APPLYING WELLS QRA WITHIN THE REGULATORY FRAMEWORK FOR WELL INTEGRITY IN BRAZIL

This analysis is based on my background experience in Brazilian Regulations applied for Wells Integrity, my own views and interpretation of the documents referenced.

This document continues the analysis from my article REGULATORY DEVELOPMENTS FOR WELL INTEGRITY IN BRAZIL - ANALYSIS OF ANP TECHNICAL NOTE NO. 9/2024.

1. ANP’s Repair Prioritisation Plan Proposed in Technical Note No. 9/2024/SSO-CSO/SSO

In the Technical Note No. 9/2024, National Agency of Petroleum, Natural Gas and Biofuels - ANP ( ANP - Agência Nacional do Petróleo, Gás Natural e Biocombustíveis ) proposes a strategy for prioritising repairs for Operators and highlights the need to establish an action plan, approved by an appropriate management level, that includes recommendations, control measures and mitigating actions based on a specific risk analysis. Below are the deadlines proposed by the agency:

“6.2.1. Eruptive wells with two degraded barriers (primary and secondary): 30 days for repair;

6.2.2. Non-eruptive wells with two degraded barriers (primary and secondary): 60 days for repair;

6.2.3. Eruptive wells with one degraded barrier (primary or secondary), in a situation of temporary abandonment without monitoring: 90 days for repair;

6.2.4. Producing wells (eruptive or non-eruptive) with a degraded barrier (primary or secondary): 120 days for repair;

6.2.5. Non-eruptive wells with a degraded barrier (primary or secondary), in a situation of temporary abandonment without monitoring: 180 days for repair;

6.2.6. Eruptive wells with a degraded barrier (primary or secondary), in a situation of temporary abandonment with monitoring, intervention, injecting, operating for disposal or closed: 270 days for repair;

6.2.7. Non-eruptive wells with a degraded barrier (primary or secondary), in other situations not yet mentioned in this topic: 360 days for repair.”

However, ANP recognises the complexity and the limitation of available rigs for intervention; after all there are more than 500 wells for repair as referenced in the note. It also recognises that due to the non-prescriptive nature of the National Technical Regulation for Well Integrity (RANP 46/2016), Operators have room to adopt adequate mitigation deadlines to keep their wells in safe conditions. But ANP in item 6.4 of the note, signalling that safety and integrity must prevail over other priorities:

“6.4. Furthermore, for Operators who have eruptive wells with two degraded Well Barriers, priority must be given to allocating Rigs to carry out repairs, with other activities being suspended.”

Still, it is worth noting that the deadlines proposed by ANP may not be the most appropriate, given the impression that as with those presented by Operators, they may not be considering the risk and complexity of repair in each situation. Each well is unique, and the variables involved can vary significantly.

2. Wells QRA as a Solution for Technical Note No. 9/2024/SSO-CSO/SSO

The national regulatory framework for Well Operational Safety establishes that Operators must assess and reduce risks. Traditionally, well integrity risk management is based on subjective assessments and methodologies. However, ANP, through Technical Note ANP No. 9/2024, signposted the need for a more objective approach, although it does not prescribe the method for this.

In this sense, considering the objectives to be achieved and the challenges to be overcome in this process, Quantitative Risk Analysis (QRA) can be effectively applied to this challenge.

Wells QRA asks these basic questions:

• What is the probability of a leak from the well?
• What would the severity of a leak be if it happened?

And can provide these fundamental results for any well scenario or condition analysed:

• Risk (plotted on a risk matrix)
• Barrier Compliance level (using traffic light classification scheme)
• Whether the well can be operated or not
• Safe Service Life and Repair Response Time (grace period)

It can be applied to multiple use cases thought the well life cycle from well design risk analysis to wells portfolio cumulative risk and total location risk analysis, to well repair prioritisation to name just a few. For well repair risk prioritisations QRA allows for risk consideration and application of appropriate mitigation measures, considering safe response times, establishing an appropriate prioritisation for repair interventions and contingency planning.

However, it is essential to choose a QRA methodology that considers both components of risk: Probability and Severity. Using a methodology that emphasises only one part of this equation cannot provide a complete and accurate assessment.

An effective QRA for a well requires a granular view down to individual components (i.e. all relevant Well Barrier Elements (WBEs), Pressure Sources and Sinks and Voids (cavities) within the well) and consideration of how they are interconnected. A building block for this was presented by NOROG (now Offshore Norway) WIF as below.

WBE components such as the X-tree, wellhead, DHSV, casing, cement, production tubing, packer, sealing formation etc. have specific characteristics that vary according to the project and operating conditions. All need to be managed effectively to ensure the integrity of the well. Possible leakage paths from the reservoir to the surface, and /or between other pressure source / sinks, through these WBEs represent complex variables that cannot be fully assessed using qualitative methodologies.

The Quantitative Risk Analysis (QRA) methodology applied for wells has been refined by GMVi i in Empirica software, illustrated here:

This represents a low-resolution model for a simple well. Numerically, the components in this model can be expressed as follows:

• 31 Well Barrier Elements
• 74 Failure Modes
• 2,473 Leak Paths (just considering reservoir as a pressure source)
• 7,954 Leak Paths (considering all pressure source /sinks)

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So, consider the complexity of managing the risk for a hypothetical field with 100 wells. The numbers above would scale significantly, presenting a substantial management challenge, especially because each well is unique, share some similarities but they are not identical, and each one require careful monitoring, maintenance, and optimisation to ensure efficient production and safety.

Although some onshore wells in Brazil could have simpler completions with fewer WBEs, Failure Modes and Leak Paths, other variables increase the risk. Examples include wells drilled before current legislation, with potential flow intervals without isolation, and eruptive wells without DHSV installed.

Another key point to emphasise is that more complex wells will have a greater number of WBEs, Failure Modes, and tens, or potentially hundreds of thousands of Leak Paths, increasing the risk and requiring more robust and effective management methodologies.

Therefore, it is important to note that when it comes to wells, there is no comfort regarding the risk, whether:

• Onshore: Higher Probability of Failure (more numerous and older wells)
• Offshore: Higher Severity due to Failure (more productive wells)

While qualitative analyses are valuable, QRA provides a more comprehensive and objective approach for evaluating wells with numerous components, potential leak paths, and other variables that qualitative methods may inadequately address.

Finally, despite the schedules for repairing wells with degraded barriers proposed by ANP to Operators, the agency leaves room for the use of other repair deadlines, as long as they are technically justified, adequately contingent and based on risk (ANP Technical Note No. 9/2024). Then, it is essential to use a methodology that ensures robustness and adequately justifies repair response times associated with these mitigation plans.

Quantitative Risk Analysis (QRA) is an effective means of calculating repair response times based on the probability and risk, removing the need for subjective judgment. It can be applied to balance the interests of the Regulatory Agency and Operators’ mutual interest to have safe wells that are available for production while also considering resource availability.

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3. Referencies

Empirica Q Version 1.3.11.5 ? Girling & Company Software Limited, 2024. QRA Methodology Software for Wells.

INTRODUCTION TO WELL INTEGRITY - 04 December 2012 - Norwegian Oil and Gas Association's Well Integrity Forum (WIF) and professors at NTNU and UiS.

National Agency of Petroleum, Natural Gas and Biofuels (ANP), Technical Regulation of the Well Integrity Management System (WIMS), 2016. RANP No. 46/2016.

TECHNICAL NOTE No. 9/2024/SSO-CSO/SSO/ANP-RJ - Analysis of data from wells with degraded barriers and proposed action for Operators and inspection for ANP.