Karl-Heinz Wolf

Wettability determination by contact angle measurements: hvbB coal–water system with injection of synthetic flue gas and CO2

Geological sequestration of pure carbon dioxide (CO(2)) in coal is one of the methods to sequester CO(2). In addition, injection of CO(2) or flue gas into coal enhances coal bed methane production (ECBM). The success of this combined process depends strongly on the wetting behavior of the coal, which is function of coal rank, ash content, heterogeneity of the coal surface, pressure, temperature and composition of the gas. The wetting behavior can be evaluated from the contact angle of a gas bubble, CO(2) or flue gas, on a coal surface. In this study, contact angles of a synthetic flue gas, i.e. a 80/20 (mol%) N(2)/CO(2) mixture, and pure CO(2) on a Warndt Luisenthal (WL) coal have been determined using a modified pendant drop cell in a pressure range from atmospheric to 16 MPa and a constant temperature of 318 K. It was found that the contact angles of flue gas on WL coal were generally smaller than those of CO(2). The contact angle of CO(2) changes from water-wet to gas-wet by increasing pressure above 8.5 MPa while the one for the flue gas changes from water-wet to intermediate-wet by increasing pressure above 10 MPa.

CO2 enhanced coalbed methane production in the Netherlands

The technical and economical feasibility of CO2 sequestration in deep coal layers combined with enhanced coalbed methane (ECBM) production in the Netherlands has been explored. Annually, 3.4 Mtonne CO2 from chemical installations can be delivered to sequestration locations at 15 €/tonne and another 55 Mtonne from power generating facilities at 40–80 €/tonne. Four potential ECBM areas have been assessed, of which Zuid Limburg is the best location for a test site, while the Achterhoek is more suitable for future large-scale CO2 sequestration. Between 54 Mtonne and 9 Gtonne CO2 can be sequestered in the four areas together, heavily depending on available technology for accessing the coal seams. At the same time, between 0.3 and 60 EJ of coalbed methane can be produced. The optimal configuration may have 1000 m spacing between production wells, and extreme inseam drilling. The price of coalbed methane may become competitive with natural gas when a bonus for CO2 sequestration is applied of about 25 €/tonne. For the long term, on-site hydrogen or power (SOFC) production with direct injection of produced CO2 seems most attractive. Further study is required, most notably more accurate geological surveys, assessment of drilling costs in Dutch context, and environmental impacts of ECBM.

Improved manometric setup for the accurate determination of supercritical carbon dioxide sorption.

An improved version of the manometric apparatus and its procedures for measuring excess sorption of supercritical carbon dioxide are presented in detail with a comprehensive error analysis. An improved manometric apparatus is necessary for accurate excess sorption measurements with supercritical carbon dioxide due to the difficulties associated with the high sensitivity of density for pressure and temperature changes. The accuracy of the apparatus is validated by a duplicate measurement and a comparison with literature data. Excess sorption and desorption of CO(2) on Filtrasorb 400 at 318.11 K up to 17 069 mole/m(3) (15.474 MPa) were selected for this validation. The measured excess sorption maximums are 7.79+/-0.04 mole/kg at 2253 mole/m(3) for the first sorption isotherm and 7.91+/-0.05 mole/kg at 2670 mole/m(3) for its subsequent desorption isotherm. The sorption and desorption peaks of the duplicate experiment are 7.92+/-0.04 mole/kg at 2303 mole/m(3) and 8.10+/-0.05 mole/kg at 2879 mole/m(3), respectively. Both data sets show desorption data being higher than the sorption data of the same data set. The maximum discrepancy between the desorption and sorption isotherms of one data set is 0.15 mole/kg. The discrepancy between the two excess sorption isotherms is 0.12 mole/kg or less. The a priori error of the excess sorption measurements is between 0.02 and 0.06 mole/kg. The error due to He contamination is between 0.01 and 0.05 mole/kg. The difference between the a priori uncertainty and the observed maximum discrepancies is considered to be acceptable. The sorption isotherms show identical qualitative behavior as data in the literature. The quantitative behavior is similar but the peak height and the linear decrease in excess sorption at high gas densities are 10% higher. A plot of the excess sorption versus the density can be used to obtain the sorbed phase density and the specific micropore volume. These sorbed phase densities are in excellent agreement with the data in the literature. Furthermore, the excess sorption data scaled to this specific micropore volume in this work and in the literature collapse on a single curve when plotted versus gas density.

Shale Gas Formations and Their Potential for Carbon Storage: Opportunities and Outlook

Shale gas resources are proving to be globally abundant and the development of these resources can support the geologic storage of CO2 (carbon dioxide) to mitigate the climate impacts of global carbon emissions from power and industrial sectors. This paper reviews global shale gas resources and considers both the opportunities and challenges for their development. It then provides a review of the literature on opportunities to store CO2 in shale, thus possibly helping to mitigate the impact of CO2 emissions from the power and industrial sectors. The studies reviewed indicate that the opportunity for geologic storage of CO2 in shales is significant, but knowledge of the characteristics of the different types of shale gas found globally is required. The potential for CO2 sorption as part of geologic storage in depleted shale gas reservoirs must be assessed with respect to the individual geology of each formation. Likewise, the introduction of CO2 into shale for enhanced gas recovery (EGR) operations may significantly improve both reservoir performance and economics. Based on this review, we conclude that there is a very good opportunity globally regarding the future of geologic storage of CO2 in depleted shale gas formations and as part of EGR operations.

Negative Saturation Approach for Non-Isothermal Compositional Two-Phase Flow Simulations

This article deals with developing a solution approach, called the non-isothermal negative saturation (NegSat) solution approach. The NegSat solution approach solves efficiently any non-isothermal compositional flow problem that involves phase disappearance, phase appearance, and phase transition. The advantage of the solution approach is that it circumvents using different equations for single-phase and two-phase regions and the ensuing unstable procedure. This paper shows that the NegSat solution approach can also be used for non-isothermal systems. The NegSat solution approach can be implemented efficiently in numerical simulators to tackle modeling issues for mixed CO2–water injection in geothermal reservoirs, thermal recovery processes, and for multicontact miscible and immiscible gas injection in oil reservoirs. We illustrate the approach by way of example to cold mixed CO2–water injection in a 1D geothermal reservoir. The solution is compared with an analytical solution obtained with the wave-curve method (method of characteristics) and shows excellent agreement. A complete set of simulations is carried out, which identifies six bifurcations. The two main bifurcations are (1) when the most downstream compositional wave is replaced by a compositional shock and (2) when an extra Buckley–Leverett rarefaction appears. The plot of the useful energy (exergy) versus the CO2 storage capacity shows a Z-shape. The top horizontal part represents a branch of high exergy recovery/relatively lower storage capacity, whereas the bottom part represents a branch of lower exergy recovery/higher storage capacity.

Interfacial Tension and Contact Angle Determination in Water-sandstone Systems with Injection of Flue Gas and CO2

Carbon capture and storage (CCS) has the potential for reducing CO2 emissions to the atmosphere. This option includes storage strategies such as CO2 injection into deep saline aquifers, depleted oil and gas reservoirs, and unmineable coal seams. This process is largely controlled by the interactions between CO2, the reservoir fluid and reservoir rock. In particular, the wettability of the rock matrix has a strong effect on the distribution of the injected CO2 into geological formations. In this study, the wetting behavior of Bentheimer sandstone slabs and CO2 and/or flue gas is investigated by means of contact-angle measurements. In addition, the interfacial tension between CO2 and/or flue gas and connate water was determined. The experiments were conducted in a pendant-drop cell, adapted to allow captive-bubble contact-angle measurements and performed at a constant temperature of 318 K and pressures varying between 0.2 and 15 MPa, typical in-situ conditions. The experimental contact angle measurements show that the Bentheimer sandstone/water system is (and remains) water-wet even at high pressures with CO2 and/or flue gas injection. The determined data of the contact angle of the water–sandstone system demonstrate a strong dependence on the bubble size and surface roughness with CO2 and flue gas injection.

A geothermal site combined with C02-storage

Introduction: Following two geothermal projects in Bleiswijk (for glashouses,1700 m depth) and the Hague (6000 houses), students of Delft University, Department of Applied Earth Sciences, started a feasibility study where casing drilling with composite pipe and CO 2-injection are combined with the production of geothermal energy. An anticlinal structure is present below the campus, which holds the Jurassic aged Rijswijk and Delft highly permeable sandstone members at a depth between 1.8 and 2.4 km. This member can produce about 150 m 3 of water per hour at 75° C. In urban environments, small operational footprints are essential for drilling a productionand a CO 2injection well (Fig.1a). By using new light-weight composite materials for wells with casing drilling technology, only small drilling rigs are required. The composite material is less susceptible to corrosion and enables co-injection of CO 2 with the returning water (Wolf et al. 2007). Geology: Several hydrocarbon exploration wells have been drilled around Delft, of which one on the University Campus. 2D and 3D seismic have been shot to primarily explore the regionally oil bearing Rijswijk formation above the Delft sandstones. The sands are part of the Upper Delfland formation and of Upper Jurassic (Kimmeridge) age. The overburden (1650 m) consists of mainly Cretaceous, Tertiary and Quaternary chalks, limestones, claystones, clays, siltstones, and sandstones. The target Delft sandstone for heat production and CO 2 storage is composed of sheets of amalgamated transgressive and coastal-barrier sands, rapidly alternating with clays, which were deposited on a Late-Kimmeridgian discordance. The 3D seismic shows an anticlinal structure of the Rijswijk sandstone member (fig 1b) covered by the mentioned sediments. No major structural phenomena, like faults, block faulting, erosion planes, etc., do cross the Delft sandstone in the area of interest. First studies by Smits (2008), de Boer (2008) and Eldert (2008) show promising reservoir qualities for the sandstone member; high permeability and porosity. Based on the petrophysics of the neighboring wells, the geothermal prognosis and reservoir properties for the area have been reconstructed: 1) At a depth of 2300 m, it is expected to produce water with a temperature of about 75°C. 2) A productionand injection rate over 150 m /hr should be feasible. 3) With carefully planned productionand injection wells, the original warm water and colder CO 2-saturated re-injected water will not interfere for at least 30 years (fig. 1c). The local geology of small oilfields shows that geothermal heat production and CO2-storage options in the sandstone members are positive; i.e. a potential large reservoir volume with high permeabilities and a proper seal. Surface Infrastructure and implementation of geothermal energy: The University Campus has an on-site79 MW power plant with two cogeneration units for base-load and three gas boilers for peak demand. The geothermal heat will contribute up to 5 MW continuously (95000 GJ), cutting CO 2 emission with 5000 tons annually, while reducing costs for base-load heat production. For optimal heat gain, the productionand injection well should be co-located with the power-plant. This gives spatial constrains on operations and the drilling of 2.5 km deep large-diameter holes with heavy equipment should be avoided. Unconventional Drilling: The casing drilling with composite pipe here introduced finds its origin at Delft University and is further developed by an industrial consortium (Acquit BV). It resulted in a light weight concept where a composite casing pipe is combined with the casing drilling methodology. This almost buoyant casing pipe needs considerably less working space and existing civil pile drilling units can be used to drill wells (Leijnse, 2008). The composite casing pipe has a better insulation, improved skin and a better endurance for corrosion (CO 2-rich return water). Further, for monitoring, it is possible to implement P,Tsensors. Overall construction and operation costs can be significantly reduced, but the composite casing will be more expensive. Second phase CO 2-Injection Delft University has applied for the geothermal exploration license under and around its campus grounds. The “first phase” exploration is focusing on the construction of a normal geothermal system. In the second phase, a research program for CO 2 capture and storage will be realized. For removing the CO 2 from the power plants’ flue gas, several capture techniques are studied. One of the options is adding CO 2 at low pressure (about 20 bar) as being 10% of the re-injected water volume (Smits, 2008). Gas can diffuse into the water achieving undersaturated conditions before it reaches the target member. The injected water is heavier Climate Change: Global Risks, Challenges and Decisions IOP Publishing IOP Conf. Series: Earth and Environmental Science 6 (2009) 172025 doi:10.1088/1755-1307/6/7/172025

Transition to sustainable use of fossil fuels: Impacts of CFF options and societal preferences

Publisher Summary Identification of promising integral strategies and trajectories for a transition toward sustainable fossil fuel use is complex. The objective of this chapter is to identify promising integral strategies and trajectories for a transition toward sustainable fossil fuel use. The discussion focuses on the intertwined elements of the research program. First, identification and investigation of promising options and technologies for fossil fuel utilization with CO 2 recovery and sequestration, followed by quantitative system analysis and assessment of performance and impacts (efficiency, economics, and environmental impacts and risks). Second, development and deployment of an Information and Choice Questionnaire method for measuring and analyzing societal preferences on the options (and impacts) identified under first step. The discussion investigates the influence of expert information on preferences of the general public at an early stage of development of clean fossil fuel options.

Characterization of Fontainebleau Sandstone: Quartz Overgrowth and itsImpact on Pore-Throat Framework

Fontainebleau sandstone outcrop is a prime example of a simple natural porous medium because of its pure mineral composition (0.995 Quartz) and an almost constant grain size in large sample blocks. It is widely used to investigate the correlation between the simple petrophysical properties independently of other parameters. This paper shows an experimental evaluation of Fontainebleau sandstone properties and their characteristics to advance understanding on the quartz overgrowth and the petrophysical and electrical transport properties. In order to acquire the pore and grain frameworks, we measure and quantify spatial attributes of the grain and pore’s matrix by Computed Tomography (CT) image analysis, associated to stereological measurements and statistical 2D/3D reconstructions. In addition, the regular petrophysical laboratory methods are applied and connected to the spatial results. Furthermore, our graphical methods are compared to pre-existing literature. The main contribution of this work is the impact of quartz overgrowth on the pore-throat framework. Our laboratory experimental measurements provide comprehensive information in petrophysical and petrological data of Fontainebleau sandstone. We conclude that Fontainebleau sandstone outcrop displays consistent and homogenous properties. The clay in the studied samples of Fontainebleau sandstone are almost not exists and does not play any role in the pore framework. This ensures repeatability and reproducibility of our flow experiments in porous media. It provides comparable core flow experimental in our study of the oil mobilization process in the porous media. We demonstrated that the quartz overgrowth (i.e. cementation) is playing a central role in the porethroat geometry and impacts both permeability and porosity by reducing the pore-throats (i.e. coordination number).