Prior to any fishing operations ensure that all personnel involved are aware of their duties by means of a pre-operation safety meeting.
Dressing the Tools
Take a new grapple, grapple control and guide and assemble the overshot. Ensure that the correct type and size of grapple is used.
Preparing the Cable
The following procedures should be adhered to when preparing the cable for the cut and thread method:
1. Pull the cable to 2000 lbs above normal tension to remove any slack.
2. Clamp the cable hanger on the cable. ENSURE the proper size bushings are used. Secure the clamp.
3. Mark the cable 5 - 7 ft above the cable hanger.
Note: If the cable is key seated or the well is highly deviated, allow 9 - 10 ft.
4. Slack off the cable until the clamp supports the weight of the cable.
5. Cut the cable at the mark.
Rigging the Derrick
Since the travelling block must be used to handle the drill pipe, the sheave in the derrick must be rearranged. Attach the top sheave to one of the beams from the water table in such a way that it will not interfere while handling the drill pipe. If necessary re-position the logging truck before rigging up onshore.
The lower sheave on the rig floor must be moved in such a position that it will not interfere while tripping pipe.
The tension meter should be assembled on the lower sheave.
Cut and Thread Assembly
A spear head and rope socket is made up on the end of the cable remaining in the well.
A rope socket sinkerbar and spear head overshot are made up on the end of the cable hanging in the derrick.
A pull test should be performed as follows:
1. Latch the spear overshot to the spear.
2. Do not remove the cable hanger.
3. Mark the cable next to the rope sockets with tape.
4. Apply normal logging tension plus 2 000 lbs. on the cable.
5. Check if the cable has slipped in either rope socket after 5 minutes.
6. Slack off the tension and try to dissemble the overshot without using the extractor tool.
Note: If this cannot be done and if there is little or no slippage, the pull test is considered good.
Running the overshot (Stripping Over)
The following procedure should be adhered to while running the overshot:
1. Pick up the first stand of drill pipe and attach the proper sub.
2. Pull the spear head overshot to the derrickman.
3. Guide the overshot into the first stand of pipe.
4. Thread the spearhead (well end of cable) through the overshot.
5. When the spearhead overshot comes down through the drillpipe and sub, Pick up the spear and stab it into the overshot.
6. Attach the overshot to the drill pipe and make up connections.
7. Pull up on the cable to lift cable hanger from the rotary
8. Remove the cable hanger. Ensure that all tools are secure to avoid dropping in the well.
9. Ennter the length of the overshot and sub to the pipe tally.
10. Adjust the cable tension to normal plus 2 000 lbs.
11. Lower the first stand of pipe into the well slowly, and watch the tension meter. Hang off pipe in the slips.
12. Plkace a C-plate in the slot between rope socket and spear. Slack off the cable until it is supported by the C-plate.
13. Realease the overshot using special tongs.
14. Pull the overshot up to the Derrickman who should have another stand of drillpipe ready.
15. Drop the overshot through the drillpipe and LATCH onto the spear.
16. Pock upP on the cable and remove the C-plate.
17. Bring up the tension on the line to normal plus 2 000 lbs.
Make up and slowly lower in the stand of drillpipe. Do not rotate the pipe inside the hole.
18. RepeatT the above procedure for each stand until the overshot reaches the stuck tool.
Note: Cable tension and string weight should at all times be monitored very carefully.
Latching onto the Stuck Tool
If the 2000 lbs overpull maintained on the cable drops while stripping over, this could indicate that the tool or cable has become free. The following programme shall be adhered to:
1. Circulate to clean the grapple.
Note: A special circulation sub has to be installed.
2. Attempt to pull the cable into the overshot. If this is not successful continue stripping over.
3. Once the overshot is a short distance above the fish, circulate the string and the top of the fish clean record pump rate and pressures.
Note: In case a radioactive source is in the hole , the mud returns should be monitored continuously with a Gamma Ray tool while circulating.
4. Do not fish with the pump on.
5. Proceed with stripping over. As soon as there is any indication that the overshot is on the fish, stop and pull up 3 m with the drill pipe.
6. Lower the drillstring and lartch onto the fish. Do not locate or engage the logging tool with more than 20 000 lbs or the weight advised by the Logging Contractor. A pressure increase shall indicate if the fish is caught in the overshot. A cable head tension increase when lowering the drillstring, or a decrease when pulling the drillstring indicates that the fish is connected.
7. Observe the cable tension. If the tension drops, there is a good chance that the fish has been latched on. Repeat this procedure a few times to make sure this is the case. If there is no drop in tension, Go down with the overshot a little deeper than before and repeat the procedure.
Note: A good indication that the fish has been latched on to is an increase in cable tension whilst going down.
8. Do not use the pump to check if the tool has been latched into the overshot.
Note: In case the overshot has been equipped with circulation ports, a short circulation is permitted to check on the difference in pressure.
9. If all indications show that the tool is latched, Prepare to break the weak point and pooh.
Breaking the Weak Point and POOH
The following procedure should be adhered to when breaking the weak point and POOH.
1. Pull up to normal tension plus 2 000 lbs on the cable. Install the cable hanger.
2. Bring down the elevator and clamp the cable hanger to the elevator.
3. Pull up the elevator very slowly with 1 000 lbs increments and break the weak point.
4. Do not break the weak point using the logging winch.
5. Cut off both rope sockets and conect the ends with a square knot. Remove the cable hanger.
6. POOH with the cable using the logging winch.
7. POOH slowly with the drillpipe without rotating.
Note: Rotation of the pipe may disengage and drop the fish.
8. Secure the tools using the C-plate in the normal fashion when the tool and overshot are at surface.
9. Disconnect the head and use a thread protector to pull out the tool.
Note: If a radioactive tool is stuck, the weak point shall not be broken. Reverse strip out of the hole.