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University of Edinburgh

Tracing CO2 from pipeline to subsurface storage site

Supervisors:Prof. Stuart Haszeldine, Dr. Stuart Gilfillan, Dr. Chris McDermott, Dr. Polly Arnold,University of Edinburgh & David Campbell ScottishPower.

Background: A primary requirement for the success of Carbon Capture and Storage (CCS) technology is

the proven ability to safely transport, inject and store CO2 in the subsurface on a long-term basis. A majorissue regarding acceptance of both CO2 transport networks and subsurface storage sites is the risk offailure of CO2 containment and the subsequent environmental impact. A key aspect to reducing theserisks is the development of monitoring strategies that permit ongoing assessment of the containmentintegrity of both pipelines and storage reservoirs.

This PhD programme has two specific aims:

1. Identify and quantify how 'foul smelling' organic compounds could be added to transportedCO2 to act as early indicators of CO2 leakage from pipelines.

At low concentrations and in normal atmospheric conditions CO2 is a relatively harmless gas to humanhealth. However, at concentrations above 10% by volume CO2 (4% mass 4,000ppm) can cause adverse

health effects and above 5% mass poses a significant asphyxiation hazard. CO2 is denser than air andtherefore in the event of chronic leakage from a pipeline or a capture plant CO2 could accumulate in lowlying outdoor areas such as valleys, road cuttings, caverns, tunnels and basements. As CO2 is acolourless odourless gas it is possible that such a leakage event could go undetected until theconcentration of CO2 had reached lethal levels. This detection problem could be addressed by odorisingthe CO2 with 'foul smelling' organic compounds. Thiols and thioethers are commonly added to domesticnatural gas as their scent is so strong that it can be detected by the human nose at concentrations as lowas 10 ppb. CO2 is already odorised in fire suppression systems, typically using oil of wintergreen. Whilstthese odorants are added to low pressure distribution supplies, they are not added to gas transported inlong distance high pressure pipelines. Problems with odorants could be reaction with transmission orborehole pipework at elevated temperatures, and interaction with rock or formation of a separate phaseduring deep geological injection. This project intends to quantify the potential value, and drawbacks, ofodorising CO2 in high pressure pipelines and determine the most effective odorants for this purpose.

2. Investigate how noble gases could be used as effective early warning tracers of CO2 migrationin engineered CO2 storage sites.

Noble gases are conservative tracers within the subsurface, and combined with carbon stable isotopes,have proved to be extremely useful in determining both the origin of CO2 and how the CO2 is storedwithin natural CO2 reservoirs from around the world. One application of this could be the artificialfingerprinting of stored CO2 with noble gases, to create distinctive signatures of original ownership. Thisstudy will make theoretical calculations of noble gas co-transport with CO2 under subsurface conditions.

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Then laboratory experiments of supercritical and gas phase CO2 through porous and fractured rock willbe used to calibrate the predictions. Thirdly, observations of natural sites will be used to establish the keycontrols on the transport of the noble gases through typical reservoir facies, how the transport time foreach noble gas compares with that of CO2 and how noble gas isotope ratios are affected by passagethrough rock. Data gained from the experimental work would establish if particular noble gases could beused as early warning tracers in an engineered storage site. The result of the modelling will be used topredict how effective these tracers would be in a real world storage site. A basic design and costing of thefingerprinting process will be undertaken.

Methods: This project will be primarily experimental in nature and sample analysis will be undertakenusing existing experimental equipment within the Scottish Carbon Capture and Storage Centre.Experiments on CO2 odorants will be undertaken in the recently refurbished, state of the art, JosephBlack CO2 chemistry laboratory within the School of Chemistry. Core flow and transport experimentsusing CO2 and noble gases will be undertaken on rocks representative of storage sites, including poroussandstones and less porous mudrocks, sealed in a reactive vessel at the School of GeoSciences. At alarger scale, building on previous work, several highly fractured porous samples are available for thefurther investigation of flow and transport within fracture networks on noble gas and CO2 flow rates.Modelling of the results of these experiments will also be carried out using GeoSys/RockFlow, an existingmodular accessible environmental software code in order to investigate the evolution of similarpreferential flow paths within true scale engineered CO2 storage sites.

Training: The student will be trained in the experimental sampling methodology and laboratory analysistechniques for measuring CO2, organic compounds and noble gases along with hydro-geologicalmodelling, coupled process modelling and C++.

Facilities: The student will be based within the Scottish Carbon Capture and Storage centre (SCCS),(http://www.sccs.org.uk) at the University of Edinburgh. SCCS is the largest carbon storage grouping inthe UK, comprising in excess of 65 researchers, and is unique in its connected strength across the fullCCS chain and unique in its biochar capability. The three partner institutions (the University of Edinburgh,Heriot Watt University, and the British Geological Survey) together have an unparalleled range and depthof expertise.

Industry Links: This project has been driven by talks with Scottish Power and David Campbell fromScottishPower will act as an industrial co-supervisor. The student will spend periods of time atScottishPower beginning with a week's induction programme. The student will receive an overview of theentire organisation including Energy Wholesale, Energy Networks and Energy Retail and will visit variousbusiness locations and undertake basic safety training.

In each of the following years the student will be expected to spend time at Scottish Power and this willinclude a project placement aimed at understanding the business case of large CCS projects. In additionto these block placements the student will present results to Scottish Power in order to ensure strongdialogue continues throughout the project. This will have two objectives, firstly, for knowledge transfer toensure that the Scottish Power has a full understanding of the odorant and noble gas tracing technologiesbeing developed. Secondly, this will ensure commercial relevance. The student will be regularlyencouraged to consider the economic and technical relevance of their work.

Applications are invited from graduates in Geology, Physics, Engineering, Maths, Chemistry, or similar.To apply please send a covering letter and a CV detailing 2 referees to Dr. StuartGilfillan (stuart.gilfillan@ed.ac.uk ). The closing date for applications is the 1st September 2010.

For informal enquiries and more details on the PhD project or Scottish Carbon Capture and Storage,

please contact Dr. Stuart Gilfillan (stuart.gilfillan@ed.ac.uk, +44 131 650 7010) or visit our

website www.sccs.org.uk.

http://www.sccs.org.uk/mailto:stuart.gilfillan@ed.ac.ukmailto:stuart.gilfillan@ed.ac.ukhttp://www.sccs.org.uk/mailto:stuart.gilfillan@ed.ac.ukmailto:stuart.gilfillan@ed.ac.ukhttp://www.sccs.org.uk/http://www.sccs.org.uk/