P.2 ~ Abandoned but not forgotten: managing wells near end of life

Many producing offshore oil and gas fields include a mixture of operating, suspended, and abandoned wells. One continuing challenge for the operators is to distinguish between those wells that have been suspended (i.e. for workovers) or abandoned safely, and those that are not correctly treated. Well integrity management systems combine well operating and production data within a framework for decision-making, management processes, and organizational structure.

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In the US, regulatory standards require specific provisions for plugging and documenting oil and natural gas wells before they are abandoned. P&A regulations vary to some degree among states, but all prescribe the depth intervals that must be cemented, as well as the materials allowable in plugging practices.

Despite a consensus that the processes and regulation relating to abandonment need to be vastly improved, wells continue to be plugged at the lowest possible cost and in accordance with the minimum requirements mandated by regulators. This is because P&A work is capital-intensive and provides no return on investment for operators.

In the US and Europe, the OSPAR Convention – the current legal instrument guiding international cooperation on the protection of the marine environment – mandates that an abandoned well remains the responsibility of the owner. According to a report issued last year by the UK's Royal Academy of Engineering on decommissioning in the North Sea, should ownership of an asset be transferred during the field's lifespan, liability transfers to the new owner in most cases. However, there are cases where it remains with the seller. For example, should a new owner default, liability reverts to the original license holder. As such, the report notes that there is a generally accepted understanding within the industry that, "if you put it there, you take it away." Operators must therefore take the utmost care to protect the environment at all stages of the P&A process to avoid potential remediation or litigation costs should issues with an abandoned well arise at a later date.

It is worth noting that recent high profile incidents in theGulf of Mexico and the North Sea occurred during operations related to well abandonment. These events serve to highlight the importance of adopting an asset management strategy that ensures the continuous integrity of wells from design and construction, to operation, and finally abandonment.

Getting ahead of the curve

Scaling, corrosion, and failed well barrier equipment are all common issues that call for vigilance to minimize the risk of leakage. The fact is that thermodynamics always catches up with you: When there is a piece of unprotected steel in the ground it will corrode. Any new engineering system will have some failures due to human error or material defects. There will also be a steady rate of failures that can be corrected routinely by maintenance and repair, before corrosion or fatigue damage eventually sets in.

However, many oil and gas operators find that the level of well "infant mortality" is far too high – wells that come into service and quickly develop various integrity issues. Equipment leak testing and annulus pressure monitoring also identify a high frequency of failures with the associated maintenance demands that this brings. As a consequence, many wells are terminated prematurely before the end of their cost-effective life. Tools that allow well integrity to be controlled at every step tackle all these problems and result in wells achieving their design objectives. An advanced well integrity system enables operators to consolidate all of their well data and manage the full lifecycle of their wells.

Using web-based well integrity management software with smart functionality make it possible to acquire information from multiple sources – including third-party databases and legacy systems – and to display it in a single management dashboard. This provides an instant view of current well integrity status as well as historical key performance indicators (KPIs) at a well, field, or enterprise level.

Operators receive email warnings of wells where conditions indicate that well barriers are failing and there is a risk of a leak. The software also performs added-value analysis of the data collected to identify developing problems. This allows operators to track wells that are at risk of failing and to take preventative action to keep them safely in production. In addition, they can ensure a safe and effective P&A or well suspension at the first attempt because the well condition is known in detail.

If a well is suspended properly, and the operator has a full history of the materials used, equipment installed, and the damage the well may have sustained over its life, it may also be possible to recover or re-design the well. Thanks to advances in drilling and well design, temporarily abandoned wells could prove to be extremely valuable assets. Crucially, using historical well integrity data to improve front-end processes and equipment selected based on past performance and lessons learned can drive down operating costs, optimize maintenance, reduce workovers, and increase profitability of well operations in the long term.

Editor's note: Intetech, which was recently acquired by Wood Group, is now known as Wood Group Intetech, part of Wood Group Kenny.

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