Ákos Török

Budapest University of Technology and Economics, Engineering Geology and Geotechnics, Faculty Member

Followers

109

Following

Co-authors

Mentions

Public Views

Address: Department of Engineering Geology and Geotechnics
Budapest University of Technology and Economics
Müegyetem rkp. 3.
Building K, (185).
Budapest, H-1111
HUNGARY

less

Interests

Uploads

Papers by Ákos Török

Thermophysical properties of potential geothermal reservoir rocks: an outcrop analogue study of the sedimentary series of the Buda Mts., Hungary

EGUGA, Apr 1, 2012

ABSTRACT The detailed knowledge of sedimentary features from microscopic to regional scales is re... more ABSTRACT The detailed knowledge of sedimentary features from microscopic to regional scales is regarded as crucial in reservoir characterization and prediction of deep geothermal systems. Generally, in the early stages of reservoir exploration, characterization of the reservoir is accomplished by evaluation of drilling data and seismic surveys. However, for reservoir prognosis, the main geothermal parameters such as permeability, thermal conductivity, and reservoir heat flow have to be quantified with respect to a 3D structural model. Outcrop analogue studies serve to predict such subsurface thermophysical properties, and based on detailed facies analysis, the geothermal exploration concept becomes more precise and descriptive. Our data from the Meso- and Cenozoic sedimentary series of Budapest include carbonates and clastic sediments of Triassic, Eocene, and Oligo-Miocene age as well as Pleistocene travertine, exposed on the western side of the river Danube. Field and laboratory analyses reveal distinct horizons of different geothermal potential and thus, enable us to identify and interpret corresponding exploration target horizons in geothermal prone depths of the Pannonian Basin. Upper Triassic limestones (Main Dolomite, Budaörs Dolomite, Mátyáshegy Limestone) show values of thermal conductivity in the range of 2,0 to 3,5 W/(m·K). Matrix permeabilities measured with a gas mini-permeameter span in the range of 10-12 to 10-14 m2. Additionally, these limestones are highly fractured and show a different degree of karstification increasing the fluid migration. Thus, hydrothermal exploration of such limestone reservoirs in geothermal prone depths of about 5 km known from the Zala and Danube basins of W Hungary is seen very promising. Miocene bioclastic limestones (e.g, Tinnye Limestone) reveal lower values of thermal conductivity in the range of 1,0 to 1,5 W/(m·K). On the other hand, they are characterized by much higher permeabilities (10-11 to 10-12 m2). Depending on their occurrence in the deep subsurface, they might be considered as reservoir rocks. Marls and travertines show values of thermal conductivity in the range of 2,0 to 2,5 W/(m·K). Matrix permeabilities of marls are low (10-15 to 10-16 m2), whereas travertines are characterized by the highest permeabilities up to 10-11 m2. Both, marls and travertines are not considered as deep geothermal reservoir rocks: marls due to their low permeabilities, and travertines due to their occurrence mostly in surface outcrops. Clastic sediments of Palaeo- and Neogene age are grouped into low permeable and low heat conducting clays (e.g., Kiscell Clay), and high permeable, high heat conducting sandstones (e.g., Hárshegy Sandstone). Thus, hydrothermal exploration of high permeable sandstone reservoirs in geothermal prone depths known from different basins in Hungary (e.g., Central Great Plain) is also seen very promising. Based on these preliminary results, further outcrop analogue studies will serve as a powerful tool to predict such subsurface properties and thus, finally lead to a better understanding of deep geothermal reservoirs in the Pannonian Basin.

Comparison of water absorption methods: testing the water absorption of recently quarried and weathered porous limestone on site and under laboratory conditions

EGU General Assembly Conference Abstracts, Apr 1, 2017

Download

Influence of mafic nano-additives on lime-based renders

EGU General Assembly Conference Abstracts, Apr 1, 2018

Download

Construction technology and materials of a medieval fortress at Balaton Highland (Hungary)

EGU General Assembly Conference Abstracts, Apr 1, 2019

In-situ diagnosis of stone monuments; the Ruin Garden in Székesfehérvár

EGU General Assembly Conference Abstracts, May 1, 2014

Skid resistance and surface roughness testing of historic stone surfaces: advantages and limitations

EGUGA, Apr 1, 2013

ABSTRACT Skid resistance tests are mostly applied for testing road surfaces and almost never appl... more ABSTRACT Skid resistance tests are mostly applied for testing road surfaces and almost never applied for testing stones at cultural heritage sites. The present study focuses on the possibilities of using these techniques in assessing the surface roughness of paving stones at a historic site. Two different methods were used in a comparative way to evaluate the surface properties of various types of stones ranging from travertine to non-porous limestone and granite. The applied techniques included the use of SRT pendulum (Skid Resistance Tester) providing USRV values and a mobile equipment to analyze the surface properties (Floor Slide Control) by surface profiling and providing angle of friction. The main aims of tests were to understand the wearing of stone materials due to intense pedestrian use and to detect surface changes/surface roughness and slip resistance within few year periods. The measured loss in surface slip resistance (i.e. USRV values) was in the order of 20% for granites, while most limestones lost at least 40% in terms of USRV values. An opposite trend was detected for a porous travertine type, where the surface became rougher after years of use. The limitations of these techniques are also addressed in the paper. The tests have shown that the introduction of the use of these equipments in heritage studies provide useful information on the longevity of historic stone pavements that are open for public use.

Geothermal energy from the Pannonian Basins System: An outcrop analogue study of exploration target horizons in Hungary

EGUGA, Apr 1, 2015

Comparative study of porous limestones used in heritage structures in Cyprus and in Hungary

EGU General Assembly Conference Abstracts, Apr 1, 2015

Thermal dilatation, density, porosity and tensile strength of porous Miocene limestone

EGU General Assembly Conference Abstracts, Apr 1, 2015

Salt damage of stone, plaster and painted layers at a medieval church, South-Hungary

EGUGA, Apr 1, 2016

The use of limestone in the medieval masonries of Assisi region, Italy

EGUGA, Apr 1, 2018

Download

Stone and render of Medieval Church of Tök (Hungary); diagnosis and non-destructive testing

EGUGA, Apr 1, 2018

Moisture distribution in the stone portal of a church: how it influences the salt accumulation in porous limestone

EGUGA, Apr 1, 2017

Az andezit sziklafalak felületi tulajdon-ságainak változása magnézia hatására

Fiatal Müszakiak Tudományos Ülésszaka, 2006

Download

The relationship between the bulk density, the apparent porosity and ultrasonic pulse velocity of highly porous limestone, examples from Hungary

Download

Surface strength and durability assessment of stones by using non-destructive tests, such as Schmidt hammer and Duroskop

EGU General Assembly Conference Abstracts, Apr 1, 2012

Petrophysical and Mineralogical Studies of Burnt Sandstones

Historical monuments have always been in the centre of scientific interest. Natural disasters lik... more Historical monuments have always been in the centre of scientific interest. Natural disasters like fire can strongly damage or even may ruin these ancient buildings. Fire disaster related changes in the petrological and petrophysical properties of the building materials can often lead to stability problems. Historical monuments built of sandstone were studied. The results of the petrological, petrophysical and thermal analyses often refer to the behaviour of the supporting structures exposed to fire. Sandstones with different cement types may show different fire resistance. The comparison of the results can provide useful information when replacing historical stone material, or one have to choose the suitable restoring method for the damaged building part.

Download

Hungarian travertine: weathering forms and durability

... In: V Fassina (ed.). 9th International Congress on Deterioration and Conservation of Stone-Ve... more

Centrifugal model test on a riverine landslide in the Three Gorges Reservoir induced by rainfall and water level fluctuation

Geoscience frontiers, May 1, 2022

A 4-es számú metróvonal Rákóczi téri állomásának mérnökgeológiai elemzése

Az elmúlt száz évben számos terv került kidolgozásra Budapest metróhálózatának kiépítése kapcsán.... more Az elmúlt száz évben számos terv került kidolgozásra Budapest metróhálózatának kiépítése kapcsán. A tervek között egyezés volt abban, hogy a 4-es számú vonal kösse össze Dél-Budát (Móricz Zsigmond körtér) a városközponton keresztül Zuglóval (Bosnyák tér), úgy hogy kapcsolódjon a 2-es és a 3-as számú vonalakhoz is. A 60-as évek közepétıl a 80-as évek elejéig a metró vonalak építéséhez, az UVATERV és a METRÓBER megbízásából, az OFKFV kivitelezésében mintegy 500 kutató magfúrás mélyült, melyekbıl 180 darab a 4-es vonal szakaszvariációinak közelébe esett (Szlabóczky, 1998). Az 1970-es évek elején elıvették a korábbi nagyvonalú tanulmányokat, és ezzel megkezdıdött a közel 30 évet igénybe vevı "építést elıkészítı" tevékenység. A pénzügyi és ütemezési elıirányzatok folyamatos változása, és sok huzavona után azonban csak 2003-ban parafálták a metrószerzıdést, így a metróberuházás is csak ekkor indulhatott el. Végül 2006-ban a város több pontján megindultak az állomásépítések, illetve az alagútépítés. A 4-es metró építése egyelıre két szakaszban zajlik Az elsı szakasz a Kelenföldi pályaudvartól a Keleti pályaudvarig tart, egy 7,3 km hosszúságú alagútpárból és 10 megállóhelybıl áll. A tervezett második szakasz a Keleti pályaudvart és a Bosnyák teret kötné össze, ami további öt állomást és 4 km hosszúságú alagút megépítését jelentené. A vonal a 2-es metróhoz a Keleti pályaudvarnál, a 3-as metróhoz pedig a Kálvin térnél kapcsolódik. 2 FÖLDTANI VISZONYOK Budapest változatos domborzatát a Duna kétfelé választja. Ny-i oldalán hegyvidék (Budai-hegység), K-i oldalán pedig síkvidék (Pesti-síkság) terül el. A Budai-hegység területétnek morfológiáját a tektonikai mozgások következtében kiemelt alaphegység rögvonulatai adják. A Pesti-síkság teknıs szerkezető, melyet a Duna ártéri hordalékokkal töltött fel (Schafarzik et al., 1964).

Download

Thermophysical properties of potential geothermal reservoir rocks: an outcrop analogue study of the sedimentary series of the Buda Mts., Hungary

EGUGA, Apr 1, 2012