A widely accepted definition of well integrity is “the application of technical, operational, and organizational solutions to reduce risk of uncontrolled release of formation fluids throughout the lifecycle of a well”. Technical solutions refers to the physical well barriers that contain pressure and hydrocarbons. The failure of a well barrier compromises well integrity, resulting in loss of production and harm to personnel, environment, assets, and the operator’s reputation. Operational and organizational solutions include the planning, design, guidelines, and procedures that help achieve and maintain well integrity.
A well barrier is often referred to as an envelope consisting of one or more well barrier elements (WBEs). Examples of WBEs include drilling fluid, BOPs, the wellhead, casing, cement, packers, and other well components. The failure of a single WBE can cause the well barrier envelope to fail. For wells that are capable of sustained flow to the wellhead, the O&G industry uses two barrier envelopes—primary and secondary—for a high level of reliability.
The primary barrier envelope consists of WBEs that are, or might be, in direct contact with well pressure to prevent unintentional flow of reservoir fluid to surface or another zone. The secondary barrier envelope consists of barrier elements that are, or might be, exposed to contact with well pressure should any primary barrier element fail.
Think of the primary barrier envelope as being inside the secondary barrier envelope. If an element that is part of the primary barrier envelope fails, the elements in the secondary envelope must prevent the release of reservoir fluid to the surface or to another zone.
The primary and secondary barrier envelopes change as wells progress through lifecycle phases, as shown in the table below. For example, the primary barrier envelope during drilling operations is the overbalance hydrostatic pressure from the drilling fluid, but during production the primary barrier envelope includes the casing, cement, production tubing, packers, and downhole safety valves. This is why it’s important for operators to have clear and accurate well barrier diagrams to help all stakeholders visualize changes to well barriers and assess risk over the life of a well.
| WELL LIFECYCLE | PRIMARY BARRIER ENVELOPE | SECONDARY BARRIER ENVELOPE |
|---|---|---|
| Drilling | • Drilling fluids • Completion fluids | • Casing cement • Casing • Wellhead • BOP |
| Production | • Casing cement • Casing • Packer • Tubing • Downhole Safety Valve | • Casing cement • Casing • Wellhead • Tubing hanger • Christmas tree |
| Intervention | • Casing cement • Casing • Deep-set plug • Overbalanced mud | • Casing cement • Casing • Wellhead • BOP |
| Plug & Abandonment | • Casing cement • Casing • Cement plug | • Casing cement • Casing • Cement plug |
With every well, there are challenges to assessing risks to well integrity. Well conditions change and there are multiple ways that well barriers can fail.
Wells are initially designed and constructed based on certain criteria. However, a well’s operating conditions or utilization may change during its lifecycle, adversely affecting the integrity of critical WBEs. For example, during the life of a well:
Any one or a combination of the above events can diminish the integrity of individual WBEs. Therefore, an effective well integrity management program is needed to validate the integrity of the WBEs to operating conditions that may be different from the original assumptions when the well was drilled.
Well barrier elements can experience leak paths due to mechanical stresses, temperature changes, and exposure to corrosive substances. The figure below shows some of the potential leak paths in WBEs.
Here are some strategies for mitigating risks to well barrier integrity:
International industry associations and standardization organizations have issued the following standards, guidelines and recommended practices related to well integrity.
“Blowout Prevention Equipment System for Drilling” is a standard that provides requirements for the installation and testing of blowout prevention equipment (BOP) systems on land and marine drilling rigs.
“Deepwater Well Design and Construction” is a recommended practice (RP) that aims to improve safety and reduce the chance of losing well control or damaging the environment. It includes considerations for barrier and load cases. This RP is based on the complexity of deepwater operations, which requires a thorough understanding of well design criteria and the equipment associated with them.
“Guidelines for Well Integrity in Drilling Well Operations” is the Norwegian O&G industry standard that defines the minimum functional and performance requirements for well barriers throughout a well’s life cycle. The standard focuses on how to conduct operations and what equipment should be used and is concerned with drilling, completion, and abandonment activities.
“Well Integrity – Life cycle governance” offers guidance to well operators on managing well integrity throughout the well’s life cycle. It is intended for use in the petroleum and natural gas industries worldwide and applies to all wells regardless of their age, location, or type. This part of ISO 16530 addresses the minimum compliance requirements for well operators to claim conformity with this part of ISO 16530. The document addresses each stage of the well life cycle, as defined by six phases: the basis of design, design, construction, operation, intervention, and abandonment.
Well schematics and well barrier diagrams are two distinct methods of illustrating WBEs and their role in integrity management. Each method has its specific applications, contributing to a comprehensive understanding of well integrity management strategies.
A well schematic is an illustration that shows the arrangement of the main WBEs within the well system. The schematic typically includes well and location information, annotations that describe the lithology, depths of the casing and cement sections, descriptions of the major WBEs, mud weights, and formation temperatures.
For years, engineers have used various applications to create well schematics including spreadsheets, word processors, CAD programs, and other planning tools. This has resulted in duplicate data entry with increased potential for errors, change management challenges, and communication and workflow issues during handovers between well phases. Digital well schematic software allows engineers to build well barrier plans in a centralized cloud-based repository that tracks the location and information about each WBE in every well.
Digital well schematics provide several benefits:
For seamless well diagramming, reach out to IPT and discover our user-friendly tool! Contact us now to explore how our easy well diagramming tool can revolutionize your workflow.
Well barrier diagrams display color-coded primary and secondary barrier envelopes and may illustrate all potential leak paths from the reservoir to the surrounding environment. These diagrams describe the status of barrier elements and are valuable for evaluating the consequences and likelihood of specific scenarios. Well barrier diagrams quantify the likelihood of consequences depicted in the diagram, making them useful for risk assessment and decision-making.
Digital well barrier diagrams provide some of the same benefits as well schematics, plus:
The development of well integrity software applications and associated technologies has accelerated since 2010 with the increased digitization of the O&G industry after several catastrophic incidents.
Well integrity software applications define the commitments, requirements, and responsibilities of an organization to ensure the integrity and safety of oil and gas wells throughout their lifecycle. The primary aim is to mitigate the risks associated with uncontrolled releases of formation fluids, which can lead to environmental harm, injuries, and financial losses. This is achieved by identifying potential integrity threats, implementing preventive measures, and regularly monitoring well conditions to prevent leaks or failures. IPT offers rigorous well integrity software and expert advisory services for advanced well integrity management at every stage of the well lifecycle. The software encompasses tools for constructing detailed wellbore schematics, which serve as the foundation for developing barrier schematics and plans essential for test planning and generating comprehensive test plan reports with complete documentation of surface and subsea WBEs to be tested. IPT’s integrity tests leverage proprietary algorithms that significantly reduce pressurized time for testing WBEs and remove validation subjectivity, saving rig time and reducing risk. Additionally, IPT’s well integrity management solutions allow collaboration and handover among teams, while tracking all changes and maintaining versions over the complete lifecycle of wells. IPT’s expert advisors are available to support the process wherever required, whether onsite or remotely. With decades of experience, they excel in generating and optimizing integrity test plans, offering expert assistance before, during, and after testing operations, regardless of location worldwide.
Ready to enhance your well integrity management? Contact us today to learn more about our advanced software solutions and expert advisory services. Don’t wait—reach out today to ensure the safety and reliability of your oil and gas wells.
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