Wellbore stability is an oil-and-gas-industry business imperative. It is essential to the realization of a well’s economic potential throughout drilling, completion, and production phases. A properly designed wellbore architecture can help reduce the costs of primary operations by minimizing non-productive time due to drilling delays or even unplanned casing strings. It can also avert the need for remediation if designed to address fluid/gas flow in the annulus that can lead to wellbore integrity issues and/or interfere with production.
A properly designed resin system can help with wellbore stabilization and the hydraulic annular seal by complementing the cement sheath during drilling and completion operations. A resin system can also be used to regain wellbore architecture integrity should remediation be required. Lastly, a properly designed resin system can be used as a primary application with chemical disposal and injection wells and deliver secure plug and abandonment of wells at the end of life.
LockCem™ Cement
LockCem™ cement is a proprietary blend of a water-tolerant resin, WellLock® resin system*, with any class of Portland cement. This blend is compatible with Halliburton additives, enabling the cement system to be customized for specific pumping-operations and wellbore conditions. Research has shown that the addition of resin to cement can result in improved mechanical properties in comparison to the base cement.
LockCem cement provides the best of both the resin and the cement qualities, while overcoming the challenges of oilfield resin use. Only a percentage of the overall blend involves the resin system, which enables the economic use of the high-volumes of slurry required for primary cementing while conveying specific properties for improved cement-system performance. The resin transmits long-term performance advantages to the cement sheath including increased compressive strength, a lower Young’s modulus for greater ductility, and an increase in shear bond strength. Permeability of the cement can also be significantly reduced due to the incorporation of resin in the design.
The resin system in LockCem cement forms a dense, highly cross-linked matrix. The extent of the cross-linking reaction is determined primarily by volume, temperature and time. The distribution of resin throughout the slurry acts like shock absorbers between the particulates of the cement, increasing ductility and the resiliency to withstand stress from load-inducing events throughout the life of the well.
Research has shown that the addition of resin to a cement system can result in a lower density and improved mechanical properties in comparison to the base cement. This chart provides data indicating an increase in shear bond and compressive strength of LockCem cement versus the base slurry.
WellLock® Resin
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).
For more specifications:
http://www.halliburton.com/en-US/ps/cementing/cementing-solutions/resins/default.page?node-id=hfqela4d
A properly designed resin system can help with wellbore stabilization and the hydraulic annular seal by complementing the cement sheath during drilling and completion operations. A resin system can also be used to regain wellbore architecture integrity should remediation be required. Lastly, a properly designed resin system can be used as a primary application with chemical disposal and injection wells and deliver secure plug and abandonment of wells at the end of life.
LockCem™ Cement
LockCem™ cement is a proprietary blend of a water-tolerant resin, WellLock® resin system*, with any class of Portland cement. This blend is compatible with Halliburton additives, enabling the cement system to be customized for specific pumping-operations and wellbore conditions. Research has shown that the addition of resin to cement can result in improved mechanical properties in comparison to the base cement.
LockCem cement provides the best of both the resin and the cement qualities, while overcoming the challenges of oilfield resin use. Only a percentage of the overall blend involves the resin system, which enables the economic use of the high-volumes of slurry required for primary cementing while conveying specific properties for improved cement-system performance. The resin transmits long-term performance advantages to the cement sheath including increased compressive strength, a lower Young’s modulus for greater ductility, and an increase in shear bond strength. Permeability of the cement can also be significantly reduced due to the incorporation of resin in the design.
The resin system in LockCem cement forms a dense, highly cross-linked matrix. The extent of the cross-linking reaction is determined primarily by volume, temperature and time. The distribution of resin throughout the slurry acts like shock absorbers between the particulates of the cement, increasing ductility and the resiliency to withstand stress from load-inducing events throughout the life of the well.
Research has shown that the addition of resin to a cement system can result in a lower density and improved mechanical properties in comparison to the base cement. This chart provides data indicating an increase in shear bond and compressive strength of LockCem cement versus the base slurry.
WellLock® Resin
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).
For more specifications:
http://www.halliburton.com/en-US/ps/cementing/cementing-solutions/resins/default.page?node-id=hfqela4d
