Hasil untuk "Petrology"

Zhe Ban, Carlos Pfeiffer

Abstract Data reconciliation techniques have been the subject of many classic studies in the data conditioning process. By reconciling the measurements, accurate estimation of the system output and unmeasured variables is provided. However, accurately determining measurement noise and parameter uncertainty in real time remains a significant challenge. How to simultaneously estimate parameters in the system has been attracting considerable interest. So far, very little attention has been paid to time-varying parameter estimation in oil production systems. In particular, estimation of parameter dynamics and the corresponding uncertainty without prior knowledge remains challenging. This work extends a previous study on dynamic parameter estimation by considering scenarios where parameters change both gradually and abruptly. To address these dynamics, nonlinear filtering methods are employed and compared. A comparative analysis was conducted using both quantitative metrics and visualization plots to evaluate the performance of various approaches. Under the same abrupt parameter change scenario, nonlinear filter-based methods demonstrated superior performance in parameter estimation, achieving a root mean square error of $$6.56 \times 10^{-11}$$ , compared to $$7.84 \times 10^{-11}$$ for the MCMC-based method-even without the use of prior information. Additionally, nonlinear filters showed a significant advantage in simultaneous state estimation, with a root mean square error of $$1.94 \times 10^{4}$$ , markedly lower than the $$1.47 \times 10^{6}$$ observed with the MCMC-based approach. The effectiveness of nonlinear filtering methods was further validated in scenarios involving gradual parameter changes, again without relying on prior knowledge. This work provides an important opportunity to advance the understanding of dynamic parameter estimation in the gas and oil industry, and the improved model can possibly be applied to real-time optimization and model-based control. Graphical abstract

Jianli Qiang, YanChi Yang, Mingjin Cai et al.

Abstract Due to the fluid leak-off effect in the reservoir, the bottomhole pressure decreases after the pumps are shut down. Analyzing the shut-in pressure decline curve of a fractured well is a common method for determining fracturing parameters. Although the G-function pressure decline analysis method briefly explains the pressure decline process, it is not accurate for calculating fracture parameters in fractured low-porosity gas reservoirs. This paper considers the influence of natural fractures on the leak-off coefficient and proposes an approach to evaluate fracture complexity by using the fluctuation characteristics of the construction pressure curve and the G-function characteristics during fracture closure. In this study, the pressure decline curve was segmented to determine fracture parameters, and a shut-in pressure decline analysis model for fractured low-porosity gas reservoirs was established. The fracture complexity is characterized by the fluctuation of the superposition derivative curve, and the approximate series is calculated to quantitatively evaluate fracture complexity. Field data from multiple wells were used to calculate the approximate series, thereby verifying its practicality. Results from actual case data show a positive correlation between fracture complexity and the approximate series. Additionally, this paper adopts a comprehensive filtering model to remove the noise caused by water hammer effects during the shut-in process, improving data quality and analysis accuracy. The feasibility and reliability of the model are validated using actual data from fractured wells in the Dabei Oilfield.

Xu Yang, Weijun Shen, Xizhe Li et al.

Abstract For reservoirs exhibiting severe heterogeneity due to prolonged water flooding, conventional polymer flooding demonstrates limited capacity to alter reservoir properties under such conditions. Crosslinked polymer flooding, characterized by its three-dimensional network structure, significantly enhances reservoir conformance, sweep efficiency, and oil displacement efficiency, making it a key technique for strongly heterogeneous reservoirs in the middle to late stages of development. In this study, a geological model based on a one-injection–one-production well pattern was constructed to simulate the crosslinked polymer flooding process. The model incorporates critical factors including formation heterogeneity, wall adsorption, and the inaccessible pore volume associated with polymer injection. Using the Computer Modelling Group’s Steam, Thermal, and Advanced Processes Reservoir Simulator (CMG-STARS), model was validated through grid independence analysis and calibrated via history matching. A systematic investigation was conducted to assess the influence of key parameters—namely, crosslinked polymer concentration, injection rate, and injection strategy—on oil displacement performance. The results indicate that, under the studied conditions, a well spacing of 200 m, a mass concentration of 0.55%, and an injection rate of 400 m³/d effectively reduce polymer adsorption and shear degradation while promoting the formation of a stable gel, thereby enhancing plugging efficiency. An injection strategy initiated at a 35% water cut, combined with 2–3 alternating cycles, was found to mitigate water channeling through early-stage reservoir modification. This study identifies the dominant factors controlling the oil displacement performance of crosslinked polymer systems, clarifies their relative advantages and limitations compared to conventional polymers, and offers a reliable reference framework for parameter selection in field-scale crosslinked polymer flooding operations.

Rodrígues-Navarro Carlos

Lime mortars and plasters have been used as building materials since the origins of pyrotechnology in the Levant ca. 12,000-14,000 years ago, and currently are experiencing a revival as compatible and sustainable materials in heritage conservation and modern construction. Extensive research has recently explored ways to improve their properties, particularly using Nature as an inspiration. Such a biomimetic approach is enabling the functionalization of lime mortars and plasters via different strategies that are reviewed here and include accelerated setting via enzymatic-like catalyzed carbonation, increased toughness via inter- and intracrystalline additive incorporation, modification of surface wettability and enhanced self-cleaning ability via surface microtexturing and photoactive nanoparticle incorporation, anti-biofouling capacity, increased radiative cooling, or self-healing properties.

Abdul Rehman Baig, Sulaiman A. Alarifi, Mobeen Murtaza et al.

Abstract Sand production in oil and gas wells is a significant concern, leading to equipment erosion, reduced well productivity, and safety hazards. Researchers have developed an eco-friendly solution to consolidate sand via an Enzyme-induced Carbonate Precipitation (EICP) process. It fortifies loose sand in wells, preventing it from resurfacing. This study addresses this challenge by developing a novel EICP solution effective at high temperatures (120 °C). This advancement goes beyond previous formulations, which often exhibited low strength at elevated temperatures. In this study, we developed six different solutions to consolidate sand at different temperatures with various bio- and synthetic polymers, the resulted sand consolidation has been tested by obtaining the precipitation composition after consolidation, visualizing consolidated sand structures, assessing strength and measuring permeability of the consolidated sand. AN 125, a synthetic copolymer based on Acrylamide and 2-Acrylamido-2-Methylpropane Sulfonic Acid (AM-AMPS), emerged as the most effective additive. It fostered the strongest consolidated sand at both temperatures (2,175 psi at 70 °C and 2,155 psi at 120 °C). It also exhibited superior thermal stability compared to bio-polymers like xanthan gum, which degraded at 120 °C. The EICP solution with AN 125 led to a moderate permeability decrease of around 30% during simulated sand pack flooding, indicating minimal impact on well flow. The developed formulation offers a robust and environmentally friendly approach to sand consolidation in oil and gas wells, enhancing well integrity and production efficiency. Furthermore, this work emphasizes the significance of a proper methodology towards evaluating the suitability of bio-polymers and synthetic copolymers for sand consolidation using EICP formulations.

Valerio Cerantola, Christoph J. Sahle, Sylvain Petitgirard et al.

A pressure-induced change in hybridization of carbon from sp 2 to sp 3 occurs between 40 GPa and 112 GPa, according to laboratory experiments and ab initio simulations, which could increase the potential for storage of carbon in lower mantle silicate melts.

Rustam F. Bulgakov

Vertical motions, especially in the active continental margins such as Kuril-Kamchatka transition zone, are still pure studied. One of the factors significantly affecting the amplitudes and directions of vertical motions is mantle convections. Estimates of the amplitudes of vertical motions in region have been obtained by means of numerical modeling of the mantle convection made by the method of finite elements. The values of emergences in the area of Sakhalin Island and the Kuril Ridge from 0–3 to 13 m were obtained with the accepted rates of mantle convection from 1 to 5 mm/year. The results obtained should be taken into account when reconstructing neotectonic history of the region and assessing the geodynamic situation in the region of the Sea of Okhotsk.

S. R. Taylor

Ali K. Darwesh, Thorkild M. Rasmussen, Nadhir Al-Ansari

Abstract Oil well drilling data from 23 oil wells in northern Iraq are analyzed and optimized controllable drilling parameters are found. The most widely used Bourgoyne and Young (BY) penetration rate model have been chosen for roller cone bits, and parameters were extracted to adjust for other bit types. In this regard, the collected data from real drilling operation have initially been averaged in short clusters based on changes in both lithology and bottom hole assemblies. The averaging was performed to overcome the issues related to noisy data negative effect and the lithological homogeneity assumption. Second, the Dmitriy Belozerov modifications for polycrystalline diamond bits compacts have been utilized to correct the model to the bit weight. The drilling formulas were used to calculate other required parameters for the BYM. Third, threshold weight for each cluster was determined through the relationship between bit weight and depth instead of the usual Drill of Test. Fourth, coefficients of the BYM were calculated for each cluster using multilinear regression. Fifth, a new model was developed to find the optimum drill string rotation based on changes in torque and bit diameter with depth. The above-developed approach has been implemented successfully on 23 oil wells field data to find optimum penetration rate, weight on bit and string rotation.

Jing Li, Xiao-Rong Li, Hong-Bin Zhan et al.

Abstract Fracability is a property that indicates how easy reservoir rocks can be fractured in hydraulic fracturing operations. It is a key parameter for fracturing design and evaluation. In order to utilize continuous logging data to predict fracability, synchronous tests of dynamic and static mechanical parameters of rocks under different confining pressures were conducted on 13 tight sandstone samples derived from the central Junggar Basin, China. A modified formula between dynamic and static mechanical parameters was established. Fracability of the tight reservoir in the Junggar Basin was then evaluated based on brittleness index, fracture toughness, and fracability index. The effectiveness of fracturing was analyzed combined with the oil testing curve after hydraulic fracturing. The results show that: (1) The distribution of oil-bearing formations in the studied area coincides well with stratum of higher fracability index. (2) The critical fracability index is determined to be 0.3, three formations are selected as fracturing candidates, and a thin mudstone interbed is identified in the oil-bearing formation. (3) Well testing curve verifies the reliability of the fracability evaluation method and the accuracy of the modified formula between dynamic and static mechanical parameters. This study provides useful information for improving fracturing operations of tight oil and gas reservoirs.

Márta Polgári, Márta Polgári, Ildikó Gyollai et al.

Sedimentary black shale-hosted manganese carbonate and oxide ores were studied by high-resolution in situ detailed optical and cathodoluminescence microscopy, Raman spectroscopy, and FTIR spectroscopy to determine microbial contribution in metallogenesis. This study of the Urucum Mn deposit in Brazil is included as a case study for microbially mediated ore-forming processes. The results were compared and interpreted in a comparative way, and the data were elaborated by a complex, structural hierarchical method. The first syngenetic products of microbial enzymatic oxidation were ferrihydrite and lepidocrocite on the Fe side, and vernadite, todorokite, birnessite, and manganite on the Mn side, formed under obligatory oxic (Mn) and suboxic (Fe) conditions and close to neutral pH. Fe- and Mn-oxidizing bacteria played a basic role in metallogenesis based on microtextural features, bioindicator minerals, and embedded variable organic matter. Trace element content is determined by source of elements and microbial activity. The present Urucum (Brazil), Datangpo (China), and Úrkút (Hungary) deposits are the result of complex diagenetic processes, which include the decomposition and mineralization of cell and extracellular polymeric substance (EPS) of Fe and Mn bacteria and cyanobacteria. Heterotrophic cell colonies activated randomly in the microbialite sediment after burial in suboxic neutral/alkaline conditions, forming Mn carbonates and variable cation-bearing oxides side by side with lithification and stabilization of minerals. Deposits of variable geological ages and geographical occurrences show strong similarities and indicate two-step microbial metallogenesis: a primary chemolithoautotrophic, and a diagenetic heterotrophic microbial cycle, influenced strongly by mineralization of cells and EPSs. These processes perform a basic role in controlling major and trace element distribution in sedimentary environments on a global level and place biogeochemical constraints on the element content of natural waters, precipitation of minerals, and water contaminants.

Arman Darvish Sarvestani, Ali Moazami Goodarzi, Ali Hadipour

Abstract Oil production could be increased by using optimization techniques in each stage of oil production system from field to production unit. However, the maximum profit will be obtained once integrated optimization of surface and subsurface components of the oil production system is implemented. In addition, when using high-tech equipment and facilities, an integrated study of well and surface facilities affects the economic benefits significantly. In this work, one of the Iranian brown fields (mature or declining production fields) was studied to find the best renovation plan with maximum profits. The base scenario was designed with four stages of separation, and the high-pressure gases from the first and the second separator were planned to be sold, while the low-pressure gases from subsequent stages were supposed to be flared. In this paper, two additional scenarios, namely separator optimization and full optimization, were proposed and 12 cases were defined. In the full optimization scenario, low-pressure gases were prevented from being flared. It was observed that by stopping the flaring systems, gas production rate increases as high as 20% and 150 to 200 MW power will be generated in all cases during the next 20 years. Finally, economic evaluation for all of the cases was done and different cases were compared in terms of incremental annual worth and payback period.

Payam Roohbakhsh , Mohammad Hassan Karimpour , Azadeh Malekzadeh Shafaroudi

Introduction Kuh Zar Au-Cu deposit is located in the central part of the Torud-Chah Shirin Volcanic-Plutonic Belt, 100 km southeast of the city of Damghan. Mineralization including quartz-base metal veins are common throughout this Cenozoic volcano-plutonic belt (Liaghat et al., 2008; Mehrabi and Ghasemi Siani, 2010). The major part of the study area is covered with Cenozoic pyroclastic and volcanic rocks that are intruded by subvolcanic rocks. This paper aims to study the geological, geochemical and petrogenesis of the area using exploration keys for new mineral deposits in the Torud-Chah Shirin zone. Materials and methods To better understand the geological units and identify the alteration zones of the area, 200 rock samples were collected from the field and 132 thin sections with 15 polished thin sections were prepared for petrography and mineralization studies. Ten samples of intrusions with the least alteration were analyzed using the XRF at the East Amethyst Laboratory in Mashhad, Iran. These samples were also analyzed for trace and rare earth elements using ICP-MS, following a lithium metaborate/tetraborate fusion in the Acme Analytical Laboratories Ltd, Vancouver, Canada. 137 geochemistry samples were prepared by the chip composite method of alteration and mineralization zones and were analyzed in the Acme laboratory by Aqua Regia AQ250. Results The geology of the area consists of pyroclastic (crystal tuff) and volcanic rocks with andesite and latite composition, which were intruded by subvolcanic intrusive rocks with porphyritic texture and monzonitic composition. Monzonite rocks were intruded by younger subvolcanic units with dioritic composition. The intrusion of monzonitic pluton and stocks led to the formation of QSP, propylitic, carbonate and silicification-tourmaline broad alteration zones in the area. Monzonite rocks accompanied with disseminated mineralization of about 1 to 10% of pyrite and these sulfides have been converted to secondary iron oxides such as goethite, hematite and limonite. Lithogeochemical exploration revealed Au (up to 598 ppb), Ag (up to 3747 ppb), Cu (up to 679 ppm), Pb (up to 1427 ppm) and Zn (up to 1013 ppm) anomalies. Based on geochemical studies, intrusive rocks have characteristics of high-K Calc-alkaline to slightly shoshonitic and they are within metaluminous to the slightly peraluminous range. Enrichment of LREE versus HREE, enrichment of LILE and depletion in HFSE indicate that the magma was formed in the subduction zones. The negative Eu anomaly is due to the presence of plagioclase as a residual mineral in the magma source. The parent magma is probably formed by the partial melting of amphibolites. The presence of monzonite porphyry source rock, QSP and propylitic alterations, pyrite disseminated mineralization and geochemical anomalies of Au and Cu in the Kuh Zar deposit represents Au-Cu porphyry mineralization in the area. Discussion Tectonic setting discrimination diagrams (Pearce et al., 1984) show that subvolcanic rocks plot almost on the fields of the volcanic arc granites (VAG). In the Rb/Zr vs. Nb diagram from (Brown et al., 1984), the samples are plotted in the field of primitive island arc/continental margin arc. The Torud-Chah Shirin Belt is a part of the Alborz magmatic assemblage (AMA). The AMA has been interpreted to represent the subduction of the Neo Tethyan oceanic lithosphere beneath the Central Iranian continental microplate and the subsequent continental collision of the Arabian and Iranian microplates in the late Cretaceous-early Cenozoic (Berberian and Berberian, 1981; Berberian et al., 1982; Alavi, 1994; Golonka, 2004). Acknowledgement This study has been supported by the Research Foundation of the Ferdowsi University of Mashhad, Iran (Project No. 27126.3). The authors would like to acknowledge the East Amethyst Laboratory for XRF analysis. We also thank the Gold Company of Iran for providing conditions for camping and accommodation. References Alavi, M., 1994 .Tectonics of the Zagros orogenic belt of Iran: new data and Interpretations. Tectonophysics, 22(1): 211–238. Berberian, F. and Berberian, M., 1981. Tectono-plutonic episodes in Iran. In: F.M. Delany and H.K. Gupta (Editors), Zagros Hindukosh. Himalaya Geodynamic Evolution. American Geophysical Union, Washington DC, pp. 5–32. Berberian, F., Muir, I.D., Pankhurst, R.J. and Berberian, M., 1982 .Late Cretaceous and early Miocene Andean type plutonic activity in northern Makran and central Iran. Journal of the Geological Society, 139(5): 605–614. Brown, G.C., Thorpe, R.S. and Webb, P.C., 1984. The geochemical characteristics of granitoids in contrasting arcs and comments on magma sources. Journal of Geological Society, 141(3): 413–426. Golonka, J., 2004. Plate tectonic evolution of the southern margin of Eurasia in the Mesozoic and Cenozoic. Tectonophysics, 381(1-4): 235–273. Liaghat, S., sheykhi, V. and Najjaran, M., 2008. Petrology, gheochemistry and genesis of Baghu turquoise, Damghan. Journal of Science, University of Tehran, 34(2): 133–142. (in Persian with English abstract) Mehrabi, B. and Ghasemi Siani, M., 2010. Mineralogy and economic geology of Cheshmeh Hafez polymetallic deposit, Semnan province, Iran. Journal of Economic Geology, 2(1): 1–20. (in Persian with English abstract) Pearce, J.A., Haris, N.B.W. and Tindle, A.G., 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks, Journal of Petrology, 25(4): 956–983.

Yu-Wei Liu, Xi-Wu Liu, Yong-Xu Lu et al.

Abstract Fracture systems in nature are complicated. Normally vertical fractures develop in an isotropic background. However, the presence of horizontal fine layering or horizontal fractures in reservoirs makes the vertical fractures develop in a VTI (a transversely isotropic media with a vertical symmetry axis) background. In this case, reservoirs can be described better by using an orthorhombic medium instead of a traditional HTI (a transversely isotropic media with a horizontal symmetry axis) medium. In this paper, we focus on the fracture prediction study within an orthorhombic medium for oil-bearing reservoirs. Firstly, we simplify the reflection coefficient approximation in an orthorhombic medium. Secondly, the impact of horizontal fracturing on the reflection coefficient approximation is analyzed theoretically. Then based on that approximation, we compare and analyze the relative impact of vertical fracturing, horizontal fracturing and fluid indicative factor on traditional ellipse fitting results and the scaled B attributes. We find that scaled B attributes are more sensitive to vertical fractures, so scaled B attributes are proposed to predict vertical fractures. Finally, a test is developed to predict the fracture development intensity of an oil-bearing reservoir. The fracture development observed in cores is used to validate the study method. The findings of both theoretical analyses and practical application reveal that compared with traditional methods, this new approach has improved the prediction of fracture development intensity in oil-bearing reservoirs.

B. Ghosh, B. K. Sahoo, B. Chakraborty et al.

Abstract The quality of coke affects the performance of the blast furnace, factors affecting coke quality include coal properties, coal charge granulometry and carbonization conditions. The coke properties include the size analysis, cold strength (Micum Indices-M40, M10) and hot strength (Coke Reactivity Index-CRI, Coke Strength after Reaction-CSR) properties and structural properties such as coke structure and texture. Structural properties comprise the porosity, pore-cell wall thickness and pore sizes, while textures consist of the carbon forms in the coke. In present work, advanced method such as image analysis method was used to interpret coke microstructure. Conventional methods such as determination of coke porosity by measurement of real and apparent density and mercury porosimetry have a number of limitations. Coke size, magnification, number of image frames captured, process of pellet preparations and coke properties such as M40, M10, CRI and CSR (low, medium and high values) were taken as variables for experimental purposes. The coke structure parameters such as porosity, length, perimeter, breadth, roundness, pore-wall thickness and pore size distribution of the pores were determined by image analysis method. This method provided average porosity in addition to pore-wall thickness and pore-size distribution. The pore wall thickness measurement by image analysis method provided significant correlations with M40, CRI and CSR values. This explained the usability of image analysis for coke structure measurement.

S. Morse

Stanka Šebela, Ira D. Sasowsky

Iz 3-eh različnih lokacij v Postojnskem jamskem sistemu in iz ene lokacije v Planinski jami smo analizirali 28 vzorcev za paleomagnetizem. To so prvi objavljeni rezultati o paleomagnetizmu jamskih sedimentov iz teh dveh jam. Sedimenti kažejo normalni magnetni obrat saj so bili odločeni v Brunhes normalnem obdobju (mlajše od 0,73 Ma). V zgornjem nivoju sistema Postojnskih jam pa sedimenti kažejo magnetni obrat, ki ga uvrščamo med 0,73-0,90 Ma We completed paleomagnetic analyses of 28 samples of cave sediments from 3 different locations in Postojnska jama cave system and one location in Planinska jama cave. These are the first published paleomagnetic studies of cave sediments from these caves. These sediments showed normal polarity, and were deposited during the Brunhes Normal Epoch (younger than 0,73 Ma). However, an additional more complex sediment deposit in an upper section of the Postojnska jama cave system, showed reverse polarity, probably indicating an age between 0,73 and 0,90 Ma.

Zvezda Delak Koželj

Prispevek opredeljuje vlogo dejavnosti varstva dediščine v območjih zavarovane krajine oziroma parkov, ki vsekakor presega običajne delovne postopke. Izpostavlja vlogo etnologa konservatorja s poudarkom na pomenu temeljnih raziskav izbranega območja kot osnove za načrtovanje obsega vsebine, predstavitve dediščine, upravljanja, skratka celovitega razvoja zavarovanega območja. The article is defining the role of heritage - conservation activity in sites of protected landscape and parks respectively; the activity which by all means surpasses the habitual working processes. It exposes the role of ethnologist - conservationist with the stress on inevitability of basic researches on the chosen site, which should serve as grounding for planning the complex development of the protected region (i.e.: the extent of content, heritage presentation, management, ...).

S. Jakobsson

Celalettin Şimşek, Birol Kaya, Ahmet Alkan et al.

Menderes Massive is a NE–SW-trending metamorphic terrain in western Anatolia. The massive is composed of regionally metamorphosed rocks of mica-schist and marble. The Bozdag Mountain is the main horst system in Kucuk Menderes river basin. It is composed of several N-S oriented small horsts and grabens and contains important karst features, such as poljes and sinkholes. Ayvacik and Subatan Poljes are typical closed depressions draining into Ayvacik and Subatan sinkholes (ponors). Both are developed along the N-S directed fault system. The main objective of this study is to determine the karstification and hydrogeochemical features of water circulating in marble terrain and controlled by deep sinkholes in the Bozdag Mountain. Detailed speleological studies demonstrated that the degree of karstification of marble rock depends on the regional tectonic structure, the mineralogy of marble and the water recharge rate into the sinkholes. Tritium isotope and tracer tests indicate very fast flow and connection between Subatan surface water and a spring in lower elevations with high Ca and Mg ion concentration at the south of the study area.   Hidrogeologija in hidrokemija marmornega vodonosnika s ponornim točkovnim napajanjem (Masiv Meredes, zahodna Turčija) Masiv Menderes je območje metamorfnih kamnin v zahodni Anatoliji, Turčija. Razteza se v smeri SV–JZ in je sestavljeno predvsem iz regionalno metamorfiziranih sljudnih skrilavcev in marmorjev. Goro Bozdag sestavlja sistem manjših grud in tektonskih jarkov, orientiranih v smeri sever-jug. Masiv je delno zakrasel, s tipičnimi kraškimi oblikami, med katere spadata tudi polji Ayvacik in Subatan, ki se drenirata skozi istoimenske ponore. Obe polji sta razviti v prelomni coni orientirani v smeri sever-jug. Glavni namen opisane raziskave je določiti stopnjo zakraselosti območja in hidrokemične lastnosti vode, ki teče skozi marmornati masiv. Podrobne speleološke raziskave so pokazale, da je zakraselost močno pogojena z regionalno geološko strukturo, mineraloško sestavo marmorja in velikostjo dotokov v ponore. Izotopske analize tritija in sledenje podzemnih voda kažejo na hiter tok in povezavo med poljem Subatan in visoko mineraliziranimi izviri na jugu obravnavanega območja.