First pass effect (FPE), defined as single-pass complete or near-complete reperfusion during endovascular thrombectomy for large artery occlusion (LAO) strokes, is a significant performance metric, which is increasingly utilized to determine the success of mechanical thrombectomy (MT). To evaluate the value of the innovatively proposed combined angiographic technique (CAT) for predicting FPE in anterior circulation stroke patients with LAO. We retrospectively reviewed our prospectively collected data for anterior circulation LAO patients treated with MT between January 2019 and December 2022. FPE was defined as single pass of the device, near-complete/complete reperfusion of the LAO and its downstream territory (mTICI 2c/3) after MT, and no use of rescue therapy. The cohort was categorized into the FPE and non-FPE groups. Angiography is performed with an intermediate catheter and micro-catheter, which we refer to as the CAT, to determine the location and length of the thrombus body during the procedure. The sensitivity, specificity, and positive and negative predictive values of the CAT in predicting FPE were assessed. A total of 217 patients with anterior circulation occlusion were included in the final analysis. Among them, combined angiographic technique was conducted in 94 (43.3%) patients. Patients with FPE used the CAT prior to MT at a higher rate than those without FPE (69.2% vs 11.3%, P < .001). The sensitivity, specificity, positive predictive value, and negative predictive value of the CAT in predicting FPE were 69.2%, 88.6%, 88.3%, and 69.9%, respectively. Our study showed that the CAT is technically safe and easily applied in clinical practice, which may be helpful for neuro-interventionists to select the appropriate thrombectomy strategy and optimal material combination during the procedure. Further prospective multicenter studies need to validate this safe and efficient technique in a large patient cohort.

In this study, a two-dimensional pipeline small leak detection based on time series imaging is introduced. First, the sampling points and data of pipeline signals are converted into polar diameters and polar angles in polar coordinate system to form vectors, and then the inner product between vectors is mapped to 2-dimensional pixels through the use of Gram angular field (GAF). The resulting image preserves both the temporal and spatial features of the original signal. Wavelet threshold (WT) denoising and adaptive segmentation constant approximation (APCA) are used to denoise and fit the original signal in order to ensure the noise immunity and computational efficiency of the imaging. The image generated after WT-APCA-GAF processing is input into Swin Transformer for training, and the final identification accuracy of small leakage can reach 100%, effectively avoiding the problem of missing and false positive in detecting small leaks.

Flue gas recirculation technology and air-staged combustion technology are both effective methods for reducing the production of NOX in coal-fired boilers. However, the synergistic effect of air-staged combustion technology and flue gas recirculation technology on NOX generation characteristics in S-CO2 boilers needs further study. The formation characteristics of NOX in the main combustion zone of coal combustion were studied experimentally when flue gas recirculation and air-staged combustion were combined. The results indicate that as the recirculation flue gas is injected at deeper levels, there is a gradual decrease in the concentration of NOX along the path, And the concentration of O-2 also decreases gradually. The concentration of NOX decreases as the excess air coefficient decreases. The concentration of O-2 increases as the excess air coefficient increases. Additionally, the NOX concentration at the furnace outlet increases with the increase of the excess air coefficient. Along the axial direction of the one-dimensional flame combustion furnace, the NOX production along the way and the NOX concentration at the outlet decrease with the increase of the flue gas recirculation position. Flue gas recirculation in air-staged combustion is an effective method for reducing NOX emissions. The positioning of flue gas recirculation significantly impacts NOX emissions. The NOx concentration is lowest when the flue gas recirculation rate is 27% and the mixing position of the recirculated flue gas is 300 mm with an excess air coefficient of 0.8.

The industrial torch system is used to handle large amounts of flammable, toxic, and corrosive gases emitted during accidents or normal production processes. It utilizes open flames to burn off the gas pollutants. This study employs computational fluid dynamics (CFD) to investigate the combustion characteristics and efficiency of flames under high-velocity jet, aiming to address the issue of low combustion efficiency under high-velocity jet conditions. A three-dimensional flame model was established using methane and air as fuel, in order to investigate the variations and impact mechanisms of the combustion flame temperature field and carbon dioxide mass fraction distribution under different jet velocities, pilot component temperatures, and equivalence ratios. The reasons for low combustion efficiency under high-velocity jet conditions were analyzed. It was proposed to increase the combustion efficiency of the flame by raising the temperature of the pilot component, which differs from the traditional method of adding combustion-assisting gases. The combustion efficiency of flames under various operating conditions was evaluated. The results showed that as the jet velocity (v) increased from 49.6 m/s to 65 m/s, the height of the combustion flame in the vertical direction decreased continuously. Additionally, the high-temperature region at the center of the flame gradually decreased, leading to a 5.26% decrease in the highest flame temperature and a 3% decrease in combustion efficiency. When v = 70 m/s, the high-velocity fuel flow penetrated the ignition source, causing a large amount of methane to escape into the atmosphere without combustion, resulting in flame extinction. Elevating the temperature (T) of the pilot component can reduce the impact of high-velocity jet on combustion efficiency. When T = 2000 K, the flame reignites with a combustion efficiency of 94.1%. As the mass flow rate of the fuel composition inlet is reduced from 33.45 x 10-5 kg/s to 12.74 x 10-5 kg/s, the highest temperature of the combustion flame drops from 2072 K to 1451 K. As the equivalence ratio (phi) increases from 1.05 to 1.2, the height of the combustion flame in the vertical direction decreases continuously, resulting in a 0.7% decrease in the highest flame temperature and a 10.5% decrease in combustion efficiency.

Injecting carbon dioxide into shale reservoirs achieves geological carbon sequestration (GCS), effectively reducing atmospheric carbon dioxide levels. Rock wetting characterizes the strength of the interaction between fluids and rocks, thereby determining fluid distribution, which is crucial for GCS trapping efficiency. In this study, the dynamic wetting of H2O-montmorillonite 2 O-montmorillonite and CO2-H2O-montmorillonite 2-H 2 O-montmorillonite systems was studied using molecular dynamics (MD) simulations. Montmorillonites with different lattice substitution arrangements based on pyrophyllite are strongly water-wet, and a precursor film forms at the leading edge of the bulk water. Na+ + controls precursor film formation, which is rapidly spreading forward at a constant speed along the lattice substitution site lines based on Na+ + distribution. The lower the proportion of Al3+/Si4+ 3 + /Si 4 + lattice substitution in the Si-O tetrahedral layer on the fluid side, the higher the degree of water-wetness. The competitive adsorption of carbon dioxide and water molecules reduces the degree of spreading, resulting in a decrease in the degree of water-wetness. However, compared to the H2O-montmorillonite 2 O-montmorillonite system, the spreading behavior remained unchanged. High carbon dioxide pressure caused the wetting to change from strongly water-wet to weakly water- wet, however no wetting reversal was exhibited. The wetting changes were particularly prominent near the supercritical carbon dioxide pressure, with a limit of 18 MPa. For the first time, this study distinguished the dynamic behaviors of bulk water and precursor films, revealed the formation mechanism of precursor films, and revealed the control mechanism of carbon dioxide pressure on dynamic wetting from a molecular perspective. The quantitative relationship between the contact angle and flow velocity at different carbon dioxide pressures presented in this study could effectively guide the establishment of a fluid force equation for infiltrating flow, providing theoretical support for GCS numerical simulation research.

The flow behavior of shale reservoirs is extremely complex. The mainly used development method of large-scale volume fracturing of horizontal wells is associated with a series of problems such as low productivity in general, fast decrease in productivity, and difficulty to increase productivity. Therefore, it is necessary to evaluate the productivity of shale oil wells and determine the key control factors. Considering low-velocity non-Darcy flow, this paper establishes an analytical solution model for productivity calculation of multi-fracture shale oil horizontal wells with coupled matrix-fracture flow. Calculating the oil production rate by considering low-velocity non-Darcy flow in shale oil reservoirs obtains values closer to the actual oil production rate on site. The average relative error of the oil production rate of the H8 shale oil well is 4.27%. The average relative error of the oil production rate of the TMS shale oil wells is 34.97%, which exceeds the rate of the semi-analytical model by 47.84%. Sensitivity analysis shows that the oil production rate of multi-fracture shale oil horizontal wells is most sensitive to fracture cluster spacing and flowing bottom hole pressure. With decreasing fracture cluster spacing and flowing bottom hole pressure, both the matrix pressure gradient and the apparent permeability of the matrix increase. These increases not only increase the oil production rate but also reduce the influence of the non-Darcy effect on the oil production rate caused by boundary effect. In addition, the limits of the impact of non-Darcy effects caused by boundary effect on oil production rate have been clarified. The results enable not only the prediction of the oil production rate, cumulative oil production, and recovery factor of multi-fracture horizontal shale oil wells, but also the finding of the shale oil sweet spot according to the influence of matrix permeability and crude oil viscosity on the oil production rate.

Background: The standard treatment for internal carotid artery (ICA) dissection is obscure. Current therapeutic strategies include the use of antiplatelet drugs, anticoagulant drugs, intravenous thrombolysis, and endovascular treatment. Endovascular treatment is important in acute internal carotid artery dissection. This study reports two acute internal carotid artery dissection cases that were treated successfully using the Xpert-Pro peripheral self-expanding stent system. Case summary: The first case was of a 38-year-old male patient with transient speechlessness and paralysis of the right limb in July 2021. Cervical computed tomographic angiography (CTA) showed ICA occlusion on the left side. Digital subtraction angiography (DSA) showed severe stenosis of the C1 segment of the left internal carotid artery with intermural hematoma. The patient subsequently underwent Xpert-Pro peripheral self-expanding stent implantation, and his condition stabilized. The second case was of a 56-year-old male patient with speechlessness and paralysis of the right limb. Cervical CTA showed a dissected left ICA, and DSA showed an occluded left ICA and middle cerebral artery. The patient subsequently underwent stent implantation, and his condition stabilized.

The recovery of heavy oil is challenging due to its high viscosity. Especially in water flooding, the high viscosity of heavy oil induces a high water/oil mobility ratio, resulting in frequent channeling and fingering. In the present work, the viscosity reduction in heavy oil caused by foaming agents is studied. Among the studied foam systems, the KX-048 foaming agent had the best oil viscosity reduction performance. It also shows excellent foaming performance, including large foam volume, long foam half-life, and high foam comprehensive index. With the reduction in oil viscosity, the KX-048 foaming agent decreases the foam/oil mobility to 0.28, which is beneficial for controlling gas channeling and fingering in foam flooding. Moreover, Foam flooding experiments in heterogeneous sand-pack models indicate that KX-048 has excellent efficiency in improving oil recovery, especially in the low-permeable tube. The chosen KX-048 foaming agent could provide a promising pathway for improving heavy oil recovery.

Pore-scale modeling plays an indispensable role in unveiling the migration mechanism of oil pollutants into the water-saturated soil. Navier Stokes equations and conservation of mass, coupled with the phase field method, are employed to investigate the effect of soil wettability on oil pollutants migration into the soil porous media. The results show that the oil-water interface in the migration process does not advance evenly in three wetting states. When the model system is in oil-wetting state, oil pollutants obviously migrate at a higher speed. Through monitoring the evolution of oil front location and analyzing the velocity distribution vertical to the flow direction at the central axis of the model, the channel corresponding to the peak velocity is the dominant flow channel for the oil pollutants. This study will have the potential ability in obtaining the pore-scale migration regulation of oil pollutions as well as more accurately predicting the pollution range.

BZ oilfield is the first oilfield successfully developed with large-scale horizontal well pattern in Bohai sea. In order to study the well pattern suitable for offshore fluvial sedimentary oilfield, based on the characteristics of offshore oilfield, such as large well spacing, few wells and complex well pattern, the authors designed a set of heterogeneous reservoir models under the guidance of similarity theory. The different well patterns, different displacement rates and different heterogeneity were simulated. The different displacement effects were studied by measuring the electrical characteristics, injection volume, oil production and water production of the model. It is found that the horizontal well pattern is used for low-speed development, the water breakthrough of oil wells is slow in the relatively homogeneous reservoir. In the heterogeneous high permeability reservoir(Jk = 4), the oilfield adopts low-speed development by using staggered well pattern, the water breakthrough of the oil well is slow, and the EOR is large. In the heterogeneous high permeability reservoir(Jk = 6), the oilfield adopts the combined well pattern for low-speed development, the EOR is large. This study deepens the understanding of the development law of horizontal well pattern and the distribution law of remaining oil, and provides a basis for oilfield development and adjustment.

TZ83井区鹰山组缝洞型碳酸盐岩凝析气藏是塔里木盆地塔中Ⅰ号气田奥陶系大型碳酸盐岩凝析气藏的重要组成部分.通过井-震标定、地震资料精细解释,利用曲率、相干和波阻抗等地震属性识别研究TZ83井区环状断溶体储层.研究表明:①环状断溶体储层主要发育于鹰山组一段—良里塔格组五段,为环状洞穴层;②加里东中期广泛发育的不整合岩溶形成了环状断溶体的雏形,加里东晚期—海西期形成的X剪切断裂控制了环状断溶体储层发育的规模;③油气分布主要受环状断溶体储层发育规模的控制,可划分为3个相对独立的油气藏,这3个油气藏的硫化氢含量、气油比和开发特征均表现出极大的差异性.指出TZ83井区环状断溶体是在弱走滑条件下受X剪切断裂影响而形成,储层发育具有选择性、受控性、继承性和不均匀性的特点,这与塔里木盆地其他地区受大型区域性走滑断裂控制的断溶体,在储层形成机理及油气分布等方面存在较大差异.

大港油田沧东凹陷页岩油水平井钻井过程中面临着破岩效率低、井眼轨迹控制难度大、摩阻扭矩大、完井管柱下入困难等技术难题,影响了页岩油的勘探开发效益.为了解决这些问题,进行了激进式水力参数设计、异形齿PDC钻头研制、深层水平段高效钻井技术、旋转导向井眼轨迹控制技术、强抑制强封堵高性能水基钻井液技术和旋转引鞋+旋转下套管工艺等技术攻关研究,形成了大港油田页岩油水平井钻井关键技术.该技术在13口页岩油水平井进行了现场应用,平均机械钻速13.16 m/h,钻井完井周期50.62 d,井下故障时效低于0.1％,均创造了大港油田的钻井纪录.研究与应用表明,大港油田页岩油水平井钻井关键技术为沧东凹陷页岩油高效勘探开发提供了技术支撑,也为国内页岩油水平井安全高效钻进提供了借鉴.

为了解决顺北油气田碳酸盐岩裂缝性气藏钻井过程中溢流和漏失同存的问题,保证钻井安全,分析了其溢流和漏失同存的原因,制定了首先暂堵裂缝阻止气体侵入井筒、然后在气体侵入井筒的情况下控制气体侵入量和上窜速度以保证钻井安全的技术思路,并将裂缝性气藏暂堵技术、控压钻井技术和高温气滞塞技术进行集成,形成了顺北碳酸盐岩裂缝性气藏安全钻井关键技术.应用该关键技术时,先用裂缝性气藏暂堵技术阻止气体进入井筒;发现气体侵入井底时,用控压钻井技术控制气体侵入量;气体侵入井筒的情况下,用高温气滞塞技术降低气体上窜速度,保障钻井安全.顺北油气田在应用碳酸盐岩裂缝性气藏安全钻井关键技术后,解决了溢流和漏失同存的难题,提高了钻井速度,保证了钻井安全.

Over-displacement technology often occurs in the fracturing process of horizontal gas wells. The effect of horizontal shale gas wells productivity with different fracture morphology considering over-displacement were analyzed by numerical simulation. The results show that the over-displacement productivity is only 12.3%-15.0% of the equilibrium displacement productivity considering the complete fracture closure, and the fracture morphology has no effect on the productivity. Therefore, the amount of over-displacement hydrofrac fluid should be minimized in horizontal gas well, the fracturing fluid can rapidly gel-break and flowback after fracturing, proppant can flow back or settle at the fracture seam, and complex fractures can be formed near the wellbore as far as possible, so that it can reduce the impact of over-displacement on productivity. This study can provide a theoretical basis for fracturing design and productivity prediction of horizontal gas wells.

In order to screen out the optimal microemulsion oil drive system, the effect of micro emulsion performance on the residual oil of pore is selected, and the remarkable effect of improving recovery rate is proved from both macro and micro aspects by analyzing the fissure core oil drive experiment and the distribution law of the residual oil of the pore. The results showed that the best microemulsion system is made of positive octane 8mL, water 8mL, 4.5% mass fraction of the beetroot, 6% mass score of positive butanol, 5% quality score of NaCI. And that microemulsion system has a smaller particle size distribution range, higher viscosity, strong stability and a smaller proportion of pore residual oil.

Alkali–surfactant–polymer (ASP)-produced effluent contains polymer, alkali and surfactant, and it has higher content of suspended oil droplets and suspended solids than ordinary effluent. To decrease environmental pollution caused by the discharge of produced effluent, the feasibility of re-injecting a new ASP flooding system prepared with ASP-produced effluent was studied and discussed in this paper. The results of the experiments reveal that three main factors affect the performance of the new ASP system: the polymer concentration, the suspended oil droplet and suspended solids content and the salinity of the ASP-produced effluent. It is recommended that the average content of suspended oil droplets and suspended solids does not exceed 500 mg/l and that the salinity does not exceed 8000 mg/l when the produced effluent is introduced into a new ASP system. Subsequently, a laboratory displacement experiment on ASP flooding was performed. The experimental results reveal that the oil recovery of the new ASP flooding system was improved by 20.38%, and the ultimate oil recovery was 65.46%, which is 0.65% higher than that of an ASP flooding system prepared with ordinary effluent. ASP-produced effluent and ordinary effluent achieve nearly the same oil recovery. However, ASP-produced effluent is more environmentally friendly. An oil displacement test of ASP flooding with a new ASP flooding system was conducted in block A of W oil field, and good development results were achieved: The 25 production wells in the pilot test area were all effectively improved, with the minimum water cut reduced by 14.40% and the average daily oil production increased by 51.28 tons.

为明确多元热流体增产机理、优化多元流体组成,以便为科学编制多元热流体热采的工程方案提供技术支持,通过室内实验研究了温度和气体对渤海南堡油田稠油物性的影响.结果表明,在56～120℃范围内,含天然气稠油和脱气稠油黏度均随温度升高而迅速降低,温度升高到120℃时的原油降黏率约为92％,继续升高温度对稠油黏度的影响较小.在同等条件下,CO2比N2更易溶解到原油中,尤其是在温度较低的条件下.注入N2对改善稠油黏度的作用较小,只在100℃以下时略有降黏效果,温度超过120℃时稠油黏度增加.温度低于160℃时,注入CO2可以显著降低稠油黏度.将稠油加热至80℃并注入天然气和CO2体积比约为2:1的混合气体至16.86 MPa可使稠油黏度降低90％.通过升高温度和注入气体两种途径均可使稠油黏度大幅降低.考虑到注汽设备、热损失和注汽成本等因素,"适度加热,辅以注气"的开采技术可以达到较好的降黏效果,可用于海上稠油开采.

通过单因素实验和正交实验考察了聚合物浓度、交联剂浓度、稳定剂浓度及氯化铬/乳酸摩尔比对凝胶性能的影响,研制了一种适用于高矿化度低渗透裂缝性油藏的弱凝胶体系配方,并对弱凝胶体系的驱油效果进行了研究.实验结果表明,在实验温度32℃、地层水矿化度为29500 mg/L条件下,优选出弱凝胶体系配方为:聚合物质量浓度2000 mg/L,稳定剂质量浓度800 mg/L,交联剂质量浓度200 mg/L,三氯化铬/乳酸的摩尔比为1:8;弱凝胶体系注入量越大(0.3～0.6 PV),低渗层采收率提高值越高,对于层间差异大的油层,或对于存在高渗透率的油层,加大注入凝胶量才能调整流量分配,注凝胶后的注入水更多的进入低渗透油层驱油,采收率提高值大于15％.

— The vortex drainage gas recovery technology has the advantages of no need for moving pipe column and long maintenance period. Through the mechanism and numerical simulation results of the vortex tool, the geometric parameters of vortex tools suitable for gas well parameters in Daqing oilfield are optimized by using parameter optimization software. The height of liquid is calculated by following the Bernoulli equation. The field application shows that vortex tool has realized the effective separation of water-gas, and changes the flow state of the mixed phase water-gas. However, the positioning depth of vortex tool is too deep, and its swirling distance is insufficient. The gas well is further optimized for drainage gas recovery technology. The results show that better drainage gas recovery results can be obtained by adopting two-stage vortex tool and foam drainage gas recovery. Then, the gas well has a remarkable effect of drainage gas recovery. The decline trend of oil pressure, gas production and water production of the gas well has been significantly improved. The low pressure, low water content and low production gas wells can be effectively promoted by adopting two-stage vortex tool and foam drainage gas recovery. The vortex drainage gas recovery technology provides a technical support for the sustained and stable production of Daqing oilfield.