Gas-liquid Ratio Research Articles

Study on Parameters Optimization and Adaptation of Nitrogen Foam Flooding in Reservoirs with High Water Cut and High Permeability

Most oil reservoirs in China have entered the stage of high water cut. Affected by the heterogeneity of the reservoir, the water flow dominance channel is easily formed between injection-production wells in the plane direction of such reservoirs, and the phenomenon of water channelling is intensified. Therefore, a numerical simulation study of nitrogen foam flooding is carried out in this paper. According to the reservoir characteristics of the target block, the adaptability of nitrogen foam flooding to reservoirs in the ultra-high water cut stage is studied, the parameters of injection and production are optimized, and the applicable limits of nitrogen foam and the sensitivity of reservoir parameters are analysed. The optimization results of foam flooding indexes obtained through numerical simulation are as follows: the injection method of nitrogen foam is a mixed injection, the injection volume is 0.3 PV, the injection rate is 200 m3/d, the concentration of foaming agent is 0.5 wt%, and the gas–liquid ratio is 1: 1. The results show that for high-water-cut reservoirs, nitrogen foam flooding technology can effectively improve the water flooding effect of reservoirs and enhance oil recovery. It exhibits excellent adaptability to such reservoirs and has a very board application prospect. The results of numerical simulation optimization can provide theoretical guidance for field applications.

Research on the Development, Testing, and Evaluation of the Dual-Opening Anti-Blowout Oil Draining Device

During the tripping of the sucker rods and tubing from the wells with sucker rod pumps (SRP) in Tarim Oilfield, there are multiple challenges encountered, such as heavy oil, deep pumping, substantial load differences, and corrosive gas like H2S, etc., making the traditional anti-blowout oil draining device inefficient for operational needs and environmental requirements during pumping and intervention of the producing wells. In order to resolve such problems, Tarim Oilfield has developed a novel anti-blowout oil draining device with dual-opening function of rupturing + impacting by referring to the structure of high-pressure rupturing oil draining device with high opening success rate and conducting structure analysis, strength checks, and flow capacity calculations of the oil draining valves. The novel anti-blowout oil draining devices have passed a series of mechanical tests, corrosion resistance tests, and functional tests, such as indoor constant tensile stress-corrosion test, tensile strength test, collapse strength test, HIC test, electrochemical corrosion test, and tests of tool opening and closing, making up and breaking out, etc. The theoretical calculation and test show that the novel dual-opening anti-blowout oil draining device can not only meet the requirements of deep pumping, high gas-liquid ratio, substantial loading differences, and H2S corrosion resistance, but also be used in highly deviated wells, horizontal wells, and heavy oil producers. To conclude, the novel anti-blowout oil draining device will not pose any impacts on pump colliding operations. Moreover, the pump colliding operation can be used to eliminate the gelled debris attached to the pump valve and ball seat while ensuring anti-blowout oil drainage, returning the producer back to normal production.

Interaction of fuel spray and air swirl on the combustion of residue oils

Effervescent atomization technology was applied in Waste Lubricant Oils (WLO) combustion. The tests were conducted in a 150 kW prototype boiler with a horizontally oriented cylindrical shape combustion chamber in which the combustion process was studied in terms of the interaction between a swirling air flow and fuel spray pattern. The combustion performance was assessed by continuously monitoring gaseous emissions, particularly carbon monoxide (CO) emission. Two different air feeding strategies were tested, varying in swirl number and six different configurations of the injection nozzle orifice. Three nozzles had a single orifice varying in diameter and discharge end geometry, and the others had three divergent orifice arrangement varying in cone angle and diameter. At the same time, the gas-to-liquid ratio (GLR) of the effervescent atomizer was also investigated, allowing to draw important illations about its influence on the combustion efficiency. The results show that the use of effervescent atomizers allows to burn of WLO, with CO emissions as low as 15 ppm at 8% of oxygen (O2) when using a three orifice of 1 mm with 15° of cone angle nozzle. This result was achieved by applying high-intensity combustion air flow swirl. However, the one orifice nozzles with penetrant spray pattern combined with low swirl intensity air flow also produced satisfactory results. With CO emissions of 27 ppm at 8% of O2 with a 1.2 mm single orifice nozzle. Furthermore, it was also demonstrated that the increment of the GLR in a range between 0.25 and 0.35 can be responsible for the reduction of 40 to 50% of the CO emissions when burning WLO.

Three-dimensional interface structures and characteristics in a stratified gas–liquid pipe flow

In this study, the air–water flow in a pipe with a diameter of 100 mm was tested to investigate the three-dimensional (3D) interfacial characteristics of gas–liquid stratified flow in horizontal and slightly inclined pipes. The gas–liquid stratified flow interface exhibited a nonflat phenomenon (concave or convex). In particular, this phenomenon was verified by the transformation of the interface shape when the gas–liquid ratio exceeded 200 and 5 in the horizontal and inclined pipes, respectively. Compared with the flow in the horizontal pipe, the liquid holdup gradually decreased with an increase in the inclination angle in the downward stratified flow, and liquid height changes at the center was slight; however, the convex interface shape was obvious. In addition, the interface exhibited regular fluctuations in the flow direction under fixed operating conditions. Therefore, the hypothesis of a nonflat interface for stratified flow was proposed based on the experimental phenomena, and the interface shape function and flow equations were constructed to predict the degree of interface bending and critical conditions for gas–liquid stratified flow by analyzing the theoretical and influencing factors. The acceleration pressure drop was introduced to quantitatively characterize interfacial fluctuations in the flow direction; therefore, a modified model for nonflat stratified flow was developed. The proposed model could characterize the interface features in both the cross-sectional and flow directions of the pipe and provided a solution for the 3D interface of stratified flow. A comparison with the experimental results revealed that the proposed model performed the prediction satisfactorily. By solving the proposed model, the interfacial information in the pipe cross section and flow direction can be effectively predicted.

Preparation of fluorine-free foam extinguishing agent based on silicone and hydrocarbon surfactants for markedly suppressing the pool fire

To solve the serious environmental hazard of fluorinated aqueous film-forming foam (AFFF), it is urgently to develop environmental-friendly fluorine-free foam extinguishing agents. In this study, a highly effective phosphate betaine silicone surfactant (PPSS) was prepared successfully, and then combined with various hydrocarbon surfactants to prepare the fluoride-free foam extinguishing agents. The effect of PPSS on the surface tension, foaming ability, foam stability and fire-extinguishing efficiency of fluoride-free foam extinguishing agents were investigated. The results show that the surface tension of PPSS is as slow as 20.68 mN/m, which imparts a lower surface tension to the mixed systems of PPSS and hydrocarbon surfactants. Especially, the mixture of PPSS and sodium alpha-olefin sulfonate (AOS) possess the lowest surface tension of 22.95 mN/m compared to the CTAB/PPSS and LAD-30/PPSS mixed systems. Moreover, AOS/PPSS mixture presents the excellent comprehensive performance with the critical micelle concentration (CMC) of 0.165 g/L, the surface tension at CMC value of 22.95 mN/m, the initial foam height of 111.9 mm, and the foam stability of 83.45%. Fire-extinguishing tests show that the foam obtained from AOS and PPSS exerts a wonderful fire-extinguishing efficiency compared to two commercial fire-fighting foams. In addition, the fire-extinguishing efficiency of foam extinguishing agents is closely related to the gas–liquid ratio. When the gas–liquid ratio is 17, the foam shows the maximum temperature reduction rate of 6.05 °C/s as well as the minimum extinguishing time of 38.9 s.

Effect of gas on separation performance of an axial hydrocyclone for preliminary water separation

Hydrocyclones have become the preferred solution to the high water cut of fluids produced in oil wells. However, the gas associated with these fluids affect the separation efficiency of hydrocyclones. In the present study, the impact of gas on flow field stability and oil–water separation performance of an axial hydrocyclone for preliminary water separation was investigated theoretically and experimentally. The results show that small amount of gas enhanced oil-water separation, while large amount impeded it. The oil concentration of the outflow water first decreased and then increased with the increasing gas liquid ratio. The gas liquid ratio corresponding to the inflection point was 5% in slug flow regime and 8% in bubble flow regime. For different split ratios and water cuts, the impact of the GLR on the separation performance followed similar patterns. The gas decreased the oil concentration by 8.8% at most when the GLR was <5%. It decreased the oil concentration by 12.5% at most when the GLR was 7%–30%. The results obtained in this study show the relevant effect of gas in the functioning of hydrocyclones for the preliminary water separation and the importance of the reasonable control of GLR to reduce the impact in the separation performance.

Study on formation characteristics of carbon dioxide hydrate in modified carbon microtube system

The slow formation rate and low nucleation rate of carbon dioxide hydrate were common problems in current research. Many scholars focused on the promotion of gas hydrates by carbon nanotubes, whereas they ignored carbon microtubes, which were similar in structure and properties to carbon nanotubes and had more structural advantages. In this article, the effects of system temperature (1, 2, and 3 °C), pressure (3, 3.5, and 4 MPa), gas–liquid ratio (3:2, 4:1, and 5:1) and different types of carbon microtube concentration (0.01, 0.05, and 0.1 mg/mL) on the growth kinetics of carbon dioxide hydrate were investigated using orthogonal experiment method in a high-pressure reactor. The results revealed that compared to the pure carbon microtube system, amination, carboxylation, and hydroxylation carbon microtube systems improved the probability of carbon dioxide hydrate generation by 11–22%, with the shortest induction time of 0.23 hour. The highest gas storage capacity was 31.71 V/V under the carboxylated carbon microtube system. In the pure carbon, aminocarbon, carboxylated carbon and hydroxylated carbon microtube systems, the primary factors affecting the induction time were temperature, gas–liquid ratio, pressure and concentration. The gas–liquid ratio was the primary factor influencing the gas storage capacity of the carboxylated carbon microtubes; however, temperature was the primary factor affecting the gas storage capacity of the remaining three systems. Finally, we compared the effects of modified hydrophilic groups on the formation of carbon dioxide hydrate and made a conjecture.

Research on Mechanism of Dynamic Evolution Vibration Characteristics of Horizontal 90 Deg Elbow Flow Pattern

AbstractPipeline vibration induced by fluid flow can cause pipeline fatigue damage, which seriously endangers the safety of the operation. This paper aims to clarify the dynamic variation law of pipeline vibration induced by gas–liquid two-phase flow in the elbow and the influence of different gas–liquid ratios on the dynamic evolution of two-phase flow patterns. The volume of fluid (VOF) method is used to capture the flow pattern characteristics to explore the complex information of dynamic flow pattern evolution. The vibration characteristic mechanism corresponding to the evolution of the flow pattern is explored based on the time and frequency domain, and the origin of the exciting force of the elbow is explored according to the momentum balance equation. The simulation results show that the VOF method can well capture the characteristics of slug flow developed by the interphase instability mechanism. After phase space reconstruction, the dynamic evolution mechanism of the flow pattern is complex and the chaotic characteristics of slug flow are strong. The evolution of the flow pattern is related to the increase in wave height. The superficial velocity of the liquid phase is more sensitive to the flow pattern's formation mechanism than the gas phases. The amplitude of the wave strongly depends on the Vsg and Vsl. There is a strong correlation between the main exciting force pulsation and momentum flux pulsation.

Flow-Induced Vibration of a Reversed U-Shaped Jumper Conveying Oil-Gas Two-Phase Flow

Subsea jumpers connecting the underwater wellhead and nearby manifold commonly undergo flow-induced vibration (FIV) due to the spatially frequent alteration in the flow direction, velocity, pressure and phase volume fraction of the oil–gas two-phase flow, potentially leading to fatigue damage. This paper reports the numerical results of the FIV of a reversed U-shaped jumper excited by gas–liquid two-phase flow, which evolves from the initial slug flow with a fixed gas–liquid ratio of 1:2 when transporting through the jumper. The FIV response and flow pattern evolution are examined with a gas flow rate of Qg = 4–12 kg/s and a liquid flow rate of QL = 96–288 kg/s. When the gas–liquid flow passes through the jumper, the flow regime subsequently presents the slug flow, bubble flow, churn flow and imperfect annular flow. The out-of-plane response frequency coincides with the pressure fluctuation frequency for the four connecting bends, suggesting the fluid–structure interaction (FSI). Nevertheless, the vibration displacement is limited with the maximum value less than 0.0014D (where D is the jumper diameter) in the present considered flow rate range.

Gas-Liquid Flow Pattern and Hydrate Risk in Wellbore during the Deep-Water Gas-Well Cleanup Process.

The wellbore fluid flow characteristics and hydrate flow assurance problems during the deep-water gas well cleanup process seriously affect the safety of gas well testing. Aiming at the process of deep-water gas well cleanup where the liquid gas ratio changes dramatically, this study reveals the distribution law of gas-liquid flow patterns in the wellbore. Combined with the clean test conditions of deep-water gas wells, the transient numerical simulation and analysis are carried out. At the same time, a hydrate risk prediction model suitable for the well cleanup process is established to predict the hydrate risk under different cleaning conditions. The research results are as follows: (1) after flowback, the temperature at the wellhead and mud line presents different characteristics of temperature change, the wellhead temperature decreases first and then increases, while the flow temperature at the mud line rises first and then decreases; (2) slug flow and annular flow are more likely to occur in the wellbore under low wellhead pressure. Bubble flow often appears in the initial stage of flowback under high wellhead pressure and gradually changes into slug and annular flow patterns in the middle and late stages; (3) at the same flowback time, the wellbore will also present different flow patterns along the way. The lower part of the well bore mainly presents bubble flow and slug flow, and the upper and middle parts of the well bore mainly present annular flow patterns; (4) high liquid-gas ratio conditions, proper well cleaning speed, and the use of hydrate inhibitors can effectively reduce the hydrate risk during the cleaning process of deep-water gas wells.

Screening of Absorbents for Viscose Fiber CS2 Waste Air and Absorption–Desorption Process

Screening of absorbents is essential for improving the removal rate of carbon disulfide (CS2) waste air by absorption. In this work, the UNIFAC model in Aspen Plus was utilized to calculate the excess Gibbs function and absorption potential of the binary system of CS2 with various alcohols, ethers, esters, amines, and aromatic hydrocarbons. The results were used to quantitatively compare the efficiency of each solvent for CS2 absorption. The theoretical predictions were then verified by absorption experiments in a packed tower. The results showed that the performance of various solvents to CS2 roughly followed the order of esters &lt; alcohols &lt; amines &lt; heavy aromatics &lt; glycol ethers. Meanwhile, N-methyl-2-pyrrolidone (NMP) is the optimal absorbent for CS2 waste air treatment. Additionally, the process parameters of absorption and desorption of NMP were optimized. The results illustrated that the average mass removal efficiency of CS2 by NMP is 95.2% under following conditions: liquid–gas ratio of 3.75 L·m−3, a temperature of 20 °C, and inlet concentration lower than 10,000 mg·m−3. Under the conditions of 115 °C, 10 kPa, and a desorption time of 45 min, the average desorption rate of CS2 is 99.6%, and the average water content after desorption is 0.39%. Furthermore, the recycled lean liquid can maintain an excellent CS2 purification effect during the recycling process.

Dynamic Features of Nonaqueous Foam in Fracture Systems

The use of foam as a fluid for gas mobility control has become increasingly popular due to its effectiveness. However, the destabilization of aqueous foam by oil has led to a growing interest in nonaqueous foam. Despite this, there have been limited studies on the dynamic features of nonaqueous foam in fractures. In this study, we investigate the impact of roughness and fracture width on the flow behavior of non-aqueous foam using both microscopic visualization and macroscopic core flooding techniques. We also uncover the regeneration and regulation mechanisms of non-aqueous foam, while establishing a control group of aqueous foam for comparative purposes. Our experimental results show that as the roughness of the fracture increases, the pressure difference generated by both foams also increases, but decreases as the fracture width increases. Moreover, the optimal gas–liquid ratio for aqueous foam is 2:1, while that of nonaqueous foam is 1:2. Nonaqueous foam tends to be captured and deformed when transported through rough fracture surfaces. This deformation causes necking separation, which eventually leads to the generation of new foam. Furthermore, roughness anchors the foam, prolonging its stay in the fracture and increasing seepage resistance. The presence of kerosene in the fractured shale core reduces the stability of nonaqueous foam, as evidenced by a ∼23.3% decrease in differential pressure.

STUDY OF GAS-LIFT VALVE OPERATION

Gas lifts are versatile, dependable lifting systems that provide numerous options. This article discusses typical problems with gas lift valves used in geotechnical applications. What could result in such operational and well-related flaws. A closed system powered by high pressure gas is a gas lift system. Gas lifts are frequently adaptable, dependable lift systems with a variety of manufacturing options. For all operations, adding gas from an outside source lowers the fluid pressure level, which forces more fluid to be kept in conditions with high water retention. Excellent product quality, changeable gas lift complex, and lift depth. Where possible, involuntary injection gas tensions and volumes are extremely rare and can support various synthetic buoyancy types. By lowering the fluid's pressure stages with the use of an extraterrestrial gas penthouse, more fluid may be stored in the Force as the descent goes on. As you alter the parameters, consider how other elements alter. The behavior of gas lift valves is predicted using a variety of techniques. These techniques additionally consider additional factors. The Thornhill-Craver equation is the formula most frequently used to forecast the performance of throttle valves. The interpretation of gas lift taps is overestimated by the Thornhill-Craver equation, particularly for big ports, according to Gerberding and Acuna. Gas lifts are not appropriate for combined liquids, supersaturated Neptune, or thick, abrasive paintings. , which focuses on how to increase the performance of weak gas lift taps, highlighting the necessity of their complicated design, does not function well for grabbing old wells or extending inflow lines with external internal compasses. Keywords: Gas liquid Ratio (GLR), Fluid, Pressure, Gas Lift Valves (GLVs), Injection Gas, Bottom Hole Pressures (BHPs)., Continuous Flow, Intermittent Flow.

Study on removing marine multiple pollutants in raw exhaust gas with a novel composited method combined with pre-agglomeration and wet scrubbing technology.

Most of the existing oxidation denitrification methods need longer residence time to obtain higher NOx removal efficiency. In this study, urea peroxide (CO(NH2)2·H2O2) was first used for removing SO2 and NOx on diesel engine bench. The addition of ferrous sulfate can enhance the oxidant capacity of the solution. The better removal efficiency and lower nitrate content in liquid can be achieved in short exhaust gas residence time. The raw gas flow and residence time contained the actual application situation in ships and have high reference value. The removal efficiency decreased with the increase of gas flow, and the reaction temperature, urea peroxide concentration, liquid-gas ratio were the main factors. The optimal Fe2+ concentration of 50mmol/L and pH value of 4 were determined. The urea peroxide concentration, reaction temperature, and liquid-gas ratio were 9%, 70℃, and 10L/m3 respectively. The maximum gas treatment capacity was about 100L/min, and residence time was close to 10s for the scrubber. The pre-agglomerating method were used to improve the particle capturing efficiency combined with spray technology. The composited method can realize the synchronous and efficient removal of multiple pollutants in a single scrubber. The possibility of application on ship was further increased.

Surfactant-Containing Foam Effectively Enhanced the Removal of Polycyclic Aromatic Hydrocarbons from Heavily Contaminated Soil.

Surfactant remediation has an excellent record of removing polycyclic aromatic hydrocarbons (PAHs). By using simulation experiments, we investigated the properties and mechanism of a surfactant-containing foam and its effect on PAH removal. Our results suggest that the optimal conditions by foam washing are as follows: 40 mmol·L-1 of rhamnolipid and fulvic acid mixed surfactant (V: V = 3:1), with 70:3 and 20:3 foam gas-liquid ratio for naphthalene and phenanthrene, respectively (pH 6, 50°C, 2 h). Under the optimal conditions, 60.1% and 56.68% removal efficiencies were achieved against naphthalene and phenanthrene from contaminated soil, respectively. These values were lower than those from the simulated media (76.69% and 70.43% for naphthalene and phenanthrene, respectively). The strong PAH adsorption on the soil particles antagonized volatilization, the key PAH removal mechanism by foam leaching. Therefore, this research provides relevant information for using surfactant foam to remediate heavily PAH-contaminated soils.

Novel atomizer concept for CCS applications: Impinging effervescent atomizer

The concept design, testing of spray characteristics, and performance comparison of an original type of atomizer, the impinging effervescent atomizer (IEA), are introduced in this study. The liquid impinging is beneficially deployed in plain-orifice and external mixing twin fluid atomizers. IEA uses a collision of two or more effervescent liquid streams to improve the atomization and alter the spray characteristics. The Phase Doppler Anemometry (PDA) measurement technique and high-speed visualization of the liquid discharge and spray structure were used. The discharge coefficient (Cd), atomization efficiency (ηa), spray characteristics as a spray cone angle (SCA), integral Sauter mean diameter (ISMD), integral relative span factor (IRSF), and droplet size and velocity distribution inside the spray were investigated. The correlations for Cd, SCA, ISMD and IRSF are provided for a fast and reliable atomizer design to fit any application and operating conditions. The IEA provides a controllable SCA governed mainly by the exit orifice geometry. The ISMD is primarily controlled by the gas to liquid ratio (GLR) and the inlet pressure (pin). The impinging angle (β) has little effect on ISMD. A narrower droplet size distribution, mass redistribution within the spray, and a more uniform droplet size spatial distribution were observed for the IEA in comparison to other tested atomizers. The IEA spray covers 116% more area than single-orifice effervescent sprays, and the area coverage can be controlled by β. This coverage increases by 177% if β changes from 15 to 45°. Spray eccentricity (e) decreases with the increase of the number of the exit orifices (No) resulting in a more uniform droplet spatial distribution. The β, GLR and pin have no effect on e. The ηa of the IEA is equivalent to other internally mixing twin-fluid atomizers; the atomization air contains more than 90% of the delivered energy. The favourable IEA spray characteristics, such as IRSF, ISMD, spray coverage, SCA and ηa, enable the potential use of IEA in mass-transfer related processes and especially in CO2 capture columns.

Gas–Liquid Flow Behavior in Condensate Gas Wells under Different Development Stages

The phase state prediction methods of condensate gas are relatively mature, but the effect of phase changes on gas–liquid mixture flow behavior and the liquid-carrying capacity of gas has not been researched in detail. This study applied PIPESIM software to predict the fluid phase properties under different development stages of a condensate gas reservoir in Shengli Oilfield and determined the phase diagram and physical properties of the well stream on the basis of the optimized equation of state (EOS). Then the influence of phase change characteristics on wellbore flow behavior and critical liquid-carrying gas velocity was analyzed. The study showed that compared with the early development stage, fewer heavy components are produced and the produced gas–liquid ratio is increased in the late stage of the condensate gas reservoir. In addition, the pressure loss of fluid is decreased, the critical liquid-carrying gas velocity and flow rate are reduced, and the liquid-lifting difficulty is reduced for gas. The reason is that the liquid density decreases obviously due to the phase change, while the gas density is almost unchanged, and the oil–gas surface tension decreases obviously, resulting in a decrease in the critical liquid-carrying gas velocity. At the same time, the variation in the gas compressibility factor is very small, which leads to a decrease in the critical liquid-carrying gas flow rate.

Study on fire extinguishing performance of different foam extinguishing agents in diesel pool fire

The physical properties and fire extinguishing performance in diesel fire of aqueous film-forming foam (AFFF) and protein foam (PF) were studied, and the fire extinguishing mechanism of different foams were also analyzed. The results show that 6%AFFF and 6%PF have better performance than that of 3%AFFF and 3%PF, respectively, and AFFF possess higher expansion ratio, 25% drainage time and surface tension than PF at the same concentration. The fire extinguishing test show that the extinguishing performance of foam enhanced with the increase of gas-liquid ratio firstly, and decreased subsequently. The best fire extinguishing performance were achieved when gas-liquid ratio of 6%AFFF and 6%PF were 17 and 20, and the extinguishing agent dosage were 229 ml and 260 ml, respectively. Compared with PF, the fire extinguishing time and agent dosage of AFFF are reduced by 10% and 6.15% respectively at gas-liquid ratio of 20. Besides, AFFF can form more dense, stable and high-multiple foam cover layer, endow it with better fire extinguishing performance than PF. However, PF can reduce the temperature around the oil pool more quickly, showing better cooling effect than AFFF.

NUMERICAL SIMULATIONS OF NITROGEN FOAM AND GEL-ASSISTED STEAM FLOODING FOR OFFSHORE HEAVY OIL RESERVOIRS

Chemical-assisted steam flooding is a promising method for heavy oils. However, few researches have investigated the performance of nitrogen foam and gel-assisted steam flooding (NFG-A-SF) on offshore heavy oil reservoirs. In addition, the effects of operational parameters on the performance of NFG-A-SF are still unclear. In this study, a numerical simulation model was developed to simulate NFG-A-SF processes for offshore heavy oil reservoirs. Then, a comparison of NFG-A-SF and steam flooding was made to assess the feasibility of NFG-A-SF in a well group at Oilfield L, a typical offshore heavy reservoir of Bohai Bay, China. Finally, sensitivity analysis was conducted to investigate the effects of the chemical agent type, injection mode, injection timing, cycle number of gel and nitrogen foam, polymer concentration, crosslinking agent concentration, foaming agent concentration, and gas-liquid ratio on NFG-A-SF performance. The results showed that, compared with SF, the NFG-A-SF has better performance, which is a potential and effective method for offshore heavy oil reservoirs. The NFG-A-SF should be implemented as early as possible. During the NFG-A-SF processes, gel slugs should be injected alternately with nitrogen foam slugs, and the gel slugs should be injected first before nitrogen foam slugs. Considering the economic benefit, there are optimum cycle numbers of gel and nitrogen foam, gas-liquid ratio, concentrations of polymer, crosslinking agent, and foaming agent.

Study on flue gas denitration method based on multistage high gravity technology

According to the mechanism of wet denitration, H2O2 solution and KOH solution are used as absorbents, and the two-stage countercurrent high-gravity rotating packed bed is used as the reaction equipment. The rotating speed, gas-liquid ratio, temperature, H2O2 solution concentration and KOH solution concentration are changed respectively to explore the impact of various factors on the denitration efficiency, and finally determine the best experimental conditions for flue gas denitration. The experimental results show that when the rotating speed reaches 900 rpm, the gas-liquid ratio is 12:1, and the temperature reaches 36 °C, using 0.20 mol/l of H2O2 solution and 0.10 mol/l of KOH solution as absorbents, the denitration efficiency can reach the best, and the best denitration efficiency is 95.71%.