Well integrity comes of age

Dr Liane Smith, Wood Group Intetech, UK, looks at the history of well integrity management, its deployment today and its role in the future.

Hit by a reduction in revenue, oil and gas operators are currently focusing on cost-saving initiatives and pulling back from more speculative investments. Exploration activity has experienced a strong downturn; instead operators are concentrating on squeezing maximum value from existing assets.

User-focused well-integrity management software is needed to achieve total operational control.

However, getting maximum production out of these assets, particularly older ones that are close to or even beyond their originally anticipated lifespan, requires vigilance. Optimised production from wells must be achieved without worsening damage mechanisms such as erosion and corrosion. Tuning chemical treatments to optimise production in wells which have a tendency to scale requires continuous attention if costly chemicals are not be wasted through over-treatment. Evidence-based decision making is needed when evaluating whether a well that is exhibiting symptoms of a potential problem is safe for continued operation.

When there are so many parameters to monitor and when timely warning and responses are necessary, a well integrity management system, delivered through user-focused software, is needed to achieve total operational control.

A decade of development

It is now almost 10 years since the first operators took the step of implementing well integrity management. Those pioneers worked without the benefit of international standards for guidance. At that point, only the NORSOK standard D010 on well integrity existed (published in 2003); API RP 90, with its focus on annulus pressure management, did not appear until 2008.

It is really only since Macondo in April 2010 that the industry has pooled its expertise to generate international guidelines and standards on well integrity management. In 2012, Oil and Gas UK generated well-received guidelines on well integrity and on suspension and abandonment. Two years later, the international standard ISO 16530 Part 2 on well integrity management in the operational phase was published.

In the unconventional arena, the Queensland Code of Practice for coal seam gas (CSG) well head emissions, detection and reporting was published in 2011, followed in 2013 by the Code of Practice for constructing and abandoning CSG wells.

Successful deployments

Operators today benefit enormously from these initiatives and can apply many excellent concepts to the optimisation of their well integrity management procedures to achieve both economic advantage and safe operation. Yet even without such guidance, early adopters of well integrity management software were able to derive economic benefit.

The earliest applications of these systems were in fields producing hydrogen sulphide. The focus was on leak prevention in the face of particularly toxic well fluids. However, because most wells have the potential for catastrophic failure, as well as less dramatic but still reputation-damaging leaks, the software spread in application to both conventional and unconventional wells.

Well integrity management software has since been adopted by operators of mature fields to reduce the costs associated with shut-in wells. Evidence from the field suggests that up to half of all shut-in wells and half the workovers have been caused by integrity problems. But where state-of-the-art well integrity management software has been used, operators have been able to get on top of those problems and stop them dominating and interfering with production.

In at least one case, an operator has been able to halve the numbers of wells that are shut in due to well integrity problems within two years of implementing well integrity management software. Because the software was able to identify the most problematic wells and highlight the specific issue that needed to be addressed, the operator could design a permanent solution to the problem. In this instance, well intervention moved on from being a fire fighting activity focused on treating symptoms and became a more strategic and proactive function that focused on dealing with underlying root causes.

Well integrity tools have also been used to optimise the frequency of preventative maintenance, often focusing on specific at-risk equipment in order to keep it operational for a longer period. With the information provided by well integrity systems, operators can minimise production downtime by planning repair-and-replacement work on equipment with a high likelihood of failure to coincide with other interventions on the well.

New levels of insight

Since the early days, the levels of control have become even more granular. Information gained from well integrity management systems enables operators to take preventative action against an asset’s underlying weaknesses, or to proactively respond as minor problems arise.

Modern well integrity management software can generate figures to show the frequency of equipment failure and mean-time-to-failure. This data pinpoints which specific types of equipment or models work reliably and which are more prone to problems, enabling operators to identify which wells have the more problematic equipment installed. This in turn enables evidence-based, performance-led decisions regarding maintenance, which has helped to reduce the frequency of routine preventative maintenance (PM) for wells with more reliable equipment.

Proprietary information remains the basis for effective decision-making, but well reliability software also enables operators to share their barrier element-reliability data with other operators. It helps enhance an operator’s knowledge of areas where they may have less experience, and broadens the statistical base for future decision making by drawing on existing asset data for use in quantitative risk analyses.

These highly evolved systems sit at the heart of preventative and proactive maintenance operations: resolving issues in a timely fashion, instead of waiting for problems to escalate. The commercial advantages have become clear, as have the benefits of improved safety and compliance records.

Maximising output from ageing assets

All of which brings the industry up to date in the current low-price environment. With opportunities to invest CAPEX in new and potentially more risky sites, keeping older assets in production has become a favoured option.

However, this requires an even higher level of vigilance. Environmental limits define the conditions that will prevent the acceleration of asset deterioration as well as catastrophic failure. Every well has a set of operational limits, as defined in ISO 16530, within which safe operation is proven, and all assets must be maintained within their safe operating envelope at all times.

Inevitably, such operational limits need to be reviewed as assets age, and will typically become tighter over time. For example, as wall thickness decreases thanks to corrosion and wear, so operational pressure limits are reduced and tolerable corrosion rates constrained. Either the frequency or the concentration of corrosion-inhibitor treatment may need to increase as a result.

Keeping track of these and all other relevant parameters across multiple assets requires integrity management systems that can react quickly to any breaches of these safe limits. Although global controls are often set, they still need to ensure that the nuances of individual wells are accounted for.

The right technology will allow operators to run each well to a unique set of proven operational limits. It also provides some form of real-time rapid response (typically involving email alerts being automatically sent to key parties) so that operators can respond immediately if limits are exceeded. Without this form of rapid response, wells can only be run at very conservative, centrally established limits – with inevitable consequences for profitability. In the case of ageing assets, where the safe operating envelope offers operators very little room to manoeuvre, integrity management enables them to make the most of their assets by ensuring they work safely at the boundaries of performance.

An unconventional future

Looking beyond the current price environment, the future of oil and gas production will involve greater exploration and exploitation of unconventional fields such as shale gas. Plans for shale gas may currently be dialled down in key areas, but the new generation of shale gas operators recognise the benefit of advanced well integrity management tools in countering the reputational damage caused by reported loss of integrity by some international shale operations.

Here the advantages of well integrity management are not confined to optimising output from wells, but also addressing opposition to fracking operations and shale gas production. Well integrity management software is already being deployed to monitor and trend the fluid composition in the relevant aquifers before, during and after drilling and fracking to identify any possible fluid contamination from well construction and fracking. It is likely that regulatory bodies will wish to see such a level of control being implemented more widely, and there is even the potential for trend data to be made publicly accessible to provide ongoing reassurance to local populations.

Well integrity management tools are also being deployed in other unconventional areas. Coalbed methane fields in Australia have a particular focus on using advanced tools to monitor for leakage. In this instance the concern is more around protecting local environments from gas emissions, as well as ensuring the health and safety of operating staff and other land users. Faced with responsibility for several thousand wells, operators have little option but to use software that is able to monitor well data and report exceptions simply to keep on top of operations.

Lessons, trends and challenges

After 10 years of direct operational experience, a number of clear trends and important challenges have emerged in well integrity management. The first is that there has been a keen desire to move to a global approach by operators with international operations. This has created challenges for software, in that it must be applicable in various jurisdictions with national or regional regulations providing the framework for integrity controls.

The second is that global systems need to integrate a diverse array of legacy third-party software and databases which contain different parts of the integrity story. Relevant data is typically stored in a variety of repositories: production data, for example held by operations; preventative and corrective maintenance in maintenance management systems; and drilling activity records in drilling information systems.

To obtain a comprehensive view of the well’s performance, well integrity engineers often have to keep an eye on the output of a number of different systems. Which leads to the final and perhaps most fundamental challenge for monitoring and managing well integrity. Monitoring multiple systems is error-prone and can create gaps in the integrity picture. But getting part, or even most, of the information is not good enough: operators that do not have the whole story do not have any of the story.

If there is a possibility that the information gathered is even partially inaccurate or incomplete, they cannot be confident about the conclusions they reach, or sure that proposed actions are the right ones to take. For well integrity technology to deliver on its promises, it needs to deliver a holistic view of any given well and field. The integration piece is therefore of critical importance.

The long-term view

Operators need to be aware that what they are managing today is not going to remain constant. The safe operating envelope of each well needs review, adjustment and tightening over time.

Integrity challenges will also evolve. The water cut rises in oilfields over time and once water breakout conditions are reached and the limit of water-carrying capacity of the water-in-oil emulsion is exceeded, corrosion rates can accelerate rapidly. Well integrity management systems that incorporate advanced corrosion modelling capabilities can generate the real-time evolution of corrosion rates, automatically triggering chemical treatment workflows to bring the corrosion back under control.

Implementing a software system is generally a long-term decision so it is important that the system implemented is structured in a flexible way to be future proof. The integrity challenges of tomorrow may be hard to anticipate today, but it is wise to be prepared. The ability to quickly adjust to new threats will be essential.

Adapted by David Bizley

Published on 14/05/2015

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