Microannular leak paths between the casing string and cement sheath can result in the migration of hydrocarbons or previously injected fluids to the surface or into nearby aquifers. Operators need to protect against microannular migration over the entire life of the well, including abandonment.
Total annular isolation is required in at least one point in the well to help prevent microannular fluid and pressure migration between casing string and the cement sheath.
The Weatherford Micro-Seal® isolation system unit (MSIS-U) incorporates ultraslow swell-rate elastomer seals, specifically designed for microannular isolation.
The stand alone, slip-on device is designed to swell against the OD of the casing and into microannular spaces that may form after the cement is in place. When deployed with our industry-leading mechanical cementing products, the MSIS provides maximum standoff to achieve the most efficient displacement of mud and the most effective placement of cement. The systems provide the best possible chance of achieving isolation to reduce remedial cementing operations and expensive workovers.
The hybrid elastomers used in the swellable systems have an ultraslow, swell-rate formulation designed specifically for microannular isolation.
The elastomers have been designed so that they do not react with fluids in the well when the pipe is run or with the mix water in the cement as it is curing. The MSIS-U also features a unique swell cage to provide extra strength while the end rings protect the elastomer during run-in.
The MSIS-U is a customizable system comprised of a family of elastomers and centralizer designs for deployment in a range of wellbore geometries and reservoir temperatures.
The elastomer is available in a slow-swelling form for deployment in wells with ambient temperatures of 66°C up to 150°C (150°F to 300°F) to prevent premature swelling and sticking prior to arriving at the designated isolation point. For wells in the range of 38°C (100°F) or lower, another elastomer can be used to swell more quickly and provide faster microannular isolation.