scholarly journals Laboratory and modelling investigations of potential geochemical reactions upon seasonal heat storage in Danish geothermal reservoirs

2020 ◽  
Author(s):  
Hanne Dahl Holmslykke ◽  
Claus Kjøller ◽  
Rikke Weibel ◽  
Ida Lykke Fabricius
Keyword(s):  
Calcium Carbonate ◽  
Elevated Temperatures ◽  
Heat Storage ◽  
Petrographic Analysis ◽  
Formation Water ◽  
Geothermal Reservoirs ◽  
Deep Aquifers ◽  
Two Samples ◽  
Geochemical Reactions ◽  
Sandstone Formation

<p>Seasonal storage of excess heat in hot deep aquifers is one of the considered solutions to optimize the usage of commonly available energy sources. This study investigates the risk of damaging the reservoir through potential geochemical reactions induced by the increased reservoir temperature upon injection of heated formation water. Three core flooding experiments were performed at reservoir conditions and temperatures up to 150°C with cores from two potential Danish geothermal reservoirs and with synthetic brine as the flooding fluid. The tested reservoir sandstones comprise two samples with different mineralogy from the Upper Triassic – Lower Jurassic Gassum Sandstone Formation and one sample from the Lower Triassic Bunter Sandstone Formation. For the calcium carbonate-containing Bunter Sandstone formation, the experiments were performed with Ca-depleted synthetic formation water to avoid loss of injectivity by calcium carbonate scaling at elevated temperatures. The interpretation of the laboratory experiments was supported by petrographic analysis of the cores prior to and after the flooding experiments and by geochemical modelling. The results show that heating induced a series of silica dissolution/precipitation processes for all three sandstones, including dissolution of quartz, alteration of Na-rich feldspar to kaolinite, replacement of plagioclase with albite and precipitation of muscovite, depending on the sandstone. These processes are not expected to significantly deteriorate the physical properties of the reservoir. However, for the Bunter Sandstone Formation, flushed with Ca-depleted brine, a significant portion of the cementing calcite dissolved. In the reservoir, this may ultimately reduce the mechanical strength of the geological formation. Thus, this study suggests that heat storage in geothermal reservoirs can be technically feasible in typical and extensive Danish geothermal sandstone reservoirs. However, in reservoirs containing calcium carbonate, means for avoiding calcium carbonate precipitation during heat storage should be chosen with caution to minimise possible reservoir damaging side effects.</p>

Effect of Warm Rolling on Microstructure and High Temperature Mechanical Behavior of a Nano-Structured Al-8Fe-2Mo-2V-1Zr Alloy

2005 ◽  
Vol 486-487 ◽  
pp. 411-414 ◽  
Author(s):  
Won Yong Kim ◽  
Jae Sung Park ◽  
Mok Soon Kim
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Elevated Temperatures ◽  
Hot Extrusion ◽  
Warm Rolling ◽  
Spray Forming ◽  
Grain Structure ◽  
Average Grain Size ◽  
Two Samples ◽  
Additional Process

Mechanical properties of a nano-structured Al-8Fe-2Mo-2V-1Zr alloy produced by spray forming and subsequent hot-extrusion at 420°C were investigated in terms of tensile test as a function of temperature. Warm rolling was adapted as an additional process to expect further refinement in microstructure. Well-defined equiaxed grain structure and finely distributed dispersoids with nano-scale in particle size were observed in the spray formed and hot extruded sample (as-received sample). The average grain size and particle size were measured to 500 nm and 50 nm, respectively. While it was found that warm rolling gives rise to precipitate fine dispersoids less than 10 nm without influencing the grain size of matrix phase, in the temperature range of RT∼150°C, distinguishable changes in ultimate tensile strength were not found between the as-received and warm-rolled samples. At elevated temperatures ranging from 350 to 550°C, warm-rolled sample showed a higher value of elongation than as-received one although similar values of elongation were observed between two samples at temperatures lower than 350°C.

PHASE-CHANGE MATERIAL: NATURAL RUBBER COMPOSITES FOR HEAT STORAGE APPLICATIONS

2020 ◽  
Vol 93 (1) ◽  
pp. 208-221 ◽  
Author(s):  
Minna Poikelispää ◽  
Sasu Ruokangas ◽  
Mari Honkanen ◽  
Minnamari Vippola ◽  
Essi Sarlin
Keyword(s):  
Natural Rubber ◽  
Phase Change ◽  
Thermal Energy ◽  
Elevated Temperatures ◽  
Storage Capacity ◽  
Heat Storage ◽  
Damping Properties ◽  
Rubber Composites ◽  
Good Ability ◽  
Natural Rubber Composites

ABSTRACT Global warming and environmental awareness in general have increased the research into thermal energy storage fields. Phase-change materials (PCMs) are efficient in storing thermal energy because of their high latent heat during the phase change. As the phase change is often based on the melting of the PCM, they need to be encapsulated, for example, by dispersing the PCM to a polymer matrix. In this study, the feasibility of the use of paraffin–natural rubber composites in applications requiring both the good ability to store heat energy and good vibration-damping properties is studied. This includes studies on PCM concentration and the microencapsulation of the PCM. It was found that the heat storage capacity increases with increasing PCM content, although the theoretical maximum capacity is not achieved because the PCM is released during vulcanization and the paraffin blooms. In addition, the loss factor was found to be increased at elevated temperatures, indicating improved damping properties. The encapsulation of PCM is found to have a positive influence on the heat storage capacity and the mechanical and damping properties of the rubber compound.

Effect of Sand Content on the Filter Cake Properties and Removal During Drilling Maximum Reservoir Contact Wells in Sandstone Reservoir

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Badr S. Ba geri ◽  
Mohamed Mahmoud ◽  
Saleh. H. Al-Mutairi ◽  
Abdulazeez Abdulraheem
Keyword(s):  
Calcium Carbonate ◽  
Filter Cake ◽  
Flow Line ◽  
Drilling Fluid ◽  
Horizontal Section ◽  
Fluid Properties ◽  
Porosity And Permeability ◽  
Sand Particles ◽  
Sandstone Reservoir ◽  
Sandstone Formation

The drilling mud program contains many tests such as filtration rate and filter cake properties to select the proper drilling fluid additives that yield the standard ranges of the viscosity, filtration rate, etc. However, the physical and chemical changes in the mud composition during the mud circulating will cause changes to the filter cake properties. The changes in the filter cake properties should be considered in the mud design program to prevent the problems associated with the change in the drilling fluid properties. For long horizontal wellbores penetrating plastic formations, the two sources of solids in filter cake are drilling chemical additives and formation cuttings (sand particles in the case of sandstone reservoir). This study focuses on the effect of introducing sand particles from the drilled—formations on the filter cake properties. Real drilling fluid samples from the field were collected at different location during drilling a 3600 ft of the horizontal section of a sandstone formation. Calcium Carbonate (CaCO3) was used as weighting material in this filed. The drilling fluid samples were collected at two different points: the flow line coming from the well after shale shaker and the flow line going to the well to verify the effect of separation stages on filter cake properties. The primary drilling fluid properties of the collected samples were measured such as density and rheological parameters. High pressure high temperature (HPHT) filter press was used to perform the filtration and filter cake experiments at 300 psi differential pressure and room temperature (25 °C). The mineralogy of the external filter cake formed by fluid loss cell is determined using SEM (scanning electron microscopy) and XRD (X-ray diffraction). Finally, solubility test was conducted to evaluate the effect of sand particles on filter cake removal (containing Calcium Carbonate as weighting material) using chelating agent: glutamic diacetic acid (GLDA) at pH 4. The results showed that for long horizontal sections, the effect of introducing sand particles to the composition of the filter cake can cause significant change to the properties of filter cake such as mineralogy, thickness, porosity, and permeability. For instant the thickness of filter cake increased about 40% of its original thickness when drilling sandstone formation in horizontal well due to fine sand particle settling. The filter cake porosity and permeability increment in the first 2000 ft part of the horizontal section was observed clearly due to the irregular shape of the drilling particles. However for the points after the first 2000 ft of horizontal lateral, the porosity and permeability almost remained constant. Increasing the sand content up to 20% degrade the dissolution rate of calcium carbonate in the GLDA (pH = 3.8) to 80% instead of 100%.

scholarly journals Decarbonising the Portland and other Cements—Via Simultaneous Feedstock Recycling and Carbon Conversions Sans External Catalysts

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2462
Author(s):  
Sheila Devasahayam
Keyword(s):  
Carbon Dioxide ◽  
Calcium Carbonate ◽  
Magnesium Oxide ◽  
Carbon Footprint ◽  
Elevated Temperatures ◽  
Clean Energy ◽  
Magnesium Carbonate ◽  
Methane Emissions ◽  
Carbon Conversion ◽  
Waste Plastics

The current overarching global environmental crisis relates to high carbon footprint in cement production, waste plastic accumulation, and growing future energy demands. A simultaneous solution to the above crises was examined in this work. The present study focused on decarbonizing the calcination process of the cement making using waste plastics and biowastes as the reactants or the feedstock, to reduce the carbon footprint and to simultaneously convert it into clean energy, which were never reported before. Other studies reported the use of waste plastics and biowastes as fuel in cement kilns, applicable to the entire cement making process. Calcination of calcium carbonate and magnesium carbonate is the most emission intensive process in cement making in Portland cements and Novacem-like cements. In the Novacem process, which is based on magnesium oxide and magnesium carbonates systems, the carbon dioxide generated is recycled to carbonate magnesium silicates at elevated temperatures and pressures. The present study examined the Novacem-like cement system but in the presence of waste plastics and biomass during the calcination. The carbon dioxide and the methane produced during calcination were converted into syngas or hydrogen in Novacem-like cements. It was established that carbon dioxide and methane emissions were reduced by approximately 99% when plastics and biowastes were added as additives or feedstock during the calcination, which were converted into syngas and/or hydrogen. The reaction intermediates of calcination reactions (calcium carbonate–calcium oxide or magnesium carbonate–magnesium oxide systems) can facilitate the endothermic carbon conversion reactions to syngas or hydrogen acting as non-soot forming catalysts. The conventional catalysts used in carbon conversion reactions are expensive and susceptible to carbon fouling. Two criteria were established in this study: first, to reduce the carbon dioxide/methane emissions during calcination; second, to simultaneously convert the carbon dioxide and methane to hydrogen. Reduction and conversion of carbon dioxide and methane emissions were facilitated by co-gasification of plastics and bio-wastes.

Rock and age relationships within the Talkeetna forearc accretionary complex in the Nelchina area, southern Alaska

2020 ◽  
Vol 57 (6) ◽  
pp. 709-724
Author(s):  
John Barefoot ◽  
Elisabeth S. Nadin ◽  
Rainer J. Newberry ◽  
Alfredo Camacho
Keyword(s):  
Subduction Zone ◽  
Elevated Temperatures ◽  
Accretionary Prism ◽  
Fault System ◽  
Petrographic Analysis ◽  
Spreading Ridge ◽  
Current Configuration ◽  
Ridge Subduction ◽  
South Central ◽  
Subduction Zone Processes

Subduction zone processes are challenging to study because of the rarity of good exposures and the complexity of rock relationships within accretionary prisms. We report the results of field mapping and petrographic, geochemical, and geochronological analyses of the McHugh Complex accretionary prism mélange in south-central Alaska that was recently exposed due to retreat of the Nelchina Glacier. Our new mapping and analyses of the mélange, as well as adjacent Talkeetna arc intrusives, suggests that the previously mapped trace of the Border Ranges fault should shift northward in this location. Detailed petrographic analysis places this mélange exposure with the Potter Creek assemblage of the McHugh Complex. Blocks of pillow lavas within the mélange have both mid-ocean ridge basalt and intra-plate geochemical affinities, attesting to the complex relations of subduction-zone inputs in an alternating erosive–accretionary margin. A new zircon U–Pb age and geochemical analyses of a set of felsic dikes that cross-cut the accretionary sequence provide constraints on the regional tectonic evolution, including near-trench plutonism associated with the migration of a subducting spreading ridge along the southern Alaska margin during the Paleocene–Eocene. The McHugh section and cross-cutting dikes in this location are pervasively hydrothermally altered, which we attribute to elevated temperatures related to ridge subduction. Late-stage motion along the Border Ranges fault system, which is also recorded in the area, may also have contributed to the widespread alteration. Our data indicate that the Talkeetna volcanic arc and associated accretionary prism sediments were in their current configuration by 55 Ma.

scholarly journals The geomorphic significance of hurricanes on coral-fringed calcium carbonate coastlines: Hurricane Wilma 15-25 October 2005, northeastern Yucatan Peninsula, Mexico

2021 ◽  
Author(s):  
◽  
Nicholas Paul Everett Mulcahy
Keyword(s):  
Calcium Carbonate ◽  
Large Scale ◽  
Morphological Changes ◽  
Yucatan Peninsula ◽  
Petrographic Analysis ◽  
Barrier Beach ◽  
Hurricane Wilma ◽  
Storm Waves ◽  
Yucatán Peninsula ◽  
Barrier Beaches

<p>Hurricanes and tropical storms can cause large scale morphological changes to barrier beach systems in tropical environments. Many such systems are fronted by coral reefs; however, unlike siliciclastic barrier beaches, little is known about the significance of hurricanes to barrier beach evolution on coral-fringed calcium carbonate coastlines. This study provides a detailed assessment of the impacts of Hurricane Wilma, a major hurricane, on the reef-protected and exposed barrier beaches of northeastern Yucatan Peninsula, Mexico. The study considers both the short (0-8 months) and medium term (8-56 months) response, and postulates the significance of major storm events over the longer term.  Hurricane Wilma made landfall in late October 2005 as a Category 4 hurricane, bringing sustained wind speeds of 67 ms-1, and storm waves with significant wave heights (HS) ≈ 13 m. The storm persisted for over 20 hours, while storm waves inundated the low lying barrier beaches and rainfall flooded inland wetlands and lagoons.  To determine the impacts of Hurricane Wilma and quantify post-storm recovery of reef-protected and unprotected barrier beaches, geomorphic mapping and post-storm surveying (2006 and 2010) was completed at 49 locations between Punta Nizuc and Punta Maroma. In addition, 220 sediment samples were collected from across barrier beaches and the backreef lagoon for textural and petrographic analysis. Satellite imagery was also used to quantify immediate storm impacts and recovery of the shoreline.  Barrier beaches were found to have responded to storm waves in two broadly different ways: reef-protected beaches accreted by between 2.1 and 24.6 m, as the beach and foredunes were reworked. In contrast, unprotected beaches underwent erosion of over 10 m. By 2006, reef-protected beaches had undergone rapid shoreface and beachface adjustment. Over the next four years, these beaches gradually transgressed landwards and aggraded subaerially as they readjusted to their pre-storm equilibrium beach profile. Exposed beaches responded much more rapidly than those protected by reefs, with shoreline adjustment occurring within eight months of the storm. Subaerial beach development was, however, much slower, requiring extended calm conditions to infill the eroded beach. The storm and post storm geomorphic responses were found to be highly variable alongshore, and influenced by several factors, including dune height, beach width, and wave exposure.  The results indicate that under the contemporary climatic conditions hurricanes are key drivers of barrier beach evolution over the short (0-8 months) to medium terms (8-56 months), but are not so influential over longer time scales. However, an expected increase in the number of major storms (category 3-5) in the future may increase the significance of hurricanes to longer term barrier evolution, with the storm impacts likely to be greater and the recovery times longer. Understanding these responses is particularly critical as many areas continue to be developed, and as the coral reef protecting the coastline becomes threatened by the implications of climatic change.</p>

Pre-drilling geothermal assessment of porosity and permeability of the Bunter Sandstone Formation, onshore Denmark

1969 ◽  
pp. 33-36
Author(s):  
Morten Leth Hjuler ◽  
Lars Kristensen
Keyword(s):  
Climatic Conditions ◽  
Geothermal Area ◽  
Robust Method ◽  
Reservoir Properties ◽  
Geothermal Reservoirs ◽  
Exploration Risk ◽  
Porosity And Permeability ◽  
Sandstone Reservoirs ◽  
Sandstone Formation

Denmark constitutes a low-enthalpy geothermal area. Current geothermal production takes place from two sandstone-rich formations: the Bunter Sandstone and Gassum Formations. These formations form major potential geothermal reservoirs, but information about the permeability of the potential sandstone reservoirs is difficult to obtain. This may be explained by deposition in a variety of environments under different climatic conditions, and by variable diagenetic overprint (Olivarius et al. 2015). Thus, the sandstone characteristics and properties are diverse, and in areas where wells are scarce, the assessment of the extent and reservoir properties of sandstone layers is associated with much uncertainty. In order to reduce exploration risk it is therefore essential to develop a robust method for prediction of porosity and permeability prior to drilling.

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