A challenging yet promising environment for the development of innovative techniques for the well abandonment area is emerging in the Brazilian O&G market. Given the expected amount and the wide variety of conditions in which many wells find themselves, several approaches and intervention strategies should be used to abandon wells.
In this context, there will not be a single approach or technique for all abandonment interventions, especially in the onshore environment. In fact, everything indicates that interventions that use a balanced (cost-benefit) combination of various techniques and approaches will have higher success rates. These combinations, if well planned, can bring several benefits through the optimization of the intervention's time-cost as well as a significant reduction in risks related to control, well integrity and safety of the operation.
In a scenario with full adherence to regulatory requirements for abandoning wells, the intervention can be categorized into 2 types:
Using a Workover Rig: where it is necessary to remove the existing completion and then install the WBS (Well Barrier Schematics, translated from Portuguese) in the quantities and depth indicated. For this purpose, an intervention rig or workover should be used to remove the completion and subsequent installation of the CSBs.
Rigless: where the installation of the WBS is done without the need to remove the completion, that is, the existing completion will be an integral part of the abandoned well at the end of the process. In this case, there is no need for an intervention rig, and all operations necessary for the installation of the WBS are carried out through the existing completion, that is, in thru-tubing mode.
In both cases described above, good industry practices must be considered to preserve, maintain control and integrity of the well during and after the entire abandonment process.
In the case of rigless/thru-tubing interventions, there is a great potential to reduce the total operating costs, although, in general, it requires a greater number of activities and, consequently, more time for execution. There are several approaches and thru-tubing techniques used in the stages of preparation of the well until the installation of the WBS as following:
Slickline - A thin non-electric metal cable used for selective placement and retrieval of accessories and/or tools in the well.
Wireline - electrical cable used to lower and retrieve specialized tools from the well with the ability to collect and transmit data to the surface.
Coiled Tubing - A long, continuous flexible tube wound on a spool (for transport) that is lowered/pushed into the well for various purposes, from simple circulation/placement of fluids, installing/recovering accessories and/or tools, even more complex operations such as logging, perforation, etc.
The techniques described above are conventional approaches, widely applied and known in the O&G industry, however there are other techniques under development that may add value in well intervention and abandonment scenarios. As with alternative materials for the composition of WBS (discussed by A|F Consulting Partners in the article Alternative and Emerging Materials for Wells Abandonment), they must be pre-tested and validated in the field before being used as a viable option. Likewise, these new techniques should follow the criteria of the local Well Integrity Management System and good industry practices.
The future demand and challenges for abandoning wells in Brazil bring an interesting opportunity as an area for the implementation of innovative solutions, whether in alternative materials, new approaches and intervention techniques. And not only in the technological area but also in the scope of operational process management, where the concept of integrated project management gains strength due to the benefits of optimization and cost reduction, now with an emphasis on reducing carbon emissions and adherence to an ESG posture (environmental, social and governance).
Finally, it is always worth pointing out that all this will only be possible, under a consensus, through the involvement of a well-trained workforce qualified in the technical-regulatory requirements that the well intervention and abandonment area requires. In this sense, operators, service companies, academic area and regulatory agents should cooperate to establish a favorable environment for this to be established, as well as the implementation of innovative solutions (alternative materials, new techniques, etc.) for the challenges posed to abandonment of wells.