Fluid Formation Research Articles

Tourmaline chemical composition and boron isotopic composition at the Longmenshan pegmatite in Dahongliutan area, West Kunlun: Implication for rare-metal Li-Be mineralization

Tourmaline is a common mineral in rocks. It can record geological information during its formation and is a geochemical tracer. Its in-situ element and boron isotope tests provide a broader application perspective. Therefore, the chemical and boron isotope characteristics of tourmaline can be used to trace the mineralization of pegmatite-type rare metals. West Kunlun is an important Li-Be metallogenic belt, and many important Li-Be deposits have been developed. Longmenshan is one of the recently discovered pegmatite-type Li-Be deposits in the Dahongliutan area. There are barren and spodumene-bearing pegmatites that all contain tourmaline in Longmenshan. According to their occurrence, crystal form, and chemical composition, the tourmalines in Longmenshan are divided into two types: Tur-I tourmaline in the barren pegmatite close to the granite and Tur-II tourmaline from the spodumene-bearing pegmatite. Compositionally belongs to the alkali group and schorl-dravite solid solution series, with Tur-I being mainly schorl and Tur-II being schorl-dravite. Tur-I tourmalines are rich in Li, Sn, V, Cr, Zn, and Mn, while Tur-II tourmalines are rich in Be, Sr, and Sc. The δ11B of the Tur-I tourmalines hosted in the barren pegmatite and Tur-II from the spodumene-bearing pegmatite ranges from −8.38‰ to −6.81‰ and from −10.00‰ to −6.41‰, respectively. These characteristics indicate that the formation fluid of tourmaline in Longmenshan is mainly derived from magma, and other fluids are rarely involved. The large range of B isotope variation indicates that the Tur-II tourmalines are more obviously affected by fluid activity.

Prediction of Phase Equilibrium Conditions and Thermodynamic Stability of CO2-CH4 Gas Hydrate

With the large-scale promotion and application of CO2 flooding, more and more engineering problems have emerged. Due to the high CO2 mole fraction, the associated gas of CO2 flooding very easily forms solid hydrates, compared to conventional natural gas. This has resulted in production decline or shutdown. Understanding the phase equilibrium conditions for hydrate formation in production fluids is crucial for hydrate prevention and control. In this study, accurate predictions of CO2-CH4 mixed gas hydrate formation conditions were performed using theoretical models. The temperature and pressure ranges for hydrate formation were calculated for different CO2 mole fraction, ranging from −11.5 °C to 20.85 °C and from 0.81 MPa to −28.1 MPa, respectively. Based on the calculated phase equilibrium data, a multi-parameter empirical model was developed using polynomial fitting. The calculation errors for the multi-parameter empirical model were 3.09%. The multi-parameter empirical model established in this study can avoid complex thermodynamic equilibrium calculations and has the advantages of simplicity, high accuracy, and wide coverage of downhole conditions. Based on the calculated phase equilibrium data, the dissociation enthalpy of CO2-CH4 hydrate below and above the freezing point of water was calculated. The results showed that an increase in CO2 mole fraction led to an increase in hydrate dissociation enthalpy and enhanced thermodynamic stability, making hydrate prevention more challenging. Our work can contribute to the optimization of CO2 production fluid treatment processes and the development of hydrate prevention and control technologies.

Geochemistry of high temperature initial geothermal fluids in the Dabie orogenic belt

Analyzing the genesis and resource potential of orogenic geothermal systems poses significant challenges due to their complex geological backgrounds and evolutionary histories. This paper presents a novel synthesis of hydrogeochemical and isotope geochemical data, coupled with geological and geophysical results, to comprehensively understand the origins of deep, high-temperature orogenic geothermal systems. This understanding is achieved through the utilization of advanced geochemical modeling techniques to analyze the geochemical attributes of initial geothermal fluids. The hydrochemical and H/O/S isotopic composition of a total of 67 geothermal and non-geothermal water samples from the Dabie orogenic belt (DOB) were analyzed. Integrated multicomponent geothermometry (IMG) was employed to reconstruct the characteristics of the initial geothermal fluids, and PHREEQC inverse simulations creatively determined the most likely pathways of their genesis and evolution. The findings indicate that all geothermal waters from the three major geothermal fields of Luotian, Yingshan, and Yuexi are alkali-sulfate type waters. The initial geothermal fluids are acidic sulfate type with reservoir temperatures of 156–222 °C, 115–179 °C, and 100–189 °C, respectively. The primary processes responsible for the formation of these initial geothermal fluids are the dissolution of anhydrite from sulfide oxidation and, to a lesser extent, direct sulfide oxidation. Generally, the formation of geothermal systems in the investigated geothermal fields is associated with the extensional collapse and lithospheric thinning of the Dabie orogen since the Early Cretaceous Period. The spatial distribution of the three geothermal fields in this study corresponds to the tectonic-magmatic framework of magmatic intrusion-induced domes (Luotian and Yuexi) in the DOB. The reactivation of the Tan-Lu Fault during the Cenozoic Era suggests the presence of a deep heat source comprising magmatic and metamorphic components. This heat source, combined with the infiltration of paleo-atmospheric and modern atmospheric precipitation water along regional fault systems, results in the formation and gradual dilution of initial geothermal fluids. Neutralization occurs through interactions with calcite and fine-grained sodium aluminosilicates, ultimately leading to the formation of the collected geothermal water. The conceptual model established in this study elucidates the distinctive genesis and formation mechanism of the orogenic geothermal system exemplified by the DOB.

Mathematical model of the dependence between cerebral ventricular size and capillary pressure in laboratory animals

Aim: To adapt a mathematical model describing the interaction between fluid media and brain matter for the purpose of definition of the dependence between brain ventricle size and capillary pressure in laboratory animals of two genotypes, BALB/c and C57BL/6. Material and methods. The study included 4 male mice of each inbred strain C57BL/6 and BALB/c at the age of 12 weeks. The brain and cerebrospinal fluid system images were obtained using an 11.7 T horizontal MR scanner (Bruker, BioSpec 117/16 USR, Germany). An axial section at the level of -0.5 mm from bregma was chosen as the geometry for mathematical modelling. To describe the data obtained, the mathematical model was adapted by selecting a scale factor based on the known values of the cerebrospinal fluid formation rate for humans and mice. Results and discussion. The same qualitative pattern of relationship between capillary pressure and mean ventricular wall displacement was observed for all animals considered. Although the selected genetic strains of BALB/c and C57Bl mice differ significantly in terms of cerebral ventricle size, these differences in animal genotype did not affect the nature of this relationship. Changing the parameters of the fluid media interaction in the area of compression or moderate ventricular dilation almost does not lead to an exit from the physiologically acceptable capillary pressure value. In this case, the size of the ventricles changes significantly. In the area of large ventricular dilation, in contrast, there is little change in ventricular size, and this is accompanied by a dramatic increase in capillary pressure far beyond physiologic limits. Thus, the change in ventricular size is an adaptive process associated with pressure fluctuations caused by changes in intracranial fluid flow. The mere fact that some of the values reach the zone of physiologically unacceptable pressures associated, in fact, with death, provided that there is practically no change in ventricular size indicates that such a situation is rarely realized and is possible in case of violation of intracranial fluid media flows associated with the fact that the increase in ventricular size limits adaptive capabilities. Conclusions. The presented animal model will further increase the understanding of the pattern we have established and allow us to move on to attempts at prediction.

Shaping epithelial lumina under pressure.

The formation of fluid- or gas-filled lumina surrounded by epithelial cells pervades development and disease. We review the balance between lumen pressure and mechanical forces from the surrounding cells that governs lumen formation. We illustrate the mechanical side of this balance in several examples of increasing complexity, and discuss how recent work is beginning to elucidate how nonlinear and active mechanics and anisotropic biomechanical structures must conspire to overcome the isotropy of pressure to form complex, non-spherical lumina.

Direct measurement of hydrate equilibrium temperature in CO2 and CO2 rich fluids with low water content

A high-pressure experimental setup was used to obtain experimental data on the hydrate equilibrium (melting) temperature (HET) of hydrates formed from low water content CO2 and CO2 rich mixtures. A novel method was used to measure hydrate formation temperature in addition to melting temperature directly at realistic temperature/pressure conditions encountered in transport by pipelines or ship. The method can be used to evaluate the likelihood of hydrate formation in pipelines/ships transporting pure CO2 and CO2 coming from capture processes as well as from high CO2 content produced gas. The data generated from the measurement can also be used to investigate the kinetics of hydrate formation and dissociation in low water content fluids at pipeline/ship conditions. This paper details the experimental equipment, methods, test fluids and results. Experimental results are compared against predictions of the simplified cubic plus association equation of state (sCPA-EoS) coupled with the van der Waals and Platteeuw solid solution theory.

Effect of eccentricity on electromagnetic logging signals with LWD and VEMKZ instruments (numerical simulation results from some publications)

During drilling, formation fluids are pushed aside by mud filtrate. As a result, the electrophysical properties of rocks near the borehole wall change. Sounding methods are used to determine the resistivity of the part of the reservoir that is remote from the well and unchanged during drilling. Among these methods, electromagnetic logging has the best spatial resolution. However, when analyzing the practical data of electromagnetic sounding, "wrong" ratios of signals from probes of different lengths are often observed, including those showing penetration in impermeable rocks. One of the reasons may be the influence of the shift of the device from the axis of symmetry of the medium. The paper considers the results of numerical simulation of signals from decentralized probes of LWD and VEMKZ instruments in some models.

Olivine formation processes and fluid pathways in subducted serpentinites revealed by in-situ oxygen isotope analysis (Zermatt-Saas, Switzerland)

Dehydration of serpentinites plays a crucial role in mass transfer into the Earth's interior by releasing aqueous fluids and forming new minerals. These minerals, such as metamorphic olivine, can serve as tracers of fluid-related processes. High-pressure (HP) antigorite, metamorphic olivine, and coexisting magnetite in serpentinites from a continuous, km-scale outcrop within the Zermatt-Saas HP ophiolite were analyzed in situ for trace elements and oxygen isotopes to identify differences in the initial serpentinization conditions and to investigate fluid pathways during subduction-related metamorphism. The oxygen isotopic composition, and As and Sb concentrations in antigorite reveal two distinct serpentinization conditions within the studied region: i) high As and Sb (1–25 μg/g and 0.5–5 μg/g, respectively), coupled with δ18O of +6 to +7 ‰, suggesting serpentinization at relatively low temperatures near the seafloor, and ii) low As and Sb (0.03–5 μg/g and ≤ 0.1 μg/g, respectively), coupled with mostly lower δ18O of +4 to +6 ‰, suggesting serpentinization at higher temperatures by interaction with fluids deeper below the seafloor.Olivine produced in situ by the brucite + antigorite dehydration reaction during subduction shows isotopic equilibrium with antigorite, and coexisting magnetite with ∆18OAtg-Ol of +1.5–2.5 ‰ and ∆18OOl-Mt of ∼+3 ‰ at reaction temperature conditions of 550–600 °C. The obtained isotopic signatures of metamorphic olivine with δ18O values of +1 to +2 ‰ and + 4 to +5 ‰ correspond to two different isotopic compositions of the released fluid of +5 to +6 ‰ and + 8 to +9 ‰ at these temperature conditions. This suggests that fluids released from subducted serpentinites may have variable δ18O under forearc conditions. The presence of fluids with variable δ18O can cause olivine in structures associated with fluid flow (e.g., shear bands, shear zones and veins) to be in isotopic equilibrium with magnetite, but in either isotopic equilibrium or disequilibrium with antigorite. Isotopic equilibrium with antigorite is achieved when the fluid responsible for olivine crystallization is internally derived. Isotopic disequilibrium is due to an externally derived fluid released by dehydration of serpentinite with a different isotopic composition than the serpentinite with which the fluid interacts. The restricted occurrence of non-equilibrated olivine only in shear bands and nearly pure Ol-veins indicates channelized fluid flow in subduction zone settings and demonstrates that isotopic disequilibrium can be used as a tracer for fluid infiltration.

Dynamic Simulation Platform Aids Deep Transient Tests, Well-Control Safety

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215454, “Enhancing Well-Control Safety With Dynamic Well-Control Cloud Solutions: Case Studies of Successful Deep Transient Tests in Southeast Asia,” by M. Ashraf Abu Talib, SPE, M. Shahril Ahmad Kassim, and Izral Izarruddin Marzuki, SPE, Petronas, et al. The paper has not been peer reviewed. _ The complete paper addresses challenges related to well control and highlights the successful implementation of deep transient tests (DTT) in an offshore well performed with the help of a dynamic well-control simulation platform. The paper aims to provide insights into the prejob simulation process, which ensured a safer operation from a well-control perspective. Additionally, a comparison between simulated and actual sensor measurements during the DTT operation is presented. DTT DTT is a formation-testing (FT) method that allows pressure transient tests that reach deeper into the formation compared with conventional interval pressure transient tests (IPTT). DTT enables the testing of formations with higher permeability, greater thickness, and lower viscosity and real-time measurement of crucial parameters. During a DTT, formation fluid is pumped from the reservoir; upon stopping the pump, the formation pressure begins to recover as fluid further from the wellbore replaces the extracted fluid. By analyzing the resulting pressure transient, properties such as formation permeability, permeability anisotropy, and other characteristics can be determined. DTT allows for a better understanding of reservoir characteristics and rock heterogeneity. When properly designed and executed, DTT can reveal potential baffles and boundaries within the radius of investigation. A further advantage of DTT over drillstem tests (DST) is its minimal fluid flow, which allows for the attainment of objectives while contributing to the United Nations sustainable development goals. In DTT operations, the FT tool is connected to the drillpipe through a circulating sub and a slip joint. The circulating sub plays a critical role in DTT operations because it enables the continuous mixing of pumped formation fluid with circulated mud and facilitates its transportation to the surface (Fig. 1). Typically, a constant circulation rate ranging from 100 to 250 gal/min is maintained. During circulation, the annular preventer is closed and the mud/hydrocarbon mixture is directed through the choke line to the mud/gas separator (MGS) once it reaches the surface. No formation fluids are flared during DTT operations. Instead, the circulated oil is retained in the mud and only small amounts of gas are vented. By use of a slip joint, the FT remains anchored to the borehole wall. A high-resolution pressure gauge is used to capture and interpret even minor pressure fluctuations during the pressure transient buildup.

Wellbore pressure model for drilling fluid in ultra-deep rock salt formations at high temperatures and pressures

The Kuqa Mountain front area of Tarim is rich in oil and gas resources, but the development of ultra-deep rock salt formation is common, leading to a narrow safety density window and significant impacts on engineering operation safety and wellbore quality, such as overflow and leakage. Managed pressure drilling (MPD) is an effective solution to the problem of drilling in narrow density windows, and a precise wellbore pressure calculation method is essential to ensure the reasonable determination of MPD parameters. Conventional wellbore pressure models treat fluid properties as constant and do not consider the impact of ultra-deep rock salt formation on wellbore pressure calculation, leading to incomplete calculation accuracy that cannot fully meet engineering requirements. In this paper, an improved wellbore temperature field model coupled with the rock salt formation is established. Additionally, rheological experiments on drilling fluids used in the field are conducted and a prediction model for shear stress and density is established based on the varying degrees of temperature and pressure influences. Based on the temperature field of the wellbore and the rheological experimental, a wellbore pressure prediction model is established, and field application is conducted in Keshen Well X. By comparing the measured values, the overall error does not exceed 5%. Compared with neighboring blocks, the rate of penetration has been increased by 73.8%, and the drilling efficiency has been significantly improved. The use of wellbore pressure calculation method, which is studied in this paper, has facilitated efficient operations in drilling ultra-deep rock salt formation.

Controls on Mineral Formation in High pH Fluids From the Lost City Hydrothermal Field

AbstractAlthough the serpentinite‐hosted Lost City hydrothermal field (LCHF) was discovered more than 20 years ago, it remains unclear whether and how the presence of microbes affects the mineralogy and textures of the hydrothermal chimney structures. Most chimneys have flow textures comprised of mineral walls bounding paleo‐channels, which are preserved in inactive vent structures to a varying degree. Brucite lines the internal part of these channels, while aragonite dominates the exterior. Calcite is also present locally, mostly associated with brucite. Based on a combination of microscopic and geochemical analyses, we interpret brucite, calcite, and aragonite as primary minerals that precipitate abiotically from mixing seawater and hydrothermal fluids. We also observed local brucite precipitation on microbial filaments and, in some cases, microbial filaments may affect the growth direction of brucite crystals. Brucite is more fluorescent than carbonate minerals, possibly indicating the presence of organic compounds. Our results point to brucite as an important substrate for microbial life in alkaline hydrothermal systems.

Bacteria Living in Biofilms in Fluids: Could Chemical Antibiofilm Pretreatment of Culture Represent a Paradigm Shift in Diagnostics?

Biofilms are multicellular aggregates of bacteria immersed in an extracellular matrix that forms on various surfaces, including biological tissues and artificial surfaces. However, more and more reports point out the fact that even biological fluids and semifluid, such as synovial liquid, blood, urine, or mucus and feces, harbor "non-attached" biofilm aggregates of bacteria, which represent a significant phenomenon with critical clinical implications that remain to be fully investigated. In particular, biofilm aggregates in biological fluid samples have been shown to play a relevant role in bacterial count and in the overall accuracy of microbiological diagnosis. In line with these observations, the introduction in the clinical setting of fluid sample pretreatment with an antibiofilm chemical compound called dithiothreitol (DTT), which is able to dislodge microorganisms from their intercellular matrix without killing them, would effectively improve the microbiological yield and increase the sensitivity of cultural examination, compared to the current microbiological techniques. While other ongoing research continues to unveil the complexity of biofilm formation in biological fluids and its impact on infection pathogenesis and diagnosis, we here hypothesize that the routine use of a chemical antibiofilm pretreatment of fluid and semi-solid samples may lead to a paradigm shift in the microbiological approach to the diagnosis of biofilm-related infections and should be further investigated and eventually implemented in the clinical setting.

Numerical investigation of double emulsion formation in non-Newtonian fluids using double co-flow geometry

This paper uses the Volume of Fluid (VOF) method to simulate a double Co-Flow microfluidic device that can produce double emulsions in both Newtonian (water) and non-Newtonian fluids. The simulation is 2D axisymmetric and involves three phases. A model is evaluated in this study to examine how the size and double emulsion’s generation rate are impacted by factors such as phase velocity, viscosities, interfacial tension, and the rheological properties of non-Newtonian fluids. The model predicted the process of emulsification successfully in dripping and jetting regimes and predicted the impacts of phase velocity on the dimension and frequency of compound droplets. Increasing the flow rate of the inner phase causes the inner droplets to grow, while the outer droplet dimensions remain mostly unchanged. Vice versa, an increase in outer phase flow rate reduces compound droplet size. However, when the middle phase's flow rate is enhanced, the size of detached droplets in the inner and outer phases undergoes opposite changes, i.e., decreasing and increasing, respectively. The results showed that in non-Newtonian fluids, smaller droplets are formed compared to water, and the diameter of the double emulsions formed decreases with the rise in the viscosity at zero shear rate of the non-Newtonian fluid.

Multi-isotopic composition (Li and B isotopes) and hydrochemistry characterization of the Lakko Co Li-rich salt lake in Tibet, China: Origin and hydrological processes

A comprehensive comprehension of the origin and ore-forming process of lithium brine deposits is imperative prior to engaging in lithium resource exploration, development and utilization. Nevertheless, the provenance of lithium in salt lakes has always been controversial. The lithium and boron (Li and B) isotopes, which serve as discerning geochemical tracers, can facilitate the monitoring of geological processes and sources. In this study, we investigated the hydrochemistry, Li and B isotope characteristics of surface brine and recharge river samples collected from the Lakko Co on the Qinghai-Tibet Plateau in China. The dissolved Li concentrations range from 0.11 to 590.8 mg/L, δ7Li and δ11B values exhibit a range of 0.75∼8.11 ‰ and -18.29∼-4.01 ‰, respectively. Concentrations of elements such as Rb, and Cu are relatively high and exhibit a strong correlation with Li. Ions composition and content ratios indicate the deep origin of Li and B. The analysis of δ7Li and δ11B suggests that, apart from hot spring, weathering of surrounding rocks also contributes to the presence of Li and B. Besides, variations in δ11B values within the lake brine analysis may be attributed to the deposition of water Magnesite at the lake bottom. The findings suggest that the recharge water system and hot springs serve as the primary source of Li and B in Lakko Co. Additionally, the interaction between water and rock in the deep crust as well as chemical weathering in the shallow environment, significantly contribute to formation of Li-rich fluids. The transportation process is characterized by the precipitation of secondary mineral, resulting in an increase of δ7Li and δ11B. Furthermore, the presence of water Magnesite in the lake brine leads to fluctuations in δ11B. This investigation of the lake contributes to a more comprehensive understanding of the origins and mechanisms involved in the transportation and storage of lithium in lithium-rich salt lakes.

Experimental Study on Carbon Dioxide Flooding Technology in the Lunnan Oilfield, Tarim Basin

The Lunnan Oilfield in the Tarim Basin is known for its abundant oil and gas resources. However, the marine clastic reservoir in this oilfield poses challenges due to its tightness and difficulty in development using conventional water drive methods. To improve the recovery rate, this study focuses on the application of carbon dioxide flooding after a water drive. Indoor experiments were conducted on the formation fluids of the Lunnan Oil Formation, specifically investigating gas injection expansion, thin tube, long core displacement, oil and gas phase permeability, and solubility. By injecting carbon dioxide under the current formation pressure, the study explores the impact of varying amounts of carbon dioxide on crude oil extraction capacity, high-pressure physical parameters of crude oil, and phase characteristics of formation fluids. Additionally, the maximum dissolution capacity of carbon dioxide in formation water is analyzed under different formation temperatures and pressures. The research findings indicate that the crude oil extracted from the Lunnan Oilfield exhibits specific characteristics such as low viscosity, low freezing point, low-medium sulfur content, high wax content, and medium colloid asphaltene. The measured density of carbon dioxide under the conditions of the oil group is 0.74 g/cm3, which closely matches the density of crude oil. Additionally, the viscosity of carbon dioxide is 0.0681 mPa·s, making it well-suited for carbon dioxide flooding. With an increase in the amount of injected carbon dioxide, the saturation pressure and gas-oil ratio of the crude oil also increase. As the pressure rises, carbon dioxide dissolves rapidly into the crude oil, resulting in a gradual increase in the gas-oil ratio, expansion coefficient, and saturation pressure. As the displacement pressure decreases, the degree of carbon dioxide displacement initially decreases slowly, followed by a rapid decrease. Moreover, an increase in the injection rate of carbon dioxide pore volume leads to a rapid initial improvement in oil-displacement efficiency, followed by a slower increase. Simultaneously, the gas-oil ratio exhibits a slow increase initially, followed by a rapid rise. Furthermore, as the displacement pressure increases, the solubility of carbon dioxide in water demonstrates a linear increase. These research findings provide valuable theoretical data to support the use of carbon dioxide flooding techniques for enhancing oil recovery.

Reaction path model of the formation of abiotic immiscible hydrocarbon fluids in subducted carbonated serpentinites, Lanzo Massif (Western Italian Alps)

Fluids generated from subducted slabs participate in the cycling of deep carbon in the crust and upper mantle. In these fluids, aqueous carbon species vary in oxidation state between +IV and -IV depending on whether the fluids are oxidizing or reducing, respectively. Most studies of subduction-zone fluids have focused on oxidized carbon species. However, recent studies of natural samples have demonstrated the occurrence of deep, reducing fluids, generated in both subducted oceanic upper mantle and crustal rocks. CH4-H2-rich fluid inclusions in subducted carbonated serpentinites have demonstrated the existence of abiotic, immiscible, hydrocarbon fluids at upper mantle conditions. To investigate the formation of such immiscible hydrocarbon fluids during the evolution of subducted carbonated serpentinites, we used equilibrium constants from the Deep Earth Water model to carry out predictive chemical mass transfer modeling to simulate the alteration reactions. A novel feature of the models was the inclusion of an immiscible hydrocarbon fluid containing six components (CH4,f,C2H6,f,C3H8,f,isoC4H10,f,CO2,f,H2,f). This feature enabled prediction of the formation of a separate immiscible fluid in equilibrium with aqueous species and minerals.We developed a predictive reaction path model of invasive H2,f reacting with carbonated serpentinites and interstitial aqueous fluids for comparison with the natural samples from the Lanzo Massif, western Italian Alps. Over a range of temperatures and pressures, immiscible hydrocarbon fluids formed in association with altered mineral assemblages. Reaction progress caused the transformation of carbonated serpentinites and the formation of clinopyroxene, brucite, graphite, and hydrocarbon fluids, along with changes of pH, logfO2, and aqueous species. CH4,f was the most abundant hydrocarbon species in all the models. The overall results at 2.0 GPa and 400 to 450 °C were consistent with the natural samples from the Lanzo Massif. Interestingly, large amounts of H2O formed due to oxidation of H2. More hydrocarbons and H2O formed in models with lower fluid/rock mass ratios or with more reactant H2. Models at different pressure and temperature conditions showed similar results with some variation in the relative stabilities of aragonite, graphite and olivine solid solution, and associated differences in mineral sequences, hydrocarbon fluids, values of aqueous species, and the final logfO2 and pH. Our models strongly support the laboratory and field evidence that reduction of carbonated serpentinites by infiltrating H2 fluids can cause the formation of immiscible, abiotic hydrocarbon fluids in subduction zones.

Research and application of low oil-water ratio organoclay-free oil-based drilling fluid technology

This paper introduces the formation and application of a low oil-water ratio organoclay-free oil-based drilling fluid. Shale oil and gas are important alternative energy sources. Due to the extremely complex geological conditions, oil-based drilling fluid technology is commonly used to reduce complexity. Although some achievements have been made, there are still problems such as unstable wellbore, difficult rheological control, and high cost. A stable and low-viscosity water-in-oil emulsion system was successfully prepared by using optimized fatty acid imidazolines emulsifier and alkyl alcohol ether wetting agent, which enabled the oil-based drilling fluid to have a larger solid and water phase capacity. On this basis, a special poly-fatty acid amide rheological modifier was used to assist in the regulation of rheological parameters, resulting in a low-viscosity and high-shear structure of the oil-based drilling fluid. This effectively ensured the efficiency of cuttings carrying while reducing the adverse effects of viscosity on Equivalent Circulating Density(ECD). The low oil-water ratio oil-based drilling fluid technology has been applied in a shale gas drilling platform in southern Sichuan, China, which greatly reduces the cost of oil-based drilling fluid while ensuring drilling efficiency.

Jetting and droplet formation of particle-loaded fluids

Inkjet printing is an attractive method for patterning and fabricating objects across many areas of industry. There is a growing interest in the printing of inks with high particle-loading, such as inks containing glass frit, ceramic and functional inks. However, the use of these inks is often limited due to uncertainty regarding the impact of their rheology on the printing process. Understanding of the role of complex rheology in the jetting of loaded inks is therefore needed to facilitate the wider application of inkjet printing. Here, we characterize the complex rheology and the jetting of model dispersion inks (containing 10, 15, and 23 vol. % TiO2 nanoparticles) and compared them with those without particles. The jetting of the model fluids was conducted with a commercial inkjet printhead (nozzle diameter 34 μm) and visualized with stroboscopic and ultra-high-speed imaging. For low particle concentrations, droplet formation is generally similar to those of unloaded inks, provided their Ohnesorge number and Weber number are matched, although the filament of the loaded model fluid tends to have earlier break-off, having a shorter length. The jetting reliability decreased with increase in particle-loading until reliable jetting can no longer be achieved, due to local particle–particle interactions in the ink channel and in the filament during the fast extensional thinning process. A jetting map is presented which illustrates the influence of particle-loading on the droplet formation, and indicates that the acceptable range of Ohnesorge number for jetting is reduced as the particle-loading is increased.

Investigation of plugging materials for strengthening the bottomhole zone of wells in conditions of aggressive formation fluids

Investigation of plugging materials for strengthening the bottomhole zone of wells in conditions of aggressive formation fluids

Clinical Characteristics of Lung Abscess Caused by Streptococcus Constellatus Infection.

This study aimed to understand the clinical characteristics of pulmonary abscess caused by Streptococcus constellatus infection. The clinical manifestations, laboratory examination, drug sensitivity, chest CT manifestations, and treatment and prognosis of patients with pulmonary abscess caused by Streptococcus constellatus infection were retrospectively collected and analyzed. A total of 9 cases of pulmonary abscess caused by Streptococcus constellatus infection were confirmed; one case was confirmed by traditional cultures, while metagenomic next-generation sequencing (mNGS) confirmed the other 8 cases. All of the 9 patients had different degrees of cough, sputum, fever, chest pain, and/or dyspnea, and the physical examination showed fast breathing, reduced respiratory sound, or moist rales on the affected side. In laboratory tests, 8 patients had elevated white blood cells and hypoproteinemia upon admission. Blood gas analysis showed an oxygenation index < 300. The antimicrobial susceptibility testing results in 1 patient with culture-confirmed pathogen diagnosis showed that Streptococcus constellatus was susceptible to ampicillin, penicillin G, cefotaxime, ceftriaxone, cefepime, meropenem, chloramphenicol, linezolid, levofloxacin, and vancomycin and resistant to tetracycline and clindamycin. Relevant antibiotic resistance genes were not detected by mNGS in the 8 patients with negative culture and positive mNGS results. A chest CT showed lung consolidation or cavity formation in 9 patients admitted to the hospital, and 5 patients had pleural effusion. 3 cases were admitted to the respiratory intensive care unit (RICU) and 6 cases were admitted to the general ward. There were 3 cases of nasal catheter oxygen inhalation, 1 case of mask oxygen inhalation, and 5 cases of non-invasive ventilator assisted ventilation. All patients received penicillin or respiratory quinolones anti-infection therapy, and 3 cases were treated with a thoracic closed drainage tube. All patients were discharged from the hospital after improvement, and the hospital stay was 15 - 23 days. Patients with pulmonary abscess caused by Streptococcus constellatus infection have an urgent condition and rapid progression. It is helpful to use mNGS combined with traditional culture as soon as possible to identify the pathogenic bacteria. Penicillin antibiotics should be the first choice for pulmonary abscess caused by a suspected Streptococcus constellatus infection. If a patient´s condition worsens during the treatment, especially for patients who have lesions involving the interlobar fissure or pleura, compressive atelectasis caused by pleural fluid formation or an increase in the amount of pleural effusion needs to be highly suspected.