Fractures and microannuli within and around the cement sheath can lead to annular production of unwanted water, reservoir liquids, or gas which can travel to surface. This can result in leaks in wells that have been plugged, or lead to annular pressure buildup in producing wells, which may then require well shut-in until remediated to prevent casing collapse or wellbore failure. Leaking wells pose a costly environmental hazard, and curtailing or shutting in a producing well has substantial financial impact which in some cases can reach hundreds of millions of dollars per well per year. This paper presents work on a new resin system for sealing such microfractures and annuli to prevent unwanted flow and return wells to a desired safe and profitable state. This new approach is based on a water-soluble resin which is crosslinked to provide controllable gel times that can be tuned to meet operational needs. Data will be presented on measurement techniques, thermal stability, and resistance to hydrostatic pressures. The water based fluids are designed for deepest possible penetration into microfractures and annuli to provide the best seal against unwanted fluid flow. The treatment fluids are solids-free with low viscosity during the pumping stage, and exhibit a rapid right angle set at the desired temperature. An example would be a resin system designed for use in 120°F conditions with a gel set time achieved in one hour. Depending on the formulation, reasonable gel times from 1-2 hours have been achieved for application temperatures from 40°F to 200°F. Data will be presented on the long term stability and resistance to pressure and fluid influx over time. Case studies will also be described as available. This novel solids-free resin system is ideal for either top-down squeezes down the annulus or via downhole milling and injection to seal unwanted production zones. This work involves novel chemistry that provides an easy to apply water based product, with lower cost, and higher performance sealing system than anything currently available. They also represent a environmentally preferable alternatives to currently used fluids based on epoxy systems and monomers. The wide application temperature window makes it ideal for both onshore and offshore applications.

Novel water based resins for wellbore annular repair

254th National Meeting (2017)

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