Rapid surface detection of CO2 leaks from geologic sequestration sites

AbstractThis study focuses on developing a method to characterize and detect leakage of carbon dioxide from a geologic sequestration site using a Picarro gas analyser, and to systematically evaluate the robustness of detection ability and optimize the data acquisition parameters by testing under varying conditions at the Zero Emissions Research and Technology field site in Bozeman, MT. It was determined (1) both 12CO2 or 13CO2 measurements provide equally good leak detection ability, (2) wind speed and direction does not limit detection ability with a sampling height less than 30cm, and (3) δ13C measurements did not provide a reliable method for leak detection with our data acquisition strategy

CO2 Interim storage: Technical characteristics and potential role in CO2 market development

AbstractIn the absence of legislation that imposes a price on CO2 emissions, few significant economic incentives currently exist for largescale commercial application of CO2 Capture and Storage (CCS). A novel technique, currently under development, shows potential to add value to sequestered CO2, promote its utilization, and bridge the gap between its supply and demand, thus allowing the development of fully-integrated and reliable CO2 market. This technique is referred to as “ CO2 Interim Storage”, or briefly, CIS. CIS involves storing CO2 for a finite period of time to be subsequently utilized in CO2 Enhanced Oil Recovery (EOR) and potentially other industrial processes. The feasibility of CO2 storage is assessed based on three major variables: The distance between CO2 source and storage medium, the general trend of CO2 storage in and delivery from the storage medium (primarily governed by the market dynamics of supply and demand), as well as the frequency of CO2 injection into and extraction from the storage medium. The importance of CIS as a major tool for CO2 market and infrastructure development becomes clear upon comparing this new technology to the widely implemented underground natural gas (NG) storage and assessing its role in energy hybridization and in meeting variable and localized CO2 demand. In this study, the flow of CO2 in underground storage reservoirs is numerically simulated to provide general analysis of the technical aspects associated with varying CO2 injection rates. The simulations show that the CO2 plume and pressure buildup profiles are comparable for constant and variable injection rates. Also, in the cases of variable injection, the pressure variation dampens as injection proceeds with time. In addition, a casestudy is conducted in which CIS is implemented to meet the CO2 demand for EOR operations in the state of Wyoming from CO2 emissions of in-state coal power plants. This is achieved via modeling an integrated source-sink CO2 network. The results show that the economic attractiveness of the project is dependent on the availability of CO2, the distance between CO2 sources, interim storage sites, and sinks, as well as the price and demand of CO2 for EOR

Recent Progress in Predicting Permeability Distributions for History Matching Core Flooding Experiments

AbstractLaboratory core flooding experiments coupled with CT scanning has been shown to be very useful for examining CO2-brine displacement processes. These experiments can be used to measure core average properties such as absolute and relative permeability, and also to examine sub core-scale saturation and porosity distributions. By examining the sub core scale fluid distributions during the displacement process, it is possible to study the displacement efficiency of CO2-brine drainage processes, residual trapping and fluid saturation at the millimeter to sub-millimeter scale. One potentially useful tool for studying CO2-brine systems is using numerical simulation to replicate and study these core flooding systems. This could be used to study the interactions and relative impact of different parameters such as capillary pressure, relative permeability and heterogeneity on brine displacement by CO2 under various flow conditions.One challenge to successfully conducting such numerical experiments has been accurate representation of the permeability distribution inside the core at the millimeter and sub-millimeter scale. Other simulation parameters can all be measured using laboratory experiments, but permeability must be derived from other properties at the core and sub core-scale. Previous work has shown that predicting sub core-scale permeability distributions based on porosity does not result in accurate representation of permeability at such a small scale. To improve these predictions, a new method based on capillary pressure and was developed and used to accurately predict sub core-scale permeability distributions in a relatively homogeneous Berea sandstone.The work presented in this paper uses the same method to calculate permeability in a strongly heterogeneous sandstone core from the Otway Basin Pilot Project in Australia. Simulations show that the results are consistent with previous results in the homogeneous cores, with statistically significant capability to predict sub core-scale CO2 distributions in the core. Due to the extreme heterogeneity of the core used in this study, the average match is not as good as for a relatively homogeneous rock core, however, a visual comparison shows that the results are still very good, and that the new method used to calculate permeability may still be valid even in the presence of strong heterogeneity

Experimental Investigation of a Capacity-Based Demand Response Mechanism for District-Scale Applications

District heating and cooling systems incorporating heat recovery and large-scale thermal storage dramatically reduce energy waste and greenhouse gas emissions. Electrifying district energy systems also has the effect of introducing city-scale controllable loads at the level of the electrical substation. Here we explore the opportunity for these systems to provide energy services to the grid through capacity-based demand response mechanisms. We present both a planning approach to estimate available demand-side capacity and a control framework to guide real-time scheduling when the program is active. These tools are used to assess the technical feasibility and the economic viability of participating in capacity-based demand response in the context of a real-world, megawatt-scale pilot during the summer of 2018 on the Stanford University campus

Capacity investigation of brine-bearing sands of the Frio Formation for geologic sequestration of CO2

The capacity of fluvial brine-bearing formations to sequester CO2 is investigated using numerical simulations of CO2 injection and storage. Capacity is defined as the volume fraction of the subsurface available for CO2 storage and is conceptualized as a product of factors that account for two-phase flow and transport processes, formation geometry, formation heterogeneity, and formation porosity. The space and time domains used to define capacity must be chosen with care to obtain meaningful results, especially when comparing different authors’ work. Physical factors that impact capacity include permeability anisotropy and relative permeability to CO2, brine/CO2 density and viscosity ratios, the shape of the trapping structure, formation porosity and the presence of low permeability layering.National Energy Technology LaboratoryBureau of Economic Geolog

Capillary Heterogeneity in Sandstone Rocks During CO2/Water Core-flooding Experiments

AbstractWe have successfully applied a novel experimental technique to measure drainage capillary pressure curves in reservoir rocks with representative reservoir fluids at high temperatures and pressures. The method consists of carrying out 100% CO2 flooding experiments at increasingly higher flow rates on a core that is initially saturated with water and requires that the wetting-phase pressure is continuous across the outlet face of the sample. Experiments have been carried out on a Berea Sandstone core at 25 and 50°C and at 9MPa pore pressure, while keeping the confining pressure at 12MPa. Measurements are in good agreement with data from mercury intrusion porosimetry. The technique possesses a great potential of applicability due to the following reasons: (a) it can be applied in conjunction with steady-state relative permeability measurements, as it shares a very similar experimental configuration; (b) it is faster than traditional (porous-plate) techniques used for measuring capillary pressure on rock cores with reservoir fluids; (c) by comparison with results from mercury porosimetry, it allows for the estimation of the interfacial and wetting properties of the CO2/water system, the latter being unknown for most rocks; (d) by combination with X-ray CT scanning, the method allows for the observation of capillary pressure–saturation relationships on mm-scale subsets of the rock core. The latter are of high relevance as they directly and non- destructively measure capillary pressure curve heterogeneity in sandstone rocks