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Zonal Isolation to the Extreme

16–21 February 2014 :: Vilamoura, Portugal


Technical Agenda

Session 1: Introduction to Zonal Isolation

Session Managers: Iain Whyte, Klisthenis Dimitriadis, and Gary Evans

With so much emphasis on the need for exceptional well integrity one must ask—what is successful zonal isolation, and how is it defined in all shapes and guises?

The answer to this question will inevitably affect our standards and determine whether current standards are appropriate and consistent for each well type and situation. It would be interesting to see how many of our wells actually meet these standards from cradle to grave. Defining and measuring acceptable limits is a big discussion likely to lead to several iterations.

This session will introduce the wide ranges of environments in which our wells are drilled and examine the range of different company and legislative standards in use today.  We will invite participants to complete a brief survey on their thoughts on current standards and how their company interprets, achieves and verifies well integrity standards. The results will be collated for further discussion in session 9 (Abandonment Isolation). Areas to be explored by the questionnaire:

  • What defines zonal isolation success
  • What are the standards that need to be met from a legislative and intra-company perspective
  • Where the ‘bar’ is at the moment, and where do we want to raise it to
  • How consistent are these standards among different countries and companies
  • Do we fully understand everything we have in the “toolbox” and how much of it is commonly used
  • What is the implication of “inheriting” wells of questionable isolation standards and do we always fully appreciate what we are getting

Session 2: History Cases of Failures

Session Managers: Tore Fjagesund and Paul Hopmans

Case histories will be presented of accidents and some close calls. How has zone isolation, or lack of such, contributed to these incidents. What have we learnt from this? We have heard and seen speculations and facts of loss of isolation being one of the root causes, has this affected how we do our planning today? To what extent is the loss of zone isolation affecting our planning and risk assessment? How is the need for zone isolation affecting the establishment of barrier definitions in the wells? Moreover, what technologies are needed and how urgent are they required to mitigate future failures or facilitate the effective implementation of the lessons learned processes in to the design or repair of wells?

Session 3: How Do We Ensure Lifecycle Design?

Session Managers: Valerie Wilson and Philip Wodka

The industry is working to develop a standardised design that meets the business objectives of the well while creating and sustaining well integrity through the lifecycle, which commences with the conceptual and detailed design of the well, continues with construction and the operational phase, and ends with the final abandonment of the well.

This session will address what is needed to identify potential hazards and to define appropriate barriers and operational philosophies that are capable of mitigating the hazards, assure well integrity, and ensure compliance with safety and environmental standards—where we are today and where we may need improved understanding.

In this session we will explore such topics as:

  • What hazards are we trying to mitigate?
  • Which hazards may lead to isolation failure during installation?
  • Can we incorporate well integrity mitigation options in the planning?
  • Regulatory requirements—what standards govern? What is in development? What should we be looking at? Abiding by? Concerned about? What influence do we have?
  • Basis of design and ability to identify and understand the hazards: Significant contributions to overall risk? Requirements posed by potential future use of the well and abandonment?

Session 4: Well Engineering Tools and Standard

Session Managers: Gunnar de Bruijn and Bill Hunter

When designing a well to meet lifecycle requirements engineers have access to a wide range of tools, standards and recommended practices (RP’s) that can be used to help plan for the required level of well integrity. In this session, we will first look at the tools in present use, including software and physical modeling and testing. Then we will examine the standards and RP’s used by practitioners. The applicability of API Standard 65-2, Norsok D010, ISO 15630 Part 2, and other industry standards to all types of wells including HPHT, thermal recovery wells and deep water wells will also be examined.

From this we will aim to identify key well design engineering zonal isolation needs that remain unmet by the available toolset and brainstorm potential ways of meeting these.

Session 5: Design Against Zonal Isolation Hazards

Session Managers: Vidar Rygg and Jip van Eijden

We explore new ideas within reach of today’s technology:

  • Zonal isolation risk mitigation
  • Planning of zonal isolation
  • Preventive vs. corrective zonal isolation
  • Novel isolation methods
  • Blue sky science

For decades, steel and cement have been used for well construction. The materials have had two objectives—supporting the casing/tubing mechanically to the adjacent well section(s), and isolating pressurised zones from each other. Are we making it difficult by trying to achieve both objectives with one material? Can we combine materials that are better suited for one specific purpose? During the well life pressure seals may be compromised even if the mechanical properties are upheld. Can we build in self-healing or redundant functions? Can permanent monitoring of annuli act as an early warning system and reduce cost of, or need for, repair? Can we design subsea wells differently? Do we sacrifice robustness when we design more and more complex wells?

The benefit of preventive design may not be properly addressed if cost of remediation and final abandonment is underestimated. Do we properly incorporate NPV of improved zonal isolation when designing a new well today?

Session 6: Well Integrity Hazards During Construct Phase

Session Managers: Bill Hunter and Valerie Wilson

In this session we will explore well integrity issues, specific to zonal isolation that may arise during the well construction phase.

Group discussions and breakout sessions will be used to identify technology options, gaps, and proposals to address these issues. “Blue sky” ideas will be a particular focus.

Well integrity hazards to be examined will include:

  • Compromised zonal isolation behind casing’s, allowing fluid movement between zones—what are the primary causes and how can we mitigate against this risk?
  • Are there well construction techniques in use that may jeopardise zonal isolation? If so, what are the alternatives?
  • Trapped annular pressure—also referred to as, APB or thermal casing pressure—methods for addressing? Living with? Designing for?
  • Can well integrity be compromised by fracturing operations? This session will explore this question.

Overburden isolation, growing crystals or chalk—can we use adaptive isolation methods to provide supplementary or even primary zonal isolation?

Session 7: Evaluation, Verification, and Assurance

Session Managers: Paul Hazel and David Stiles

Evaluating and assessing the ability of a barrier to provide pressure isolation is critical to well integrity. The end goal must be an assurance, that there is effective pressure isolation in the well for all barriers including cement, metal-to-metal-seals, swellable elastomers and all other barrier mechanisms. We need to know what is being evaluated, methods of diagnosis, and acceptance criteria to assure the integrity of the barrier for the life of the well.

In this session, we will attempt to define exactly what the criteria should be for acceptance of a barrier. We will question whether barriers need to be physically tested or if a more basic but less certain confirmation of barrier installation is acceptable. Within that framework, we will debate the effectiveness of the current evaluation and verification methods used by the industry today. Gaps will be identified between the effectiveness of the methods currently available and the requirements for meeting the agreed acceptance criteria. This session will address evaluation, not just immediately after barrier installation but throughout the life of the well to abandonment and beyond. To that end, the group will be asked to consider permanent and continuous monitoring solutions. At the conclusion of the session the participants will be challenged with brainstorming blue sky ideas for advancing the future of barrier evaluation, verification and assurance.

Session 8: Restoring Zonal Isolation

Session Managers: Vidar Rygg and Philip Wodka

Previous sessions will have covered designing new wells with the allowance for mitigating action, evaluation, and assurance criteria. However, the industry sits with a portfolio of legacy wells which have been constructed to highly varying standards and with different levels of quality assurance, evaluation, and verification during the execution. Additionally, these wells have degraded over time. This session will explore what new methods and technology, including blue sky ideas, we will need to understand and restore zonal isolation where it might be lacking or where it has failed in these legacy wells. Some topics to be explored are:

  • What is our legacy—can we quantify it to manage risk and prioritise solutions?
  • How do we know what we have got?
  • The ability to assess conditions of wells behind concentric cemented casing strings
  • What are the assessment standards?
  • Are they meeting regulatory requirements?
  • Which tools and techniques do we lack today to restore zonal isolation?

Session 9: Abandonment Isolation

Session Managers: Gert Jan Heerens and Simon Sparke

There is no such thing as a leakproof gas well. The gas industry knows this; in fact, it has known it for decades that 7% of the gas wells are leaking. "You can have changing geological conditions where a well could be repressurised," said Andy Radford, a petroleum engineer for the American Petroleum Institute.

"I've seen casing they've pulled out of these old wells. It looks like a worm has eaten it," said petroleum geologist Norman J. Hyne. Any holes, cracks or spaces can open a path for repressurised oil or gas to surge to the surface slowly or, in extreme cases, as a bigger blowout.

Permanent well abandonment creates new challenges. It forces the industry to develop innovative sealing solutions for zonal isolation which assures these solutions work reliably long after the well has been abandoned. Being able to do that requires monitoring capabilities that are themselves robust in the long term.

Current practice is to apply cement as a sealing material around the steel casing and the production pipe. The ultimate goal is to reach the same sealing performance of the cap rock in order to restore the initial natural barrier function. The next important requirement of zonal isolation is long term reliability. Factors that can have an adverse influence on sealing reliability are formation changes, and the presence of (bio) chemical or thermal fluctuations. Experience shows that projecting the zonal isolation performance over hundreds of years can be problematic, not least due to the lack of long term data. Given the large number of already abandoned wells, a critical look into past abandonment performance (good or bad) could offer great insights on sealing performance projections into the future. This is a prerequisite for further advancements in plug and abandonment technology.  We could perhaps learn from the nuclear industry since they have to handle installation and storage integrity over time scales of thousands of years.

Abandonment integrity is an area that concerns equally the industry, the society, and the regulators. Best practices, guidelines, minimum standards, and regulations are necessary in order to ensure profitability, sustainability and safeguarding the public interest. When compiling these standards deep technical knowledge and understanding of the associated risks are required if they are to be effective. The question is whether the current regulation is sufficient and what scientific premises is it based on.

In this session we will discuss the following key topics:

  • What does long-term or forever actually mean in practice? Can we learn from the nuclear industry facing the similar time scales?
  • Some wells will be abandoned while some others may be put to a different use (gas or CO2 storage). Should we adopt a different approach for each type?
  • Is (portland) cement the best sealing material or are there other sealing material solutions
  • Do we have reliable data of current wells sealing performance?
  • Is there sufficient knowledge or experience for compiling effective abandonment legislation? What is missing?
  • How to identify the knowledge gap? How to fill it?
  • Research and full scale project are expensive. Do we have adequate models available to predict future sealing integrity and the factors that affect it?

Session 10: Blue Sky Wrap-Up

Session Managers: Tore Fjagesund and Paul Hopmans

What are the blue sky opportunities with recognised game changing technologies required to meet the challenges for new and legacy wells with respect to zonal isolation lasting for well lifecycle and beyond? What are the priorities of industry zonal isolation technology requirements? How are these requirements ranked and against what criteria, how important is it, who will take ownership and more importantly what is the easiest to get and most effective to implement? Create an industry technology staircase for the next 5 years that is aligned with legislative requirements and industry needs, in a joint effort to build an agile roadmap that is maintained and achievable. Challenge of ownership and momentum in how to deliver the technology staircase through a Jointed Industry Project (JIP) or a SPE technical workgroup, creating white papers that could be the basis for change in industry standards and technology.