Epoxy resin cement ensures zonal isolation for abandoned offshore well

Summary

Petrobras used ResinLock Cem™ epoxy resin and cement system to ensure cement barriers within the production string and annulus, enabling permanent abandonment of a deviated well in the Campos Basin.

Objective

Petrobras was performing a permanent abandonment of a highly deviated offshore well located in shallow water. To meet Brazil’s regulatory standards, the operator needed to establish two competent cement barriers—one within the production string and another in the annulus between the production string and casing—to ensure complete isolation of the zone of interest.

In the first operation of this type with SLB, Petrobras planned to pump a slurry directly down the production string, through perforations in the tubing, and up the annulus—placing the slurry in the annulus and the production string in a single operation. To achieve this, Petrobras required a slurry with tight fluid loss and free fluid control. SLB proposed using the ResinLock Cem system, a specially formulated blend of cement slurry and epoxy resin, for its optimal slurry and set cement properties, which include thickening time, compressive strength, tensile strength, and shear bond. SLB also recommended pumping heavy brine and surfactant spacer fluids prior to the resin cement system, which would maximize cement-to-casing bonding, mitigate the impacts of contamination, and improve slurry injectivity.

Results

To prepare the final resin slurry system, SLB added 10% resin by volume to the base cement slurry. In total, 97 bbl of the ResinLock Cem system were pumped from a moored vessel. The cementing job placed 545 m of cement outside the tubing and 366 m inside the tubing. Petrobras planned the top of cement to be 179 m deeper inside the tubing—ensuring that logging tools could be run to evaluate cement quality behind the tubing. At the end of the pumping treatment, fluid equilibrium inside the well was controlled by maintaining pressure until the slurry set. After waiting on cement, the operator ran a cement bond long and tagged the top of cement inside the tubing. Logging results showed that the ResinLock Cem system provided high bond quality throughout the zone of interest, confirming complete isolation of the target zone.

As a result of the successful operation, Petrobras applied the ResinLock Cem system in 15 subsequent wells using various placement techniques, including bullheading through tubing and coiled tubing. Petrobras plans to continue using the system in upcoming well abandonment projects.

Diagram of the well schematic identifying the production string and casing.

Well schematic showing placement of the cement inside and outside the production tubing.

Cement bond logs confirming high bond quality.

Logged section of uncemented pipe (left) and logged section of cemented pipe confirming isolation (right). Well logs confirmed high bond quality between the casing and the wellbore, meeting the intended design criteria for permanent well abandonment.