Time on location: 2 hours 

Time on location: 14.5 hours

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 

 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     

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

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 

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 

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   

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   

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 

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     

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   

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

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    

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 

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

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  

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 

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 

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.

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 

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   

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

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 travelled, 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   

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.