Analysis of the Drag Reduction Performance and Rheological Properties of Drag-Reducing Additives.

In the practical application of hydraulic rotating machinery, it is essential to thoroughly explore drag reduction and rheological characteristics of drag-reducing additives to optimize machinery efficiency and reduce equipment consumption. This paper combines simulation and experimental approaches to investigate the drag-reduction performance and rheological properties of drag-reducing additives. Numerical simulations are initially conducted to investigate the shear-thinning properties of drag-reducing fluid and explore variations in drag-reduction rate. Turbulent phenomena characteristics are described by analyzing turbulent statistical quantities. Subsequently, the rheological behaviors of polyethylene oxide (PEO), cetyltrimethyl ammonium chloride (CTAC), and their mixed solutions under different conditions are scrutinized using a rotational rheometer. The findings indicate that the drag reduction effect amplifies as the rheological index n and characteristic time λ decrease. The numerical simulations show a maximum drag reduction rate of 20.18%. In rheological experiments, a three-stage viscosity variation is observed in single drag-reducing additives: shear thickening, shear thinning, and eventual stabilization. Composite drag-reducing additives significantly reduce the apparent viscosity at low shear rates, thereby strengthening the shear resistance of the system.

Molecular Simulation of Surfactant Displacement of Residual Oil in Nanopores: Formation of Water Channels and Electrostatic Interaction.

The water-oil-rock system's surfactant and electrostatic interactions are essential for removing oil droplets from rock substrates. Our work illustrates the impact of surface charge on the oil contact angle in an ideal system comprising silica, water, and dodecane; smaller contact angles are observed for more polar substrates. Modifying the polarity of the model silica surface allows for the observation of the creation of heteromolecule channels and the process of stripping crude oil while accounting for the impacts of water flow and different types of surfactant molecules. In solutions containing ionic surfactants, the injection and diffusion of water molecules between the oil layer and the silica substrate are facilitated by the disturbance of the oil molecules by the surfactant molecules. By comparing different surfactants in water flow, the characterization of water molecular channels and the stripping process of crude oil can be observed. The disruption of oil molecules by the surfactant molecules has been found to enhance the injection and diffusion of water molecules between the oil layer and the silica substrate in solutions containing ionic surfactants. The size of the contact angle and the extension of the water channel are simultaneously greatly influenced by the surfactant's molecular characteristics and the substrate's polarity. These simulation results show that several factors influence the process of water molecule channel creation that water molecules diffuse, and the detachment of oil from the silica substrate is facilitated by the migration of surfactants to the bottom of the oil molecule and the electrostatic interactions between the water molecules and the silica substrate.

Emulsions synergistic-stabilized by a hydroxyl sulfobetaine surfactant and SiO2 nanoparticles and their potential application for enhanced oil recovery.

The emulsions formed by conventional surfactants have poor stability in high temperature and high salinity reservoirs, which limits the fluidity control ability of emulsion flooding systems. Hydroxyl sulfobetaine surfactants have excellent emulsifying properties and can maintain good activity under high temperature and high salinity conditions. In this study, an emulsion synergistic-stabilized by hydroxyl sulfobetaine surfactant LHSB and SiO2 nanoparticles was reported for the first time, and the feasibility of its enhanced oil recovery was investigated. The results show that the stability, temperature and salt resistance of the emulsion were significantly improved after adding nanoparticles, which positively affected the exploitation of harsh reservoirs. The synergistic-stabilized mechanism between LHSB and SiO2 nanoparticles was revealed by the measurements of zeta potential, surface tension and contact angle. Moreover, core flooding experiments reflect the emulsion synergistic-stabilized by LHSB and SiO2 nanoparticles can effectively enhance oil recovery by 11.41%. This study provides an emulsion flooding system with excellent performance for enhanced oil recovery in harsh reservoirs.

Plugging Characteristics and Evaluation Predicting Models by Controllable Self-Aggregation Nanoparticles in Pore Throat Microcapillaries.

Injecting nanoparticle profile agents into low-permeability heterogeneous reservoirs to plugging water breakthrough channels is a widely used technical method to enhance oil recovery. However, insufficient research on the plugging characteristics and prediction models of nanoparticle profile agents in the pore throat has led to a poor profile control effect, short profile control action time, and poor injection performance in the actual reservoir. This study uses controllable self-aggregation nanoparticles with a diameter of 500 nm and different concentrations as profile control agents. Microcapillaries of different diameter sizes were used to simulate the pore throat structure and flow space of oil reservoirs. Based on a large number of cross-physical simulation experimental data, the plugging characteristics of controllable self-aggregation nanoparticles in the pore throat were analyzed. Gray correlation analysis (GRA) and gene expression programming algorithm (GEP) analysis were used to determine the key factors affecting the resistance coefficient and plugging rate of profile control agents. With the help of GeneXproTools, the evolutionary algebra 3000 was selected to obtain the calculation formula and prediction model of the resistance coefficient and plugging rate of the injected nanoparticles in the pore throat. The experimental results show that the controllable self-aggregation nanoparticles will achieve effective plugging when the pressure gradient is greater than 100 MPa/m in the pore throat, and when the injection pressure gradient is 20-100 MPa/m, the nanoparticle solution will be in the aggregation to breakthrough state in the pore throat. The main factors affecting the injectability of nanoparticles, from strong to weak, are as follows: injection speed > pore length > concentration > pore diameter. The main factors affecting the plugging rate of nanoparticles, from strong to weak, are as follows: pore length > injection speed > concentration > pore diameter. The prediction model can effectively predict the injection performance and plugging performance of controllable self-aggregating nanoparticles in the pore throat. The prediction accuracy of the injection resistance coefficient is 0.91, and the accuracy of the plugging rate is 0.93 in the prediction model.

Synthesis and Evaluation of Interfacial Properties and Carbon Capture Capacities of the Imidazolium-Based Ionic Liquid Surfactant.

Ionic liquid as a chemical flooding agent has broad application prospect in enhancing oil recovery. In this study, a bifunctional imidazolium-based ionic liquid surfactant was synthesized, and its surface-active, emulsification capacity, and CO2 capture performance were investigated. The results show that the synthesized ionic liquid surfactant combines the characteristics of reducing interfacial tension, emulsification, and CO2 capture. The IFT values for [C12mim][Br], [C14mim][Br], and [C16mim][Br] could decrease from 32.74 mN/m to 3.17, 0.54, and 0.051 mN/m, respectively, with increasing concentration. In addition, the emulsification index values are 0.597 for [C16mim][Br], 0.48 for [C14mim][Br], and 0.259 for [C12mim][Br]. The surface-active and emulsification capacity of ionic liquid surfactants improved with the increase in alkyl chain length. Furthermore, the absorption capacities reach 0.48 mol CO2 per mol of ionic liquid surfactant at 0.1 MPa and 25 °C. This work provides theoretical support for further CCUS-EOR research and the application of ionic liquid surfactants.

Jiaji (EX-B2)-Based Electroacupuncture Preconditioning Attenuates Early Ischaemia Reperfusion Injury in the Rat Myocardium.

BACKGROUND: Acupuncture preconditioning was able to reduce the extent of ischaemia reperfusion (I/R) injury. Previous studies have shown that electroacupuncture (EA) pretreatment at T4-T5 Jiaji (EX-B2) acupoints had cardioprotective effects against myocardial I/R injury. However, the molecular mechanism remains inconclusive. METHODS: Wistar rats were pretreated with electroacupuncture for 7 days at the Neiguan (PC6), T4-T5 Jiaji (EX-B2), Yanglingquan (GB34), and Quchi (LI11) acupoints, which belong to different meridians. Then, we investigated the genome-wide gene expression profiles of rats prestimulated at these acupoints after I/R injury. RESULTS: Our study revealed previously unknown cardioprotective roles of T4-T5 Jiaji (EX-B2) acupoints in the I/R progression. The extent of myocardial injury was significantly decreased in the Jiaji group compared with the I/R group. In addition, our data are among the first to link the EA preconditioning at Neiguan (PC6) acupoints and circadian rhythm in the I/R model. Also, for the first time, we explored the meridian and acupoint specificity involved in EA pretreatment at the heart meridian, in which Yanglingquan and Quchi acupoints were selected as the control group for heart-divergent-meridian and nonheart-meridian acupoints. CONCLUSIONS: The present study suggested that EA pretreatment at Jiaji alters genome-wide gene expression and protects the rat myocardium against I/R injury, which are most likely through neurohumoral regulation.

Combination of Scalp Acupuncture with Exercise Therapy Effectively Counteracts Ischemic Brain Injury in Rats.

BACKGROUND: Stroke is one of the leading causes of death and disability worldwide. Scalp acupuncture and exercise therapy have been proven as two effective methods for the treatment of stroke. However, their combined action and mechanisms have not been fully elucidated. The present study aimed to investigate the protective effect of scalp acupuncture combined with exercise therapy on neurons in rats with ischemic brain injury. METHODS: 100 rats were randomly divided into 5 groups including sham group, model group, acupuncture group, rehabilitation group, and experimental group (scalp acupuncture combined with exercise therapy). Middle cerebral artery occlusion (MCAO) model in rats was established according to Longa modified suture method to mimic ischemic stroke. The modified Bedexer's neurological function score was used to evaluate the neurological deficits of rats and the brain infarct volume was measured using 2, 3, 5-triphenyl tetrazolium chloride monohydrate (TTC) staining. Moreover, the apoptosis in the hippocampus was detected by western blotting and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The pro-inflammatory cytokines such as interleukin-1 beta (IL-1ß) and tumor necrosis factor-alpha (TNF-α), reactive oxygen species (ROS) and superoxide dismutase (SOD) were determined by corresponding kits. Immunohistochemistry or immunofluorescence was performed to detect the expression of brain-derived neurotrophic factor (BDNF), S100ß and glial fibrillary acidic protein (GFAP) in the hippocampi of rats. RESULTS: The neurological deficit score, the expression levels of apoptotic factors such as cleaved caspase-3 and Bax, and the TUNEL-positive cell rate of the experimental group were significantly lower than those of the acupuncture group and the rehabilitation group. However, apoptosis inhibitor Bcl-2 showed downregulated expression in the MCAO model rats but this trend was reverted by single and combinatorial treatments. In addition, the contents of TNF-α, IL-1ß and ROS in the acupuncture group and the rehabilitation group were significantly lower than those in the model group, but higher than the experimental group. While the opposite results were obtained in SOD activity. Furthermore, compared with the model group, the ratios of BDNF, S100ß, and GFAP-positive cells in the acupuncture, rehabilitation and experimental groups were significantly increased, and the highest ratios were recorded in the experimental group. CONCLUSIONS: This study demonstrated that scalp acupuncture combined with exercise therapy effectively counteracts ischemic brain injury via the downregulation of pro-inflammatory mediators and ROS, the increased production of the antioxidant enzyme SOD, neurotrophic factor BDNF and astrocyte activities.

[Protective effect of acupuncture preconditioning on oxidative stress injury induced by myocardial ischemia-reperfusion injury in rats].

OBJECTIVE: To observe the protective effect of acupuncture preconditioning at "Jiaji" (EX-B 2) on acute myocardial ischemia-reperfusion injury (MIRI) in the rats and explore the mechanism. METHODS: Fifty Wistar rats were randomly divided into a control group, a model group, a Jiaji group, a Neiguan group and a Quchi group, 10 rats in each one. In the Jiaji group, the Neiguan group and the Quchi group, electroacupuncture was given for preconditioning at "Jiaji" T4~T5 (EX-B 2), "Neiguan" (PC 6) and "Quchi" (LI 11) for 7 days before modeling. In the control group and the model group, the regular feeding was given, without any acupuncture. At the end of acupuncture, except the control group, ligating the left anterior descending coronary artery (LAD) was adopted to duplicate MIRI models in the rest groups. Electrocardio-gram (ECG) was monitored and ST-segment shift was analyzed. HE staining method was adopted to observe the morphology of cardiac tissue in the rats of the groups. The transmission electron microscope was used to observe myocardial cell ultrastructure. WST-1 method was used to determine the activity of serum superoxide dismutase (SOD), TBA method was used to determine the content of serum malondialehyde (MDA) and the real-time fluorescent quantitative PCR method to determine the expressions of Nrf 2 in ischemic myocardial tissue and downstream HO-1 gene. RESULTS: Compared with the control group, after LAD ligation, ST-segment was elevated and depressed in ECG apparently after reperfusion in the rest groups (all P<0.05). The ST-segment elevation in the Jiaji group and the Neiguan group was less than that in the model group (both P<0.05). Compared with the model group, SOD activity was increased apparently in the Jiaji group and the Neiguan group (both P<0.05), and MDA content was reduced apparently (both P<0.05). The effects in the Jiaji group were better than those in the Neiguan group (both P<0.05). Pathologically, "Jiajia" (EX-B 2) and "Neiguan" (PC 6) all improved the morphology of cardiac tissue and cell ultrastructure. The effects in the Jiaji group were much more significant and the improvements in the Quchi group were not apparent. Compared with the control group, the expressions of Nrf 2 and HO-1 gene in myocardial tissue were down-regulated in the model group (both P<0.05). Those were up-regulated apparently in the Jiaji group and the Neiguan group as compared with the model group (P<0.05, P<0.01). The up-regulation times of the expressions of Nrf 2 and HO-1 gene in the Jiajia group were the highest in comparison. CONCLUSIONS: Acupuncture preconditioning at "Jiaji" (EX-B 2) has the protective effect on cardiac ischemia and reperfusion damage, which is probably relevant with the up-regulation of Nrf 2-ARE pathway expression, the activation of endogenous anti-oxidative pathway, the improvement of oxygen free radical scavenging capacity and the alleviation of lipid peroxide damage.

[Effect of "Jiaji"(EX-B 2)-electroacupuncture Preconditioning on Expression of Cytochrome P 450 Signaling Pathways in Myocardial Ischemia-reperfusion Rats].

OBJECTIVE: To investigate the effect of "Jiaji"(EX-B 2)-electroacupuncture(EA) preconditioning on the myocardium and expression of cytochrome P 450 signaling pathways of myocardial cells in myocardial ischemia-reperfusion injury(MI/RI) rats. METHODS: Sixty male Wistar rats were randomly divided into sham operation, model, Jiaji, Neiguan(PC 6), Yanglingquan(GB 34) and Quchi(LI 11) groups (n=10 in each group). MI/RI model was established by occlusion of the descen-ding anterior branch of the left coronary artery. EA preconditioning was respectively applied to EX-B 2, PC 6, GB 34 and LI 11 for 30 min, once daily for 7 days. The ECG-ST segment was detected before and after the modeling. The contents of serum creatine kinase-MB(CK-MB) and lactate dehydrogenase(LDH) were detected by ELISA and microplate method separately. The expression levels of myocardial CYP 450 related genes cyp 1 a 1, cyp 2 b 2, cyp 2 c 11, cyp 4 a 2 were detected by Real-time PCR. RESULTS: Thirty minutes after ligation the changes of ECG-ST segment displacement of the Jiaji group and Neiguan group were signifi-cantly lower than that of the model group(P<0.01), and the change was significantly lower in the Neiguan group than in the model group(P<0.01) 30 minutes after reperfusion. Compared with the sham operation group, the activities of serum CK-MB and LDH were significantly increased in the model group(P<0.01). Compared with the model group, the activities of serum CK-MB and LDH were significantly decreased in the Jiaji, Neiguan and Yanglingquan groups (P<0.01). Compared with the Jiaji group, the activity of serum LDH was significantly increased in the Quchi group, while the activities of serum CK-MB were significantly increased in the Quchi and Yanglingquan groups (P<0.05). Compared with the sham operation group, the expression levels of myocardial cyp 1 a 1 and cyp 2 b 2 mRNAs were significantly higher in the model group(P<0.01), while the expression of cyp 2 c 11 mRNA was lower(P<0.01). Compared with the model group, the expression levels of cyp 1 a 1 and cyp 4 a 2 mRNAs were lower in the Jiaji, Neiguan and Yanglingquan groups (P<0.01), while the expressions of cyp 2 b 2 and cyp 2 c 11 mRNAs were higher(P<0.01). Compared with the Jiaji group, the expression of cyp 1 a 1 mRNA was lower in the Neiguan group, while the expression of cyp 2 b 2 mRNA was higher(P<0.05). CONCLUSIONS: EA preconditioning at Jiaji(EX-B 2) can reduce serum myocardial enzymes of myocardial ischemia-reperfusion rats, lower the ST segment of electrocardiogram, up-regulate myocardial CYP 450 epoxygenase cyp 2 b 2 and cyp 2 c 11 mRNAs expression, down-regulate ω-hydroxylase cyp 1 a 1 and cyp 4 a 2 mRNAs expression, thus play a role in myocardial protection.