Unplanned Sustained Annulus Pressure (SAP) in the A Annulus (sometimes referred to as the tubing/casing annulus or TCA), is the most common of all well integrity management challenges. Typically, this is as a result of a failure in a well integrity barrier envelope element / component. Monitoring for this situation is of critical importance because it generally means the ‘double barrier' well integrity policy that most OPCO's follow is breached. Depending on the nature of the SAP, it is often necessary to close in the well pending workover. In other cases, where a workover is not economically viable, the well may be prematurely abandoned. Alternatively, the wells may remain in operation ‘under dispensation'.
In the cases where wells continue to operate ‘under dispensation' increased manpower is required for monitoring and manual bleed down. This is to avoid the SAP exceeding the Maximum Allowable Annulus Surface Pressure (MAASP) and to monitor for any changes in the nature of the SAP. In addition to the obvious increased risks associated with a pressurized annulus, where only a single barrier to flow exists, other significant risks are also, often unknowingly, accepted. This is due to the way annulus pressure is typically measured and recorded. These annulus pressure measurement risks and a field proven solution to mitigate them, are described in this paper.
The paper also describes a field proven solution to the challenge of managing wells with unplanned SAP in the A annulus. It involves retrofitting technologies, which were originally developed for use in gas lifted wells, where the wells are designed to cater for planned SAP in the A annulus.
A leak from the A annulus of a gas lifted well would usually pose a higher risk of an explosion than would be the case from a non gas lifted well with SAP in the A annulus. Consequently, the paper therefore concludes that the approach used to provide a double barrier envelope to prevent a gas release from the A annulus in gas lifted well, can therefore also be applied in non gas lifted wells, where the SAP in the A annulus is unplanned. As a result, the risks of operating wells ‘under dispensation' are reduced. Wells which previously had to be killed or plugged pending workover or abandonment, may also be reclassified as ‘capable of operating under dispensation'.
The paper describes how the system can be automated, to facilitate autonomous annulus pressure monitoring and bleed off without manual intervention. It goes on to discuss how the nature of the SAP can also be tracked and the sampling frequency optimised.
Finally the paper describes how these technologies can be retrofitted to existing wells. This is possible, without the need for workover, annulus depressurization, wireline intervention or significant wellbay piping modifications.