The ControlSEAL resin has five to six times the compressive strength of cement and four to five times more tensile strength, according to CSI Technologies.
As the oil and gas industry continues to face financial pressure resulting from the low cost of crude, the historically resilient offshore market has complied by reducing new drilling activity and directing attention to existing assets. During this downturn, there has been a steady climb in activity focused on intervention and decommissioning. Potentially less obvious than the effort to increase output from existing producers, via intervention, has been the increased decommissioning and abandonment activity.
“This is likely a function of a number of things: availability of personnel – previously in drilling – increased pressure from environmental regulators, and a reduced cost in rig rate and associated services … would seem to make this as good as time as any,” said Travis Baughman, Technical Sales Manager at CSI Technologies, a Wild Well Control subsidiary.
This increased activity in both well intervention and decommissioning has brought long-standing well integrity challenges back to the forefront. Working with old wells, whether through abandonment or recompleting/intervention, the repair of barriers that have failed over time is often required. These barrier types vary from compromised cement sheaths, leaks/cracks/holes in tubulars, packer leaks, etc. These particular failure mechanisms often exhibit very low injectivity and, subsequently, require low-volume, high-pressure treatment techniques.
This can be particularly difficult to repair when attempting to use a conventional cement. A cement slurry is a specific balance of liquid and solid components, which, once allowed to cure, create the desired solid mechanical barrier. Prior to cure, however, this balance of slurry components is susceptible to separation and contamination, which can ultimately compromise the treatment.
“Contamination is a leading cause of ‘low-volume’ remedial cement failures in any well configuration,” Mr Baughman said. “When you consider the increasing depths and restricted geometries of today’s ultra-deepwater drilling profiles, the risk of contamination is significantly increased.”
ControlSEAL resin, designed in conjunction with Wild Well Control and CSI Technologies in 2005, was developed as a specific technology to mitigate these low-volume isolation challenges. Originally crafted as an urgent response to a hurricane season that resulted in downed platforms and damaged subsea structures in need of a high-performance sealant, the product has since found application in the intervention and abandonment industry.
It is a hydrocarbon-based epoxy resin and is naturally immiscible in water-based fluids, demonstrating coalescing properties once static. These properties are critical to mitigate against the effects of contamination when small volumes are to be used. The product also demonstrates a Newtonian-type flow behavior and can be designed “solids-free,” allowing it to be pumped into tight places conventional cement systems would pack off. This allows it to penetrate deep into microannuli or microchannels where it will harden.
“ControlSEAL resin’s depth of penetration is significantly better than cement as solid separation known to occur across pressure drops or restricted flow paths does not alter the resin’s ability to achieve set mechanical performance,” Mr Baughman said.
The compressive strength of the resin is two to three times higher than that of conventional cement, while the tensile strength is four to five times higher in most cases. Because cements are particularly susceptible to tensile-stress failure, this particular mechanical property is specifically important. This, coupled with its innate chemical resistance, gives the resin advantages for improved life-of-well integrity compared with cement.
Resins have not replaced conventional cement systems, however. “I feel industry leaders are very diligent and responsible when it comes to modifying well construction/barrier techniques like that of casing and cement,” Mr Baughman said.
“In many minds, products like ControlSEAL are still very new. As technology continues to advance, we are now able to quantify some potential shortcomings in conventionally accepted cement systems while evaluating alternative materials for improvement. It is for this reason we are seeing a significant interest regarding the furthered evaluation and understanding of the ControlSEAL resin technology by industry leaders and regulators alike.
“As this information gap closes and the industry becomes more comfortable with the technology, I believe you will see an increase in use, like we are seeing now in abandonment and intervention operations, eventually coupled with conventional cement for primary well construction.”
CSI RESIN SEALANT
Long-term zonal isolation issues with oilfield cement annuli commonly result from cyclic temperature and pressure loading during the lifetime of the well. Cement mechanical properties such as brittleness and low tensile strength affect the long-term durability of the cement seal. Remediation of zonal isolation failures, such as microannuli, can be both costly and challenging to execute successfully. The relatively large particle size of Portland cement compared to a micro annulus means that it is difficult for the cement to penetrate far enough to create an effective seal.
CSI Resin Sealant was designed to address these issues and reduce remediation costs to the operator. CSI Resin Sealant is a bipartite system of an epoxy resin and chemical hardener. Unlike previous oilfield sealants, this system is insensitive to water contamination and will not dilute. CSI Resin Sealant can be effectively designed for a temperature range of 40°F to 300°F at densities ranging from 7.0 ppg to 19.0 ppg.
Features of CSI Resin Sealant
A solids-free formulation means that the resin can be squeezed deeper into a micro annulus to create a stronger seal, eliminating the need for repeating remedial cement jobs.
Low rheology means that the sealant can be easily mixed and pumped.
Used with conventional oilfield equipment such as pumps, batch mixers and dump bailers.
Cohesive properties ensure that the sealant will remain stable at downhole conditions.
Free falls through water and re-forms in the zone of interest.
Can be drilled out with standard oilfield drill bits or can withstand perforation.
Outperforms conventional Portland cement for compressive strength, tensile strength and shear bonding.
Non-shrinking and impermeable for long-term durability
CSI RESIN SEALANT CASE HISTORY #1
A client with a well located in the Gulf of Mexico was having problems with a leaking production packer. They were experiencing communication between the tubing/casing annulus and had made several unsuccessful attempts to resolve this issue. The leaking packer was preventing the well from being put on production. CSI Technologies was called out to pump CSI Resin Sealant into the annulus to the top of the production packer, essentially locking the tubing in place and sealing the annulus so gas lift production could resume. After 24 hours, a successful positive pressure test was performed, indicating that the CSI Resin Sealant had successfully set against the top of the packer and sealed the annulus.
CSI RESIN SEALANT CASE HISTORY #2
During P&A operations on an offshore well, an operator had made repeated attempts to seal the 9 7/8” casing, however gas continued to leak to the mud line between the 9 7/8” x 13 1/3” annulus. After multiple attempts, the operator selected remediation by CSI Resin Sealant. A window was milled through the 9 7/8” casing in the area of the leak, and 13 bbls of 16.5 ppg resin was pumped. The set time was 4 hours and the bottom hole temperature was 85oF. After the resin was placed, the well was shut in for 24 hours with pressure. After 24 hours, no bubbling was observed in the annulus, indicating a successful job.
About CSI Technologies
Founded in 2000 by current president Fred Sabins, CSI Technologies was formed to provide the oil and gas industry with independent, objective, high-quality cementing services and R&D. In 2004, CSI Technologies became a wholly-owned, independent subsidiary of Superior Energy Services, reporting through Wild Well Control. In 2013, CSI moved into a new 28,000-ft2 state-of-the-art cement laboratory facility for conventional field service testing, specialized laboratory testing, and research projects.
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