WellLock® resin is designed to help provide wellbore integrity, thus contributing to environmental sustainability and social responsibility. It can act as an annular barricade against water and gas leaks.
Annular flow behind casing and liners (sustained casing pressure) can be experienced anywhere in the world. Experts agree that the cause of this is very complex and is likely to occur as hydrostatic pressure is no longer transferred from the slurry column to the formation during the initial hydration or transition period to a set cement sheath; or due to water or gas flow through microannuli that may form over time if the cement sheath has not been designed with mechanical properties required to withstand events during the life of the well.
The mechanical properties of WellLock resin such as density, elasticity, and strength can be tailored to meet a variety of wellbore challenges. Applications include situations where water or gas leaks need to be prevented or remediated:
- Primary zonal isolation
- Secondary annular barrier
- Remediation for annular pressure buildup or water / gas breakthrough
- Disposal wells
- Plug and abandonment
WellLock resin is not a cement system. On the contrary, the Poisson’s ratio of WellLock resin is closer to that of rubber, whereas cement is closer to that of glass. In other words, cement is inherently stiff and this resin is inherently flexible. Some formulations of WellLock resin have achieved compressive strength of up to 48,500 psi.
The shear bond strength of cement is generally 10% of the compressive strength (100-900 psi); and the shear bond strength of WellLock resin is consistently above 1000 psi. Significantly, when pumped ahead of cement, a film of WellLock resin is left behind on the formation and outer diameter of the casing and can increase the shear bond strength of cement up to six-fold (6X).
Transition of WellLock resin from a liquid to a solid is another difference. The transition involves formation of covalent bonds via cross-linking reaction that initially builds viscosity, and the resin continues to transmit hydrostatic pressure to the formation. Importantly, at the cross-over point a non-porous three-dimensional network begins to form, the resin continues to transmit hydrostatic pressure to the formation until an impermeable barrier of cured resin forms. One foot of resin has been observed to resist a pressure differential of 1,000 psi. Both the cross-linked molecules and continuous transfer of hydrostatic pressure throughout the set time create a resistance to liquid or gas channeling.
This resin is resistant to acid, base, salts and hydrocarbons. The temperature range of WellLock resin is 60°F-200°F (16°F-93°C) BHCT (bottom hole circulating temperature), up to 225°F (107°C) for BHST (bottom hole static temperature).