Quantifying rates of CO2 dissolution in U.S. natural CO2 reservoirs through integration of noble gas and 3D reservoir modelling techniques

This project will generate new knowledge relevant to the worldwide problem of engineering secure CO2 storage. You will be trained in 3D reservoir modelling techniques and noble gas isotope and igneous rock geochemical interpretation. You will apply these techniques to provide a time-series of CO2 dissolution rates across the series of natural CO2 reservoirs found in the Colorado Plateau region of the USA. This aims to provide greater understanding of the key controls on CO2 dissolution rates, determine if they can be enhanced through injection strategies and inform how they can be better incorporated into predictive models of CO2 storage.

Background: CO2 capture and storage (CCS) is the only industrial scale technology that can directly reduce the CO2 emissions produced by the combustion of fossil fuels. Given global reliance on fossil fuels for energy and industrial manufacturing needs, CCS is an essential technology for the global drive to reduce anthropogenic CO2 emissions to the atmosphere following the recent ratification of the Paris Agreement to combat climate change. CO2 captured from various energy producing sources will be injected into depleted oil and gas reservoirs or deep saline formations for storage. For the safety of this storage to be assured it is essential that it can be shown that CO2 can be retained safely in the subsurface over a minimum of 10,000 years. The only means to provide reassurance of storage over these timescales are to study natural CO2 reservoirs, some of which have contained CO2 for millions of years[1]. Despite extensive research, the controls and timescales that each of these trapping mechanisms act on CO2 contained in different reservoirs is still uncertain[2].

Work by the principle supervisor has identified that solubility trapping is a key mechanism of CO2 trapping in a number of natural CO2 reservoirs across the Colorado Plateau area of the US[3]. This study also found limited geochemical evidence for significant mineral trapping in these reservoirs. Recent research has built on these findings by integrated noble gas measurements in the Bravo Dome natural CO2 reservoir with 3D modelling of the reservoir structure to calculate the total amount of CO2 dissolved and also identified the age of CO2 charge into the reservoir[4].

Proposed Research: The initial phase of the project will construct 3D reservoir models in industry standard software of the individual CO2 reservoirs using publicly available well logs and geophysical data. These will be combined with discovery pressure data to calculate the amount of CO2 stored in each reservoir prior to commercial extraction commencing.

The second stage will Integrate noble gas measurements from each reservoir with well log records of the gas/water contact to calculate the amount of CO2 lost to solubility trapping in each well, following the methods used in Bravo Dome[3] and then interpolate this to obtain the total volume of CO2 lost to solubility trapping across the entirety of each CO2 reservoir. Thorough the interpretation of legacy pressure and measured noble gas data the likely CO2 charge direction will be determined and combined with existing dates and geochemical compositions of nearby igneous rocks, to deduce age of CO2 charge. Combining the charge timing and degree of CO2 loss to solubility trapping for each reservoir to deduce the rate of CO2 dissolution in each reservoir.

The final phase will compare and contrast the CO2 dissolution rates in each reservoir with the reservoir geometry, properties and structure in order to deduce the key differences and similarities between each reservoir and identify the key controls on CO2 dissolution rate. This knowledge will be used to ascertain how CO2 dissolution can be enhanced through injection strategies and inform how they can be accurately incorporated into predictive models of CO2 storage.

Requirements: Applicants are invited from UK/EU citizens who should have, or expect to gain, a 2:1 BSc or MSc in the GeoSciences, Physical Sciences, or Mathematical Sciences. It is not expected that you will arrive with all the skills.