API Casing Pipe Damage Repairing Technology

In oil field development, API casing is usually damaged due to various reasons such as improper production methods, improper production stimulation measures, too frequent well workovers, working in an unrepaired state, high-pressure injection, etc. So how do you repair oil well casing to restore production? Let's find out in this article.

API Casing Damage Repair Technology:

- Casing diagnostic technology

Casing Diagnostic Technology. This technology is used to detect and inspect casing leaks, reductions and ruptures. At present, many advanced casing diagnostic instruments have appeared, such as borehole television, borehole imaging, electronic multi-point monitors, etc. But in practice, they usually diagnose the casing condition through prints or experience, which can easily lead to misjudgment and construction failure.

- Casing drilling technology

Casing drilling technology. This is the basis of casing repair technology. Repair work can only be carried out after the pipe has been effectively opened. There are three ways to open holes: mechanical shaping, explosion shaping and milling.

- Mechanical shaping

Mechanical shaping includes two types: casing inflation and casing molding. Instruments include pear-shaped tube dilators and reels. Under the action of gravity and downward impact, the pear-shaped tube expander wedges into the deformed shell, causing it to expand and return to its original size.

- Explosive plastic surgery

Explosion shaping is a treatment for severely deformed casings. Send the shaping arm to the preset position of the wellbore. The explosion of the boom will generate shock waves and high-pressure gases, which propagate through the oil and gas in the pipeline and act on the inner surface of the casing. The casing and cement outer ring will expand, increasing the inner diameter. After blast shaping, casing is usually used to reinforce the lower liner and repair site.

- Milling pipe opening technology

For curls and burrs caused by corrosion damage to the perforations and packer seat seals, milling cones can be used to grind the deformed parts.

For severely damaged well casings, we usually use milling methods to break through. The tool should reach the deformed casing without deflecting. The tools for casing and pipe expansion include: eccentric pipe expander, movable guide milling cutter, repair milling drum, ball shaper, and probe type milling cone.

For wellbores with severe deformation and large diameter changes, cone milling is harmful. They can cause case thinning, leaks, and cracks. A milling cutter matching the casing should be selected.

- Casing repair technology

Casing repair is the main technology for casing repair. It is only 1/3-1/2 of the cost of casing window side drilling or casing replacement. Currently there are two technologies, one is bellows technology and the other is hydraulic expansion tube technology. The repaired pipeline can withstand high temperatures of 350℃and high pressure of 15MP. High strength ensures it works well in hot wells. The inner diameter remains almost unchanged and the hole shrinkage is less than 10mm.

To sum up, the current casing repair technology is becoming more and more perfect, but there are still many problems. Only by accurately diagnosing casing damage can a reasonable repair plan be formulated.