Welcome to the July 2010 edition of Quintessa Update, the electronic newsletter of
This edition covers Quintessa's scientifically-based consultancy, contract research and software for supporting decisions related to the geological storage of CO2 , natural gas and acid gas.
With assistance from Quintessa, Shell is developing a decision support tool for evaluating sub-surface CO2 storage risks consistently across a portfolio of sites. The tool is based on Quintessa's TESLA decision support software, which implements Evidence Support Logic (ESL), and an associated decision tree. Risks are classified into four categories: Capacity; Injectivity; Containment; and Monitoring. Each of these categories corresponds to a branch of the decision tree. The figure shows part of the containment branch. The top (root) node of this branch corresponds to the hypothesis that CO2 containment can be demonstrated. This hypothesis is supported by other hypotheses at the next level of the tree. Where appropriate these hypotheses are in turn supported by other hypotheses and so on, until a level of the tree is reached at which the hypotheses can be answered directly by evaluating site information. Evidence for and against each of the lowest level hypotheses, or 'leaf hypotheses' is judged independently and propagated through the tree by a numerical algorithm that combines evidence values for leaf hypotheses with the same parent hypothesis, using user-defined 'sufficiencies' (weights). Users may only input evidence values and may not change the tree's structure or the 'sufficiencies'. Consequently, the tool ensures that conversations among different project teams cover the same issues within each of the risk categories, to a similar level of detail. Users may embed supporting text and documentation within a tree, thereby producing an audit trail.
For more information, please contact Richard Metcalfe.
QPAC is Quintessa's general-purpose modelling software for solving systems of partial differential and algebraic equations. It is used to solve a wide range of problems including those with strongly-coupled non-linear processes. It uses a 'model as input' approach whereby the conceptual and mathematical model itself forms part of the input to the software. QPAC is being used to model the performance of CO2 geological storage at the systems level, for example to support the development of monitoring strategies, and for investigating detailed issues such as the degradation of cement well seals. One application is to develop simplified models that can be used to investigate the potential significance of very low-probability hypothetical CO2 leakage scenarios. The example above shows output from a systems model designed to explore the potential significance of hypothetical CO2 leakage via a fault plane. The model was used to determine the combination of fault and aquifer permeabilities that would cause the fault to by-pass the intermediate and shallow aquifers. Here, after 5000 years, CO2 reaches the surface and very little enters these aquifers, which means that no credit should be taken for secondary storage capacity within them.
For more information, please contact Alex Bond.
CO2ReMoVe is being carried out under the 6th Framework Programme of the European Union (EU), with funding from the EU and a number of major energy companies. The project aims to investigate the long term reliability and safety of geological CO2 storage. Another objective is to provide R&D to support the development of guidelines for site certification and accepted standards for policy makers, regulators and industry. Quintessa has contributed the following outputs to the project: 1. a structured scenario development methodology; 2. a systems level modelling tool based on Quintessa's QPAC-CO2 software; 3. a decision support tool for integrating different performance-relevant information, based on Quintessa's TESLA software. These methods and software tools are being applied to several demonstration CO2 storage projects that are being studied as part of CO2ReMoVe. In July 2010, Quintessa will be contributing a lecture on PA modelling at a Summer School organised by the CO2ReMoVe Research Partnership, to be held at Imperial College, London.
For more information, please contact Richard Metcalfe.
The British Geological Survey (BGS) has recently evaluated the potential for leakage of natural gas from Underground Gas Storage (UGS) facilities in salt caverns and depleted oil/gas reservoirs on behalf of the Health and Safety Executive (HSE). Quintessa was sub-contracted by BGS to support this project by developing leakage scenarios and carrying out simple scoping calculations to evaluate the likely significance of leakage. The BGS component of the work is reported in HSE RR605, which provides context, background and data for the work reported by Quintessa in HSE RR606. This approach to gas reservoir integrity risk assessment is being further developed and applied to potential new storage facilities.
For more information please contact Sarah Watson.
Six people from
Quintessa will be participating in the 10th International Conference
on Greenhouse Gas Control Technologies (GHGT10) to be held in Amsterdam in
September 2010 (Richard Metcalfe,
Philip Maul, Laura Limer,
Alex Bond, Alan Paulley and
Hiro Takase). They will be presenting the following papers:
Please get in touch if you would like to meet up in Amsterdam.