London April 2017 Biannual: Understanding micro to macro scale processes

This blog was created by Masoud Babaei and Michael Onoja.

Chair: Stuart Haszeldine, SCCS/University of Edinburgh

There was a group of around 20 attendees for this parallel session. The presentations focused on a range of CCS activities spanning across disparate length scales. There as Q&A at the end of each talk and the questions were mostly concerned about the scale of each study.

Stuart Gilfillan

Dr Stuart Gilfillan kicked off the session with a presentation on the estimation of residually trapped CO₂ in a saline reservoir using oxygen isotope signature of the CO₂. He defined the concept of residual trapping of CO₂ during geosequestration as the disconnected droplets of CO₂ which are rendered immobile in pore spaces of the porous media. It is well known that assessing the degree of residual trapping (as a mechanism of CO₂ trapping) is particularly difficult. Stuart and collaborators demonstrated the use of oxygen isotopes for measuring CO₂ residual saturating for CO₂CRC Otway Site in Melbourne Australia where 65,000 tonnes of CO₂ have been injected. Stuart showed that a shift in formation water fractionation due to CO₂ contact with water can be used to estimate 14 ± 9 % residual CO₂ saturation. The scale of measurement was limited to wellbore area (∼20 m of wellbore) similar to noble gas applications and neutral logging measurements.

Sam Krevor

Dr Sam Krevor presented findings for a recent project on multi-scale characterization of CO₂ storage in the UK. His presentation was the first series in a project that included two investigative components: 1) Advanced Petrophysics led by his team in Imperial College London, and 2) Reservoir Simulation, led by Dr Hayley Vosper in British Geological Survey. Sam and his team conducted laboratory experiments in studying the impact of heterogeneity on key fluid processes in carbon sequestration namely primary drainage, secondary imbibition, and residual trapping. He stated that the impact of relative permeability on the injectivity in the reservoir is both uncertain and significant. And that this variation in relative permeability hinges on the natural rock heterogeneity in the system. Sam and his team were able to show that the impact is significant on a case-dependent basis. Heterogeneity has smaller effects on relative permeability in high flow potential cases in contrast to low flow potential cases. Sam ended his presentation by referring those present to the following article: Reynolds & Krevor, 2015, Wat. Res. Res. paper for a more comprehensive information.

Harun Mahgerefte

Prof. Harun Mahgerefte presented the objectives and challenges of the project CO₂QUEST (Techno-economic Assessment of CO₂ Quality Effect on its Storage and Transport). Harun emphasised on the importance of holistic approaches in considering and planning for CO₂ injection in depleted gas fields. Harun discussed about a wide range of considerations for CCS including effects of impurities of CO₂ on pipelines, flow regime heterogeneities in pipelines by experimental facilities, costs analysis and finding optimal solution, crack propagation tests by cooling CO₂ in buried pipelines, vertical CO₂ release experiments alongside the pipelines and tests on dispersion of plume. Harun finished his presentation by reiterating on the importance of looking at the overall picture of CCS rather than isolated components.

Hayley Vosper

Dr Hayley Vosper’s presentation was the second series in the project, ‘multi-scale characterization of CO₂ storage in the UK’. Hayley showed that hysteresis must be incorporated in relative permeability models of numerical simulation systems. As an example on Bunter Sandstone Model, Hayley and her team showed that using 12 wells and 2MT/annum from Drax PowerStation, constrained injection by fracture pressure and 50 years length of injection, while hysteresis does not affect the injectivity, it affects the fate and transport of CO₂ injected. They estimated a capacity of 736 Mt CO₂ for Bunter Sandstone Model. A secondary example used to show that for methane depleted South Morecambe field, numerical simulation-based capacity is 800 Mt CO₂ which agrees well with CO₂STORED database. In terms of pressure, Hayley showed that the build-up will be higher than initial hydrostatic pressure but lower than the fracture pressure.