Wireline perforating is one of the earliest perforating methods used in oil fields since the adoption of perforating completion. It involves using a wireline to convey the perforating gun to the target formation inside the casing for positioned perforation. The perforating gun can be either a gun-type or a gunless-type perforator.
On-site Operation
1. Understand the well conditions and assign tasks to each position.
2. The wellhead worker directs the winch to align with the wellhead, installs the wellhead equipment, assembles the sheaves, and connects the magnetic locator. The driver secures the outriggers. The gun loader is responsible for on-site gun loading. The instrument operator connects wires, calibrates instruments, prepares casing and operation tables, and provides the gun loader and wellhead worker with a list of gun lengths, depths, and run numbers as per the loading order.
3. The gun loader brings the loaded gun to the wellhead. The wellhead worker attaches the gun using the magnetic locator, lowers it to the wellhead, and signals the driver to stop. After grounding the firing line, it's connected to the gun. The winch operator is instructed to zero and run in hole, while the instrument operator tracks depth and monitors downhole gun movement to prevent obstructions.
4. When the perforating gun reaches near the depth of the casing pup joint, the instrument operator signals the winch operator to stop. The instrument switches to measurement mode, and the winch operator adjusts the cable for depth correlation. After correlating with the casing pup joint depth, return to measurement mode and continue tracking to about 2-3 meters below the standard collar of the first perforation interval, then stop.
5. The instrument operator selects the perforation program according to the operation table, choosing the standard collar and pull-up value for the first perforation. Re-enter measurement mode and instruct the winch operator to pull up for firing. When the depth reaches the selected standard collar, the pull-up value begins to trigger. When it returns to zero, instruct the winch operator to stop. The team leader and operators verify the selected standard collar, pull-up value, gun number, and length. Upon confirmation, the team leader orders the operator to connect the firing line to the instrument. The surface firing panel is energized for detonation.
6. After firing, the operator instructs the winch operator to continue pulling up the cable while measuring. Stop at 2-3 meters above the upper collar of the third casing joint above the next perforation interval's standard collar. Mark the cable clearly near the winch drum. Then, instruct the winch operator to quickly pull the cable to the wellhead.
7. Repeat the above steps for subsequent perforations until the entire operation is complete. After completion, continue pulling up the cable to three casing joints above the last perforation collar, then run back down to the first perforation interval. Finally, pull up the cable, measuring the entire perforation position to the casing pup joint used for depth correlation.
8. If the pull-up triggering fails due to weak collar signals or high interference, exit the measurement interface, lower the cable to the initial stopping position, reselect the perforation program, and re-trigger for firing.
9. If triggering occurs at the wrong depth due to high interference, and if the distance to the correct standard collar is still sufficient, cancel the trigger. The instrument will automatically re-trigger when reaching the standard collar.
10. If the perforating gun fails to detonate due to assembly or equipment issues, follow step 6 to mark the cable clearly, then pull the gun out of the hole for inspection before running it back in for perforation."
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