Wyniki wyszukiwania - BazTech

1

Groundwater-yielding capacity, water-rock interaction, and vulnerability assessment of typical gneissic hydrogeologic units using geoelectrohydraulic method

Akingboye Adedibu Sunny, Bery Andy Anderson, Kayode John Stephen, Ogunyele Abimbola Chris, Adeola Adedapo Oluwasanu, Omojola Olumide Olubusayo, Adesida Adeola Samuel

Acta Geophysica

|

2023

|

Vol. 71, no. 2

697--721

EN

Geohydraulic parameters, namely hydraulic conductivity (K), transmissivity (T), effective porosity (φ), permeability (kp), anisotropy coefficient (λ), and longitudinal conductance (S), of aquifer units in Etioro-Akoko, southwestern Nigeria, were evaluated using the Schlumberger vertical electrical sounding (VES) technique. This study aimed to understand the hydrodynamics and water–rock interaction of the near-surface crustal architecture to determine the groundwater yield and vulnerability of the aquifer units in the study area. A total of 7 model curve types were generated for fifty-two geoelectrical surveyed points, with percentage distributions in the order of HA>AA>H>KH>A>HK>AK. The VES curve models constrained the subsurface layers into topsoil, weathered units, weathered/fractured bedrock units, and fresh bedrock. The weathered and fractured aquifer zones occurred at the depths of 8 m and>16 m (with depths exceeding 26.5 m for some sections). The K and T values for the aquifer units varied from 0.1901 to 0.6188 m/day and 0.7111 to 6.3525 m2/day, respectively. These parameters coupled with the aquifer φ (18.03–23.35%) and kp (0.028–0.089 µm2) classified the delineated aquifer units as low to moderate groundwater-yielding capacity aquifers, with recorded resistivity values between 85.1 Ω-m and<613.0 Ω-m. The observed positive correlations and R2 values with>32–100% prediction rates affirmed the dependence of K on T, φ, and kp for effective water–rock interactions and groundwater transmissibility. The recorded S values (0.0146–0.162 mhos) and low logarithm hydraulic resistance, Log C (0.89–1.75 years), suggested poor to weak aquifer protective capacity ratings, resulting in high aquifer vulnerability index delineated across the study area. As a result, deep-weathered/fractured aquifers should be exploited for sustainable potable groundwater supplies. However, intended wells/boreholes in the study area must be developed properly for long-term groundwater abstraction to alleviate potable groundwater deficit and optimize future operational drilling costs.

2

Deterioration law of intermittent jointed sandstone mechanical properties under water-rock interaction

Chen Guangbo, Li Yuan, Li Tan, Zhang Guohua

Acta Geophysica

|

2022

|

Vol. 70, no 4

1923--1935

EN

In water-rich mines, water conservancy, and hydropower projects, the rock mass is immersed in water for a long time, which leads to changes in its mechanical properties and affects the safety and stability of the engineering rock mass. Based on the long-term immersion of rock mass with intermittent joints by water, uniaxial compression tests were carried out on prefabricated intermittent jointed sandstone with five inclinations (0°, 30°, 45°, 60°, 90°) and three connectivity ratios (0.25, 0.50, 0.75) under different immersion times to study sandstone with intermittent joints’ mechanical response and deterioration mechanism. The research shows that: (1) With the increase of the joint inclination, the compressive strength and elastic modulus of the sandstone with intermittent joints first decreased and then increased, showing a U-shaped distribution. The compressive strength and elasticity of the sample with an inclination of 60° reach the minimum value; at the initial stage of immersion, the deterioration effect of the sample is more significant, and the deterioration effect decreases gradually with the increase in immersion time; in the initial stage of water immersion, the deterioration effect of the sample is more significant, and with the increase of the immersion time, the deterioration effect gradually weakens. (2) Immersion time and joint inclination have a great influence on the included angle, number, and mode of failure cracks. With the increase in immersion time, the plastic characteristics of the sample increase obviously, showing the characteristics of loose and weak; with the increase in joint inclination, the failure mode of the sample gradually changes from tension failure to tension shear failure, and tension failure. The influence degree of joints on failure is weak-induction-control-induction. (3) Under the water–rock action, the cement between mineral particles of the sample is gradually dissolved, the cementation of mineral particles is weakened, and the mineral particles develop into layered and fake structure, which gradually evolves from dense structure to porous loose structure. (4) The deterioration mechanism of the mechanical properties of the sandstone with intermittent joints under the water–rock action was analyzed from the perspectives of physics, chemistry, and mechanics. The deterioration of the mechanical properties of the sample is a process of gradual accumulation of damage.

3

Infuence of CO2–water–rock interactions on the fracture properties of sandstone from the Triassic Xujiahe Formation, Sichuan Basin

Li Hongfei, Xie Lingzhi, Ren Li, He Bo, Liu Yang, Liu Jun

Acta Geophysica

|

2021

|

Vol. 69, no. 1

135--147

EN

Carbon dioxide (CO2) storage in deep saline aquifers has been lauded as one of the most efective techniques to mitigate greenhouse efects globally. Nevertheless, despite many investigations, clarifying the infuence of CO2–water–rock inter actions on the fracture characteristics of sandstone remains a challenge. In this work, the fracture properties of sandstone collected from the Triassic Xujiahe Formation are systematically studied in tests simulating CO2 sequestration. The results indicate that the water–rock interactions occur in a system of sandstone and CO2 solution. Due to the interactions, the poros ity of sandstone specimens slightly increases from 8.24 to 8.45% when immersed in CO2 solution and from 8.20 to 8.40% in pure water after 28 days. In addition, the parameters of fracture toughness, tensile strength, uniaxial compressive strength and elastic modulus are reduced by 24.12%, 27.16%, 31.78% and 33.21% after immersion in pure water, while they are reduced by 24.05%, 29.72%, 30.75% and 25.79% after immersion in CO2 solution, respectively. These results suggest that the mechanical properties of the Xujiahe sandstone deteriorate after soaking. The results also show that the critical fracture energy of sandstone specimens after immersion in the CO2 solution is 10.4% lower than that in pure water and 24.1% lower than that under natural drying conditions. These research results have great signifcance for understanding the dissolution processes during CO2 sequestration and their infuence on the fracture properties of sandstone, which may be theoretically instructive for CO2 storage in the Xujiahe Formation in the Sichuan Basin.

4

Development and application of an experimental device for measuring storage coefficient in a coal mine underground reservoir

Wang Bei-Fang, Sun Ke-Ming, Liang Bing, Sun Wei-Ji

Archives of Mining Sciences

|

2019

|

Vol. 64, no. 4

655--670

EN

With the rise of coal mine underground reservoir engineering in the Shendong Mining Area, the space time dynamic evolution prediction of storage coefficient is becoming one of the critical technical problems for long-term reservoir operation. This coefficient directly determines the storage capacity and the comprehensive benefits of the operation of a coal mine underground reservoir. To this end, the proposed underground reservoir in Daliuta coal mine (No. 22616 working face) is selected in this study for the development and application of an experimental device to measure the storage coefficient. Rock and coal fragments from similar materials are prepared, which are filled and loaded according to the caving rock nature as well as the lumpiness and accumulation mode characteristics pertaining to No. 22616 working face. Subsequently, the measured storage coefficient under circulating water injection conditions revealed a four-dimensional spatial and temporal pattern. It followed the law of storage coefficient under joint interaction of water-rock and stress. The results showed that, prior to the experiment, rock and coal fragments made from similar materials had good water resistance when the paraffin content was set at 8%. The three stress zones were defined based on a theoretical analysis, which were applied on the corresponding loads. During the experiments, significant regional differences were found in the top surface with persisting subsidence of each stress loading zone. Hence, compared with its initial state, the maximum subsidence in the stress stability zone, the stress recovery zone, and the low-stress zone was 7.89, 5.8, and 1.83 mm, respectively. While the storage capacity and the storage coefficient gradually decreased, the former ranged from 0.2429 to 0.2397 m3, and the latter ranged from 0.270 to 0.266. The experimental results are verified by drainage engineering tests in the Shendong Mining Area. In essence, the storage coefficient had remarkable spatial distribution characteristics and a time-varying effect. In space, the stor-age coefficient increased with height along the vertical direction of the coal mine underground reservoir. However, it decreased with the distance from the boundary of the dam body in the horizontal direction. With time, the storage coefficient decreased dynamically. This study provides a new way of predicting the storage coefficient of a coal mine underground reservoir.

PL

Przy rosnącej intensywności prac inżynieryjnych prowadzonych w rejonie Zagłębia Węglowego w Shendong, określanie współczynnika odsączalności i jego zmienności w czasie i przestrzeni stało się jednym z głównych problemów w długofalowej eksploatacji górniczej, mającej wpływ na kształtowanie się współczynnika odsączalności oraz na całościowe korzyści płynące z eksploatacji złoża. Zaproponowano by rejon prac wydobywczych prowadzonych w ścianie No 22616 w kopalni węgla Daliuta wykorzystany został jako teren eksperymentalny dla pomiarów współczynnika odsączalności dla zbiornika podziemnego znajdującego się w kopalni węgla. W tych warunkach przetestowano opracowane narzędzie pomiarowe. Do eksperymentu przygotowano fragmenty skał i węgla o podobnym składzie jak w rejonie ściany 22616, z zachowaniem ich układu zalegania i zwięzłości; następnie obciążono je w sposób analogiczny do obciążeń działających w warunkach rzeczywistego prowadzenia stropu. Dokonano pomiaru współczynnika odsączalności po wpompowaniu do próbek wody, w rezultacie uzyskując czterowymiarowy rozkład współczynnika odsączalności w czasie i przestrzeni w warunkach wzajemnych oddziaływań pomiędzy wodą a warstwami skał, oraz w warunkach działających naprężeń. Wyniki eksperymentu były następujące: Przed rozpoczęciem eksperymentu, wykorzystywane fragmenty skał i węgla charakteryzowały się wysoką odpornością na wodę gdy zawartość parafiny wynosiła 8%; następnie trzy obszary próbek wyodrębnione w oparciu o analizy teoretyczne i charakteryzujące określony poziom naprężeń poddano wielokrotnemu działaniu naprężeń o kontrolowanej wielkości. W trakcie trwania eksperymentu zaobserwowano znaczące różnice lokalne na powierzchni, w postaci utrzymującej się niecki osiadania nad poszczególnym strefami oddziaływania naprężeń. W porównaniu do stanu początkowego, maksymalne wartości osiadania w strefie stabilnych naprężeń, w strefie odprężenia i w strefie niskich naprężeń wyniosły odpowiednio: 7.89 mm, 5.8 mm i 1.83 mm. Współczynnik odsączalności stopniowo malał, od początkowego zakresu 0.270-0.266 do zakresu końcowego 0.2429 m3-0.2397 m3. Wyniki badań eksperymentalnych potwierdzone zostały następnie poprzez badania od-prowadzania wody przeprowadzone w rejonie Zagłębia Węglowego Shendong. Stwierdzono, że współ-czynnik odsączalności wykazuje znaczną zmienność w czasie i przestrzeni. W ujęciu przestrzennym, wartość współczynnika odsączalności wzrasta wraz z wysokością mierzoną w kierunku pionowym osi zbiornika podziemnego, z kolei maleje ona wraz z odległością od granicy tamy mierzonej w kierunku poziomym. W ujęciu czasowym, wartość współczynnika odsączalności gwałtownie rośnie w czasie. Badania powyższe dostarczyły nowych metod do prognozowania wartości współczynnika odsączalności w podziemnych zbiornikach na terenie kopalni węgla.

5

Hydrogeological settings and origin of groundwater composition in the southern part of the Gorce Mts, Kowaniec Mały catchment

Żaczek J., Porowski A.

Annales Societatis Geologorum Poloniae

|

2017

|

Vol. 87, No. 2

183--197

EN

The Gorce Mts of southern Poland occur in a natural upland area that is viewed as valuable and is protected. It has an inadequate and irregular network of long-term monitoring points at the national level with regard to groundwater quality and vulnerability to contamination. The paper discusses the results of an investigation of groundwater in the Kowaniec Mały drainage basin, in the southern part of the Gorce Massif. It provides new hydrogeochemical data that shed light on the origin and evolution of groundwater chemistry in this region. On the basis of a hydrogeological survey of 33 natural springs, trends in the spatial and temporal variation of the physicochemical properties of the groundwater are presented. Three hydrochemical types of water were distinguished, namely HCO3-Ca, HCO3-Ca-Mg and HCO3-SO4-Ca. The detailed analysis of ionic ratios shows that the dissolution of carbonates (mainly calcite) and aluminosilicates (mainly albite) played a fundamental role in the formation of the chemical composition of the groundwater in the study area. These processes are responsible for the presence of the dominant ions, such as HCO3- and Ca2+, as well as SiO2 and in part Na+ and K+. Chloride–sodium mineralization is connected first of all with recharge by rain water and the direct dissolution of halite, contained in the aquifer rocks or formed during the evaporation of the water. The most probable sources of dissolved SO42- are the atmospheric sulphates contained in recharge meteoric waters in the case of springs located at higher altitudes and the reduced inorganic sulphur compounds dispersed in fine-grained sedimentary rocks, mostly as pyrite, which undergoes oxidation during rock weathering. Ion exchange processes involving clay minerals also were present and affected mainly the concentrations of Na+ + K+ and Ca2+.

6

Pierwiastki ziem rzadkich (REE ) w wodach termalnych: występowanie, pochodzenie, znaczenie i perspektywy badań w Polsce

Porowski A., Kaczor-Kurzawa D.

Technika Poszukiwań Geologicznych

|

2016

|

R. 55, nr 1

89--102

PL

Termin „pierwiastki ziem rzadkich” (Rare Earth Elements – REE) odnosi się do piętnastu pierwiastków stanowiących grupę lantanowców (Ln3+) oraz itru (Y) i skandu (Sd). W wyniku takich procesów jak wietrzenie, rozpuszczanie, rekrystalizacja czy diageneza pierwiastki ziem rzadkich mogą być dość łatwo uruchamiane i przenoszone z minerałów i skał do środowiska wodnego. Wody podziemne wykazują podobny rozkład wzajemnych proporcji REE do ich „rozkładu” charakterystycznego dla skał, przez które przepływają. Takie podobieństwa pomiędzy REE pattern wód podziemnych i skał zbiornikowych decydują o tym, że REE są użytecznym wskaźnikiem do rozpoznawania interakcji zachodzących pomiędzy wodą podziemną a skałą zbiornikową. Analiza rozkładu zawartości REE w wodach wykorzystywana jest do identyfikacji pochodzenia wód, mieszania się wód, określania warunków równowagi w systemie woda-skała, procesów geochemicznych na drogach przepływu wód, do identyfikowania stref zasilania, czy skał zbiornikowych. W przypadku wód termalnych szczególnego znaczenia nabiera dokładne rozpoznanie składu chemicznego wód (w tym REE) i skał zbiornikowych w celu właściwego zrozumienia warunków termalnych w danym systemie. Pomimo istnienia szerokiej literatury dotyczącej badań nad geochemią REE w systemie woda-skała w różnych obszarach świata, Polska jest wciąż „biała plamą” – gdyż zawartości REE, szczególnie w wodach podziemnych, nigdy nie były na szerszą skalę badane; brak jest publikacji naukowych na ten temat. Od roku 2015 zespół naukowców z PIG–PIB oraz ING PAN podjął starania, aby zapełnić tę lukę w polskiej nauce. W roku 2015 pierwsze pilotażowe analizy zawartości REE zostały wykonane dla wód mineralnych Krynicy Zdroju oraz dla wód termalnych Poddębic. W roku 2016, konsorcjum naukowe ING PAN oraz PIG–PIB rozpoczyna realizację dużego projektu naukowego finansowanego ze środków NCN, ukierunkowanego bezpośrednio na szczegółową analizę zawartości i rozkładu REE w wodach mineralnych i termalnych Polski. Perspektywy rozwoju hydrogeochemii pierwiastków ziem rzadkich w Polsce w najbliższych latach wydają się być pozytywne.

EN

The Rare Earth Elements (REE) or rare earth metals, are commonly defined as a series of fifteen elements comprising the lanthanides group (Ln3+) plus scandium (Sc) and yttrium (Y). REE can be significantly mobilized during weathering, alteration and diagenesis processes and transferred from rocks into an aquatic environment. Groundwaters usually demonstrate REE patterns that closely reflect the REE patterns of the rock through which they flow. Such similarities between groundwater and aquifer rock REE patterns suggest that REE may be useful tracers of groundwater – aquifer rock interactions. Ample evidence hase been provided in the literature, that the analysis of REE concentration is a useful tool in tracing the origin of fluids, which is fundamental in understanding any fluid-rock system. The REE distribution in groundwater enables to study of the source of water, the state of equilibrium in water-rock system, changes in water composition by both precipitation and dissolution reactions in the aquifer including those along flow paths, groundwater and surface water mixing, biogeochemical redox processes, adsorption processes, etc. Despite the vast literature and numerous studies of REEs geochemistry reported for various regions in the world, Poland is a truly white spot, where the REE in the groundwater systems have never been deeply studied. However, since 2015, the first pilot analyses of REE in the mineral water of the Krynica Spa and the thermal waters of Poddębice have been performed. A new research project granted by the National Science Center (NCN) in 2016 for scientific consortium of ING PAN and PIG–PIB shed new light on the future development of the REE application in hydrogeochemical studies of mineral and thermal water in Poland.

7

The main hydrogeochemical processes affecting the composition of certain naturally carbonated waters of southwestern Poland

Kiełczawa B.

Geological Quarterly

|

2011

|

Vol. 55, No. 3

203-212

EN

Kłodzko region is a historical region in southwestern Poland, cutting into the territory of the Czech Republic. In geological terms, it contains (within the Polish borders) the Upper Nysa Kłodzka Graben and the Orlica-Śnieżnik Metamorphic Unit. The region abounds in naturally carbonated waters, whose composition is dominated by HCO-3, Na+, Ca2+ and Mg2+ ions. This study concerns the chemical composition of waters from particular intakes situated in Kudowa-Zdrój, Jeleniów, Duszniki-Zdrój, Polanica-Zdrój and Gorzanów. Chemical data were analysed mathematically and by hydrochemical modelling performed with the help of the AquaChem5.1 and PhreeqC codes. The chemical composition of the waters studied is shaped chiefly by hydrolysis of aluminosilicates. The major ion composition is also influenced by ion exchange (adsorption and desorption) with and dissolution of carbonate minerals. Analysis of saturation indexes showed that these waters are in equilibrium with kaolinite. Generally speaking, the chemical composition of waters in this region is determined by dissolution and precipitation of carbonates (mostly secondary) and aluminosilicates in the presence of carbon dioxide, as well as by ion exchange.