Increase Of Injection Temperature Research Articles

Effects of cushion gas pressure and operating parameters on the capacity of hydrogen storage in lined rock caverns (LRC)

Hydrogen storage in lined rock cavern (LRC) provides versatile site selection, safety, and stability, making it a crucial option. In this study, a thermodynamic mathematical model was established to describe hydrogen storage in LRC. This model is based on the principles of mass, momentum, and energy conservation while accounting for the authentic compressibility of hydrogen. The thermodynamic fluctuations throughout the seasonal cycle in LRC were computed using the COMSOL Multiphysics software. The results indicate that when the hydrogen storage reaches the operating pressure, the lower the cushion gas pressure, the greater the hydrogen injection amount, and the higher the utilization rate of storage capacity. With a cushion gas pressure of 3 MPa, the storage capacity utilization rate exceeds that at 15 MPa by 41 %. The injection rate of 0.5 kg/s results in a temperature increase of 12 °C compared to 0.27 kg/s, indicating twice the temperature rise at the 0.27 kg/s injection rate. An increase in injection temperature corresponds to higher temperature within the hydrogen storage cavern upon completion of gas injection, thereby reducing the time needed for gas injection to reach maximum operating pressure. A lower initial cavern temperature results in a longer time for hydrogen storage to reach maximum operating pressure.

Analysis of dynamic thermal behaviors for multi-stage hydraulic fracturing treatments in horizontal shale oil and shale gas wells

Accurate prediction of dynamic thermal behaviors during multi-stage hydraulic fracturing is profound which can avoid performance deterioration of fracturing fluids or failure of fracturing tools caused by severe temperature variation. This paper establishes a transient heat transfer model for multi-stage hydraulic fracturing in horizontal shale oil and shale gas wells (MFHWM), considering the real construction process of multi-stage hydraulic fracturing, the turbulent flow state, the heat source of viscous dissipation and the complex wellbore structure, which enables the accurate simulation of thermal behaviors in the early time of multi-stage hydraulic fracturing with large flow rate. The verification results of measured temperature data and simulation data prove the MFHWM has good precision. Numerical simulations indicate that the temperature distribution exhibits the characteristics of cyclic “cool-down” and “warm-back” and “stair-step” during the multi-stage hydraulic fracturing. In the “cool-down” period, the temperature drops sharply within the first hour and then the deceleration slows down. In the “warm-back” period, the temperature recovers exponentially relying on the shut-in time. The “stair-step” is caused by changing of heat transfer mechanism from convection to conduction. Moreover, the cyclic cooling has little effect on the total temperature drop and subsequent stages are not significantly cooler than previous stages. Besides, primary factors affecting temperature distributions of wellbore-formation system are discussed thoroughly. Results indicate that the viscous heat source cannot be ignored for multi-stage hydraulic fracturing and the temperature difference exhibits cyclic variation when considering and without considering the viscous heat source. In addition, the minimum temperature during each-stage-fracturing operation decreases first and then increases as the injection rate of fracturing fluid increases because of the compromise between the viscous heat source and forced convection. Furthermore, temperature distributions can be controlled by changing the injection temperature of fracturing fluid. As the injection temperature increases, a positive proportional relationship exists between the minimum temperature of fracturing fluid and the injection temperature. MFHWM can be a standalone tool to analyze temperature distributions of multi-stage hydraulic fracturing. It can also be used to provide better boundary conditions for stress analysis model of casing and cement sheath.

Numerical analysis of temperature effect on CO2 storage capacity and CH4 production capacity during the CO2-ECBM process

Temperature is a key factor affecting the CO2 injection efficiency and CH4 production efficiency, so it is of great significance to clarify the evolution diagram of temperature change during the CO2-ECBM process. In this study, the crushed soft coal seam with low permeability in Huainan coalfield was taken as the research object. Firstly, the fully coupled mathematical models of CO2-ECBM process were constructed, and the influence of temperature field on CO2-ECBM process was emphasized. Secondly, the evolution law of CO2-ECBM process at different time was revealed. Then, the effects of injection temperature and initial temperature on the CO2-ECBM process were analyzed. Finally, the evolution mechanism of reservoir temperature during the CO2-ECBM process was illustrated, and the effect of temperature on temperature field of CO2-ECBM process was further illustrated. The results show that the longer the displacement time, the CH4 concentration gradually decreased, and the CO2 concentration gradually increased. The area where the temperature changes are more concentrated focuses on the vicinity of CO2 injection well, which are mainly determined by the dominant reaction of adsorption and desorption reactions of binary gas. Reservoir temperature and permeability are positively and negatively correlated with injection temperature, respectively. Both CO2 storage capacity and CH4 production capacity increase with the increase of injection temperature, and the sensitivity of CO2 storage capacity to temperature was greater than that of CH4 production capacity. With the increase of displacement time and injection volume, the effective displacement radius increases, but the increment of influencing radius gradually decreases. The lower the initial temperature of coal reservoir, the larger the influencing radius, and which increases with the increase of displacement time. CO2 storage capacity and CH4 production capacity decrease with the increase of initial temperature. Young's modulus and Poisson's ratio can effectively change the reservoir strength. CO2 storage capacity and CH4 production capacity decrease with the increase of Young's modulus, and increase with the increase of Poisson's ratio. This study can support the engineering landing of CO2-ECBM technology in crushed soft coal seam with low permeability, and promote the realization of China's “Dual Carbon” strategic goal.

Thermal-Hydraulic-Mechanical Coupling Simulation of CO2 Enhanced Coalbed Methane Recovery with Regards to Low-Rank but Relatively Shallow Coal Seams

CO2 injection technology into coal seams to enhance CH4 recovery (CO2-ECBM), therefore presenting the dual benefit of greenhouse gas emission reduction and clean fossil energy development. In order to gaze into the features of CO2 injection’s influence on reservoir pressure and permeability, the Thermal-Hydraulic-Mechanical coupling mechanism of CO2 injection into the coal seam is considered for investigation. The competitive adsorption, diffusion, and seepage flowing of CO2 and CH4 as well as the dynamic evolution of fracture porosity of coal seams are considered. Fluid physical parameters are obtained by the fitting equation using MATLAB to call EOS software Refprop. Based on the Canadian CO2-ECBM project CSEMP, the numerical simulation targeting shallow low-rank coal is carried out, and the finite element method is used in the software COMSOL Multiphysics. Firstly, the direct recovery (CBM) and CO2-ECBM are compared, and it is confirmed that the injection of CO2 has a significant improvement effect on methane production. Secondly, the influence of injection pressure and temperature is discussed. Increasing the injection pressure can increase the pressure difference in the reservoir in a short time, so as to improve the CH4 production and CO2 storage. However, the increase in gas injection pressure will also lead to the rapid attenuation of near-well reservoir permeability, resulting in the weakening of injection capacity. Also, when the injection temperature increases, the CO2 concentration is relatively reduced, and the replacement effect on CH4 is weakened, resulting in a slight decrease in CBM production and CO2 storage.

The Effect of Avgas Fuel Injection Pressure on Injection Temperature

The use of internal combustion engines has become common in transportation, especially in aviation, one of which is the Cessna training aircraft with a piston engine. The effect of fuel injection pressure on injection temperature has been a focus of many studies because it has the potential to improve combustion efficiency. Increasing the fuel injection pressure in avgas causes an increase in injection temperature and also enhances temperature stability during injection.

Distribution characteristics of a supercritical hydrocarbon fuel jet injected into a high-speed crossflow

The mixing process and distribution characteristics of a supercritical endothermic hydrocarbon fuel (EHF) jet injected into a high-speed crossflow are investigated experimentally by the acetone Planar Laser-induced Fluorescence (PLIF) technique. The instantaneous and averaged distribution of supercritical fuel in the central plane and the cross-sectional planes with various Mach numbers, injection pressure, and temperature are measured and analyzed. A three-species surrogate is employed to calculate the flow parameters of the EHF jet. The boundary and penetration depth of the jet plume are identified by the probability density method. The mixing process of the supercritical fuel is analyzed using the fluorescence concentration distribution. Results show that the momentum flux of the EHF jet increases with the increase of injection temperature when the injection pressure is close to the critical pressure, while it decreases firstly and then increases as the injection pressure is larger than the critical pressure. The penetration depth is dominated by the jet-to-air momentum flux ratio (q), and the EHF jet plume boundary is enlarged with the increase of the q. In particular, the penetration depth formula is given in: y/d=0.67q0.97x/d0.29 for supersonic crossflow and y/d=0.15q0.57x/d0.60 for subsonic crossflow, respectively. The EHF jet plume with lower q presents a semi-circle shape in the cross-sectional plane and mainly expands in the width direction. While it mainly expands in height direction downstream as a semi-Omega shape in the larger q condition. The results indicate that the increase in injection temperature and pressure can enlarge the EHF jet plume distribution and enhance the mixing effect. In comparison, increasing the injection pressure obtain more significant benefits, providing a reference for the fuel supply system and injector design.

Influence of Palm Oil Biodiesel Blend Preheating on Performance Parameters, Emissions and Combustion Characteristics in a Stationary Diesel Engine

This research evaluates the effect of preheating in different blends of palm oil biodiesel in a stationary diesel engine. For the research development, the characteristics of performance, emissions (CO, CO2, NOx, HC, and smoke opacity), combustion chamber pressure, and heat release rates are evaluated. Experimental tests were conducted at three load conditions (50%, 75%, and 100%) and three biodiesel blends (BP5%, BP10%, and BP15%). To study the effect of preheating, a fuel injection temperature of 30 °C to 70 °C was set. The results obtained show a 6.40% increase in BSFC and a 4.41% reduction in engine BTE when running with biodiesel blends. However, preheating in biodiesel blends led to lower BSFC and higher BTE by 2.08% and 2.12%. The preheating of palm oil biodiesel (BP5%, BP10%, and BP15%) favored the decrease in CO, HC, and engine smoke opacity emission levels by 29%, 37.31%, and 7.84%. The additional presence of oxygen molecules and the increase in fuel injection temperature contribute to the formation of NOx emissions. The increase in injection temperature causes an increase in peak combustion pressure levels and heat release rate by 2.53% and 2.41%. In general, preheating palm oil biodiesel is a promising strategy to minimize the negative effects caused by the high density and viscosity of this type of fuel.

Phase separation and rheological behavior of a new biphenyl poly(aryl-ether-ketone)-bismaleimide composite resin

Ex-situ toughening technology is a good solution to improve the toughness of intrinsically brittle thermosetting resin matrix fiber composites. In order to better combine the ex-situ toughening technology with resin transfer molding (RTM) process to prepare high performance bismaleimide (BMI) resin matrix composites, in this paper, based on a new thermoplastic biphenyl polyether ketone (PAEK-B) resin, the phase separation behavior of the PAEK-B in BMI resin and carbon fiber composites, and the rheological properties of PAEK-B/BMI composite resin were studied. The results show that the phase separation behavior of PAEK-B occurs in the injection window temperature of BMI resin for a certain time, and the phase separation structure is maintained in the carbon fiber (CF)/PAEK-B/BMI composites prepared by RTM process. The solution of PAEK-B in the BMI resin is affected by the injection temperature of BMI resin. The initial viscosity of the BMI resin decreases with the increase of injection temperature, but the inflection point time of the PAEK-B/BMI composite resin decreases; The PAEK-B/BMI composite resin accords with the Winter-Chambon criterion. The tanδ of the composite resin has no dependence on the frequency, and the gel activation energy of the composite resin increases with the increase of PAEK-B content.

Study on CO2 foam fracturing model and fracture propagation simulation

CO2 foam fracturing fluid has the advantages of water saving and environmental protection, which has been widely used in unconventional oil and gas reservoir. However, there are still many technical difficulties in fracture propagation model and numerical calculation method of CO2 foam fracturing. In this paper, a CO2 foam fracturing fracture propagation model with temperature-pressure-phase coupling is established. Physical parameters of CO2 are calculated by Span-Wagner method, and the finite difference and displacement discontinuity methods are used to solve the model. Moreover, we compare the results of this model with the field measured data, KGD model and EFRAC-3D model to verify the model. The computation results show that in the process of fracturing, improving the CO2 foam quality can significantly enhance the fracturing effect. When the quality increased from 0.5 to 0.8, the fracture width raised by more than 2 times. In addition, the fracture propagation is significantly affected by injection temperature. With the increase of injection temperature, fracture width decreases continuously, and if the CO2 foam is supercritical phase state, it is not conducive to increase the fracture width.

Wellbore temperature and pressure calculation model for supercritical carbon dioxide jet fracturing

ABSTRACTA new numerical calculation model for wellbore temperature and pressure for SC-CO2 jet fracturing was proposed in this research. In our model, the impact of tubing, casing, and cement on heat transfer, and the heat generated by fluid friction losses are all taken into consideration. The CO2 physical properties are calculated by the Span–Wagner and Vesovic models. Based on our calculation model, the factors that may affect the wellbore temperature and pressure are discussed. The results indicated that ignoring the influence of the cement sheath thermal resistance on heat transfer would lead to a wellbore temperature higher than the actual value. The wellbore CO2 pressure is always higher than its critical value, but the CO2 temperature at the jet point in some cases is lower than its critical value. The wellbore CO2 temperature is increased with the increase in injection temperature and cement sheath thermal conductivity and the decrease in annulus injection rate and coiled tubing injection rate. However, the decrease in the coiled tubing injection rate and increase in the cement sheath thermal conductivity are the only effective ways to ensure that the CO2 temperature at the jet point exceeds its critical value.

Coupled thermal−gas−mechanical (TGM) model of tight sandstone gas wells

The mechanism of CO2 fracturing under coupled thermal−gas−mechanical (TGM) conditions is important for gas production in tight sandstone gas wells. In this study, a coupled TGM model was proposed on the basis of the elastic damage principal, and the coupling relationships were expressed by the governing equations. The proposed model was then tested through comparison between the numerical uniaxial compressive test and the laboratory test. COMSOL MULTIPHYSICS was adopted to calculate the coupled numerical model; the impact of injection rate and injection gas temperature was fully investigated. The research results showed that the initiation pressure stayed stable with the increase of the breakdown pressure and injection rate over a certain range (0.106 m3 s−1–0.848 m3 s−1). The seepage area under the injection rate of 0.848 m3 s−1 was 3.45 times that under the injection rate of 0.106 m3 s−1, which resulted from the gradual destruction of the samples and the formation of new fractures at higher injection rate. The initiation pressure and the breakdown pressure decreased, since tensile cracks tended to form with the increase of injection temperature. Shear cracks formed around the hole—the crush area. The tensile cracks propagated much deeper into the surrounding rock under the higher injection temperature. This research provides a study of unconventional oil and gas extraction for reference.

Numerical simulation of superheated steam flow in dual-tubing wells

In this paper, a novel model is presented to estimate the thermophysical properties of superheated steam (SHS) in dual-tubing wells (DTW). Firstly, a mathematical model comprised of the mass conservation equation, momentum balance equation and energy balance equation in the integral joint tubing (IJT) and annuli is proposed for concentric dual-tubing wells (CDTW), and in the main tubing (MT) and auxiliary tubing (AT) for parallel dual-tubing wells (PDTW). Secondly, the distribution of temperature, pressure and superheat degree along the wellbores are obtained by finite difference method on space and solved with iteration technique. Finally, based upon the validated model, sensitivity analysis of injection temperature is conducted. The results show that: (1) effect of injection temperature difference between MT and AT on temperature profiles is weak compared with that between the IJT and annuli. (2) Temperature gradient in IJT and annuli near wellhead is larger than that in MT and AT. (3) Superheat degree in both CDTW and PDTW increases with the increase in injection temperature in IJT and MT, respectively. (4) Superheat degree in IJT and MT decreases rapidly near wellhead, but the superheat degree in annuli and AT has an increase. (5) Thermal radiation and convection are the main ways of heat exchange between MT and AT. This paper gives engineers a novel insight into what is the flow and heat transfer characteristics of SHS in DTW, and provides an optimization method of injection parameters for oilfield.

Performance analysis of superheated steam injection for heavy oil recovery and modeling of wellbore heat efficiency

In this paper, a novel model is proposed for predicting thermo-physical properties of superheated steam (SHS) in SHS injection wells and for estimating wellbore heat efficiency.Firstly, a novel mathematical model is proposed for predicting pressure, temperature as well as superheat degree in SHS injection wells. Secondly, the direct and indirect methods are introduced to estimate the wellbore heat efficiency. Thirdly, the model solving process is introduced in detail. After validation of the model, sensitivity analysis is conducted. Results indicate that: (1). The superheat degree at well bottom increases with the increase of injection rate. (2). The superheat degree at well bottom increases with the increase of injection temperature. (3). The superheat degree at well bottom decreases with the increase of injection pressure. In order to obtain a higher superheat degree at well bottom, the injection pressure cannot be too high.This paper presents a basic reference for engineers in optimization of injection parameters as well as estimation of wellbore heat efficiency of SHS injection wells.

The flow and heat transfer characteristics of superheated steam in offshore wells and analysis of superheated steam performance

Abstract In this paper, a novel model is presented for predicting thermophysical properties of superheated steam (SHS) in offshore superheated steam injection wells (OSSIW). Firstly, a mathematical model comprised of mass, energy and momentum balance equations is proposed for OSSIW. Secondly, the distribution of temperature, pressure and superheat degree along the wellbores are obtained by finite difference method on space and solved by using the iteration technique. Then, model validation and sensitivity analysis are conducted. The results show that (1). The superheat degree increases at first but then turns to decrease with the increase of injection rate. (3). The superheat degree increases with the increase of injection temperature. (4). The superheat degree at well bottom increases at first but then turns to decrease with the increase of injection pressure. (5). The superheat degree in the wellbore has a drop when seawater starts to flow.

Influence of injection temperature and pressure on the properties of alumina parts fabricated by low pressure injection molding (LPIM)

The quality of ceramics parts made by powder injection molding (PIM) method is influenced by a range of factors such as powder and binder characteristics, rheological behavior of feedstock, molding parameters and debinding and sintering conditions. In this study, to optimize the molding parameters, the effect of injection temperature and pressure on the properties of alumina ceramics in the LPIM process were thoroughly studied. Experimental tests were conducted on alumina feedstock with 60vol% powder. Injection molding was carried out at temperatures and pressures of 70–100°C and 0.1–0.6MPa respectively. Results showed that increase in injection temperature and pressure and the resulting increase in flow rate leads to the formation of void which impairs the properties of molded parts. The SEM studies showed that injection at temperature of 100°C results in evaporation of binder components. From the processing point of view, the temperature of 80°C and pressure of 0.6MPa seems to be the most suitable condition for injection molding. In addition, the effects of sintering conditions (temperature and time) on the microstructure and mechanical properties are discussed. The best final properties were found using injection molding under the above stated conditions, thermal debinding and sintering at 1700°C during 3h.

Experimental study on the mechanism of carbon dioxide removing formation paraffin deposits

Formation paraffin deposits cause serious productivity damage during the process of oil production. As an effective, economical and environmentally friendly organic solvent, CO2 has many advantages in removing formation paraffin deposits. In this paper, the mechanism of action for CO2-mediated removal of formation paraffin deposits is analysed. An indoor simulation of CO2-mediated removal of formation paraffin deposits is conducted. The feasibility of removing formation paraffin deposits by CO2 is investigated and the effect of injection parameters on plug removal efficiency is discussed. The experimental results show that CO2 adsorption-induced swelling and paraffin thermal expansion are the main factors that facilitate CO2-mediated removal of formation paraffin deposits. Plug removal using CO2 requires a long injection time. As the injection temperature increases, plug removal efficiency increases. As the injection pressure increases, plug removal efficiency first increases and then decreases, which allows for determination of the optimal injection pressure.

Production performance of gas hydrate accumulation at the GMGS2-Site 16 of the Pearl River Mouth Basin in the South China Sea

In 2013, gas hydrate accumulations were confirmed in the Dongsha Area of the South China Sea by the scientific drilling expedition GMGS2. The drilling sites of GMGS2-01, -04, -05, -07, -08, -09, -11, -12, and −16 were verified with the existence of hydrate bearing layer. The gas production behavior was evaluated at GMGS2-16 by numerical simulation in this work. The scenarios of single depressurization with single horizontal well and dual horizontal wells and the depressurization in conjunction with warm brine stimulation with dual horizontal wells were carried out in this work. Simulation results indicated that gas production rate for the single depressurization with dual horizontal wells was higher than that for the single horizontal well. In addition, the gas production performance was more favorable when using the depressurization in conjunction with brine stimulation. The average gas production rate with such scenario can obtain the same order of magnitude with the minimum production level of the commercial viability of the hydrate exploitation in the Gulf of Mexico. Furthermore, the sensitivity analysis indicates that gas production rate increases with the increase of injection temperature. However, the energy loss increases with the rise of injection temperature. Increasing the injection salinity or the injection rate can increase the gas production rate as well. However, the energy ratio is the highest for the case with the middle-higher injection rate.

Experimental study of elliptical jet from supercritical to subcritical conditions using planar laser induced fluorescence

The study of fluid jet dynamics at supercritical conditions involves strong coupling between fluid dynamic and thermodynamic phenomena. Beyond the critical point, the liquid-vapor coexistence ceases to exist, and the fluid exists as a single phase known as supercritical fluid with its properties that are entirely different from liquids and gases. At the critical point, the liquids do not possess surface tension and latent heat of evaporation. Around the critical point, the fluid undergoes large changes in density and possesses thermodynamic anomaly like enhancement in thermal conductivity and specific heat. In the present work, the transition of the supercritical and near-critical elliptical jet into subcritical as well as supercritical environment is investigated experimentally with nitrogen and helium as the surrounding environment. Under atmospheric condition, a liquid jet injected from the elliptical orifice exhibits axis switching phenomena. As the injection temperature increases, the axis switching length also increases. Beyond the critical temperature, the axis switching is not observed. The investigation also revealed that pressure plays a major role in determining the thermodynamic transition of the elliptical jet only for the case of supercritical jet injected into subcritical chamber conditions. At larger pressures, the supercritical jet undergoes disintegration and formation of droplets in the subcritical environment is observed. However, for supercritical jet injection into supercritical environment, the gas-gas like mixing behavior is observed.

Effects of injection temperature on mechanical properties of bagasse/polypropylene injection molding composites

Effects of injection temperature on thermal degradation and porosity of the bagasse/polypropylene injection molding composites were studied. Above 185 ºC, incomplete filling occurred. The incomplete filling increased with increase of injection temperature. It was found that the gas generated by thermal degradation of bagasse fibers was so accumulated in the injection cylinder that the injected composites ended up with incomplete filling. A modified injection method with the venting of gas increased the complete filling percentage. Mechanical properties decreased with increase of injection temperature from 165 ºC to 260 ºC. This was due to increase of porosity and fiber shortening. The calculated flexural modulus, which incorporated the effect of porosity and fiber length, agreed well with the experimental results. Composites with maleic acid anhydride grafted polypropylene (MAPP) were also investigated. Flexural strength and impact strength were improved by 45% and 35%, respectively, by addition of 20wt% MAPP. In the MAPP composites, fiber breakages at their roots were observed in the fracture surface after an impact test, while pulled-off fibers were observed in those without MAPP.

EFFECT OF INJECTION TEMPERATURE ON DISPERSION PHASES AND MECHANICAL PROPERTIES OF POM/TPU BLENDS

The effects of injection temperature on the dispersion phase and mechanical properties of polyoxymethylene/thermoplastic polyurethane elaster(POM/TPU) blends were investigated.The experimental results showed that the notched impact strength of POM/TPU blends was greatly influenced by injection temperatures,and the highest value,19.1 kJ/m~2,appeared at 195℃,two times as high as the value obtained at 175℃.Because the viscosity ratio of POM to TPU changed with temperature,and reached 1 at around 195℃,and TPU formed strips-like structure in POM matrix along with the flow direction of the melt during injection,which could effectively absorb impact energy,prevent growth of crazes and formation of cracks.With increase of injection temperature,the average particle size of TPU decreased,and the particle size distribution became narrower.It is an effective way to toughen POM by adjusting the viscosity ratio of the dispersion phase and the matrix and controlling the morphology of the dispersion phase.