What are your options for succesful P&A?
The majority of standard P&A operations require a rig that immediately introduce increased costs to the operator. Typically plugging back of wells utilize cement or a combination of mechanical plugs and cement.
From the Well Integrity blog: Plug and Abandonment: What legislation and job design should apply?
Mechanical sealing: Cement
Mechanical sealing methods of placing a plug in a cased part of the well is a proven concept across the industry. Quite often casing integrity is compromised due to the age of these assets and can be unreliable as a result of corrosion or tubular erosion. Identifying an intact setting depth for sealing elements can prove difficult and ultimately result in failed pressure tests.
Cement is the most common material used for P&A. Placing several cement plugs on top of mechanical plugs set at various depths in the well is a common abandonment technique. If the well is intact with no difficult leaks detected outside the inner casing strings and the completion can be pulled without any issues, the placement of mechanical and cementitious plugs is a straightforward and reliable method for P&A.
Common complications
Complications with well abandonment arise when annular integrity is compromised. In order to gain access to the compromised annulus the casing must be cut and pulled, section milled, or perforated. The annulus is then typically sealed through conventional means by placing a cement plug across the target interval and squeezing cement into the leaking annulus. This can become difficult due to the inherent limitations of cement. A cement slurry is comprised of particles that can bridge off in small cracks and pores and make it difficult to squeeze off and seal small leak paths.
Other wells can have various problems with the completion, it could be leaking, broken, split, collapsed. Casing could also be collapsed. All these issues could make it hard to do a conventional P&A because you may not get to the area you want to treat with a work string.
When do you need an alternative solution?
When the well provides extra challenges, Wellcem’s resin technology and solutions can be a good alternative. Wellcem has proven multiple times that ThermaSet® resin technology is far more successful in sealing an annulus than for example by using cement.
The resin can also be made light or heavy and because it is immiscible with water, it can reach places cement cannot because cement will be diluted on the way. Therefore, the Wellcem solution is gaining popularity in P&A operations.
From the Well Integrity blog: Requirements for plug and abandonment of oil and gas wells - Legislation and Job design
