Hasil untuk "Petrology"

Arkhipov, Egor A., Zotov, Sergey I., Koroleva, Yulia V. et al.

A comprehensive study of Kaliningrad soils was conducted to assess the level and structure of chemical pollution. The study demonstrates the fundamental importance of using a local background, rather than global clarkes, for reliable assessment of anthropogenic impact. The stable polycomponent pollution of soils in Kaliningrad was identified, with the formation of clearly localized geochemical anomalies. The methods of statistical analysis and geographic information mapping revealed two main sources of pollution, spatially coinciding with the zones of intensive industrial and port activity. The most significant accumulation was found for lead and zinc, the levels of which reached the levels of "severe" pollution. The application of the index system (Igeo, PI, EF, NPI, PLI, Zc) made it possible to differentiate the territory by the degree of soil pollution and identify the nature of the sources of pollutants. The results obtained prove the need for geoecological monitoring and the development of targeted environmental protection measures for identified areas of environmental pollution.

N. Taquet, N. Taquet, N. Taquet et al.

<p>In a world increasingly impacted by climate change and natural hazards, atmospheric monitoring networks are essential for informed decision-making. During the 2021 La Palma eruption, we integrated surface and ground-based remote sensing measurements from global atmospheric network instruments, complemented by rapidly deployed sensors, to monitor volcanic gas emissions up to 140 km from the source. We used direct-sun measurements from low-resolution (EM27/SUN) and high-resolution (IFS-125HR) Fourier transform infrared (FTIR) spectrometers. On La Palma, the EM27/SUN was combined with a differential optical absorption spectroscopy (DOAS) instrument. We present new FTIR retrieval methods to derive the SO<span class="inline-formula">₂</span>, CO<span class="inline-formula">₂</span>, CO, HF, and HCl relative abundance in the plume from both low- and high-resolution solar absorption spectra. Using Sentinel-5P TROPOspheric Monitoring Instrument (TROPOMI) data, we derived SO<span class="inline-formula">₂</span> fluxes and estimated total emissions of 1.8 <span class="inline-formula">±</span> 0.2 Mt SO<span class="inline-formula">₂</span>, 19.4 <span class="inline-formula">±</span> 1.8 Mt CO<span class="inline-formula">₂</span>, 0.123 <span class="inline-formula">±</span> 0.005 Mt CO, 0.05 <span class="inline-formula">±</span> 0.01 Mt HCl, and 0.013 <span class="inline-formula">±</span> 0.002 Mt HF over the course of the eruption. These results are consistent with the mass balance derived from petrologic degassing estimates. This study demonstrates that high- and low-resolution FTIR and DOAS spectrometers, integrated within global monitoring networks, can provide quantitative constraints on volcanic gas composition<span id="page14592"/> and fluxes over large distances. Such capabilities are directly applicable to volcanic crisis monitoring, complementing dedicated networks, satellite observations and supporting improved assessments of volcanic impacts on the atmospheric composition at regional scales.</p>

Mohammad Heidary

Abstract Unambiguously determining irreducible water saturation $$\left({S}_{\rm{wirr}}\right)$$ S wirr poses a formidable challenge, given the availability of multiple independent methods. Traditional approaches often depend on semi-experimental relationships derived from simplified assumptions. These methods, originally designed for oil sandstone reservoirs, result in varying $${S}_{{\text{wirr}}}$$ S wirr values when employed in carbonate gas reservoirs. Nuclear magnetic resonance (NMR) is the most advanced technique for determining $${S}_{{\text{wirr}}}$$ S wirr . While highly accurate, the NMR-based method necessitates the laboratory measurement of the transverse relaxation time $$\left({T}_{2}\right)$$ T 2 cutoff. Laboratory-based $${T}_{2}$$ T 2 cutoff determination is resource-intensive and time-consuming. This research aims to develop a robust model for determining $${S}_{{\text{wirr}}}$$ S wirr in carbonate gas reservoirs by utilizing NMR well logging measurements and special core analysis (SCAL) tests. Various $${T}_{2}$$ T 2 cutoff values were initially employed to compute bound water saturation $$\left({S}_{{\text{bw}}}\right)$$ S bw at different depths to achieve this. Subsequently, the data points $$\left({T}_{2}, {S}_{{\text{bw}}}\right)$$ T 2 , S bw were graphed on a scatter plot to unveil the relationship between $${S}_{{\text{bw}}}$$ S bw and $${T}_{2}$$ T 2 . The scatter plot illustrates an exponential decrease in $${S}_{bw}$$ S bw with increasing $${T}_{2}$$ T 2 , forming the basis for the $${S}_{{\text{wirr}}}$$ S wirr model derived from this relationship. Finally, the parameters of the $${S}_{{\text{wirr}}}$$ S wirr model were fine-tuned using SCAL tests. Notably, this $${S}_{{\text{wirr}}}$$ S wirr model not only accurately yields $${S}_{{\text{wirr}}}$$ S wirr at each depth but also offers a dependable determination of the optimal $${T}_{2}$$ T 2 cutoff for the reservoir interval.

Robert Lončarić, Maša Surić

Alberto Fortis (1741-1803) was an Italian naturalist who had a wide range of scientific interests from linguistics and ethnology to geology, geography and hydrology. This paper presents an overview of hydrological features that Fortis recorded in two of his works: Saggio d'Osservazzioni sopra l'Isola di Cherso ed Osero (1771) and Viaggio in Dalmazia (1774). These works were a result of several Fortis' travels in the region and were noted in European scientific literature of that time. Fortis revealed to European public the eastern Adriatic coast, a then little-known part of Europe with its wide variety of natural features. Despite the scarce appearance of surface water in karst, numerous interpretations of hydrological features can be found in Fortis’ descriptions of the East Adriatic coast. He often shows a remarkable understanding of karst hydrology even though some of his ideas and explanations are dubious from the present point of view. Although Fortis is not considered a karstologist in the strict sense, his works contain elements of what will eventually become karstology.

M. P. Manu Prasanth, Kwan-Nang Pang, K. R. Hari et al.

Peter Thy, Christian Tegner, Charles E. Lesher

The Skaergaard intrusion is a layered, ferrobasaltic intrusion emplaced during the Early Eocene into the rifting volcanic margin of East Greenland. The magma chamber crystallised in response to cooling from the roof and margins upwards and inward, forming upper, marginal and bottom series, the latter referred to as the Layered Series. The phase layering in the bottom series suggests an evolved, olivine-normative tholeiitic melt saturated in plagioclase and olivine, followed by augite, and then simultaneously by ilmenite and magnetite forming primocrysts. Pigeonite appears in the lower parts and continues until the centre of the series. Apatite appears in the upper part concurrently with liquid immiscibility. Cryptic variations of the individual primocrysts record a systematic upward increase in iron and decrease in magnesium for the mafic minerals and a systematic increase in sodium and decrease in calcium for plagioclase. The appearance of pigeonite is caused by reactions and crystallisation in the trapped melt and by subsolidus adjustments without this phase reaching liquidus saturation. The high mode of olivine at the base of the upper part with the appearance of apatite is interpreted to mark the onset of liquid immiscibility. This may have led to the separation of conjugate melts with granophyre migrating upward and the basic component largely staying stationary or sinking. Petrologic and geochemical observations indicate differentiation in the lower part of the intrusion, principally controlled by crystal fractionation with the efficiency of fractionation controlled by the evolution and escape of liquid from the solidifying mush. During the final stages of solidification, the onset of liquid immiscibility and termination of melt convection impeded differentiation. Modelling by perfect Rayleigh fractionation shows that major and included trace elements conform reasonably to observations, while excluded elements deviate from model predictions. This decoupling is caused by the mobility of a granophyre component formed in the trapped melt and in the main residual magma chamber. Consequently, the sampled gabbros may not be representative of the final solid-melt mush. By restoring the gabbros to their original mush compositions, it is possible to constrain granophyre migration pathways. We suggest that the granophyre formed in the trapped melt in the lower part of the intrusion mostly migrated laterally through pressure release pathways to form lenses and pockets with only limited upward migration into the main magma reservoir. Near the end stage of differentiation, the residual magma exsolved and formed complex mixtures of ferrobasaltic and granophyric melts. Estimates predict that a substantial amount of the granophyric melt penetrated as sills into the downward crystallising, upper part of the body as well as into the host rocks. The redistribution of granophyric melts within the solidifying crystal mush complicates predictions of trapped-melt content and mass-balance calculations but helps to explain apparent decoupling of included and excluded trace elements, especially towards the end stages of evolution. Final crystallisation was controlled mostly by in situ crystallisation leaving complex mixtures of ferrodiorite and granophyre components.

Leonid M. Bogomolov1, Vladimir N. Sychev, Naylya A. Sycheva

An analysis has been performed of the change in stress drops over time during the period of foreshock activity of strong earthquakes for two seismically active regions with different geodynamic settings: the Northern Tien Shan and the Southern Kuril Islands. The catalogs of earthquake dynamic parameters, DP (source ones in English publications), in these regions, with a number of events, were used as initial data. The DP catalog for the Northern Tien Shan includes 183 records of source parameters of earthquakes with magnitudes of 2.6–6.0, and the catalog for the Southern Kurils – 264 records. The stress drop values throughout a general sampling were analyzed as well as that in foreshock periods of 500 days length before the strongest earthquakes. For each region 12 such meaningful events have been specified, the magnitudes were М > 5 for the Northern Tien Shan, and М ≥ 6.5 for the Southern Kurils. The median average values of stress drops during 500-day period have been determined. The temporal variations of stress drops have been compared with changes in the b-value parameter (angular coefficient of earthquake recurrence plot) in the same observation periods. The computation of b-value for the case of the Northern Tien Shan involved the catalog data of KNET seismological network (1994–2021, more than 10 000 events), and the catalog of International Seismological Center (ISC, 1964–2000) for the Southern Kurils. In both cases, b-values were determined in 500-day moving interval with one day step. The computation gave the result that the well-known effect of b-value growth before strong earthquakes manifested itself explicitly in the considered regions. It has been established that such increase in b-value is accompanied by a decrease in the averaged stress drop values. The obtained results showed that the monitoring of the stress drop values can be used to identify the non stationary stage of the seismic regime.

Seongin Ahn, Kyungbook Lee, Jonggeun Choe et al.

Abstract With the development of smart downhole control devices, such as the electric flow control valve (FCV), research on completion optimization using FCV control is gaining traction for successful field production management. Applying and verifying its applicability to actual assets with uncertain production issues occur are important. This study focuses on managing downhole devices to optimize fluid production in an actual onshore oil field in Alberta, Canada. The target field has been in production operation for over 20 years, and water flooding was used in the early stages of production to maintain reservoir pressure. However, according to the flow characteristics of the field, water injection caused a high water-cut issue due to water channeling. To mitigate the problem, proactive and reactive strategies were investigated to optimize FCV control. Additionally, the effect of completion optimization was estimated considering both the field-level economic value and the fluid production behavior at the device level. In most optimization cases, the cumulative water production could be reduced compared with the base case without valve control. Notably, the flow-balancing strategy increased the revenue of the target field by approximately 23 MM$ by maximizing oil production and suppressing water production. However, reactive and streamline-balancing strategies, which directly control and delay water production, undermined the economic value due to the decrease in oil production. The findings imply that FCV control strategy of suppressing only water production for the field with high water-cut could not be the optimal solution considering the reduction in oil production and the field’s revenue. The results of this study could be used as a reference to optimize downhole devices when applying water flooding in fields where high water-cut is expected.

Ilia P. Dudchenko, Dmitry V. Kostylev, Sergey A. Gulyakov et al.

This article describes the process and results of the development and testing of a cost-effective, portable, safe to move by air geophysical pulse voltage generator for seismic exploration of the subsurface. The generator is based on high-speed power electronic keys of a new generation consisting of an insulated gate bipolar transistor or a field-effect transistor based on silicon carbide, a compact power converter of alternating voltage from an autonomous generator or electric network to direct voltage using pulse-width modulation and current or voltage stabilization depending on the mode set by a researcher. Field tests were conducted to confirm the suitability of the developed design of the generator and the correctness of the chosen parameters of its elements. To this end, a detailed analysis of the effect of the developed geophysical generator on the parameters of the geoenvironment was carried out.

Leonid M. Bogomolov, Vladimir N. Sychev

Seismic activation in the period of foreshocks (prior to the mainshock) described by the model of self-developing processes (SDP) is possibly a manifestation of explosive instability of low frequency straining waves in metastable medium. To highlight so nontrivial relationship of continuous wave motions and discrete seismic events flow is a goal of this narrative. Thus, the rationale of the SDP model (the equation, in reality) has been modified, which is of importance in relevance with the article by the Malyshevs in the current issue (A.I. Malyshev, L.K. Malysheva. Precedent-extrapolation estimate of the seismic hazard in the Sakhalin and South Kurils region) which is to improve the seismic hazard estimates by means of this model. A new way to reveal the very beginning of blow-up regime after quasi-stationary one is proposed.

Shengzhu Zhang, Xu Wang, Y. Frank Cheng et al.

Abstract Oil spill-induced vapor cloud explosions in a confined space can cause catastrophic consequences. In this work, investigation was conducted on the catastrophic pipeline leak, oil spill, and the resulting vapor cloud explosion accident occurring in China in 2013 by modeling analysis, field surveys, and numerical simulations. The total amount of the spilled oil was up to 2044.4 m3 due to improper disposal. The long residence time of the oil remaining in a confined space permitted the formation of explosive mixtures and caused the vapor cloud explosion. A numerical model was developed to estimate the consequence of the explosion based on volatilization testing results. The results show that the death-leading zone and the glass-breaking zone could be 18 m and 92 m, respectively, which are consistent with the field investigation. The severity of the explosion is related to the amount of the oil spill, properties of oil, and volatilization time. It is recommended that a comprehensive risk assessment be conducted to analyze the possible consequences upon oil spilling into a confined space. Prompt collection and ventilation measures should be taken immediately after the spill occurs to reduce the time for oil volatilization and prevent the mixture from reaching its explosive limit.

M. J. Carr, E. Gazel

Li-Guo Gao, Huan-Xiang Li, Xiao-Li Song et al.

Abstract A new type of photocatalytic La3+–Zn2+–Al3+–MoO4 2− layered double hydroxide (LDH) material (molar ratio, La/Zn/Al = 1:7:2) was prepared by a complexing agent-assisted homogeneous precipitation technique. The structure of the prepared LDH material was systematically studied. Under UV irradiation, the desulfurization efficiency of the LDH material was 87% in 2 h. For La3+–Zn2+–Al3+–MoO4 2− LDH material, the introduction of MoO4 2− increased the interlayer space for promoting the adsorption of benzothiophene (BT), and MoO4 2− might provide active sites for the oxidation of BT, resulting in the high desulfurization efficiency.

Fengrui Sun, Yuedong Yao, Guozhen Li

Abstract The research course in the estimation of productivity of cyclic steam stimulation wells can be divided into three stages: (a) the mobility of heavy oil in the cold area is neglected, (b) the mobility of heavy oil in the cold area is considered—however, it is Newtonian fluid seepage, and (c) it is conserved as non-Newtonian fluid seepage in the cold area. However, the distribution of the value of starting pressure gradient in the heated area where heavy oil is still non-Newtonian fluid is neglected. In this paper, a new model is developed for productivity estimation of cyclic steam stimulation wells with consideration of the non-Newtonian fluid flow behaviors in the heated area where the temperature is higher than the turning point. New percolation equations are developed based on the new proposed concept of “the transition region” in the heated area. The results show that: (1) when the non-Newtonian fluid characteristic is neglected, the predicted results from the new model match the results from the numerical simulator perfectly, and (2) in oil field, the non-Newtonian fluid characteristic cannot be neglected. When the non-Newtonian fluid characteristic is considered in the model, the average oil production in each cycle can match the filed data better than Yang et al.’s model. This new model laid a basic reference for oil companies and researchers involved in the area when they are designing the well pattern, spacing or estimating the productivity of oil wells.

Amir Esna-Ashari, Fatemeh Sarjoughian

In the central part of the Sanandaj-Sirjan zone, there is an ultramafic rock exposure (hornblendite and pyroxenite) adjacent to Molataleb felsic complex completely located between Azna and Aligoodarz towns. The ultramafic rocks are actually cumulates derived from boninitic magma. During Upper Triassic-Lower Jurassic time the boninitic magma has been originated from mantle wedge as the result of initiation of Neo-Tethys subduction. Later, when subduction was proceeding, the felsic rocks crystallized in Middle Jurassic. Major elements composition of olivine, pyroxene, amphibole and minor plagioclase from the ultramafic rocks reveals crystallization from a sub-alkaline to calc-alkaline magma in a subduction zone setting. Primary minerals have chemical characteristics typical of those derived from a magma with low oxygen fugacity. Different methods for minerals thermobarometry indicate that amphiboles crystallized in relatively low temperature (880°C) but crystallization condition of other minerals corresponds to higher temperatures (1000-1200°c). They were crystallized at pressure condition equal to 5.85 kbar corresponding to the depth of ~17 km. It is not common that a mantle wedge at the depth of ~17 km to be affected by such high thermal gradient during the normal subduction process. Asthenospheric flow around the subducting slab edge during subduction initiation can explain high thermal gradient prevailed the infant mantle wedge. This mechanism corresponds to the boninitic nature of the ultramafic rocks.

Ji-Lei Li, Jun Gao, R. Klemd et al.

Achinta Bera, Ajay Mandal, Hadi Belhaj et al.

Abstract Surfactants for enhanced oil recovery are important to study due to their special characteristics like foam generation, lowering interfacial tension between oleic and aqueous phases, and wettability alteration of reservoir rock surfaces. Foam is a good mobility control agent in enhanced oil recovery for improving the mobility ratio. In the present work, the foaming behavior of three nonionic ethoxylated surfactants, namely Tergitol 15-S-7, Tergitol 15-S-9, and Tergitol 15-S-12, was studied experimentally. Among the surfactants, Tergitol 15-S-12 shows the highest foamability. The effect of NaCl concentration and synthetic seawater on foaming behavior of the surfactants was investigated by the test-tube shaking method. The critical micelle concentrations of aqueous solutions of the different nonionic surfactants were measured at 300 K. It was found that the critical micelle concentrations of all surfactants also increased with increasing ethylene oxide number. Dynamic light scattering experiments were performed to investigate the micelle sizes of the surfactants at their respective critical micelle concentrations. Core flooding experiments were carried out in sand packs using the surfactant solutions. It was found that 22% additional oil was recovered in the case of all the surfactants over secondary water flooding. Tergitol 15-S-12 exhibited the maximum additional oil recovery which is more than 26% after water injection.

Amila Sandaruwan Ratnayake, Chaminda Wimal Kularathne, Yoshikazu Sampei

Abstract The Mannar Basin is an under-explored offshore sedimentary basin in terms of petroleum geology. The Cretaceous to Paleogene cutting samples were collected in three offshore exploration wells (i.e. the Dorado North, Dorado and Barracuda) in the Mannar Basin. In this study, kerogen type, quantity and thermal maturity of sedimentary organic matter were ascertained using Rock–Eval pyrolysis and vitrinite reflectance analyses. In addition, 1-D basin modelling was used to analyse the timing of hydrocarbon generation in the Mannar Basin. Total organic carbon (TOC) contents and total hydrocarbon potential are higher in the Cretaceous calcareous mudstones than in the Paleogene calcareous silty/sandy mudstones. TOC contents show a negative correlation with oxygen index. Hydrogen index and oxygen index values range from 77 to 785 mg HC/g TOC and from 25 to 165 mg HC/g TOC, respectively. Organic matters were identified as mixed Type II–III and Type III kerogen. Maturity expressed in term of Tmax and vitrinite reflectance range from 332 to 456 °C and from 0.26 to 1.49%, respectively. It indicates both immature and mature sediments. In general, maturity values are relatively high in the Late Cretaceous sediments (Tmax, from 332 to 456 °C, average = 423 °C ± 25) compared to the Paleogene sediments (Tmax, from 388 to 431 °C, average 419 °C ± 10). Geochemical proxies show that oil and gas prone (Type II–III) and gas prone (Type III) kerogen-rich Late Cretaceous sediments of the Dorado and Barracuda wells have principally achieved maturity levels for oil window. Therefore, it suggests incomplete thermal conversion for the wet gas generation in the northeast part of the Mannar Basin. In the 1-D basin modelling, the maximum hydrocarbon generation was observed during the Neogene Period in the Late Cretaceous sediments of the deeper Barracuda well.

S. Salehi, S. Salehi, M. Karami et al.

Lichens are the dominant autotrophs of polar and subpolar ecosystems commonly encrust the rock outcrops. Spectral mixing of lichens and bare rock can shift diagnostic spectral features of materials of interest thus leading to misinterpretation and false positives if mapping is done based on perfect spectral matching methodologies. Therefore, the ability to distinguish the lichen coverage from rock and decomposing a mixed pixel into a collection of pure reflectance spectra, can improve the applicability of hyperspectral methods for mineral exploration. The objective of this study is to propose a robust lichen index that can be used to estimate lichen coverage, regardless of the mineral composition of the underlying rocks. The performance of three index structures of ratio, normalized ratio and subtraction have been investigated using synthetic linear mixtures of pure rock and lichen spectra with prescribed mixing ratios. Laboratory spectroscopic data are obtained from lichen covered samples collected from Karrat, Liverpool Land, and Sisimiut regions in Greenland. The spectra are then resampled to Hyperspectral Mapper (HyMAP) resolution, in order to further investigate the functionality of the indices for the airborne platform. In both resolutions, a Pattern Search (PS) algorithm is used to identify the optimal band wavelengths and bandwidths for the lichen index. The results of our band optimization procedure revealed that the ratio between R_894-1246 and R₁₁₁₀ explains most of the variability in the hyperspectral data at the original laboratory resolution (R²=0.769). However, the normalized index incorporating R_1106-1121 and R_904-1251 yields the best results for the HyMAP resolution (R²=0.765).

Rafael Ferreiro Mählmann, Ö. Bozkaya, S. Potel et al.