When water-well casings fail due to corrosion, breaches, or structural fatigue, the repair method must restore integrity without significantly reducing the wellbore’s internal diameter. This is critical because water wells are typically designed around the original casing size, with downhole equipment such as submersible pumps and packers selected to suit the original internal diameter. A substantial reduction in internal diameter can prevent reuse of the existing pump or downhole assembly, adding the cost and complexity of equipment replacement. It can also reduce the achievable flow rate or increase electricity consumption if the same flow is maintained, due to the higher pressure drop through the restricted section. As an alternative to conventional relining, the HydroFORM system uses hydroforming technology and inflatable packers to install a stainless-steel liner in place while minimising loss of wellbore diameter.

The core of this method utilises the HydroFORM system, an expandable stainless-steel tubular equipped with a vulcanised elastomer coating. By positioning a high-pressure inflatable packer inside this liner, the steel can be expanded in place, compressing the elastomer against the damaged casing to form a hydraulic seal. Depending on the extent and geometry of the casing damage, three primary hydroforming configurations can be used to restore well integrity.

Continuous HydroFORM Lining

For wells with localised casing breaches or a section of moderate damage, a continuous HydroFORM Liner™ can be deployed to cover the entire compromised zone. These expandable liners can be configured as a single continuous patch or multiple segments welded together to form a longer, unified seal.

During the hydroforming process, the elastomer coating compresses directly against the existing casing wall. This action creates a hydraulic seal along the interface and a compressed contact surface that anchors the liner in position.

Dual HydroFORM Liners with a Blank Mid-Section

When dealing with extended lengths of damaged casing, expanding a solid liner for the entire span may be unnecessary and time-consuming. In these scenarios, a straddle or dual HydroFORM configuration may be more appropriate. This configuration utilises hydroformed sections at the upper and lower extremities of the repair zone, with a standard blank liner between these two expandable ends. Once expanded, the top and bottom sections provide mechanical and hydraulic sealing, supporting the blank liner across the damaged span.

The blank liner is a liner without vulcanised elastomer. Using this lower-cost liner will reduce the overall cost of the repair. And since this part of the relining is not expanded or hydroformed, a PVC or FRP pipe can be used for the blank.

Cemented Relining with a Bottom HydroFORM Anchor

For severe structural failures where grouting the annulus is required, a hybrid approach utilises a single hydroformed section to support a cement column. The installation relies on a specialised straddle assembly comprising a High-Pressure (HP) HydroFORM packer, a straddle pipe, and a Low-Pressure (LP) cementing packer. This assembly is run inside the new liner to locate the HP packer at the expandable HydroFORM section at the bottom part of the liner. Because the two packers have separate inflation hoses, they can be operated independently.

First, the HP packer is inflated to swage or deform the base of the liner outward into sealing contact with the existing casing. This hydroformed section creates the lower anchor and bottom seal. While the HP packer remains inflated, the LP cementing packer is inflated higher up to isolate the one-way cementing valve located in the straddle zone between them.

Cement grout is then pumped down the drill rods, enters this isolated straddle zone, and is squeezed out through the valve to fill the annulus between the new liner and the original casing. The hydroformed part of the liner acts as the base for the cement column in the annulus. Once the annulus is filled, the LP cementing packer is deflated to flush out excess grout. Finally, the HP packer is deflated, and the setting tool is completely removed from the well.

The Hydroforming Installation and Verification Process

Setting tool deployment. The performance of the HydroFORM system relies on the precision of the setting tool and careful surface monitoring. The installation process begins by inserting the running tool, which serves as the high-pressure packer, into the unexpanded liner at the surface. This assembly is then run into the well to the desired depth.

Controlled expansion. Pressure is gradually increased within the packer until the steel liner yields and begins to expand. An important question during this phase is determining when the liner is fully set. This verification is achieved by comparing on-site data against pre-tested calibration values.

Surface verification. Before the operation, a liner-specific Pressure-Volume-Diameter characteristics envelope is generated off-site. During the actual run, operators continuously monitor the packer’s inflation pressure and the volume of fluid pumped. As the liner expands freely, the pressure curve follows a predictable unconfined expansion path. A distinct shift in the pressure-volume relationship indicates the point at which the liner reaches the casing wall.

Final setting and tool retrieval. Further pumping achieves the final expansion, compressing the vulcanised elastomer against the casing to complete the anchor. By comparing the real-time pumped volume and pressure against the established calibration chart, operators can verify the expanded size and confirm the installation. Following this confirmation, the internal packer is deflated and removed from the well.

Operational considerations. Because the ends of the liner remain uncoated, the final result is a smooth, tapered transition. This design detail helps prevent future downhole equipment and pumps from hanging up on the liner. Because the hydroforming process relies on hydraulics rather than rotation or heavy push-down force, it can often be performed using a simple crane instead of a conventional drill rig, reducing mobilisation costs and scheduling constraints.

See the HydroFORM Liner™ in action below:

Conclusion

Selecting the appropriate casing repair method depends on the length, severity, and geometry of the damaged interval. Continuous HydroFORM lining is suited to localised or moderate casing damage, dual HydroFORM configurations can be used for longer damaged intervals where full-length expansion is not required, and cemented relining with a bottom HydroFORM anchor provides an option for severe structural failures requiring annular grout support. Across these configurations, the objective remains the same: to restore casing integrity while limiting the loss of internal diameter, supporting continued use of existing downhole equipment where practical, and maintaining hydraulic performance within the repaired well.

Learn more about the HydroFORM Liner™ here.