Prefracturing Expandable Steel Patches | SLB

Prefracturing expandable steel patches

Restore casing integrity to allow high fracturing pressures across damaged completions

Artwork shows well pad with frac trucks and a horizontal well with multiple zones for fracturing.

Our prefracturing patches use field-proven Saltel Xpandable™ expandable steel technology and are rated up to 302 degF [150 degC]. They seal securely, while allowing passage of fracturing equipment (such as frac plugs or CT shifting tools), and withstand hydraulic fracturing pressures up to 10,000 psi [69 MPa]. Download the datasheet for detailed specifications.

Restore casing integrity to allow high fracturing pressures across damaged completions (such as leaking DV tools, split casings, or damaged frac ports that open prematurely) with minimal loss of ID.

Downhole expansion tool positioned within a Saltel expandable steel patch.
Downhole expansion tool positioned within and enlarging the topmost section of an expandable steel patch.
Downhole expansion tool positioned within a Saltel expandable steel patch.

In the Marcellus Shale, an SLB prefracturing expandable steel patch sealed off perforations about 6,000 ft into the lateral following a cement squeeze. Enabling remediation of unsuccessful primary cementing avoided a sidetrack, reducing costs by at least 17%. Read SPE-218322 for details.

Saltel expandable steel patches are a permanent solution, capable of molding to irregular geometries. Expanded with an inflatable packer downhole, the prefracturing patch has a special design to ensure sealing against the irregular profile of frac ports; it creates a high-pressure inner lining that seals off and protects damaged casing or tubing from further loss of integrity. Overlapping patches can be used across long breaches. The large ID enables nearly unrestricted access to the wellbore below, so drilling, completion, or well intervention operations can continue and frac plugs, frac balls, and most bottomhole assemblies can pass through as required. Using these patches to seal off unwanted perforations can save multiple days of rig time—hence reducing cost and emissions—and significantly improve the likelihood of success compared with cement squeezes.

Our engineered system provides a resilient and reliable seal that is able to withstand significant differential pressures and thermal cycling, which can compromise the integrity of alternative sealing technologies over time. In addition to the profiled external seals, the patches can be secured with anchoring strips to mitigate slippage risks due to axial loads and withstand the lateral forces and wear encountered if drilling ahead. The patch can be run on tubing, drillpipe, or coiled tubing.

The patch is made of high-quality stainless steel with an elastomer outer skin. It uses a profiled sealing system that conforms to varying IDs and is applied and cured in a controlled environment during manufacturing, employing different materials based on the application requirements—unlike the field-applied epoxy resin used by some providers.

How is the patch installed?

The downhole expansion tool is positioned inside the patch and its packer section is inflated enough to grip the inside of the patch. The assembly is run in hole, and once it is at depth, the packer is further inflated using pressure from surface. The top of the patch expands and is pushed against the casing or tubing being repaired to activate the outer seals and anchor the patch in place. The packer is subsequently deflated, run in another 3 ft [1 m], and reinflated. The process is repeated until the full length of the steel patch has been expanded. By expanding the patch from the top down, the risk of a stuck setting tool is minimized.