Fluid Penetration Research Articles

Linezolid does not improve bactericidal activity of rifampin-containing first-line regimens in animal models of TB meningitis

Tuberculous meningitis (TB meningitis) is the most devastating form of tuberculosis (TB) and there is a critical need to optimize treatment. Linezolid is approved for multidrug resistant TB and has shown encouraging results in retrospective TB meningitis studies, with several clinical trials underway assessing its additive effects on high-dose (35 mg/kg/day) or standard-dose (10 mg/kg/day) rifampin-containing regimens. However, the efficacy of adjunctive linezolid to rifampin-containing first-line TB meningitis regimens and the tissue pharmacokinetics (PK) in the central nervous system (CNS) are not known. We therefore conducted cross-species studies in two mammalian (rabbits and mice) models of TB meningitis to test the efficacy of linezolid when added to the first-line TB regimen and measure detailed tissue PK (multicompartmental positron emission tomography [PET] imaging and mass spectrometry). Addition of linezolid did not improve the bactericidal activity of the high-dose rifampin-containing regimen in either animal model. Moreover, the addition of linezolid to standard-dose rifampin in mice also did not improve its efficacy. Linezolid penetration (tissue/plasma) into the CNS was compartmentalized with lower than previously reported brain and cerebrospinal fluid (CSF) penetration, which decreased further two weeks after initiation of treatment. These results provide important data regarding the addition of linezolid for the treatment of TB meningitis.

Tectonic structure and stages of geological development of the Sterlitamak shikhans

The article considers the features of the tectonic structure and geological development of the Lower Permian single mountains – shikhans on the left bank of the Belaya River near the city of Sterlitamak (Republic of Bashkortostan). The analysis of published and archival materials, field research, the study of core material, lithological and structural observations allowed us to get an idea of the tectonics of single mountains (shikhans). The Shikhans are part of a single chain of carbonate massifs composed of reef facies and located submeridionally (from south to north) in the western side of the Pre-Uralian Foredeep. In the area of Sterlitamak four massivеs are brought to the surface of the Earth as part of a single Shikhan block. The tectonic structure of the territory is determined by paleotectonic (the period from 3600 to 23 million years) and neotectonic (23 – 5 million years).years and up to the present) events that are combined into periods and are divided into stages. The formation of reef complexes composing the shikhans was controlled by paleotectonic events of the collision stage of development, which led to the formation of the continental shelf margin with conditions favorable for the formation of reef communities on the border of the Pre-Uralian Foredeep during the Asselian and Sakmarian epochs (for 15 million years). Subsequent geological events – in the Artinskian and Kungur time, in the Late Permian-Early Mesozoic stage and in the Middle Jurassic-Miocene platform stage caused the destruction and leveling of the Early Permian relief, erosion of sediments and their overlap with younger sediments. The tectonic impact of the last Pliocene-Quaternary neo-orogenic stage (5 – 0 million years) is most intensively manifested in the rocks of Shikhans. It is expressed in intense fracturing and fragmentation of rocks, their recrystallization with loss of primary structural and textural features. The neotectonic movements of the blocks of the Earth's crust contributed to the removal to the surface of individual sections of the reef complexes distribution zone. The isolation of reef shikhans was a result of presence of an evaporites оver them, which were easily eroded. The tectonic effect on the carbonate rocks of reef nature contributed to the formation of zones of increased fracturing observed in the rocks of the Sterlitamak shikhans and penetration of oil-containing solutions and fluids, which formed areas of rocks with increased reservoir properties. Leaching and karst zones with residual bitumen are observed on almost all shikhans.

EXTH-56. CSF PENETRATION COMPARISON OF TWO ORAL FORMULATIONS OF APL-101 IN A PRE-CLINICAL NON-HUMAN PRIMATE MODEL

Abstract Vebreltinib (APL-101) is a potent c-Met inhibitor which has shown efficacy in murine pre-clinical models and is under clinical trial evaluation for several cancer types, including adult high-grade glioma. The capsule formulation (APL-101-Cap) was reformulated as a pill (APL-101-Pill) with the expectation of increasing bioavailability. We determined and compared the plasma pharmacokinetics (PK) and cerebrospinal fluid (CSF) penetration of APL-101-Cap and APL-101-Pill in a non-human primate (NHP) model. METHODS: Seven animals, previously developed as serial CSF access models, were utilized across all studies. One NHP was studied with both formulations. Both formulations were administered orally as a single drug/single dose in serial studies, followed by serial plasma and CSF sample collections from 0-96 hours. Dosages: APL-101-Cap 3.25 mg/kg (n = 3) or 6.5 mg/kg (n = 4) and APL-101-Pill 5 mg/kg (n = 4). The resulting plasma concentrations from each formulation were quantified by LC-MS/MS. PK parameters were calculated via noncompartmental methods, and results were analyzed to assess CNS penetration (AUCCSF:AUCPlasma) and compare formulations. RESULTS: Mean (range) for plasma and CSF PK exposure [AUCLAST (hr*ng/mL)] reported. APL-101-Cap plasma exposure, regardless of dose, was more variable than APL-101-Pill. APL-101-Pill had lower exposure in both plasma (AUC 1893.0 (841-2865)] and CSF [AUC 27.7 (5.0-65.0)] than APL-101-Cap regardless of dose [(3.25 mg/kg): plasma AUC 9621.0 (1331-23132) and CSF AUC 688.0 (24-1352); 6.5 mg/kg: plasma AUC 6208.0 (1424-19800) and CSF AUC 606.0 (34-1179)]. CNS penetrance was higher with APL-101-Cap (3.2% [0.5-5.8%] at 3.25mg/kg; 4.2% (2.4-6%) at 6.5 mg/kg), but also more variable when compared to APL-101-Pill (1.2% [0.6-2.3%]). For APL-101-Cap, one animal at 3.25 mg/kg and two animals at 6.25 mg/kg had undetectable CSF concentrations. CONCLUSION: In this NHP model, single-dose oral administration of APL-101-Pill resulted in lower, but less variable plasma and CSF exposure compared to APL-101-Cap. APL-101-Cap CSF exposure was unaffected by dose escalation.

Poromechanical modeling of fluid penetration in chemo-responsive gels: Parameter optimization and applications

As an important category of smart materials, stimuli-responsive hydrogels are highly concerned due to their extensive application possibilities and their outstanding biocompatibilities. The ability of responsive hydrogels about significant volume change by external stimuli inspires the design of electronic devices, for example, as sensors and actuators. The modeling of the hydrogel behavior enables the optimization of corresponding applications. In the present research, on the basis of the experimentally determined material parameters, a chemo-poromechanical model was implemented in COMSOL Multiphysics® to investigate the constricted swelling of hydrogels. The swelling kinetics affected by the diffusion coefficient is discussed in detail with numerical simulations.

Angiogenesis, hemocompatibility and bactericidal effect of bioactive natural polymer-based bilayer adhesive skin substitute for infected burned wound healing.

Thermal wounds are complex and lethal with irregular shapes, risk of infection, slow healing, and large surface area. The mortality rate in patients with infected burns is twice that of non-infected burns. Developing multifunctional skin substitutes to augment the healing rate of infected burns is vital. Herein, we 3D printed a hydrogel scaffold comprising carboxymethyl chitosan (CMCs) and oxidized alginate grafted catechol (O-AlgCat) on a hydrophobic electrospun layer, forming a bilayer skin substitute (BSS). The functional layer (FL) was fabricated by physiochemical crosslinking to ensure favorable biodegradability. The gallium-containing hydrophobic electrospun layer or backing layer (BL) could mimic the epidermis of skin, avoiding fluid penetration and offering antibacterial activity. 3D printed FL contains catechol, gallium, and biologically active platelet rich fibrin (PRF) to adhere to both tissue and BL, show antibacterial activity, encourage angiogenesis, cell growth, and migration. The fabricated bioactive BSS exhibited noticeable adhesive properties (P≤0.05), significant antibacterial activity (P≤0.05), faster clot formation, and the potential to promote proliferation (P≤0.05) and migration (P≤0.05) of L929cells. Furthermore, the angiogenesis was significantly higher (P≤0.05) when evaluated in vivo and in ovo. The BSS-covered wounds healed faster due to low inflammation and high collagen density. Based on the obtained results, the fabricated bioactive BSS could be an effective treatment for infected burn wounds.

Effectiveness of three auxiliary irrigation methods for cleaning the internal walls of root canals of curved isolated teeth.

This study aimed to compare the effectiveness of ultrasound and acoustic and laser cleaning of curved root canals. A total of 92 molars with independent root canals with a curvature of 20°-40° were prepared and standardized at 04 25# and stained with gentian violet solution for 72 h. Among them, 52 were randomly divi-ded into four groups for final rinsing (n=13): NI group, PUI group, EDDY group, and PIPS group. Ten samples in each group were cut horizontally along the long axis perpendicular to the root and divided into curved upper, curved, and apical segments. Images were taken with a stereomicroscope and Image J measurements were taken to calculate the depth of rinse penetration. The remaining three samples from each group were split along the long axis of the dentin, photographed by scanning electron microscope to record the dentin tubule exposure and staining layer, and scored for staining layer by double-blind method. SPSS 26.0 software was used to perform statistical analysis and select the best flushing method. An extra 40 samples were randomly divided into four groups for detection of flushing fluid penetration depth (n=10): 10, 20, 30, and 40 s. In the upper part, the mean depth of infiltration was not significantly different between the experimental and control groups (P>0.05). The PIPS group had a significantly lower smear layer score than the control group and the EDDY group (P<0.01). In the curved segment, the mean depth of infiltration was significantly greater in the PUI group than in the control group (P<0.05); the tarnish layer score was lower in each experimental group than in the control group. At the top, the mean depth of infiltration was greater in the PUI and PIPS groups than in the control group (P<0.05), and the smear layer score was lower in the PIPS group than in the other groups (P<0.05). After the time was changed, the depth of infiltration of PUI increased only in the apical segment as the flushing time increased. The PUI and PIPS methods facilitate the penetration of irrigation solution into the dentin canal in curved root canals, especially in the apical segment. The PIPS technique is effective in removing the smear layer in curved root canals.

Rice husk ash as a sustainable and economical alternative to chemical additives for enhanced rheology in drilling fluids.

Performance evaluation of drilling fluids is essential for a successful drilling project, as they not only remove drill cuttings but also prevent undesired penetration or outflow of formation fluids by sealing off wellbore walls. However, concerns have been raised about the use of chemical additives in drilling fluids due to their toxicity and non-biodegradability. To this end, agricultural waste materials are recognized as a promising alternative as they are cost-effective, environmentally sustainable, and can be used as a substitute for lost circulation materials. Rice husk ash (RHA) has become popular as an additive due to its renewable characteristics, including its large surface area, silica content, and microporous structure. This research article explores the rheological properties of drilling fluid with RHA as a filter control medium. The results showed that increasing concentrations of RHA in the drilling mud significantly improved its rheology, particularly at higher concentrations (15 and 20 wt.%). The addition of RHA modified the filtration and rheological properties of the drilling mud, resulting in improved plastic viscosity, yield point, density, gel strength, and thixotropy. However, filter loss and mud cake thickness increased at elevated RHA concentrations. Furthermore, the pH test revealed that the mud's properties shifted toward the acidic region as the RHA concentration increased. The results indicate that RHA could be used as a sustainable and cost-effective alternative to conventional chemical additives with a positive environmental impact. This study may also provide valuable insights into the use of RHA in water-based bentonite mud and could serve as a guide for future research in the drilling industry.

Temperature-sensitive and amphiphilic silica nanoparticle-stabilized Pickering emulsion for water shutoff

Due to the shale matrix's low permeability and narrow pore throats, conventional Pickering emulsion plugging agents are unable to effectively seal the formation, making it challenging to create a reliable mud cake that prevents fluid penetration. To address this issue, SiO2 nanoparticles (PEG200-SiO2-OTES) with amphiphilic and temperature-sensitive properties were synthesized for this study. These modified particles were used to prepare temperature-sensitive Pickering emulsions. The aim was to use the emulsion as a carrier to transport the nanoparticles to the specified stratum to release and seal the pore throat. This temperature-sensitive smart Pickering emulsion-based plugging agent (POOP) is used to water shutoff. The produced material had a particle size of around 20 nm, according to structural studies, and had a sensitive temperature response (response temperature of 80 °C). Furthermore, laboratory tests and characterizations revealed that the average diameter of the POOP emulsion droplets was measured to be 1.62 µm, with the emulsion exhibiting a response temperature for breakage at approximately 80 °C.The plugging agent could release PEG200-SiO2-OTES particles at the response temperature of the formation. At this temperature, the plugging agent particles undergo a transition from hydrophilic to hydrophobic, effectively sealing the low permeability (100 mD) and high permeability (1000 mD) formations with sealing efficiencies of up to 83.56% and 75.07% respectively.

A review of theories to calculate pore pressures when fluids penetrate into rocks

Quantifying the pore pressures that build up inside of the rock matrices when fluids are injected inside of them is very important. In fact, the effective stresses that a rock is subject to either decrease or increase, when a fluid is filling or is being drained out of the rock matrix, respectively, due to the simple fact the fluid pore pressure vary. Several theories have been developed to better understand the pore pressure distributions in the Earth layers. Thus, this review will allow the reader to have a better understanding of the evolution of those theories, in a single manuscript, rather than in multiple documents which, in turn, is time consuming and not user friendly. Important also to separate this review paper into two parts, depending on the study the reader needs to make when fluids are considered: (1) quantification of fracturing pressures and (2) quantification of the pore pressures due to the fluid penetration.

Recovery of heavy crude oil with electrical enhanced oil recovery using lignin nanoparticles: A review

This research work addresses the problem of extraction of heavy oil efficiently with the simultaneous use of Electrical EOR (enhanced oil recovery) and environment friendly nanofluids. The economic extraction of heavy crude oil remains a major concern to resolve as it is extremely viscous and difficult to flow, making standard extraction techniques inefficient, it is attainable by reduction of oil viscosity through implementation of EOR techniques. Electrical EOR processes utilize electrical resistance heating, microwave heating, and electromagnetic induction heating. The traditional thermal methods experience substantial heat loss to the surrounding formation in thin pay zones and through the wellbore in deep wells. This results in either early fluid injection breakthrough in high permeability zones or challenges in fluid penetration into the formations in low permeability zones and reservoir heterogeneity which makes the process less efficient. By using electrical approaches in enhanced recovery methods, these difficulties can be overcome because they are all based on the emission of specific waves to raise the temperature of the reservoir, handle difficulties of reservoir heterogeneity and heat losses in thin formations. Therefore, electrical EOR is being developed as a more advanced and efficient approach than conventional EOR methods. Additionally, nanomaterials (or nanofluids) can be used with these electrical approaches, as an effective medium to ease the heavy oil extraction, as they alter rock wettability, reduce fluid viscosity, increase thermal conductivity, and change interfacial tension, further changing the molecular interaction between the different interfaces. However, the preparation of nanomaterial for EOR poses environmental concerns. So, the objective of this review is to assess the increased efficiency of the Electrical EOR by using abundantly present eco-friendly nanoparticles such as organic polymer Lignin. This work proposes to use lignin-based nanoparticles for the first time as the best ecofriendly nanoparticle to extract heavy oil efficiently using Electrical EOR.

Effect of printing strategies on the properties of product in selective Sorel cement activation

PurposeParticles bed binding by selective cement activation (SCA) method is a computer-aided manufacturing (CAM) technique used to produce cementitious elements. A computer-aided design file is sliced to generate G-codes before printing. This paper aims to study the effect of key input parameters for slicer software on the final properties of printed products.Design/methodology/approachThe one factor at a time (OFAT) methodology is used to investigate the impact of selected parameters on the final properties of printed specimens, and the causes for the variations in outcomes of each variable are discussed.FindingsFiner aggregates can generate a more compact layer, resulting in a denser product with higher strength. Fluid pressure is directly determined by voxel rate (rV); however, high pressures enable better fluid penetration control for fortified products; for extreme rVs, residual voids in the interfaces between successive layers and single-line primitives impair mechanical strength. It was understood that printhead movement along the orientation of the parts in the powder bed improved the mechanical properties.Originality/valueThe design of experiment (DOE) method assesses the influence of process parameters on various input printing variables at the same time. As the resources are limited, a fractional factorial plan is carried out on a subset of a full factorial design; hence, providing physical interpretation behind changes in each factor is difficult. OFAT aids in analyzing the effect of a change in one factor on output while all other parameters are kept constant. The results assist engineers in properly considering the influence of variable variations for future DOE designs.

Intracranial Efficacy of Adagrasib in Patients From the KRYSTAL-1 Trial With KRASG12C-Mutated Non-Small-Cell Lung Cancer Who Have Untreated CNS Metastases.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Patients with Kirsten rat sarcoma viral oncogene homolog (KRAS)-mutated non-small-cell lung cancer (NSCLC) and untreated CNS metastases have a worse prognosis than similar patients without KRAS mutations. Adagrasib has previously demonstrated CNS penetration preclinically and cerebral spinal fluid penetration clinically. We evaluated adagrasib in patients with KRASG12C-mutated NSCLC and untreated CNS metastases from the KRYSTAL-1 trial (ClinicalTrials.gov identifier: NCT03785249; phase Ib cohort), in which adagrasib 600 mg was administered orally, twice daily. Study outcomes included the safety and clinical activity (intracranial [IC] and systemic) by blinded independent central review. Twenty-five patients with KRASG12C-mutated NSCLC and untreated CNS metastases were enrolled and evaluated (median follow-up, 13.7 months); 19 patients were radiographically evaluable for IC activity. Safety was consistent with previous reports of adagrasib, with grade 3 treatment-related adverse events (TRAEs) in 10 patients (40%) and one grade 4 (4%) and no grade 5 TRAEs. The most common CNS-specific TRAEs included dysgeusia (24%) and dizziness (20%). Adagrasib demonstrated an IC objective response rate of 42%, disease control rate of 90%, progression-free survival of 5.4 months, and median overall survival of 11.4 months. Adagrasib is the first KRASG12C inhibitor to prospectively demonstrate IC activity in patients with KRASG12C-mutated NSCLC and untreated CNS metastases, supporting further investigation in this population.

Phase II trial of lazertinib in patients with epidermal growth factor receptor (EGFR) mutation-positive (M+), metastatic non-small cell lung cancer (NSCLC) with asymptomatic or mild symptomatic brain metastases after failure of EGFR tyrosine kinase inhibitor (TKI) (KCSG LU20-15).

9054 Background: Central nervous system (CNS) metastases occur not infrequently, ultimately devastating consequences in advanced EGFR M+ NSCLC. Lazertinib, a 3rd-generation (G) EGFR-TKI, has shown potent antitumor activity in EGFR-mutant NSCLC. We conducted a phase II single-arm study of lazertinib in EGFR M+ NSCLC patients (pts) having CNS metastases to evaluate its CNS activity. Methods: The patients exhibiting CNS progression upon 1st or 2nd-G EGFR-TKIs with least one measurable CNS lesion were enrolled. The primary endpoint was intracranial objective response rate (iORR) in evaluable for response set (ERS). Secondary endpoints included iORR without T790M mutation, overall ORR (oORR), disease control rate (DCR), intracranial progression-free survival (iPFS) in ERS. Overall survival (OS) and safety analyses were performed in pts who received at least one dose of lazertinib. Cerebrospinal fluid (CSF) penetration was measured as exploratory biomarker study. Results: Of 40 pts enrolled, 38 were evaluable for tumor response. Nineteen pts harbored exon 19 deletion and 21 pts for exon 21 L858R and 30% of pts had radiologic evidence of leptomeningeal carcinomatosis (LM) with 2 cytological confirmed cases. Forty-five percent of pts received afatinib as first line treatment, followed by 42.5% of gefitinib and 12.5% of erlotinib. Baseline plasma samples of all the 40 patients obtained for liquid-based next-generation sequencing (Guardant360) and T790M was found in 5 pts prior to lazertinib treatment. iORR was 57.9% (22/38). iORR with T790M-negative, oORR, and DCR were 54.5%, 39.5%, and 97.4%, respectively. With median follow-up of 13.6 months, median iPFS and OS were not reached. Treatment-related adverse events (TRAEs) emerged in 85.0% of pts with most common TRAEs being skin rash (50.0%) and paresthesia (42.5%). Grade 3 or 4 TRAEs were reported in 10.0%. The CSF penetration rates of lazertinib and its metabolite (YH26334) were 46.2% and 33.1%, respectively in paired CSF and plasma samples, suggesting high CNS penetration efficacy. Conclusions: Lazertinib has substantial CNS activity regardless of T790M status against the progression of intracranial metastases ± LM during the treatment of 1st or 2nd-G EGFR-TKIs in metastatic EGFR M+ NSCLC pts. These results suggest that using lazertinib instead of brain local treatment would be a potential strategy in EGFR M+ NSCLC, who progressed on CNS metastases after prior EGFR-TKI. Clinical trial information: NCT05326425 . [Table: see text]

An experimental investigation of the fluid accessibility of preconditioned sulphide copper ores

Copper is crucial for a transition to a low-carbon economy and for energy-efficient technologies. In nature, can be mostly found in minerals as combination with iron and sulphide and its conversion into pure copper metal is frequently produced through comminution and concentration techniques. The use of hydrometallurgical methods has been successfully applied in the treatment of oxides and secondary sulphides, but its industrial applicability to primary ores has been very limited. The “accessibility” of the minerals is a key factor for their recovery through leaching, with surface grains being the most easily leached. This paper presents results from controlled blasting tests to investigate the effect of stress-induced damage on fluid penetration into copper ore samples. The results show that preconditioning by energetic loading can extend the Fluid Penetration depth by an average of 1.09 mm and up to 7 mm, compared to the 0.56 mm average of samples without conditioning. The experiments demonstrate that stress-induced fractures create extended fluid pathways, increasing the number of grains that can be potentially dissolved, and the presence of statistical outliers in the analysis shows that these induced microfractures can have a significant impact on fluid accessibility.

Thermoporoelastic response of a semi‐permeable wellbore subjected to convective cooling and non‐hydrostatic in situ stresses

AbstractExisting models of wellbore stability idealize the borehole wall as either a perfectly permeable or an entirely impermeable surface. The widespread observation that a shale borehole allows solvent molecules to pass through but impedes solutes suggests that the borehole wall should be regarded as a non‐ideal semi‐permeable medium. To address the magnitude and rate of fluid penetration into the formation when a semi‐permeable wellbore is exposed to a non‐isothermal drilling fluid quantitatively, this work develops analytical solutions for a semi‐permeable borehole undergoing convective cooling and far‐field non‐hydrostatic in situ stresses in the framework of fully coupled thermoporoelasticity. Integral transform and load decomposition techniques are employed to facilitate the derivation of analytical solutions. The results show that, in contrast to the permeable or impermeable borehole models, the semi‐permeable model predicts significantly different stress and pore pressure fields. The transient evolution of temperature, pore pressure, and stresses is predominantly governed by two non‐dimensional numbers: the Biot number Bi and a newly identified number πf that characterizes the capability of shale to transport fluid across the solid‐fluid interface.

Cerebrospinal fluid penetration of fosfomycin in patients with ventriculitis: an observational study

BackgroundFor treatment of ventriculitis, vancomycin and meropenem are frequently used as empiric treatment but cerebrospinal fluid (CSF) penetration is highly variable and may result in subtherapeutic concentrations. Fosfomycin has been suggested for combination antibiotic therapy, but data are sparse, so far. Therefore, we studied CSF penetration of fosfomycin in ventriculitis.MethodsAdult patients receiving a continuous infusion of fosfomycin (1 g/h) for the treatment of ventriculitis were included. Routine therapeutic drug monitoring (TDM) of fosfomycin in serum and CSF was performed with subsequent dose adaptions. Demographic and routine laboratory data including serum and CSF concentrations for fosfomycin were collected. Antibiotic CSF penetration ratio as well as basic pharmacokinetic parameters were investigated.ResultsSeventeen patients with 43 CSF/serum pairs were included. Median fosfomycin serum concentration was 200 [159–289] mg/L and the CSF concentration 99 [66–144] mg/L. Considering only the first measurements in each patient before a possible dose adaption, serum and CSF concentrations were 209 [163–438] mg/L and 104 [65–269] mg/L. Median CSF penetration was 46 [36–59]% resulting in 98% of CSF levels above the susceptibility breakpoint of 32 mg/L.ConclusionPenetration of fosfomycin into the CSF is high, reliably leading to appropriate concentrations for the treatment of gram positive and negative bacteria. Moreover, continuous administration of fosfomycin appears to be a reasonable approach for antibiotic combination therapy in patients suffering from ventriculitis. Further studies are needed to evaluate the impact on outcome parameters.

Study on Mechanism and Verification of Columnar Penetration Grouting of Time-Varying Newtonian Fluids

Penetration grouting technology is an important technical means to improve the mechanical properties of gravel soil layers, and the time-varying characteristics of Newtonian fluid viscosity have an important influence on the morphology and effect of penetration grouting. However, these time-varying properties are not considered in the current research on the mechanism of Newtonian fluid penetration grouting. In this paper, by studying the basic rheological equation of Newtonian fluids and its dynamic viscosity time-varying law, the penetration motion equation of viscosity time-varying Newtonian fluids is discussed, by means of theoretical analysis and experimental research. Based on this, the time-varying viscosity Newtonian fluid columnar penetration grouting diffusion mechanism (TVNCPGDM) equation is derived, the application scope of the equation is analyzed and a grouting experiment is designed to verify it. The results show that the theoretical value of the grouting diffusion radius calculated by the TVNCPGDM equation, is closer to the experimental value than that obtained by the equation of columnar penetration grouting without considering the viscosity time-varying Newtonian fluid, with a 12.9% improvement in accuracy. This shows that the TVNCPGDM equation derived in this paper, can better reflect the diffusion law and diffusion morphology of column penetration grouting of Newtonian fluid, which changes with time in the injected medium; and the diffusion radius obtained for penetration grouting is more in line with the actual grouting engineering demands. The research results can provide some theoretical guidance for the actual grouting of loose gravel soil layers.

High stability polymer gel for lost circulation control when drilling in fractured oil and gas formations

When drilling in fractured oil and gas formations, drilling fluid loss is prevalent, and polymer gels are commonly utilized as lost circulation materials to plug fractures in loss zones. A high stability polymer gel was synthesized in this study employing acrylamide as the polymerizable monomer, a self-synthesized microsphere containing active ethylene groups as the cross-linker, laponite as both a flow pattern regulator and a physical filler, and ammonium persulfate as the initiator. This polymer gel's complex network structure considerably adds to its mechanical and thermal resilience, and its best gelation time is 12 h at 248°. Rheological properties of the gel were studied under various conditions. When the experimental temperature is 284°, the Na+ concentration is 100,000 ppm, or the Ca2+ concentration is 1000 ppm, the G′ and G″ of the polymer gel exceeded 1000 Pa and 200 Pa, suggesting that this gel has good thermal and salt stability. Contamination resistance studies reveal that the polymer gel has adequate contamination resistance for drilling fluid and formation water penetration, with G′ and G″ exceeding 1500 Pa and 400 Pa when the volume ratio of external fluids to gellant is 6:4. Furthermore, the density of the polymer gel may be adjusted to 2.0 g/cm3 by employing barite as a weighting agent, and the addition of the barite contributed to improving the structural stability of the gel due to the filling effect in the gel's network structure. Using fractured steel cores and a visible fracture model, the dynamic filling and plugging capabilities of this polymer gel in fractures were measured. When compared to frequently used polymer gellants, the high stability polymer gellant entirely fills the fracture area and exhibits a little gravity differentiation effect in large-scale fracture. After gel formation, it exhibits outstanding plugging capability for various fracture scales at 248°. Three successful field tests in the Tarim Basin, Xinjiang, China, demonstrated that the high stability polymer gel may be used to control lost circulation in fractured formations at high temperatures.

Flow Field Simulation and Measurement in Packed Beds Based on 4D‐X‐Ray Computed Tomography

AbstractX‐ray computed tomography (XCT) combined with computational fluid dynamics (CFD) simulations have proved to be a powerful and versatile tool to describe fluids flow through packed bed systems. In this contribution, two examples of the application of XCT experiments to track the fluid flow and fluid penetration in packed bed systems are shown. The first one shows how geometrical information extracted from XCT measurements can be coupled to CFD simulations to assess fluid flows reliably. Here the example of a packed bed of three‐dimensional (3D) printed cylindrical‐shaped particles is considered. Finally, a short case study on the monitoring of the progress of the water penetration front in a packed bed composed of glass spheres using four‐dimensional (4D) XCT imaging data is presented.

Time-Dependent Effect of Seepage Force on Initiation of Hydraulic Fracture around a Vertical Wellbore

Fluid penetration into the rock during hydraulic fracturing has been an essential issue in studying the mechanism of fracture initiation, especially the seepage force caused by fluid penetration, which has an important effect on the fracture initiation mechanism around a wellbore. However, in previous studies, the effect of seepage force under unsteady seepage on the fracture initiation mechanism was not considered. In this study, a new seepage model that can predict the variations of pore pressure and seepage force with time around a vertical wellbore for hydraulic fracturing was established by using the method of separation of variables and the Bessel function theory. Then, based on the proposed seepage model, a new circumferential stress calculation model considering the time-dependent effect of seepage force was established. The accuracy and applicability of the seepage model and the mechanical model were verified by comparison with numerical, analytical and experimental results. The time-dependent effect of seepage force on fracture initiation under unsteady seepage was analyzed and discussed. The results show that when the wellbore pressure is constant, the circumferential stress induced by seepage force increases over time, and the possibility of fracture initiation also increases. The higher the hydraulic conductivity, the lower the fluid viscosity and the shorter the time required for tensile failure during hydraulic fracturing. In particular, when the tensile strength of rock is lower, the fracture initiation may occur within the rock mass rather than on the wellbore wall. This study is promising to provide a theoretical basis and practical guidance for further research on fracture initiation in the future.