Potential CO2 Storage Reservoirs Research Articles

Emissions reduction in LNG production facilities through emerging post-combustion carbon capture and storage technologies

The liquefied natural gas (LNG) sector relies extensively on gas turbines for on-site power generation and to drive refrigeration compressors. They provide an efficient and reliable energy source for LNG operations in remote locations. With upcoming changes to the Safeguard Mechanism in Australia, there is an increased focus on Scope 1 emissions, so management and targeted reduction are a priority to reduce liabilities. Despite technology advancements, gas turbines remain one of the largest sources of carbon dioxide (CO2) emissions in LNG production facilities. Also, in Australia, many facilities are not grid-connected, meaning that displacement of Scope 1 emissions through renewable electricity sourcing is a challenge. To develop deeper cuts in Scope 1 emissions, one solution is to deploy post-combustion carbon capture and storage (CCS) on existing gas turbines, with the potential to reduce associated emissions by over 90%. Globally, a number of LNG facilities are already deploying CCS to permanently store reservoir CO2 from the LNG processing trains. Several Australian LNG facilities are located in close proximity to potential CO2 storage reservoirs, meaning that a coordinated approach to both reservoir and post-combustion CO2 should be considered when sizing pipelines, shipping systems and storage wells to optimise and leverage the required investment. This paper outlines the technological, economic and policy aspects of integrating both reservoir post-combustion CCS on LNG facilities, including barriers and opportunities for deployment. It will discuss new developments and enablers for CCS to be more widely deployed at LNG production sites.

Reservoir properties and CO2 storage capacity of the Rose Run Sandstone (Lower Ordovician, Knox Group) in the Central Appalachian Basin, northeast Kentucky

The Lower Ordovician Rose Run Sandstone is a potential CO2storage reservoir in the Central Appalachian Basin in northeast Kentucky where the Kentucky Geological Survey’s 1 Hanson Aggregates research well penetrated it at drill depths of 1,000–1,009.5 m. Average Rose Run porosity and permeability from core plugs are 9.1% and 44.6 mD, respectively.In situreservoir properties were determined by step-rate testing an 18.6-m interval bracketing the Rose Run. Pressure derivative analysis of wellbore falloff pressure suggests that the Rose Run shares properties of both dual-porosity and dual-permeability reservoirs, consistent with its mixed lithologies. The Rose Run pore pressure was 9.3 MPa/km, 1.1 MPa/km underpressured compared to the expected hydrostatic gradient of 10.4 MPa/km. Average porosity of the Rose Run, at the industry-standard 7% porosity cutoff for assessing CO2storage capacity, calculated from 27 wells in the surrounding region, was 11.6% and the average net reservoir thickness was 6.2 m. Geomechanical properties of the overlying Beekmantown Dolomite show that it would act as a reservoir confining interval during CO2injection. The estimated P50supercritical CO2storage volume is 77.2 kt/km2, yielding P50storage capacity of 165.7 Mt in the region. By itself, an average surface area of 12.9 km2would be required to store 1 Mt of supercritical CO2in the Rose Run, thus lacking the volume to act as a stand-alone CO2storage reservoir in this area. It could contribute to a stacked-reservoir storage project developed in the larger Knox section, however. CO2–brine relative permeability tests suggest that nearly half of any supercritical CO2injected into the Rose Run would be residually trapped, and another portion would be trapped by mineral precipitation. The Rose Run in the KGS 1 Hanson Aggregates well is very close to the subsurface CO2critical depth in the northeast Kentucky region and lacks an updip reservoir trap. How far and fast the mobile CO2migration might occur at this site remains for future research and reservoir modeling.

Seismic reservoir characterization of potential CO2 storage reservoir sandstones in Smeaheia area, Northern North Sea

Evaluating any subsurface CO 2 storage site comprises the reservoir, seal, and overburden investigation to mitigate injection and storage-related complications. The Upper-Middle Jurassic Sognefjord, Fensfjord, and Krossfjord formation sandstones are potential CO 2 storage reservoirs at the Smeaheia area, northern North Sea. The Smeaheia area is located east of the Troll oil and gas field. The Upper Jurassic organic-rich Heather and Draupne Formation shales are the main seals for the sandstone reservoirs. In this study, we carried out a prestack seismic inversion to obtain elastic property cubes of acoustic impedance ( AI ), velocity ratio ( Vp/Vs ), and bulk density ( RhoB ). From these elastic cubes, we obtained the reservoir properties such as porosity ( Phi ), shaliness ( V sh ), and permeability ( k ) of Sognefjord, Fensfjord, and Krossfjord formations. We introduced two new equations to extract the shale volume and porosity cubes from the inverted elastic cubes in the present study. These equations are nonlinear based on the AI versus Vp/Vs rock physics template. Both equations are correlated first with the well log data and then applied on the elastic property cubes ( AI versus Vp/Vs ) to obtain the V sh and Phi property cubes. An additional porosity cube ( PhiD ) was generated from the inverted RhoB for comparison. Finally, using an empirical equation, permeability was extracted from the porosity cube. The reservoir properties we derived from 3D seismic, in addition to the well log, revealed the vertical and lateral variations of porosity, shaliness, and permeability in the Smeaheia area. We used these reservoir properties to infer the depositional environment and the viability of reservoirs for CO 2 storage. The depositional environments identified were shoreface and deltaic from the extracted sand-body geometries. We found the Sognefjord Formation possessing the best reservoir properties, followed by the Fensfjord Formation as the secondary storage potential. In contrast, the Krossfjord Formation owed the lowest reservoir quality in the Smeaheia area. • Our new equations helped to reveal the lateral variations in reservoirs and their depositional environment. • The Sognefjord is the best, and Fensfjord Formation is the second-best quality reservoir in the area for CO 2 storage. • The Krossfjord Formation is the least suitable for CO 2 storage in the Smeaheia area.

A regional CO2 containment assessment of the northern Utsira Formation seal and overburden, northern North Sea

AbstractUpscaling Carbon Capture and Storage requires identification of suitable storage sites, with robust reservoir seals. The Utsira Formation in the northern North Sea has been flagged as a target for further storage. However, there are no regional studies of seal variability addressing heterogeneities that could facilitate seal bypass. This study aims to: (a) identify, assess and map the elements that promote or restrict fluid migration, (b) develop a matrix to regionally map containment confidence (CC) and (c) rank the different areas for CO2 containment across the Utsira Formation. The seal and overburden were mapped using a high‐resolution, pre‐stack depth‐migrated 3D broadband seismic reflection dataset and 141 exploration wells. Seal geometry, sandstone presence and sandstone connectivity in the seal and overburden were assigned relative CC scores, which were summed to map overall CC of the Utsira Fm. Indicators for shallow gas and migration were mapped and correlated with the other elements. Areas with the lowest CC are in the west of the Utsira Fm. Here, sandstones within the Seal Interval are connected through the overburden via sandy submarine fans. In the southeast, dipping stratigraphy downlaps onto the Utsira Fm., increasing the potential for connection with glacially‐derived channel‐lobe systems in the overburden. The areas with the highest CC are the central and northeast parts of the Utsira Fm., where the Seal Interval is mudstone‐dominated and parallel to the reservoir, and channel‐lobe systems identified in the Overburden Interval are disconnected from the reservoir. This area coincides with a thick depocentre of the northern Utsira Fm. These results can be used to inform CO2 storage site selection and constrain future CO2 plume simulation analyses for the Utsira Fm. The CC matrix outlined here can also be adapted and applied to regionally assess the containment of other potential CO2 storage reservoirs in any setting.

Hydraulic fracturing to enhance injectivity and storage capacity of CO2 storage reservoirs: Benefits and risks

Several potential CO2 storage reservoirs have been found to have insufficient porosity and permeability to support cost effective commercial-scale injection. As a result, the use of hydraulic fracturing to enhance injectivity and storage capacity of CO2 storage reservoirs was explored. Previous modeling studies indicate that fracturing can increase storage capacity by modest to significant amounts (10%–35%), depending on model assumptions. Simulations completed as part of this study confirm that for a range of horizontal well lengths, number of fractures, fracture geometries, and fracture properties, injectivity is improved and capacity increases by 13%–71% over the base case unfractured vertical well. Intuitively, increasing the well length and number of fractures had a corresponding impact on increased capacity. Fracture area (i.e., the fracture height multiplied by its width) was an important parameter for increasing capacity but the specific geometry (e.g., the ratio of height-to-width) was unimportant. The most important aspect that affected capacity was the ability of a fracture to connect high permeability horizontal zones in the reservoir. This would allow a single well to access both layers, thereby maximizing total storage capacity of the reservoir while likely leading to an overall increase of the CO2 footprint, which is an important consideration for Class VI UIC permitting. The results of this work demonstrate that hydraulic fracturing is an attractive option to consider when faced with an underperforming geologic carbon storage site that is at risk of causing a project to fail.

A 3D geological model for a potential CO2 reservoir in the El Bierzo Basin (Carboniferous, NW Spain)

ABSTRACTA 3D geological model of the Torre‐Bembibre Carboniferous sub‐basin, a potential CO2 storage reservoir, is proposed here. The Torre‐Bembibre sub‐basin is part of the El Bierzo coal‐bearing Carboniferous basin located in the westernmost part of León province (NW Spain). It covers an area of about 150 km2. Carboniferous deposits (up to 1500 m of continental siliciclastics) are divided into nine intervals, defined by earlier coal exploration work. They were deposited as intramontane basin infill within a transpressional regime during the last stages of the Variscan Orogeny and are partially covered by Neogene and Quaternary continental siliciclastic sediments, formed by alluvial plains, fans and terraces. To resolve a 3D geological model of the Torre‐Bembibre sub‐basin, including outcropping layers and their prolongation at depth, a 3D dip‐domain method was applied, where data from all stratigraphic positions were used to compose a coherent geological reconstruction of the stratigraphic surfaces. Subsurface information was available from previous and newly acquired seismic reflection profiles and boreholes. The 3D model helped resolving some uncertainties, specifically: (i) the western termination of the Carboniferous basin under the Tertiary sediments, corresponding to an NNE–SSW normal fault, (ii) the depth and morphology of the base of the Carboniferous strata and (iii) the morphology of the intra‐Carboniferous layers. The syncline/anticline shape of the Torre‐Bembibre sub‐basin suggests a reservoir which may be capable of storing CO2 under the Tertiary cover. The total estimated volume is 6.4 km3, while the total capacity for CO2 storage could be as much as 7 Mt. The reservoir is most likely located within the major massive sandstone bodies in the Chuchu interval, in the syncline–anticline structure north of the town of Bembibre. The potential capacity of the reservoir calls for undertaking further studies using the proposed 3D geological model in order to determine more precisely the petrophysics and geometry near Bembibre.

Numerical Modeling of CO2 Migration in Saline Aquifers of Selected Areas in the Upper Silesian Coal Basin in Poland

Determining the characteristics of the dynamic behavior of carbon dioxide in a rock mass is a stage in the process of assessing a potential CO2 storage reservoir. The aim of this study was to analyze the process of CO2 storage in saline aquifers of the selected regions of the Upper Silesian Coal Basin in Poland. The construction of dynamic simulation models was based on static models of real deposit structures developed on a regional scale. Different simulation variants of the CO2 storage process were adopted, varying in terms of injection efficiency and duration of individual simulation phases. The analysis examined the influence of the degree of hydrodynamic openness of the structure on the CO2 storage process, in each of the variants. The results of numerical simulations showed that among the three analyzed geological formations, the Dębowiec formation is the most prospective for potential CO2 storage and is characterized by the most favorable geological and hydrogeological parameters. In the best variant of the simulation, in which the safety of CO2 storage in the rock mass was taken into account, the total amount of CO2 injected in a single directional well was approximately 8.54 million Mg of CO2 during 25 years of injection.

Mineral Precipitation from CO2-Saturated Water in Basalts and its Potential for Self-Sealing of Fractures and Joints

Continental flood basalts are considered as potential CO2 storage reservoirs; however, many knowledge gaps have not been addressed. This study determines whether mineral precipitation will seal joints and fractures during the vertical migration of CO2-enriched water and thereby contribute to CO2 containment. The interaction of CO2-saturated water with basalt wafers was studied in a batch reactor at a pressure of 80 bars and 60°C for a period of 44 days. Si-Al-rich minerals such as smectites and zeolites were observed in suspension at the end of the incubation. In addition, mineral precipitation on at the surface of the basalt wafers was identified as magnesite, kaolinite and Mg- and Fe-oxides. Na-rich Si-Al minerals were identified as Na-nontronite, which belongs to the smectite group. All cation concentrations declined between incubation day 6 and 44. Mineral saturation indices have been computed for the experimental solution as a function of time to observe supersaturated and undersaturated mineral phases. Smectites, zeolites, Fe-oxides, and kaolinite are observed to be supersaturated in the experimental fluid till the end of the reaction time period of 44 days which matches closely with the experimental secondary mineral phases. These secondary minerals could be potential sealants and mitigate CO2 leakage issue.

Relative Permeability of Williston Basin CO2 Storage Targets

Theoretical and preliminary laboratory-based CO2/brine relative permeability curves were generated for a set of samples representing potential CO2 storage reservoirs within the Williston Basin. Permeability, petrographic, and petrophysical properties were also determined for each sample tested. Clastic and carbonate rock types were tested in an effort to provide previously unavailable data on potential CO2 storage reservoirs. The sample set tested is considered representative of potential injection targets for rock types found throughout the world and may provide useful analogs for underexplored regions where geologic storage of CO2 is being considered.

A data driven model for the impact of IFT and density variations on CO2 storage capacity in geologic formations

Carbon dioxide (CO2) storage in depleted hydrocarbon reservoirs and deep saline aquifers is one of the most promising solutions for decreasing CO2 concentration in the atmosphere. One of the important issues for CO2 storage in subsurface environments is the sealing efficiency of low-permeable cap-rocks overlying potential CO2 storage reservoirs. Though we focus on the effect of IFT in this study as a factor influencing sealing efficiency or storage capacity, other factors such as interfacial interactions, wettability, pore radius and interfacial mass transfer also affect the mobility and storage capacity of CO2 phase in the pore space. The study of the variation of IFT is however important because the pressure needed to penetrate a pore depends on both the pore size and the interfacial tension. Hence small variations in IFT can affect flow across a large population of pores. A novel model is proposed to find the IFT of the ternary systems (CO2/brine-salt) in a range of temperatures (300–373 K), pressures (50–250 bar), and up to 6 molal salinity applicable to CO2 storage in geological formations through a multi-variant non-linear regression of experimental data. The method uses a general empirical model for the quaternary system CO2/brine-salts that can be made to coincide with experimental data for a variety of solutions. We introduce correction parameters into the model, which compensates for uncertainties, and enforce agreement with experimental data. The results for IFT show a strong dependence on temperature, pressure, and salinity. The model has been found to describe the experimental data in the appropriate parameter space with reasonable precision. Finally, we use the new model to evaluate the effects of formation depth on the actual efficiency of CO2 storage. The results indicate that, in the case of CO2 storage in deep subsurface environments as a global-warming mitigation strategy, CO2 storage capacity increases with reservoir depth.

Characterization of reservoir conditions for CO2 storage using a dimensionless Gravitational Number applied to the North German Basin

The characterization of potential CO2 storage reservoirs addresses different aspects, in particular safety and economical feasibility of a storage project. To adequately assess regions worthy of further investigation, an early site screening that considers relevant geophysical and hydro-geological criteria is required. This work is based on the Storage Catalogue of Germany [1] where different rock units of the deeper subsurface have been characterized based on minimum depth and minimum thickness criteria in order to define areas worthy of further investigation. We consider additional data for depth, temperature, and salinity which determine the fluid properties of CO2 and brine. As a screening criterion we use the Gravitational Number (Gr), which we calculate for the Middle Buntsandstein subgroup in Northern Germany, and show through numerical simulations that changes in fluid properties have a noticeable effect on storage efficiency and the amount of residually trapped CO2. We discuss the quality of Gr as an indicator for an improved understanding of storage efficiency.

Strategy for ranking potential CO2 storage reservoirs: A case study for Belgium

CO2 capture and storage (CCS) is likely to become a necessary option in mitigating global climate change. However, lack of detailed knowledge on potential deep geological reservoirs can hamper the development of CCS. In this paper a new methodology is presented to assess and create exploration priority lists for poorly known reservoirs. Geological expert judgements are used as a basis in a two-stage geo-techno-economic approach, where first an estimate of the practical reservoir capacity is calculated, and secondly source–sink matching is used for calculating an estimate of the matched capacity and the reservoir development probability. This approach is applied to Belgium, demonstrating how a priority ranking for reservoirs can be obtained based on limited available data and large uncertainties. The results show the Neeroeteren Formation as the most prospective reservoir, followed by the Buntsandstein Formation and the Dinantian reservoirs. The findings indicate that CO2 export to reservoirs in neighbouring countries seems inevitable; still, there is a 70% chance storage will happen in Belgian reservoirs, with an average matched capacity estimate of 110Mt CO2. These quantitative results confirm the qualitative resource pyramid classification of potential reservoirs. For Belgium, a high economic risk is attached to reservoir exploration and development. Exploration remains however a necessity if CCS is to be deployed. Furthermore, it is shown that the presented methodology is indeed capable of producing realistic results, and that using expert judgements for reservoir assessments is valid and beneficial.

Reaction of water-saturated supercritical CO2 with forsterite: Evidence for magnesite formation at low temperatures

The nature of the reaction products that form on the surfaces of nanometer-sized forsterite particles during reaction with H2O-saturated supercritical CO2 (scCO2) at 35°C and 50°C were examined under in situ conditions and ex situ following reaction. The in situ analysis was conducted by X-ray diffraction (XRD). Ex situ analysis consisted of scanning electron microscopy (SEM) examination of the surface phases and chemical characterization of precipitates using a combination of confocal Raman spectroscopy, 13C and 29Si NMR spectroscopy, and energy-dispersive X-ray spectroscopy (EDS). The results show that the forsterite surface is highly reactive with the primary reaction products being a mixture of nesquehonite (MgCO3·3H2O) and magnesite (MgCO3) at short reaction times (∼3–4days) and then magnesite (MgCO3) and a highly porous amorphous silica phase at longer reaction times (14days). After 14days of reaction most of the original forsterite transformed to reaction products. Importantly, the formation of magnesite was observed at temperatures much lower (35°C) than previously thought needed to overcome its well-known sluggish precipitation kinetics. The conversion of nesquehonite to magnesite liberates H2O which can potentially facilitate further metal carbonation, as postulated by previous investigators, based upon studies at higher temperature (80°C). The observation that magnesite can form at lower temperatures implies that water recycling may also be important in determining the rate and extent of mineral carbonation in a wide range of potential CO2 storage reservoirs.

Hydro-mechanical analysis of Co2 storage in porous rocks using a critical state model

A numerical model is presented to simulate the hydro-mechanical behaviour of the porous rocks that form the deep saline aquifers which are currently being considered as potential CO2 storage reservoirs. The model has taken into account the equations of state regulating the behaviour of CO2, in both the supercritical state in which will be injected, and under atmospheric conditions. Whilst the flow model is founded on a “conventional” advective/diffusive formulation, the geomechanical constitutive model used is a critical state model that includes a non-linear hypoelastic law, and a brittle/ductile yield which takes into account mechanical degradation and the effect of partial saturation caused by the CO2 flow. With this model, it will be possible to analyse the localisation of the deformation which may occur when a dilatant brittle yield is reached, and thus to analyse the role played by the preferential flow paths associated with this localisation. A partial differential equation solver based on the finite element method, which adopts a multiphysics simulation environment, has been used. After some examples of validation, the simulation of a synthetic example that highlights the capacities of the model is presented.

U.S. DOE methodology for the development of geologic storage potential for carbon dioxide at the national and regional scale

A detailed description of the United States Department of Energy (US-DOE) methodology for estimating CO2 storage potential for oil and gas reservoirs, saline formations, and unmineable coal seams is provided. The oil and gas reservoirs are assessed at the field level, while saline formations and unmineable coal seams are assessed at the basin level. The US-DOE methodology is intended for external users such as the Regional Carbon Sequestration Partnerships (RCSPs), future project developers, and governmental entities to produce high-level CO2 resource assessments of potential CO2 storage reservoirs in the United States and Canada at the regional and national scale; however, this methodology is general enough that it could be applied globally. The purpose of the US-DOE CO2 storage methodology, definitions of storage terms, and a CO2 storage classification are provided. Methodology for CO2 storage resource estimate calculation is outlined. The Log Odds Method when applied with Monte Carlo Sampling is presented in detail for estimation of CO2 storage efficiency needed for CO2 storage resource estimates at the regional and national scale. CO2 storage potential reported in the US-DOE's assessment are intended to be distributed online by a geographic information system in NatCarb and made available as hard-copy in the Carbon Sequestration Atlas of the United States and Canada. US-DOE's methodology will be continuously refined, incorporating results of the Development Phase projects conducted by the RCSPs from 2008 to 2018. Estimates will be formally updated every two years in subsequent versions of the Carbon Sequestration Atlas of the United States and Canada.

Séances plénières du 27e congrès de la SFE

Carbon dioxide (CO2) storage in depleted hydrocarbon reservoirs and deep saline aquifers is one of the most promising solutions for decreasing CO2 concentration in the atmosphere. One of the important issues for CO2 storage in subsurface environments is the sealing efficiency of low-permeable cap-rocks overlying potential CO2 storage reservoirs. Though we focus on the effect of IFT in this study as a factor influencing sealing efficiency or storage capacity, other factors such as interfacial interactions, wettability, pore radius and interfacial mass transfer also affect the mobility and storage capacity of CO2 phase in the pore space. The study of the variation of IFT is however important because the pressure needed to penetrate a pore depends on both the pore size and the interfacial tension. Hence small variations in IFT can affect flow across a large population of pores. A novel model is proposed to find the IFT of the ternary systems (CO2/brine-salt) in a range of temperatures (300–373 K), pressures (50–250 bar), and up to 6 molal salinity applicable to CO2 storage in geological formations through a multi-variant non-linear regression of experimental data. The method uses a general empirical model for the quaternary system CO2/brine-salts that can be made to coincide with experimental data for a variety of solutions. We introduce correction parameters into the model, which compensates for uncertainties, and enforce agreement with experimental data. The results for IFT show a strong dependence on temperature, pressure, and salinity. The model has been found to describe the experimental data in the appropriate parameter space with reasonable precision. Finally, we use the new model to evaluate the effects of formation depth on the actual efficiency of CO2 storage. The results indicate that, in the case of CO2 storage in deep subsurface environments as a global-warming mitigation strategy, CO2 storage capacity increases with reservoir depth.