For decades to date, Portland cement slurry has been successfully pumped in offshore and onshore environments to line wells.
In conventional cementation with Portland cement, specific additives are mixed with mixing water, and/or in the cement itself to prepare the cement paste, and then pump it into the well. As it hardens, it will act as a coating, barrier and sealing material to insulate the reservoir and formations with potential for flow, thus preventing the migration of fluids between permeable formations and to the surface or seabed.
The cement paste has also been successfully used in Solidary Barriers Set (CSB) to isolate the reservoir and permeable zones in wells that will be plugged for permanent abandonment due to the end of its production life.
Based on recent and not-so-recent research, alternative materials have appeared on the radar in place of cement paste used for abandonment plug operations.
They are:
Concentrated bentonite;
Low melting metal alloys (Bismuth);
Thermo-Activated Polymers (Resins);
Unconsolidated sand slurry;
Geopolymers;
Thermite;
The application of these materials must follow the criteria of the Well Integrity Management System (SGIP) and the good Industry practices regarding the CSB, thus ensuring the present and future integrity of the insulation.
Obviously, they must be previously tested in the laboratory and validated in the field before being used as a CSB.
Decommissioning in Brazil opens up a range of opportunities to introduce alternative materials that must be duly approved by the competent entities and by the relevant legislation. Operators should add value with a possible reduction in the costs of imminent campaigns to abandon wells.
Alternative materials can signal a significant change in the well abandonment scenario if they are economically viable, and fulfill their purpose.
It is extremely important that a well is properly and permanently abandoned the first time, thus avoiding environmental problems, life risks and unnecessary expenses for the operator.
Ensuring Safe and Responsible Well Abandonment as a Critical Part of Successful Decommissioning of Any Oil and Gas Asset:
Technological Qualification
Technical Solutions
Abandonment Programs and Procedures
Cost Analysis & Estimates
Project Management
Environmental Impact Assessment