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ISO 27914:2017 — Geological Storage of Carbon Dioxide
Requirements for site characterization, injection operations, monitoring, and closure of CO2 geological storage projects
1. Overview of ISO 27914:2017
ISO 27914:2017 provides requirements and recommendations for the geological storage of carbon dioxide (CO2) as part of carbon capture and storage (CCS) operations. This standard, developed by ISO/TC 265, covers the entire lifecycle of a geological storage project, including site selection and characterization, risk assessment, injection operations, monitoring and verification (M&V), and site closure. It applies to CO2 storage in deep geological formations such as saline aquifers, depleted oil and gas reservoirs, and deep unmineable coal seams.
The standard addresses a critical step in the CCS chain — ensuring that CO2 injected into geological formations remains permanently trapped and does not pose risks to human health or the environment.
ISO 27914:2017 establishes a systematic framework for storage project management, emphasizing the importance of a robust management system, comprehensive site characterization, and long-term stewardship planning. The standard is designed to be used by storage project operators, regulators, and stakeholders involved in CCS projects.
2. Storage Site Characterization and Selection
2.1 Geological Characterization Requirements
Before any CO2 injection begins, the standard requires thorough characterization of the storage formation. This includes evaluation of the reservoir properties such as porosity, permeability, thickness, and heterogeneity. The caprock integrity must be assessed to confirm its ability to act as a permanent barrier to CO2 migration. The standard specifies requirements for characterizing fault and fracture systems that could serve as potential leakage pathways.
| Characterization Element | Key Parameters | Assessment Methods |
|---|---|---|
| Reservoir properties | Porosity, permeability, thickness | Well logs, core analysis, seismic |
| Caprock integrity | Sealing capacity, thickness, fracturing | Geomechanical testing, seismic interpretation |
| Fault characterization | Orientation, sealing potential, activity | 3D seismic, structural modeling |
| Geochemical assessment | Mineralogy, brine composition, reactivity | Laboratory experiments, reactive transport modeling |
| Hydrodynamic regime | Formation pressure, flow direction | Pressure transient testing, hydrodynamic modeling |
2.2 Storage Capacity and Injectivity
The standard requires quantitative assessment of both storage capacity and injectivity. Storage capacity estimation must consider multiple trapping mechanisms: structural trapping, residual gas trapping, solubility trapping, and mineral trapping. Injectivity assessment evaluates the ability of the formation to accept CO2 at the required rates without exceeding fracture pressure limits. The standard provides guidance on capacity estimation methodologies including material balance, volumetric methods, and dynamic simulation.
Overestimation of storage capacity is a common pitfall. ISO 27914 requires that capacity estimates account for technical and geological limitations, including permeability heterogeneity, pressure build-up constraints, and the interplay between different trapping mechanisms over time.
3. Injection Operations and Well Construction
3.1 Well Design and Integrity
Well construction for CO2 injection follows principles similar to oil and gas wells but with additional requirements for CO2 service. The standard specifies material selection criteria to resist CO2 corrosion, including the use of corrosion-resistant alloys (CRAs) for tubing and completion components. Cement formulations must be designed to maintain integrity in a CO2-rich environment over the long term. The standard requires multiple barriers between the injected CO2 and the environment, with verification of barrier integrity through appropriate testing.
3.2 Injection Operations Management
ISO 27914:2017 requires a comprehensive operations and maintenance plan covering injection protocols, start-up and shutdown procedures, and emergency response. Injection pressure must be maintained below the estimated fracture pressure of the storage formation to prevent creating leakage pathways. The standard also requires real-time monitoring of injection parameters including pressure, temperature, flow rate, and composition at the wellhead.
Injection operations must be conducted with a robust understanding of the reservoir dynamic behavior. Pressure management is critical — excessive pressure build-up can reactivate faults or create new fractures, compromising containment integrity.
4. Monitoring, Verification, and Closure
4.1 Monitoring and Verification (M&V) Program
The M&V program is a cornerstone of ISO 27914:2017. The standard divides M&V into three phases: pre-injection (baseline), injection period, and closure period. Pre-injection monitoring establishes baseline conditions against which future changes can be detected. During injection, monitoring must track CO2 plume migration, detect any leakage, and verify that the storage formation is behaving as predicted. Post-injection monitoring continues until site closure criteria are satisfied, demonstrating that the stored CO2 does not pose future risks.
| M&V Phase | Duration | Key Monitoring Objectives |
|---|---|---|
| Pre-injection | 1-3 years before injection | Establish environmental and subsurface baselines |
| Injection | Duration of injection operations | Track plume migration, verify containment, detect leakage |
| Closure | Until closure criteria met | Demonstrate stable plume and no leakage risk |
4.2 Site Closure and Post-Closure
Site closure criteria must be defined before injection begins. The standard requires that closure can only proceed when monitoring data demonstrates that the CO2 plume has stabilized, formation pressures have declined to acceptable levels, and there is no evidence of leakage. A closure plan including well abandonment procedures, decommissioning of surface facilities, and long-term stewardship arrangements must be documented and approved.
5. Engineering Insights for Storage Projects
Based on ISO 27914:2017, successful CO2 geological storage projects require:
- A robust management system integrating technical, environmental, and stakeholder engagement aspects throughout the project lifecycle.
- Comprehensive site characterization using state-of-the-art geophysical, geological, and geochemical methods to build a reliable static and dynamic model of the storage complex.
- Risk assessment that considers all potential leakage pathways including faults, fractures, wellbores, and spill points.
- Contingency planning for unexpected events such as loss of containment, well failure, or induced seismicity.
- Long-term stewardship planning recognizing that the storage site may require monitoring for decades after injection ceases.
The single most important factor for safe CO2 storage is the integrity of the sealing system. All potential leakage pathways — through the caprock, along faults, or through legacy wells — must be assessed and addressed before injection begins.
6. Frequently Asked Questions
Q: What types of geological formations are suitable for CO2 storage under ISO 27914?
A: Suitable formations include deep saline aquifers, depleted oil and gas reservoirs, and deep unmineable coal seams. Each type has specific characterization requirements outlined in the standard.
A: Suitable formations include deep saline aquifers, depleted oil and gas reservoirs, and deep unmineable coal seams. Each type has specific characterization requirements outlined in the standard.
Q: How long must a storage site be monitored after injection ceases?
A: The monitoring duration is site-specific and determined by the closure qualification process. Typically, monitoring continues until the CO2 plume stabilizes and formation pressures decline to acceptable levels, which may range from 10 to 50 years or more.
A: The monitoring duration is site-specific and determined by the closure qualification process. Typically, monitoring continues until the CO2 plume stabilizes and formation pressures decline to acceptable levels, which may range from 10 to 50 years or more.
Q: Does ISO 27914 address induced seismicity risks?
A> Yes, the standard requires assessment of geomechanical risks including induced seismicity. Injection pressures must be managed to avoid reactivating faults or creating new fractures.
A> Yes, the standard requires assessment of geomechanical risks including induced seismicity. Injection pressures must be managed to avoid reactivating faults or creating new fractures.
Q: Can ISO 27914 be applied to CO2-EOR projects?
A: While ISO 27914 is intended for dedicated geological storage, CO2-EOR storage is covered under ISO 27916. However, the characterization and monitoring principles are similar.
A: While ISO 27914 is intended for dedicated geological storage, CO2-EOR storage is covered under ISO 27916. However, the characterization and monitoring principles are similar.