Kaistrenko, Victor M., Willis, Pascal, Razjigaeva, Nadezhda G.
et al.
On October 4(5), 1994, one of the strongest tsunamigenic earthquakes in the history of the Southern
Kuril Islands occurred, which was accompanied by large-scale tectonic manifestations. Intense shaking led to the
collapse of the entire infrastructure on Shikotan and Kunashir Islands; 11 people died. The tsunami that followed
the earthquake reached a height of about 10 m on the ocean side of Shikotan Island and was recorded along the
entire coast of the Pacific Ocean. Generally, the study of the manifestations of this event had been carried out
since October 1994 and ended in 1997 with the publication of extensive reviews. For the first time, the data on
the specific effects on the ocean surface (seaquake) that accompanied this earthquake have been collected and
systematized. In the following years, the interest in this extraordinary event initiated further research. At the same
time, the study of the deposits of the tsunami of October 4(5), 1994, in the general context of study of ancient
tsunami (paleotsunami) deposits in this region came to the fore. These studies allowed us to obtain estimates of
the "preservation"/ "erasure" of the traces of this tsunami and more ancient events on the coast of the Southern
Kuril Islands. Some important data presented in this review are being published for the first time.
Objective As an essential component of the East Asian continental margin, the southeastern coastal region of China records a complex history of regional tectonics, magmatism, and geomorphological features associated with the subduction of the Paleo-Pacific/Pacific Plate. This region serves as an ideal window for studying ocean–continent interactions related to subduction zones. During the Cretaceous period, influenced by the rollback of the Paleo-Pacific Plate, a giant rhyolitic volcanic belt approximately 1200 km in length developed along the southeastern coast of China. Among the provinces in this region, Zhejiang hosts the largest preserved area of rhyolitic volcanic rocks and retains the most well-preserved volcanic structures. Previous studies have extensively investigated the geochronology, petrology, geochemistry, and metallogenesis of these rhyolitic volcanic rocks; however, their uplift and cooling history has been largely overlooked. Methods This study conducted apatite fission track dating and HeFTy thermal history modeling on the central facies intrusive rocks (quartz syenite, syenite and monzonite) of the calderas in the Yandang Mountain and Shenxianju areas. Results All the apatite fission track dates from the Yandang Mountain and Shenxianju areas show chi-squared probability P(χ2) ≥ 0.05, indicating that the fission track dates of all specimens follow a Poisson distribution and belong to a single age population. Twenty of the total thirty-two specimens from the Yandang Mountain area yielded apatite fission track ages (pooled age and central age) between 40 Ma and 31 Ma, seven of the thirty-two specimens gave apatite fission track ages between 50 Ma to 41 Ma, with only five of the thirty-two specimens yielding apatite fission track ages ranging from 61 Ma to 51 Ma. For the Shenxianju area, the apatite fission track ages are predominantly (sixteen of the twenty-six specimens) distributed between 40 Ma and 31 Ma, with some specimens (eight of the twenty-six specimens) showing ages ranging from 50 Ma to 41 Ma and a few of them (two of the twenty-six specimens) yielding ages between 61 Ma and 51 Ma. Furthermore, the single-grain apatite fission track ages of the specimens from both the Yandang Mountain and Shenxianju areas show a unimodal distribution with a peak at 33 Ma. The mean confined track lengths of the specimens from the Yandang Mountain area vary between ~11.12 μm and ~14.09 μm with unimodal track length distributions. Specimens from the Shenxianju area yielded mean confined track lengths of ~11.11 to ~14.44 μm, also showing a unimodal track length distribution pattern. The mean Dpar values of specimens from the Yandang Mountain area range from 0.78 μm to 1.04 μm, while those from the Shenxianju area display mean Dpar values varying from 0.86 μm to 1.12 μm. The HeFTy thermal history modeling reveals a rapid exhumation and cooling event occurring from the early-Eocene to the earliest Oligocene for both the Yangdang Mountain (48 Ma to 33 Ma) and Shenxianju (52 Ma to 32 Ma) areas. The cooling rates of this event vary from ca. 8 ℃/Myr to 20 ℃/Myr for Yandang Mountain area and ca. 5 ℃/Myr to 16 ℃/Myr for Shenxianju area respectively. Conclusion Our new apatite fission track dating and HeFTy thermal history modeling results help identify an exhumation and cooling event in the Yangdang Mountain and Shenxianju areas during the early-Eocene to the earliest Oligocene epoch. Based on the results of this study and regional tectonic setting analysis, the early-Eocene to the earliest Oligocene exhumation and cooling event in the study areas is interpreted as being initially controlled by the subduction of the Izanagi-Pacific Plate ridge and later driven by the combined effects of the India-Eurasia continental collision and the rollback of the Pacific Plate. Significance This study provides important low-temperature thermal geochronological constraints on the Phanerozoic regional tectonic and geomorphological evolution of southeastern Zhejiang province.
ABSTRACT: Shale gas is abundant in the Paleozoic of the Yangtze Platform, and several high-yield shale gas fields have been built in the Upper Yangtze Platform, China. The Permian of the South Yellow Sea Basin (SYSB) in the Lower Yangtze area is considered a potential target for shale gas exploration; however, the fundamental geological conditions of shale gas have not been studied. Based on the first whole-cored scientific drilling borehole (CSDP-2) in the SYSB, detailed tests involving petrology, organic geochemistry, and reservoir physical properties were conducted to evaluate the shale gas potential of the Lower Permian. The Lower Permian is dominated by organic-rich siliceous, clay, and clay-mixed shales. The average total organic carbon content is 5.99%, and the organic matter is mainly type II1−II2, which has entered the high-over mature evolution stage. The pore types of organic-rich shales mainly include organic pores, dissolution pores, and intergranular pores, of which the meso-/macropores are well developed. The average porosity is 3.04%, and the total specific surface area and pore volume are 3.47 m2/g and 7.21×10−3 cm3/g, respectively. The average Langmuir volume obtained from the methane adsorption isotherms is 2.70 cm3/g, and methane is mainly adsorbed in the meso-/macropores. The lower Permian shales are rich in methane as indicated by gas logging results, with an average content of 7.3%, which can reach up to 65.9%. A comparison of the study area with typical shale gas fields shows that the Lower Permian is brittle and shallowly buried and has a high potential for shale gas exploration and low-cost development. The depression areas of the SYSB are overlain by thick Mesozoic–Cenozoic sediments, show higher organic matter maturity, and may have greater shale gas potential. The shale gas exploration breakthrough of the study area is of great significance to ensure the energy supply of economically developed areas on the east China.
Seyed Poorya Mirfallah Lialestani, David Parcerisa, Mahjoub Himi
et al.
Effective categorization of geothermal resources is essential for strategic and sustainable energy development. Despite the considerable geothermal potential in Spain, utilization remains limited, underscoring the need for advanced and practical assessment methods. This study proposes a structured framework for geothermal resource classification in Catalonia, based on a constructed matrix of features that integrates subsurface temperature, geothermal gradient, and thermal conductivity. The matrix enables resource clustering into potential classes, improving interpretability and regional assessment. The analysis employed predictions from a pretrained hybrid artificial intelligence model optimized using a modified Bat algorithm. At depths between 50 and 150 m, a 20–30% increase in temperature leads to a 30–50% rise in geothermal potential. Approximately 11.5% of sites exhibit high potential and 28.2% moderate potential, indicating the reliability of the adopted framework for geothermal energy source site prioritization. The proposed matrix offers a scalable tool for geothermal evaluation, minimizing exploration risk and supporting sustainable energy planning across diverse geological settings.
Dileep Kumar Balaga, Jayanta Mondal, Sandeep D. Kulkarni
Abstract To maintain performance of an aqueous-based drilling muds (ABDMs), it was imperative to understand the decay mechanism of the incorporated synthetic polymers, when exposed to the elevated temperatures. The understanding of the decay mechanism could provide a polymer replenishment strategy for the fluid to retain a specific rheology and filtrate control performance. In this context, thermal-degradation of various acrylamide co-polymers was investigated in different monovalent brines. The acrylamide co-polymers were custom synthesized, and their molecular weight and % sulfonic substitution was verified using the capillary viscometer and nuclear magnetic resonance spectroscopy techniques respectively. The co-polymer thermal degradation mechanism (i.e., polymer hydrolysis) in various monovalent brines (KCl, NaCl and NaBr) was quantified by novel titration for temperature range {121 °C, 177 °C}. The degradation response of the co-polymers was then correlated with their rheology and HPHT (high-pressure-high-temperature) filtrate performance; for instance, the titration studies showed that co-polymer degradation was 12–15% and 44–47% after sixteen hours aging at 121 °C and 177 °C respectively; correspondingly the co-polymer performance in ABDM, exhibited HPHT filtrate of 12–18 mL and 38–40 mL at those respective temperatures after sixteen hours of aging. The quantified understanding of the co-polymer thermal degradation was used to device a new approach for co-polymer replenishment strategy; it was illustrated that a 7% replenishment of the co-polymer for every eight hours, at 121 °C, enabled sustained HPHT filtrate of 12–18 mL for the studied evaluation period of thirty-two hours. The replenishment approach presented in the study would provide a valuable tool for drilling automation to ensure sustained fluid performance.
Mohammed H. Aljahdali, Amr S. Deaf, Thomas Gentzis
et al.
Integrated organic petrographic and geochemical analyses were made on organic-rich marine carbonate and mixed clastic-carbonate rocks of Middle–Late Jurassic and Early Cretaceous age from the Shushan Basin, Egypt to evaluate their hydrocarbon potential. Analyses allowed the identification of depositional settings, paleoclimate, and three third order genetic stratigraphic sequences (SQ) with deposits assigned to highstand (HST), lowstand (LST) and transgressive systems tracts (TST). Deposition of the source rocks in the rifting Shushan Basin resulted from the interaction between Neotethyan sea level changes, tectonic, and climate. The good reducing conditions developed during the Neotethyan Middle–Late Jurassic (Bajocian–Kimmeridgian) second order sea level rises and the climatically induced carbonate sedimentation resulted in the deposition of the organic-rich carbonates of the Khatatba Formation (SQ 1, early–middle TST) in inner–middle shelf settings under anoxic–dysoxic conditions. The Late Jurassic (late Kimmeridgian) uplifting resulted in the deposition of the organic-lean mixed clastic–carbonate strata of the Masajid Formation (SQ 1, latest TST) in the same shelfal and reducing conditions, which experienced a notable dilution of organic matter. The late TST deposits of SQ 1 are good to very good oil-producing source rocks, where they show average good to very good generative potential of late mature (late oil-to early wet gas-window) highly oil-prone organic matter. The Early Cretaceous (Valanginian–Albian) uplifting associated with the rifting of the Shushan Basin overprinted the Neotethyan late Valanginian–Hauterivian second order sea level rises, Aptian second order highstand sea level, and Albian second order sea level rise. The coeval climatic shift toward more humid conditions resulted in the clastic-dominated deposition of the organic-lean regressive units of SQ 2 (HST and LST of Alam El Bueib, Alamein, and Dahab formations) and SQ 3 (HST and LST of the lower–upper Kharita Formation) in marginal marine settings under anoxic–dysoxic to oxic conditions. The HST and LST deposits of the SQ 2 and SQ 3 show poor to good organic richness of early–mid mature (early–peak oil-window) oil/gas-prone and gas/oil-prone organic matter, respectively and exhibit average fair oil source rock potential with no gas generation.
Introduction
The studied area is situated 15 km away from the southwest of Maimeh at the western part of Urumieh-Dokhtar magmatic arc. This zone is a part of the Zagros orogenic belt formed due to the subduction of the Neo-Tethyan oceanic crust under the Central Iran block. The magmatic activity in the Urumieh-Dokhtar magmatic arc has begun in Eocene (Alavi, 2004) and continued until Quaternary (Ghasemi and Talbot, 2006). In the middle part of the studied area, several outcrops of the post-Early Cretaceous volcanic rocks with basaltic to andesitic composition have been seen (Vahdati Daneshmand, 2006). Until now, no petrological and geochemical data about these rocks are present. Therefore, in this study, petrographic and the geochemical features of these rocks are discussed in detail. This study aims to reveal a better understanding of the petrology and petrogenesis of volcanic rocks in the southeast of Maimeh and the middle part of the Urumieh-Dokhtar magmatic arc as a part of the Zagros orogenic belt.
Materials and methods
To reach the goal of the research, after collecting basic information using geological maps and works done in the study area, all volcanic outcrops systematically sampled, and more than 50 fresh samples were chosen and studied. Afterward, seven samples were chosen for geochemical analyses by using inductively coupled plasma mass spectrometry (ICP-MS) at the ACME Laboratories, Vancouver, Canada. The results of chemical analyses are listed in table 1.
Discussion
Based on the field observations, the volcanic rocks have basaltic to andesitic composition with plagioclase, clinopyroxene, olivine, amphibole, biotite, and opaque microphenocrysts. Clinopyroxene (probably augite) is the main minerals as phenocrysts and small mineral in the groundmass. Olivine phenocryst has undergone limited alteration to iddingsite and amphiboles show burned margin. Opacitization in amphibole occurs due to a decrease in water pressure with magma rising or as a result of the increase in temperature (Plechov et al., 2008). These rocks have microlithic porphyry, glomeroporphyry and vesicular textures. According to geochemical analysis, intermediate rocks have calc-alkaline nature and basalt is alkaline. They display enrichment in LILEs (Rb, Ba, K, Sr, U, and Th) relative to HFSEs (especially Nb, Ti, and P) and coherent REE patterns characterized by enrichment in LREEs relative to HREEs without negative Eu anomaly. These features are characteristics of subduction-related magmatism (Woodhead et al., 1993). U and Th enrichment may be due to crustal contamination (Kuscu and Geneli, 2010) or the addition of pelagic sediments and/or altered oceanic crust to the source of magma (Fan et al., 2003). The tectonic discrimination diagrams show an active continental arc setting for these rocks. Geochemical evidence shows that the volcanic rocks were originated from low degree partial melting (<0.1) of the enriched mantle with Cpx- garnet lherzolitic composition in 80 km depth. Mantle enrichment is due to the addition of aqueous fluids derived from dehydration of the subducted oceanic crust. It seems that the continuous subduction of cooled oceanic crust into the mantle along with convergence between Arabia and Central Iran plates led to low degree partial melting of the mantle and producing alkaline magmas. The ascending parental magma was differentiated and undergone AFC processes until rising from the crust. In these processes, the alkaline basalt under the influence of fractional crystallization and crustal contamination turned into intermediate compositions of calc-alkaline andesite. It seems that these rocks were formed from the subduction of Neo-Tethyan oceanic crust under the Iranian microplate in an arc magmatic zone.
Results
The post-Early Cretaceous volcanic rocks in the southeast of Maimeh is situated in the western part of Urumied-Dokhtar magmatic arc and includes most basic to intermediate associations. The rocks have the porphyritic texture with basalt to andesite composition and are characterized by alkaline to calc-alkaline affinity and enrichment in LIL elements (Rb, Ba, Th, U and …) relative to HFSE with negative Ti and Nb anomalies and highly differentiated pattern of rare earth elements, as evident in spider diagrams normalized to primitive mantle and chondrite. The significant features are mainly a result of subduction-related magmatism. Tectonomagmatic diagrams suggest an arc-related tectonic setting for these rocks. Based on the geochemical evidence, the volcanic rocks originated from low degrees (>1) partial melting of a garnet- lherzolitic mantle source that enriched by slab-derived fluids. The magma has undergone AFC processes during ascending and alkaline affinity changed to calc-alkaline nature. The volcanic rocks occurred as a result of the subduction of the Neo-Tethyan oceanic crust beneath the Central Iran microplate.
References
Alavi, M., 2004. Regional stratigraphy of the Zagros fold-thrust belt of Iran and its proforeland evolution. American Journal of Science, 304(1): 1–20. http://doi.org/10.2475/ajs.304.1.1
Fan, W.M., Guo, F., Wang, Y.J. and Lin, G. 2003. Late Mesozoic calc-alkaline volcanism of post-orogenic extension in the northern Da Hinggan Mountains, northeastern China. Journal of Volcanology and Geothermal Research, 121(1–2): 115–135. http://doi.org/10.1016/S0377-0273(02)00415-8
Ghasemi, A. and Tabatabaei Manesh, S.M. 2015. Geochemistry and petrogenesis of Ghohroud igneous complex (Urumieh–Dokhtar zone): Evidence for Neotethyan subduction during the Neogene. Arabian Journal of Geosciences, 8(11): 9599–9623. http://doi.org/10.1007/s12517-015-1883-7
Kuscu, G.G. and Geneli, F., 2010. Review of post collisional volcanism in the Central Anatolian volcanic province (Turkey), with special reference to the Tepekoy volcanic complex. International Journal of Earth Sciences, 99(3): 593–621. https://doi.org/10.1007/s00531-008-0402-4
Plechov, P.Y., Tsai, A.E., Shcherbakov, V.D. and Dirksen, O.V., 2008. Opacitization conditions of hornblende in Bezymyannyi volcano andesites (March 30, 1956 eruption). Petrology, 16(1): 19–35. http://doi.org/ 10.1134/S0869591108010025
Vahdati Daneshmand, F., 2006. Geological map of Maimeh, Scale 1:100000, Sheet No. 6256. Geological Survey of Iran. Tehran, Iran.
Woodhead, J., Eggins, S. and Gamble, J., 1993. High field strength and transition element systematics in island arc and back-arc basin basalts: Evidence for multi-phase melt extraction and a depleted mantle wedge. Earth and Planetary Science Letters, 114(4): 491–504. https://doi.org/10.1016/0012-821X(93)90078-N
Abstract Thermodynamics has been fundamental to the interpretation of geologic data and modeling of geologic systems for decades. However, more recent advancements in computational capabilities and a marked increase in researchers' accessibility to computing tools has outpaced the functionality and extensibility of currently available modeling tools. Here, we present VESIcal (Volatile Equilibria and Saturation Identification calculator): the first comprehensive modeling tool for H2O, CO2, and mixed (H2O‐CO2) solubility in silicate melts that: (a) allows users access to seven of the most popular models, plus easy inter‐comparison between models; (b) provides universal functionality for all models (e.g., functions for calculating saturation pressures, degassing paths, etc.); (c) can process large datasets (1,000s of samples) automatically; (d) can output computed data into an Excel spreadsheet or CSV file for simple post‐modeling analysis; (e) integrates plotting capabilities directly within the tool; and (f) provides all of these within the framework of a python library, making the tool extensible by the user and allowing any of the model functions to be incorporated into any other code capable of calling python. The tool is presented within this manuscript, which may be read as a static PDF but is better experienced via the Jupyter Notebook version of this manuscript. Here, we present worked examples accessible to python users with a range of skill levels. The basic functions of VESIcal can also be accessed via a web app (https://vesical.anvil.app). The VESIcal python library is open‐source and available for download at https://github.com/kaylai/VESIcal, or it can be installed using pip. It is recommended to read and interact with this manuscript as an executable Jupyter Notebook, available at https://mybinder.org/v2/gh/kaylai/vesical-binder/HEAD?filepath=Manuscript.ipynb.
Abstract Porosity is the most common form of reservoirs, and its size, shape, and connectivity directly affect the capacity of oil and gas storage and production. To study the micro–nano-pore structure characteristics of shale oil reservoirs and quantitatively characterize its heterogeneity, this work uses high-precision high-pressure mercury intrusion (HPMI) experimental techniques to study the micro–nano-pore structure characteristics of shale oil, and based on the experimental data, fractal theory is used to quantitatively characterize its heterogeneity. The results of the study show that the micro–nano-pores in the shale oil reservoir are concentrated and continuous, and the pore radius is mainly distributed among the range of 30–500 nm, nanoscale pores are an important part of the pores of the shale oil reservoir. The fractal dimension of the shale oil reservoir is larger than the fractal dimension of typical tight oil reservoirs, indicating that the heterogeneity of shale oil reservoir is stronger. The research results have some theoretical and practical significance for the production of inter-salt shale oil reservoirs.
Ebong D. Ebong, Anthony E. Akpan, Stephen E. Ekwok
Abstract Three-dimensional models of petrophysical properties were constructed using stochastic methods to reduce ambiguities associated with estimates for which data is limited to well locations alone. The aim of this study is to define accurate and efficient petrophysical property models that best characterize reservoirs in the Niger Delta Basin at well locations and predicting their spatial continuities elsewhere within the field. Seismic data and well log data were employed in this study. Petrophysical properties estimated for both reservoirs range between 0.15 and 0.35 for porosity, 0.27 and 0.30 for water saturation, and 0.10 and 0.25 for shale volume. Variogram modelling and calculations were performed to guide the distribution of petrophysical properties outside wells, hence, extending their spatial variability in all directions. Transformation of pillar grids of reservoir properties using sequential Gaussian simulation with collocated cokriging algorithm yielded equiprobable petrophysical models. Uncertainties in petrophysical property predictions were performed and visualized based on three realizations generated for each property. The results obtained show reliable approximations of the geological continuity of petrophysical property estimates over the entire geospace.
Introduction. The ground of the rheological Earth’s crust model with a barrier zone between its upper and middle parts is given. The zone is impermeable to fluids radically changes present-day understanding of the upper part lithosphere structure. A critical generalizing review for, earlier models of the continental crust structure and geological nature of K1 geophysical interface, which proposed by different authors, are is commited for consideration. Metods. The information regarding the middle crust watering is presented. The data on electromagnetic deep probing indicate that in the middle and lower crust and, possibly, in the upper mantle the content of free water makes up about 1% in volume. Therefore, there is some kind of block which does not allow for the whole water to squeezed up into the upper part of the Earth’s crust, where an open crack-pore space is filled with water under hydrostatic pressure. So, clearly expressed hydrodynamic zoning exists in the continental Earth’s crust. This universal continental Earth’s crust zoning now is confirmed by geophysics and super-deep drilling, but it is not yet enough realized by a great number of geologists and geophysicists. Discussion. In the upper crust the rocks become harder with deepening, as the effective pressure increases and stronger and stronger press down them. Geophysical studies mark this fact by the growth speed of seismic wave spreading and the decrease of electrical inductance. Lower of the pores and cracks closing horizon (lower of the barrier) the picture sharply changes. Effective pressure is falling and rocks lose fully their hardening, becoming even less hard than at the day surface. Consequently, lower of the hardest upper crust bottoms under a dense impenetrable zone extremely weakened water-containing rocks are located. The earth crust turns out to be sharply stratified into (zones) not only by the water-presence, but even more contrastingly - by rheological (hardening) properties. At any even miserable mechanical movements and deformations at the boundary of hard and weak storeys disruptions and motions is inevitably occured. Conclusions. The importance of suggested model of the crust structure for the tectonics, petrology, ore-formation, hydrogeology, oil geology, seismicity as well as for the nuclear wastes and others is considered.
Engineering geology. Rock mechanics. Soil mechanics. Underground construction
Within the framework of reinterpretation of the depositional evolution of the Komjatice depression, presence of cummingtonite in weakly lithified sediment has been detected. The sediment is formed by volcanic lithoclasts and phenocrysts with a small admixture of non-volcanic grains. The different mineral composition and various degrees of alteration of volcanic lithoclasts, together with structural features point to epiclastic origin. Therefore, the studied samples can be described as volcanic paraconglomerate and sandstone. The cummingtonite is found in rusty coloured volcanic lithoclasts and in the heavy fraction. Cummingtonite-bearing volcanic rocks have not been described so far from the Slovak Neogene volcanic fields. Therefore its presence in the studied samples represents the first indication of such volcanic rock in Slovakia. The aim of the article is to invoke interest for finding these volcanic rocks in situ.
Habibollah Ghasemi, Zakie Kazemi, Fardin Mousivand
et al.
A thick sequence of Upper Cretaceous volcano-sedimentary rocks are cropped out on the northern edge of Central Iran, southwest of Sabzevar. The volcanic rocks are dacite/rhyolite and are associated with pyroclastic rocks, including agglomerate, breccia and tuff. Dacites are the thickest felsic volcanic unit. They show felsitic porphyry, glomero-porphyry and microlitic-porphyry textures and are composed of clinopyroxene, plagioclase and quartz. Plagioclases show sieve and zoning textures. Whole-rock and clinopyroxene chemistries reveal the tholeiitic nature of these rocks. Primitive mantle-normalized spider diagrams of these rocks show negative anomalies of Nb, Ti and positive anomalies of Pb and K, which are characteristic features of the subduction environment magmas. Plot of the samples in different tectonic setting discrimination diagrams indicates their close relationships to the island arc subduction environments. The results of the clinopyroxene chemistry also indicate their augitic composition. Application of geothermobarometry diagrams show temperature ranges between 850 ºC to 950 ºC and pressures less than 5 kb for crystallization of these rocks. The results of this study show that the tholeiitic magma that formed these rocks has been generated by partial melting of a spinel lherzolitic mantle source in an island arc subduction zone during the closure of the Sabzevar Neo-Tethyan oceanic basin in the late Cretaceous.subduction zone during the closing of the Sabzevar Neo-Tethyan oceanic basin in the late Cretaceous.
Abstract Geological investigation have led to discovery of huge tar sand deposits within Afowo Formation of the Turonian–Maastrichtianage (95.9–66.0 Ma) in the Nigerian sector of the Eastern Dahomey Basin. This study aims at determining the feasibility of exploiting the major hydrocarbon resource steam assisted gravity drainage enhanced recovery technique. Samples from three core holes were dry sievied to determine the particle size distribution and their sections studied using a petrographic microscope. Clay mineral content was determined using X-ray diffraction scanning electron microscopy. The granulometric analysis shows the bituminous sediments to be generally fine grained and moderate to well sorted, and the grains are angular to subangular. Porosity ranges from 15.5 to 33.6 ɸ with average value of 26.4 ɸ, while permeability ranges from 270 to 4800 mD, with an average value of 4800 mD (very high) recorded for the sandstones. Petrographic study, scanning electron microscopy and X-ray diffractometry showed quartz as the dominant mineral component, with subordinate feldspar and other accessory minerals. The predominance of quartz is probably due to its mechanical stability. The low frequency of feldspar is attributable to its susceptibility to chemical breakdown and alteration, respectively, during transport and after deposition, with latter accounting for the observed secondary porosity. Kaolinite is the common clay mineral present in the oil sands and may not have sufficiently reduced the reservoir quality to negatively impacting enhanced recovery operation by steam assisted gravity drainage.
Abstract It is crucial to precisely estimate the water transport behaviors in shale formation. However, the present study on this subject is quite limited. A comprehensive literature review is conducted and some improvements are proposed. In this paper, an improved model is proposed to investigate the flow of water in nanopores of shale formation. First, a quadratic equation is proposed to build the relationship between water viscosity and contact angle. Then, the effect of critical thickness on water transport behaviors is discussed. Results show that: (a) the flow enhancement is smaller than 1 when the contact angle is smaller than 100° due to energy barrier induced by strong hydrophilicity of the nanopore wall; (b) the flow enhancement becomes infinite when the contact angle is approaching 180°; and (c) the flow enhancement increases with decreasing of critical thickness, especially for hydrophilic nanopores (the contact angle is smaller than 120°) and nanopores with a relatively small diameter (smaller than 50 nm).
Alhasan B. Fuseni, Abdulkareem M. AlSofi, Ali H. AlJulaih
et al.
Abstract The extreme heterogeneity of carbonate reservoirs in the form of fracture corridors and super-permeability thief zones present challenges to the efficient sweep of oil in both secondary and tertiary recovery operations. In such reservoirs, conformance control is crucial to ensure injected water and any EOR chemicals optimally contact the remaining oil with minimal throughput. Foam-based conformance control is a relatively new technology especially its use for deep diversion in high-salinity and high-temperature conditions. In this work, a laboratory study was conducted to develop and evaluate a foam-based conformance control technology for application in a high-salinity and high-temperature carbonate. Foaming agents (surfactants) were first screened for their suitability with regard to reservoir temperature and salinity where properties such as foamability and foam stability were measured. The best performing surfactants were then used to study the foam-induced mobility reduction across a core composite. The experiments were conducted at reservoir conditions. Foam stability and decay were also investigated in those permeability reduction experiments. Brine and crude oil were injected after foam formation where observed pressure drops allowed quantification of foam stability and decay; hence, the sustainability of mobility reduction. Finally, the potential improvement in reservoir contact and hence oil recovery were examined by oil displacement experiments conducted in specially prepared heterogeneous composites. For the studied conditions of high salinity and high temperature, foaming agents of the amphoteric family as well as one manufacturer proprietary surfactants blend were found suitable in terms of salt tolerance and foam stability. Using the proprietary blend and without oil in core, the generated foam reduced fluids mobility by a factor of 12. The attained mobility reduction was lower in presence of oil but was still acceptable for flow diversion purposes. Using the proprietary blend and with oil in core, the generated foam reduced fluids mobility by a factor of 6 (compared to 12 without oil in core). Oil recovery improvement with foam placement was also found to be significant. These results demonstrate the potential of foams for carbonates with harsh salinity and temperature conditions.
Majkić-Dursun Brankica, Vulić Predrag, Dimkić Milan
The formation of incrustations on public water supply well screens reduces
their performance considerably. The incrustations increase hydraulic losses,
reduce the capacity of the well and screen, affect the quality of the pumped
water and increase maintenance costs. In alluvial environments, the most
common deposits are iron and manganese hydroxides. However, the rates of
formation, compositions and levels of crystallization vary, depending on the
geochemical characteristics of the alluvial environment, the microbiological
characteristics of the groundwater and the abstraction method. Samples of 15
incrustations were collected from wells that tap shallow alluvial aquifers
and were found to be dominated by iron. XRD analyses detected low-crystalline
ferrihydrite and manganese hydroxide in the samples collected from the water
supply source at Trnovče (Velika Morava alluvial). The incrustations from the
Belgrade Groundwater Source revealed the presence of ferrihydrite and a
substantial amount of goethite α-FeOOH. Apart from goethite, greigite (Fe3S4)
was detected in three samples, while one sample additionally contained
bernalite Fe(OH)3 and monoclinic sulfur S8. Among carbonates, only siderite
was detected. Iron oxidizing bacteria generally catalyze deposition processes
in wells, while sulfate reducing bacteria (SRB) play a role in the biogenic
formation of greigite. Determining the nature of the deposited material
allows better selection of rehabilitation chemicals and procedure. [Projekat
Ministarstva nauke Republike Srbije, br. TR37014]
Félix Escolano, Alberto Mazariegos de la Serna, José María del Campo Yagüe
Relief formations characteristic of karstification processes affecting the Miocene gypsum formations existing in south-eastern Madrid have been discovered in that area of the city. These relief formations can pose significant risks to future urban development plans.
The purpose of this article is to present an integrated model created from a geomorphological analysis of south-eastern Madrid through aerial photographs, geophysical inspections (microgravimetry) and geotechnical studies (in situ drilling and testing), in order to identify and measure the morphologies associated with karstic processes whose locations, dimensions and geotechnical characteristics are prone to causing damages that could pose a potential risk. The risk analysis is based on a study of the risk factors, focusing on vulnerability and the measurement of structural mitigation measures capable of preventing the damages that could be caused by the interaction between structural foundations and the morphological consequences of karstic processes on the soil.
Ocena tveganj povezanih z zakrasevanjem miocenske sadre v jugovzhodnem Madridu (Španija)
V jugovzhodnem Madridu je veliko reliefnih oblik, ki kažejo na zakrasevanje miocenske sadre. To predstavlja tveganje, ki ga moramo upoštevati pri urbanističnem načrtovanju. V članku predstavljamo celovit pristop, ki temelji na geomorfoloških analizah aeroposnetkov, mikrogravimetričnih in geotehničnih raziskavah, s katerim smo zaznali in izmerili morfološke značilnosti, ki so povezane z aktivnim zakrasevanjem sadre. Analiza tveganj temelji na študiji dejavnikov tveganja in se osredotoča na ranljivost in oceno uspešnosti strukturnih ukrepov za blažitev vpliva zakrasevanja v prsti na strukturne temelje.
Francisco Javier Gracia, Francesco Geremia, Sandro Privitera
et al.
The Vendicari coastal lake system (SE Sicily) presents several geomorphic characteristics, which suggest it was originated as a part of a 6 km long karst polje during the Late Pleistocene sea level lowstand. Exhumed cryptokarst karren and terraced concentric surfaces point to this working hypothesis. The generation of this depression could have been favoured by the low to moderate neotectonic activity in the zone, which consisted in slight uplifting and subsequent fracturing. Open joints in the Vendicari Pleistocene carbonates show a radial outline with the prevalence of NNW-SSE discontinuities. Once formed, polje evolution would have consisted in a progressive compartmentalisation and splitting into several polje bottoms, some of which form a part of the present Vendicari lake system and are surrounded by stepped corrosion surfaces. The postglacial sea level rise had drowned most part of the original polje, which can be still recognized in the inner continental shelf. Sea level stabilization after the Holocene eustatic maximum favoured the development of a beach barrier, which generated additional coastal lakes of lagoonal type.