KEM-27 Monitoring requirements for offshore CO2 storage sites

Monitoring is a key activity in the implementation of a CO2 storage project. Monitoring is essential to assess whether injected CO2 is behaving as expected, whether any migration or leakage occurs, and whether any identified leakage is damaging the environment or human health. A site-specific monitoring plan must be submitted by any project developer during the application for a geological CO2 storage permit. Both a lack and a shortage of ‘best practices’ for monitoring of injected CO2, for depleted gas fields and saline aquifers respectively, may lead to delays during the permitting process.

The KEM-27 research question has as objective to provide guidance to CO2 storage operators, the competent authority and supervisory bodies regarding best practice monitoring plans for CO2 storage in offshore depleted gas fields and saline aquifers. The work should include detailed technical analysis of available monitoring tools and techniques, and the most appropriate means of applying them as part of an integrated risk management system for storage sites. The evaluation of the monitoring tools should also include potential innovations that as of yet cannot be considered best practice, but show promise with regards to their application in CO2 storage activities.  

RESEARCH QUESTION

The overall objective of the project was to provide guidance to CO2 storage operators, the competent authority and supervisory bodies regarding best practice monitoring plans for CO2 storage in offshore depleted gas fields and saline aquifers. The work consisted of two main tasks:

1) A technical review of all available monitoring tools and techniques that are relevant to the off-shore storage of CO2 in saline aquifers or depleted gas fields.

2) Providing recommendations for developing monitoring plans for off-shore sites of CO2 storage in saline aquifers and depleted gas fields using a risk-based approach, based on the findings from Task 1.

The results of both taks have been combined in the

KEM PROJECT FINAL REPORT with a separate EXECUTIVE SUMMARY

The technical review report provides a comprehensive list of monitoring tools and techniques that are potentially suitable for monitoring CO2 strategies in depleted offshore hydrocarbon fields and saline aquifers, with a specific focus on relevant applications in the Dutch North Sea. For each tool/technique, its purpose, application, scope, special considerations for offshore Netherlands, costs, advantages, and disadvantages are discussed. There is also a short section on data management considerations for data intensive techniques. A relatively long list of references is also provided; so, relevant literature for each tool/technique can be consulted for additional information.

The second phase report provides information on principles of development of Monitoring, Measurement and Verification (MMV) plans, and describes seven steps of MMV development: define the objectives, describe context, specify monitoring targets, screen monitoring techniques, select monitoring techniques, plan monitoring activities, and evaluate completeness. The applicability of monitoring tools and the development of MMV plan for saline aquifers and depleted hydrocarbon fields are discussed in an appendix.

The KEM scientific expert panel reviewed the project.

KEM PROJECT EVALUATION

The quality of the project team and the executed work is good. Several personnel changes is believed to have some influence on the continuity of the work and the quality of final product and causing a delay in the submission of the final report.

According to the evaluator the three main results of this study are:

1. A thorough and useful overview of available monitoring tools and techniques that are relevant to the off-shore storage of CO2 in saline aquifers or depleted gas fields, including indications of costs and advantages and disadvantages for each technique.

2. A concise description of principles and various steps of MMV plan development. An outline of basic steps for the development of an MMV plan is provided. The hypothetical example is useful, although it is not evident that applied procedure would provide a robust MMV plan.

3. It can be argued that there is no difference between storage sites in saline aquifers and depleted hydrocarbon fields as far as the applicability of various monitoring tools and techniques is concerned. The key difference between these settings is in the risk assessment.

These results are generic but provide a useful basis for developing a site-specific MMV plan for storage of CO2 in depleted offshore hydrocarbon fields and saline aquifers.