down below demco valve, shut in casing , pumped sufficient freeze gel into 4 ½ casing and down 2 inch coil to form freeze plug in the area of the cribbing using the methods mentioned above. Maintained ice and monitored pressure through the evening. In morning performed positive pressure test of 12 mPa using baker pump on freeze plug and a negative test. Damaged swedge was removed and new swedge with new master valve installed. New equipment was pressure tested using baker pump. Well was thawed using Herman nelson heaters with sufficient duct tubing to keep ignition source away from well. The freeze plug was then flowed out and the well was then tied back into the production flow lines. All equipment and personnel were then flown back to staging area.

Time on location: 3 days-due partly to helicopter restrictions and cold weather problems.

Freeze Case History 30

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Freeze and Hot Tap Case History #31

Objective: Freeze well below coil tubing b.o.ps in order to remove damaged 2 inch coil tubing in lubricator and re-attach to good coil tubing.

Well Information: 20 mpa sweet gas well with frac tool,overshot,jars, and crossover to 2 inch coil tubing stuck across master valves and coil tubing b.o.ps. Stack configuration from bottom to top consisting of two 4 1/16 master valves, flow cross with two 2 in wing valves, two foot 4 1/16 10,000 psi spool, 4 1/16 flow cross with one outlet and valve, quad coil tubing b.o.ps and twenty ft of 4 1/16 lubricator attached to injector.

Procedure: Build cribbing between bottom flow tee and upper flow tee on 2ft spool below b.o.ps. Pump freeze gel into lower and upper flow tees add ice to cribbing. Maintained ice and monitored pressure throughout evening. Wrapped steam line on lubricator to keep thawed, and kept heat on above freeze plug to allow access for pumping to pressure test and monitor. Pressure test with nitrogen to 30 mpa on top of freeze plug, do negative test and monitor for venting. Remove lubricator from top of coil tubing b.o.ps and lifted 3 ft exposing damaged coil and crossover to the jars-found that coil was collapsed from crossover to the top of the lubricators. Performed hot tap on coil just below injector pack-off as this was the closest good tubing to attach hot tap clamp. Confirmed no pressure in coil before cutting damaged coil above crossover. Re-positioned lubricator, ran out all flattened coil and cut off. Installed crimp on coil connector on good coil. Replaced crossover above jars then repositioned lubricators and reattached the good coil to the crossover, lowered lubricator and re-secured. Pressure test all connections against freeze plug with nitrogen. Removed ice and cribbing, kept positive pressure above freeze plug and handed well over to coil tubing operations for thawing.

Time on location: 36 hours.

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Freeze and Hot Tap Case History #32

Well information: 45MPA gas well. Wire line tools stuck across wellhead valves with 2 sets of wire line bops on top of well head with 80’ of lubricator on top and 2 X 2 1/16th gate valves on top of lubricator closed maintaining well control.

Objective: Inject freeze gel and freeze the three well head valves enabling the safe removal of all equipment above the well head valves and install a 4 1/16th 10K bop dressed with slip rams and pipe rams to fit the 1 ½” weight bar which is across the well head. Then add sufficient riser spool and another gate valve on top to regain proper well control and give the ability to be able to rig in proper equipment to fish out the stuck tool string.

Procedure: Upon arrival to the well site a pre job inspection occurred. The ice cribbing was assembled. The equipment above where the freeze plug was to be was wrapped with steam and heat trace as well as insulation to prevent the equipment to be removed from freezing. Utilizing 10K 3 1/16” 10’sections of lubricator filled with freeze gel and a wiper plug we used a 10K pump truck to push the wiper plug in turn pushing the freeze gel into the well bore. Once sufficient freeze gel was injected Dry Ice was added to the ice cribbing and a pressure gauge installed above where the freeze was actually going occur. The gel was then allowed to freeze for approximately 36hrs while monitoring pressure above the plug and maintaining a solid ice pack. After allowing sufficient time for the freeze to occur, a positive pressure test to 65mPa was held for 1 hour. Once the positive pressure test was confirmed a success a negative pressure test was performed at 0 mPa and held for 1 hour and was completed successfully. Another safety meeting was held involving all parties on site and ensured that all required equipment was available. Ensure good line of communication between the well control crew and the 2 picker operators involved. One picker to remove the lubricator from the well head and the other with the new set of 4 1/16th bops ready to position on to the well head. The lubricator was then unbolted from the top of the well head and swung clear of the area. The tool string was then disassembled to the lowest point above the well head, and a new fish neck installed, for future fishing operations. The 4 1/16th bop was then positioned onto the well head and tightened down and closed, and a 4’ section of 4 1/16th riser spool and two 4 1/16th gate valves was then installed on top of the bop. The BOP’s were then pressure tested and once all connections were tested, there was 50 MPA left above the freeze plug and the cribbing and ice removed allowing the thawing process to begin.

Total Time on location: 5 days.

Encana Freeze

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Freeze and Hot Tap Case History #33

Objective: Hot tap the tubing below the bridge plug and inject gel to freeze the well to allow for the removal of the drill collars.

Well information: 12MPa gas well. After success UBD operations to deepen a well, the floats did not hold pressure to allow for the trip out with the drill string. After several attempts to set a plug in the “Q” nipple just above the float sub, a bridge plug was set in the last joint of pipe above the drill collars and the drill string was snubbed out to the drill collars.
BHA: bit, bit sub with duel floats, 3m drill collar, “Q” nipple, 6 drill collars, 73mm tubing to surface.

Procedure: Confirm location of bridge plug in the last joint of tubing with plumb bob on trip out of the hole. Install safety valve in tubing and set first drill collar in slips. Install hot tap clamp and drill assembly on tubing below bridge plug. Pressure test and drill ¾” hole in tubing. Rig out drill and install gel injection equipment. Pump twice the volume of the drill collars capacity. Install cribbing and supply dry ice to area below the tubing to drill collar crossover. Freeze the gel, pressure test and break out the tubing. Install 2’pup and safety valve swivel joint and Kelly hose. Pull 2 drill collars, set ice cribbing, thaw top ice plug while freezing next plug. Pressure test through Kelly hose. Break connection and lay down double stand. Install crossover, 2’pup, safety valve, swivel joint and Kelly hose. Pull 2 drill collars and repeat freeze procedure. Repeat total procedure unit the bit is clear of the blind rams. Secure well with blind rams.

Time on location: Spot equipment and set up 2 hours, next day 13 hours of execution of freeze plugging procedure.

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Freeze and Hot Tap Case History #34 – VR-PLUG REMOVAL

Objective: Remove 2 VR plugs ceased in casing bowl assembly
• Pressure 41 mpa
• Sweet gas
• Casing valves 2 1/16 10k BX152 ring gaskets
• VR plug size 1.900 OD by 1.25” hex nut
• Confirm all data with on site personnel prior to rigging up

Procedure:
• Check and record all pressures
• Bleed off potential trapped pressure, rig in unit and conduct pressure testing of work valve and unit and VR plug assembly
• Confirm and record test
• Ensure work valve in fully opened position, advance removal tool onto VR plug and confirm by measurement and rotation resistance that tool has engaged onto hex nut
• Equalize pressure on unit to casing pressure
• Apply sufficient left hand torque to free ceased VR plug
• Continue with left hand rotation while retracting removal tool
• Fully retract tool to accommodate closing of work valve
• Close work valve, bleed off pressure, rig out VR plug removal unit, night cap casing valve. Repeat procedure on next casing valve.

Time on location: Time on location six hours from time of arrival to departure

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Freeze and Hot Tap Case History #35 – August 3, 2016

Objective: Hot Tap and freeze 3 ½” tubing to relieve trapped pressure below plug.
Well Information: Sweet well, 4600kPa on well.

Procedure:
Safety and JHA meeting with crew and company rep. Rig up and pressure test Hot tap drill, proceed to drill ½” hole to gain access to ID of 3 ½ tubing. Install cribbing and ice and start to cool pipe for 1 hr. Inject 60 L of freeze medium (GEL) into string and freeze. Preform positive (17,000 kPa) and negative (0 kPa) pressure test on plug, both passed. Remove top joint, install TSI and put 5000 kPa topside pressure to cushion plug when defrosting. Well secured, Rig out and off location.

Time on location: Time on location 14 hours

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Freeze and Hot Tap Case History #36 – August 8, 2016

Objective: Hot Tap and freeze 3 ½” tubing to relieve trapped pressure below plug.
Well Information: Sweet well, 4500kPa on well.

Procedure:
Safety and JHA meeting with crew and company rep. Rig up and pressure test Hot tap drill, proceed to drill ½” hole to gain access to ID of 3 ½ tubing. Install cribbing and ice and start to cool pipe for 1 hr. Inject 60 L of freeze medium (GEL) into string and freeze. Preform positive (12,000 kPa) and negative (0 kPa) pressure test on plug, both passed. Remove top joint, install TSI and put 5000 kPa topside pressure to cushion plug when defrosting. Well secured, Rig out and off location.

Time on location: Time on location 18.5 hours

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Freeze and Hot Tap Case History #37 – October 4-8, 2016

Objective: Freeze surface casing; Intermediate casing; Production casing and Sheared Coil string to facilitate re-dressing and re-connecting coil to continue out of hole.
Well Information: Sweet well, 21.5mPa on production, and 18 mPa on tubing.

Procedure:
Safety and JHA meeting with both crews (24hr). Hydrovac cellar to install cribbing. Fill Surface and intermediate casing with water. Surface casing will not hold water, rig in mud line and inject 15L of gel. Move mud line to Production casing and inject 100L of Gel. Move mud line to Coil and inject 80L of gel. Rig out and secure all injection points. Fill cribbing with dry ice, and proceed to install heat trace on stack and tarp, to prevent total freezing of BOP stack. Tamp and maintain ice for duration of freeze. Positive and negative pressure tests complete and held. Remove BOP stack, dress and connect coil. Reinstall BOP stack Pressure test coil and it failed. Maintain ice. Remove BOP stack, redress and reconnect coil and pressure test. Pressure test held, reinstall BOP stack and pressure test, passed. Apply 22 mPa to topside of plugs, remove heat trace and tarps. Rig out and off location, rig crew to facilitate thawing process.

Time on location: Time on location 75 hours

Freeze & Hot Tap

Freeze & Hot Tap

Freeze & Hot Tap

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Freeze and Hot Tap Case History #38 – November 9-11, 2016

Objective: Re-Abandonment. Hot tap and freeze well, below grade, to install well head and master valve for access, above grade to determine where down hole leak originated.
Well Information: Sweet well, pressure TSTM on well. Leaking through welds on top cap (Production) and weld “o” let (Production).

Procedure:
Safety and JHA meeting with crew and company rep. Rig up Hot tap drill, proceed to drill existing 3/8” torch hole to ¾” hole to gain access to ID of 7” production casing. We had to drill through casing collar. Inject 50 L of freeze medium (GEL) into surface, and 120L into production casing and freeze. No positive pressure test could be completed due to leaks. Preform negative (0 kPa) pressure test on plug, for 30 min both passed. Cut off existing collars, installed new casing strings to elevate to above grade. Install and weld new casing bowl and working valve. Pressures test all welds, bowl and valve, well secured. Rig out and off location.

Time on location: Time on location 30.5 hrs

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