Magnetic properties of polycrystalline Er6MnTe2 compound of hexagonal structure (Fe2P-type, non-centrosymmetric space group P-62m, no. 189, hP9) has been studied using dc magnetization measurements and powder neutron diffraction. The compound Er6MnTe2 orders ferromagnetically at 76 K (TC) and undergoes another transition at ∼10 K (Tm) within the ordered state. Magnetization shows a tendency to saturate at 2 K in fields of 70 kOe to 9.8 μB/Er3+. In the neutron diffraction data, commensurate magnetic reflections are present in the temperature range of 68 K to 48 K indicating collinear ferromagnetic ordering of Er sublattice with propagation vector (k0 = [0, 0, 0]). A non-collinear ferromagnetic ordering with moments in ab-plane is observed from about 38 K to 8 K. At TC, the moments at two Er sites (3f and 3g) are different whereas below Tm (i.e., at 8 K), both Er moments approach value of about 9 μB.
Abstract Late Mesozoic granitoids are widely distributed throughout the East Qinling‐Tongbai‐Dabie orogenic belt and its periphery, while large‐scale gold deposits during the same period were primarily found in the Xiaoqinling‐Xiong'ershan area, west of the Tongbai orogen. The deep dynamic mechanisms behind this phenomenon are still poorly understood. In this study, we conducted a comprehensive analysis of geochronology, petrology, geochemistry and Sr‐Nd‐Hf isotopes on the late Mesozoic Yuhuangding (YHD) and Zhulindian (ZLD) plutons in the Tongbai orogen. Zircon U‐Pb dating yields intrusion ages of ca. 140, 131, and 132 Ma for the YHD and ZLD monzogranites and mafic microgranular enclaves within the ZLD pluton, respectively. Both the monzogranites exhibit adakitic affinities with a thickened lower crust origin. Meanwhile, the Sr‐Nd‐Hf isotopic composition of the YHD monzogranites indicates an affinity with the northern Qingling (N‐QL) crust, whereas the younger ZLD monzogranite shows a distinct linkage to the southern North China Craton (S‐NCC) basement. Such isotopic dichotomy suggests that the Tongbai orogenic belt exhibits a “crocodile‐mouth” crust architecture, characterized by the northward subduction of the N‐QL crust and the southward wedged S‐NCC crust. Research data on granitoids throughout the East Qinling‐Tongbai‐Dabie orogenic belt, including their geochemical and isotopic variations, along with the seismic velocity profiles, indicate that the East Qinling‐Tongbai‐Dabie orogenic belt underwent lower crustal delamination and thinning during the early Cretaceous, which resulted in the formation of the observable high‐velocity zone (HVZ) within the upper mantle. The discontinuities of the HVZ suggest that the intense extensional environment following delamination probably created lithospheric weak zones along the west of Nanyang Basin, which in turn facilitated the contribution of mantle‐derived materials and heat, promoting the formation of granitoids and gold mineralization. These processes may be triggered by subduction and/or roll‐back of the Paleo‐Pacific plate.
Abstract The 17.44 Ma Walgidee Hills lamproite in the West Kimberley province of Western Australia is the type locality for several K-, Ba- and Ti-rich minerals characteristic of lamproites and, at 490 ha, the largest known lamproite. The Walgidee Hills pipe comprises a thin sequence of tuffs and breccia formed by explosive eruptions that excavated a large shallow crater that was infilled by lamproite magma which cooled and crystallised in situ. The lamproite is zoned in grain size, mineralogy, and mineral and rock composition from porphyritic olivine lamproite at the margin through medium-grained lamproite comprised of olivine (altered), titanian phlogopite, diopside, leucite (altered) and titanian potassic richterite to coarse gained lamproite rich in potassic richterite, priderite, jeppeite, perovskite, apatite, wadeite and noonkanbahite at the centre of the body. Compositional zoning is evident across the lamproite in phlogopite (to lower Mg and Al, higher Fe), potassic richterite (to higher Fe and Na, lower Ti), priderite (to lower Cr) and perovskite (to lower Cr and Fe, higher Na, Sr, Y, Nb, U, REE). The Walgidee Hills lamproite is ultrapotassic and ranges from olivine lamproite (up to ~21 wt % MgO, ~800 μg/g Ni, ~4 wt % K2O) to sanidine/leucite-rich lamproite (~7 wt % MgO, ≤100 μg/g Ni, ~8 wt % K2O) at the centre of the pipe. The lamproite has low Al2O3, total Fe, Na2O and CaO (except for intensely carbonate-veined rocks at the centre) and is highly enriched in TiO2 (3–6.5 wt %), Ba, Rb, Sr, Zr and LREE (LaN = 150–520 x primitive mantle). A transect and geochemical contours show MgO, Ni and Cr contents decrease and P, K, Ti, Fe, Rb, Sr, Y, Zr, Nb, REE, Hf, Pb, Th and U abundances increase inwards to the most evolved rocks at the centre of the pipe, consistent with fractionation by inwards in situ crystallisation. The parent magma is estimated from the composition of the porphyritic olivine lamproite at the margins of the pipe to have ~16 ± 1 wt % MgO, ~600 μg/g Ni, ~6 wt % K2O with La/Yb ~ 150. Modelling suggests that the most MgO-rich lamproites result from entrainment of ~15–20 wt % mantle olivine in the parent magma. Cooling of the magma resulted in fractional crystallisation of olivine and in situ crystallisation with the evolved coarse-grained lamproites at the centre of the pipe crystallised from residual magma enriched in the more incompatible elements. Mantle xenocrysts include abundant Cr–Al spinel, chrome diopside, chrome pyrope, and rare diamond. Thermobarometry on the Cr diopside xenocrysts defines a cold paleogeotherm of ~38 mW/m2 and a thick lithosphere (~235 km) extending from the Kimberley craton. Many of the Cr diopsides from the deeper lithospheric mantle are enriched in K, Ba and LREE and these, and the Ti-rich spinel xenocrysts, are inferred to be derived from metasomatised mantle peridotite. The enriched trace element and Sr–Nd–Pb isotopic signatures of the Walgidee Hills lamproite suggest derivation from or extensive incorporation of ancient formerly depleted lithospheric mantle that has undergone metasomatism and long term (≥2 Ga) geochemical enrichment including by melts from Paleoproterozoic subducted crust.
Abstract Lost circulation and mud losses cause 10 to 20% of the cost of drilling operations under extreme pressure and temperature conditions. Therefore, this research introduces an integrated system for an automated lost circulation severity classification and mitigation system (ALCSCMS). This proposed system allows decision makers to reliability predict lost circulation severity (LCS) based on a few drilling drivers before starting drilling operations. The proposed system developed and compared a total of 11 ensemble machine learning (EML) based on collection 65,377 observations, the data was pre-processed, cleaned, and normalized to be filtered using factor analysis. For each generated algorithm, the proposed system performed Bayesian optimization to acquire the best possible results. As a result, the optimized random forests (RF) model algorithm was the optimal model for classification at 100% classification accuracy based on testing data set. Mitigation optimization model based on genetic algorithm has been incorporated to convert high severe classes into acceptable classes of lost circulation. The system classifies the LCS into 5 classes where the classes from 2 to 4 are converted to be class 0 or 1 to minimize lost circulation severity by optimizing the input parameters. Therefore, the proposed model is reliable to predict and mitigate lost circulation during drilling operations. The main drivers that served as LCS inputs were explained using the SHapley Additive exPlanations (SHAP) approach.
Aliyu Adebayo Sulaimon, Sarah Abidemi Akintola, Mohd Adam Bin Mohd Johari
et al.
Abstract The use of carboxymethyl cellulose (CMC) in oil and gas well drilling operations has improved the filtration loss and mud cake properties of drilling muds. The introduction of starch has also reduced, for example, the viscosity, fluid loss, and mud cake properties of the drilling fluids. However, normal starch has some drawbacks such as low shear stress resistance, thermal decomposition, high retrogradation, and syneresis. Hence, starch modification, achieved through acetylation and carboxymethylation, has been introduced to overcome these limitations. In this study, modified starches, from cassava and maize, were used to enhance the properties of water-based muds under high-pressure high temperature (HPHT) conditions, and their performances were compared with that of the CMC. The mud samples added with acetylated cassava or maize starch exhibited the smallest filtrate volumes and filtrate losses within the American Petroleum Institute specification. Therefore, these modified starch-added muds could replace CMC as fluid loss agents since, unlike it, they can withstand HPHT conditions.
Abstract Rivers State as the nomenclature depicts is a state richly blessed with both surface and subsurface water. As a result of this, there is less problem of water scarcity, especially in the elite cities of the state, but so many other communities due to one reason or the other still wallow in abject water scarcity. In this survey, a total of seven (7) vertical electric soundings were carried out using Schlumberger configuration at Obibi community in Omuma local government area, Rivers State, to ascertain the location and depths to aquifer. ABEM terrameter SAS 300 was used in the survey with electrode spacing AB/2 of 150 m, thus probing to a depth of about 200 m. Geoelectric software (IPI2WIN) was utilized in the plotting, iteration and interpretation of the resistivity data obtained. From the quantitative interpretation and the lithology of the areas, five different subsurface layers were delineated with their geoelectric curve given as AK, AKQ and AKH. Aquifer in these areas is highly prolific and mostly located at an average depth of 52 m.
Babak Moradi, Mohammed Ayoub, Mahmood Bataee
et al.
Abstract Injection wells have long been an essential asset in enhanced oil recovery, wastewater disposal and carbon dioxide sequestration in petroleum industries. The temperature profile of fluid flow in the injection well is one of the main parameters of interest for petroleum engineers to determine optimum injection conditions and wellbore completion design especially in thermal injection projects and deep wells. In this study, the calculation involved in determining the temperature profile along the depth of wellbore has been revised to be newer and more robust via solving governing wellbore equations. The wellbore is segmented into discrete counterparts for it to be solved simultaneously in terms of mass, momentum and energy balance via wellbore governing equations. Five injection cases from the literatures, incompressible and compressible fluid flows, were used to confirm that the procedure is reproducible in terms of its behaviour, which is similar to field data. The new results acquired from the new procedure are in good agreement with field data collected with a maximum absolute error less than 3 °C.
ISME meetings have been organized regularly since 1977, and in 1986 the 4th ISME was hosted by Ljubljana. The 17th ISME was in Leipzig, Germany, where 2250 delegates from 60 countries met. During the symposium eight plenary lectures, 26 different sections and three days of poster presentations were organized. A participant could choose one of six or seven simultaneously running sections daily which covered an extremely wide set of microbial ecology from evolution, modeling of microbial interactions, review on new and existing metabolic pathways, (meta)genomics, interactions between microbes and hosts, biogeochemical cycles, bioinformatics, new methods and innovative bioremediation procedures. It became clearly evident that microbial ecology can offer some answers to many urgent global issues. Some interesting highlights from the symposium are given below.
Tuan-Feng Zhang, Peter Tilke, Emilien Dupont
et al.
Abstract This paper proposes a novel approach for generating 3-dimensional complex geological facies models based on deep generative models. It can reproduce a wide range of conceptual geological models while possessing the flexibility necessary to honor constraints such as well data. Compared with existing geostatistics-based modeling methods, our approach produces realistic subsurface facies architecture in 3D using a state-of-the-art deep learning method called generative adversarial networks (GANs). GANs couple a generator with a discriminator, and each uses a deep convolutional neural network. The networks are trained in an adversarial manner until the generator can create “fake” images that the discriminator cannot distinguish from “real” images. We extend the original GAN approach to 3D geological modeling at the reservoir scale. The GANs are trained using a library of 3D facies models. Once the GANs have been trained, they can generate a variety of geologically realistic facies models constrained by well data interpretations. This geomodelling approach using GANs has been tested on models of both complex fluvial depositional systems and carbonate reservoirs that exhibit progradational and aggradational trends. The results demonstrate that this deep learning-driven modeling approach can capture more realistic facies architectures and associations than existing geostatistical modeling methods, which often fail to reproduce heterogeneous nonstationary sedimentary facies with apparent depositional trend.
Magnesium and lithium stable isotope ratios (δ26Mg and δ7Li) have shown promise as tools to elucidate biogeochemical processes both at catchment scales and in deciphering global climate processes. Nevertheless, the controls on riverine Mg and Li isotope ratios are often difficult to determine as a myriad of factors can cause fractionation from bulk rock values such as secondary mineral formation and preferential weathering of isotopically distinct mineral phases. Quantifying the relative contribution from carbonate and silicate minerals to the dissolved load of glacierized catchments is particularly crucial for determining the role of chemical weathering in modulating the carbon cycle over glacial-interglacial periods. In this study we report Mg and Li isotope data for water, river sediment, rock, and mineral separates from the Leverett Glacier catchment, West Greenland. We assess whether the silicate mineral contributions to the dissolved load, previously determined using radiogenic Sr, Ca, Nd, and Hf isotopes, are consistent with dissolved Mg and Li isotope data, or whether a carbonate contribution is required as inferred previously for this region. For δ7Li, the average dissolved river water value (+19.2 ± 2.5‰, 2SD) was higher than bedrock, river sediment, and mineral δ7Li values, implying a fractionation process. For δ26Mg, the average dissolved river water value (−0.30 ± 0.14‰, 2SD) was within error of bedrock and river sediment and within the range of mineral δ26Mg values (−1.63 to +0.06‰). The river δ26Mg values are consistent with the mixing of Mg derived from the same mineral phases previously identified from radiogenic isotope measurements as controlling the dissolved load chemistry. Glacier fed rivers previously measured in this region had δ26Mg values ~0.80‰ lower than those measured in the Leverett River which could be caused by a larger contribution from garnet (−1.63‰) dissolution compared to Leverett. This study highlights that dissolved Mg and Li isotope ratios in the Leverett River are affected by different processes (mixing and fractionation), and that since variations in silicate mineral δ26Mg values exist, preferential weathering of individual silicate minerals should be considered in addition to carbonate when interpreting dissolved δ26Mg values.
Hossein Ghalenavi, Saeid Norouzi-Apourvari, Mahin Schaffie
et al.
Abstract In reservoir simulation, the fluid composition is usually assumed uniform for the whole reservoir, while in many reservoirs, oil and gas composition changes with depth. This phenomenon which is known as compositional grading could be significant in heavy and super heavy oil reservoirs. In these reservoirs, biodegradation and asphaltene precipitation are considered as the main reasons behind this phenomenon. Compositional grading in heavy oil reservoirs could affect fluid viscosity and vaporizing–condensing mechanism in steam-assisted gravity drainage (SAGD) operations. In this paper, through a simulation study, one of the Iranian heavy oil reservoirs which have a significant compositional grading was selected to investigate the effect of compositional grading on the performance of simulated SAGD method. The reservoir is a fractured carbonate reservoir, and its compositional grading is maintained because of the lack of convection inside the reservoir. To verify the importance of compositional grading, the performance results of the SAGD method for compositional grading case were compared with that of uniform composition case. The result showed that ignoring compositional grading would lead to underestimation of ultimate recovery in the fractured model. The study of SAGD process in a non-fractured reservoir model showed that considering compositional grading has an insignificant effect on SAGD performance.