Casing Repair
with the use of steel patches

Is an effective way of impermeability recovery for oil and gas production well bores.

• The Technology enables recovery of both horizontal and vertical columns of casings in case of threaded connections damages in order to block punched holes and repair local damages (cracks, deterioration, corrosion).
• Low prime cost along with the high Technological value make the Technology perfect for the work-over of casings with various diameters.

Steel Patch Installation Scheme

1. Corrugated steel pipe patch
2. Hydraulic jack
3. Mandrel head
4. Casing
5. Rod
6. Damaged impermeability interval
7. Steel patch set into the casing

Procedures:

1. Preparatory work
2. Production string sweeping-up (reaming if necessary)
3. Production string geophysical and Technical exploration
4. Damaged impermeability interval localization
5. Cleaning of the casing surface at the target interval
6. Cement plug set or packer installation at the target depth
7. Measuring of the casing inner surface perimeter at the target interval
8. Patch installation
9. Assembly POOH and breakdown
10.Casing investigation

The patch is a special longitudinal corrugated steel pipe of 8 - 10 meters long. The outside perimeter of the corrugated pipe is slightly more than the inner perimeter of the damaged casing to ensure  pressing-in. The external surface of the corrugated pipe is covered with special sealing material which is providing tightness between the patch and the casing and serves as a anticorrosive layer when it's installed.

Put on a mandrel head, the patch is run into the hole to the damaged interval. Then the mandrel straightens the patch at the target depth by pressing the patch against to the casing due to the pressure increase (18-25 MPa) in the tubing. The casing integrity is recovered. Decrease of the casing inner diameter is less, or equals to, 7 mm, which doesn't cause any problems for further RIH operations and well exploitation.