Injection Temperature Research Articles

A study of geothermal hydraulic fracture surface morphology and heat transfer characteristics

This study analyzed the morphological characteristics of heat-treated granite fracture surfaces subjected to cyclic hydraulic fracturing (CHF) and traditional hydraulic fracturing (THF). The differences in heat transfer characteristics between THF and CHF fracture surfaces were compared using a three-dimensional numerical heat transfer model. The heat transfer properties of CHF fracture surfaces were investigated under varying injection parameters, and corresponding mathematical models were constructed. It was found that the roughness of CHF fracture surfaces was greater than that of THF, and the heat transfer performance was superior. Specifically, the overall heat transfer coefficient (OHTC) for the C1-C3 fracture surfaces increased by 55.71, 63.40, and 75.91 W/m2/K, respectively, compared to the T1-T3 fracture surfaces. The average outlet temperature (Tout) of the CHF fracture surfaces increases with higher injection flow rates and decreases with higher injection temperatures. The OHTC and local heat transfer coefficient (LHTC) exhibit opposite trends. Specifically, injection flow rates have a quadratic polynomial relationship with the Tout and a logarithmic relationship with OHTC. Additionally, the Tout of the CHF fracture surface shows a linear positive correlation with injection temperature, while OHTC has a linear negative correlation.

Integrated Characterization of Expanding-Solvent Steam-Assisted Gravity Drainage (ES-SAGD) Processes by Using a Heat-Penetration Criterion within a Unified, Consistent, and Efficient Framework

Summary The hybrid solvent-steam injection [e.g., expanding-solvent steam-assisted gravity drainage (ES-SAGD)] is the most promising method to enhance heavy oil recovery; however, it is quite a challenge to reproduce the experimental measurements and in-situ observations because of the complicated multiphase flow behavior resulting from the coupled mass and heat transfer. In this work, an integrated technique has been developed and applied for the first time to dynamically and accurately characterize an ES-SAGD process within a unified, consistent, and efficient framework. By taking the competitive impact between heat energy and solvent dissolution, a generalized heat-penetration (HP) criterion has been derived and integrated with a numerical simulator to characterize the dynamics of solvent/steam chamber propagation conditioned to the production profiles during hybrid solvent-steam processes. This generalized HP criterion allows us to not only dynamically calculate temperature profiles beyond a solvent/steam chamber interface (SCI) but also accurately and pragmatically quantify mass and heat transfer inside the diluted oil drainage zone as well as the solvent/steam chamber. Also, comprehensive effects of the thermally sensitive co/countercurrent flows are examined with a series of multiphase relative permeabilities. Such an integrated technique has been successfully validated by reproducing the measured solvent/steam chambers in 3D physical ES-SAGD experiments. Good agreements between the simulated and measured production profiles (i.e., injection temperature, pressure, and flow rate) have been made throughout the entire production period. Not only have the measured solvent/steam chambers been reproduced but also sensitivity analyses have been performed to investigate the influences of multiphase flow behavior, solvent concentration, and grid dimension. It is found that the diffusion/dispersion coefficients and thermal properties are dependent on temperature and solvent concentrations, competitively affecting the calculated temperature distributions. Moreover, gas-liquid relative permeabilities can impose a significant impact on the SCI moving velocity as well as the oil drainage front. Such an integrated approach considerably reduces the simulation uncertainties and complexities, offering a straightforward and effective means of dynamically reproducing the observed solvent/steam chambers within a unified, consistent, and efficient framework.

Multi-software based dynamic modelling of a water-to-water heat pump interacting with an aquifer thermal energy storage system

Aquifer thermal energy storage systems may support the decarbonization of heating and cooling energy needs of urban areas, not only in heating-dominated countries but also in Southern Europe. In this framework, this work investigates the adoption of a water-to-water heat pump interacting with two aquifers and activating a small-scale district heating and cooling network serving a mixed-use district of eight residential and office buildings in Rome (Italy). The dynamic behaviour of aquifers has been replicated using the GeoSIAM software. Energy conversion systems and users’ thermal and cooling loads have been simulated in TRNSYS 18. The dynamic models have been integrated using an iterative approach based on conditions regarding plant operation and injection temperature in wells. The proposed solution has been then compared from the energy and environmental perspective with a traditional system, including an air-to-water heat pump. In addition, the balance between heating and cooling mode operation has been assessed. The results obtained encourage the adoption of aquifer thermal energy storage systems in Central Italy. Indeed, the primary energy saving, and the carbon dioxide emissions avoided are equal to 18%, whereas the imbalance between cooling and heating loads is limited to -5.2%.

Experimental investigation on fracture propagation in shale fractured by high-temperature carbon dioxide

The productivity of shale reservoirs was significantly enhanced by the high-temperature CO2 fracturing technique. The injection of high-temperature CO2 into the formation induced rock fracture propagation, creating advantageous pathways for fluid flow. In this research, a self-developed in situ high-temperature convective heat simulation experimental apparatus was employed to systematically conduct simulated experiments on high-temperature CO2 fractured shale under different influencing factors. The experimental results demonstrated that the permeability of CO2 increased as the injection temperature increased. The rock fracture pressure was effectively reduced by high-temperature CO2 fractured shale. Higher complexity was observed in fracture propagation, accompanied by a substantial increase in microcracks and branching fractures. The shale fracture pressure increased with increasing triaxial stress and CO2 injection rate. The confining pressure restricted the further propagation of fractures under relatively high stress conditions, thereby reducing the width and density of fractures, lowering the fracture complexity. Nevertheless, the thermal shock effect of the fluid was exacerbated as the injection rate of high-temperature CO2 increased. The initiation of microcracks was facilitated by the intensification of local thermal stress in shale, inducing multiple curved fractures and forming a more complex fracture network. Compared to horizontal bedding shale, the fracture pressure of vertical bedding shale was relatively higher during high-temperature CO2 fracturing. In addition, the geometric morphology of fracture propagation was more complex, characterized by rougher fracture surfaces, leading to a greater improvement in reservoir reconstruction volume. This research contributed to the optimization of CO2 resource utilization, provided experimental evidence for the application of high-temperature convection fracturing technology in in situ shale conversion projects.

Low-threshold limaçon-shaped micro-cavity semiconductor lasers with an approximate ring-shaped top contact

Based on the whispering gallery mode (WGM) characteristics in the limaçon-shaped micro-cavity, we designed a micro-cavity laser with an approximate ring-shaped top electrical contact, which theoretically realized the annular current injection and low temperature rise features in the active gain region. Then we fabricated micro-cavity lasers with approximate ring-shaped top contact at different ring widths and compared them with conventional full disk-shaped top contact lasers, and observed a lower operating injection threshold current as a consequence of this relatively straightforward and feasible technique. The threshold current density of the approximate ring-shaped top contact laser is ∼0.41 kA/cm2, which is 16% lower than that of the conventional laser. Furthermore, we obtain a maximum light output peak power of 133 mW with directional emission at a far-field divergence angle of ∼38° at a full width of half maximum (FWHM).

Study on optimization of thermal injection parameters in fractured reservoirs of HDR

ABSTRACT To improve the heat recovery of hot dry rock (HDR) and realize the efficient and sustainable development of geothermal energy, it is necessary to analyse the factors affecting the heat recovery performance of HDR fractured reservoir. In this paper, a numerical model of heat recovery in fractured reservoirs with HDR is established. The effects of injection parameters on the heat recovery performance of the Enhanced Geothermal System (EGS) are compared and analysed by means of the average temperature, heat extraction rate, production temperature and heat recovery power of matrix rocks at different locations. The influence degree of injection flow rate and injection temperature on production temperature was analysed by grey correlation analysis method. The results showed that reducing the injection temperature is beneficial to fully extract the heat energy in the rock mass. The injection flow rate is positively correlated with the heat extraction rate and negatively correlated with the extraction temperature. In this simulation scheme, the optimal results are as follows: injection temperature is 298.15K, injection flow is 12 kg/s, and the influence of injection flow on production temperature is greater than that of injection temperature. This study provides a theoretical basis for the development and utilization of geothermal energy in HDR and provides a reference for the design of engineering operation parameters.

Optimization of polypropylene high-strength injection molding welding and interface structure analysis

Secondary injection molding is an effective method for joining polymer parts, where the weld interface plays a critical role in the overall performance of the part. This study discusses the influence of injection molding parameters on the interface strength of polypropylene and polypropylene (PP-PP) secondary injection molding and analyzes the welding interface structure. The injection molding parameters for PP-PP were optimized using the Taguchi method and the signal-to-noise ratio (S/N). The optimal injection molding parameters were determined to be a mold temperature of 120°C, injection temperature of 350°C, and injection speed of 100 mm/s. The interface tensile strength was measured at 33.42 MPa, corresponding to 98.1% of the tensile strength of the base material. Among these parameters, mold temperature has the greatest influence on the strength of the welding interface. Secondly, polarizing microscopy, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were employed to observe and analyze the crystal structure and fracture failure modes at the interface. The results indicate that elevated injection molding parameters promote the formation of crystal nuclei and spherulite growth at the secondary melt interface, with the spherulite size at the interface significantly affecting the interface strength. This study offers valuable reference for the welding of other polymers and fiber-reinforced materials.

Control of the parameters of thermosetting binders directly during the molding of products made of polymer composite materials

For aviation binders at the moment there is no necessary methodological base on the basis of which it is possible to control the conditions of their curing by viscosity, reaction rate and glass transition temperature in real time. The paper presents a method of control of thermosetting binder parameters directly during the molding process. The epoxy binder VSE-59 was studied. A mathematical model of the relationship between the frequency maximum parameter of the imaginary component of the electrical impedance and the degree of curing is given, the results of dielectric analysis are compared with laboratory methods (differential scanning calorimetry and rheometry). It is shown that the convergence of the values of the degree of conversion is high. Rheological and dielectric analyses revealed a direct correlation between electrical and rheological properties in the range of injection temperatures. Equations were determined and coefficients were experimentally selected to describe the correlation between viscosity and glass transition temperature and dielectric parameters, which provides the possibility of their control in real time. The obtained results can be used to create a hardware and software base, which makes it possible to control the state of the binder at each moment of the process of forming products from polymer composite materials, as well as to carry out optimization to eliminate the emergence of conditions of uneven polymerization. Realization of the detailed control of the binder state in different parts of the product will allow to carry out verification of calculations, to predict and avoid the occurrence of warping and, accordingly, to increase the quality of composite products.

Numerical simulation for subsidence control in CO2 storage and methane hydrate extraction

Gas hydrates are increasingly viewed as a promising alternative to traditional fossil fuels. However, their extraction process poses risks to structural integrity, potentially causing significant subsidence. In this study, we developed a Thermo-Hydro-Mechanical-Chemical (THMC) model to analyze the impact of gas hydrate extraction on seabed subsidence. Our investigation focused on the influence of bottom hole flowing pressure, initial hydrate concentration, gas saturation, permeability, porosity, and rock thermal conductivity on subsidence during gas hydrate extraction via depressurization.The results show that seabed subsidence is affected by various factors such as bottom hole flowing pressure, initial hydrate concentration, gas saturation, permeability, porosity, and rock thermal conductivity. It was noted that significant subsidence is associated with low initial hydrate concentration, high permeability, porosity, low gas saturation, low rock thermal conductivity, and a notable pressure drop of 79.31%.To address this issue, we propose a seabed subsidence mitigation strategy involving CO2 injection. This approach not only safeguards offshore infrastructure and coastal communities but also helps reduce CO2 emissions, aligning with global climate change mitigation efforts. In our model, CO2 injection occurs in the subsurface reservoir at the interface between the free water zone and hydrate-bearing formations. The CO2 hydrates formation process releases heat, which dissociates methane hydrates, allowing the methane to be replaced by CO2 molecules and move towards the production well.Our analysis reveals that increasing injection temperature and rate significantly reduces subsidence. Additionally, the range of investigated injection pressures, which included pressures equal to and more than double the initial reservoir pressure, showed inconsequential impacts on seabed subsidence.The effectiveness of subsidence reduction is significantly enhanced by injecting a CO2/N2 mixture compared to pure CO2 injection. The most substantial reduction in subsidence occurred when a mixture of CO2 and N2 in a 50/50 vol/vol ratio was injected at a high rate.These findings offer crucial insights for optimizing the efficiency and control of gas hydrate extraction methods. They emphasize the importance of employing balanced injection strategies to minimize environmental risks and ensure sustainable energy extraction.

Thermo-hydro-mechanical fully coupled model for enhanced geothermal system and numerical solution method based on finite volume method

Enhanced geothermal system (EGS) has been widely used to improve the production performance of geothermal reservoirs. Extracting the heat energy from geothermal reservoirs involves complex multi-physical process, referred to as the thermal–hydro–mechanical (T–H–M) coupling. To optimize the production schedule, numerical simulator is an important tool for EGS development. However, the numerical solution method based on FVM is rare in the literature. To address this gap, in this study, we derive the mathematical equations of fully coupled T–H–M model. Then, the solution method based on FVM is established. Next, the its accuracy is verified against two cases. Last, the proposed method is applied to an EGS model to simulate the heat extraction process. The evolutions of pressure, temperature, and fracture aperture are analyzed. The effects of controlling parameters of the extraction efficiency are discussed. Results indicate that increasing the injection rate will reduce the lifespan of EGS but accelerate the energy extraction. Increasing the injection temperature can promote the heat extraction to limited extent. Increasing the matrix permeability can significantly improve the extraction efficiency. Enlarging the fracture spacing can enlarge the heat recovery rate. In addition, reducing the fracture permeability can avoid thermal shortcut and improve the production performance.

Techno-economic optimization of enhanced geothermal systems with multi-well fractured reservoirs via geothermal economic ratio

Enhanced Geothermal System (EGS) shows vast potential for exploiting deep geothermal energy sources, although its techno-economic feasibility remains uncertain. The current research challenge lies in the absence of a reliable tool to rapidly evaluate the economic gains associated with the design of geothermal reservoirs. This study aims to develop an evaluation metric to assess the geothermal economic ratio of EGS. The efficacy, practicality, and simplicity of the proposed metric were demonstrated through its application to reservoir cases involving six fracture structures and four influencing parameters. The geothermal economic ratio of the system was enhanced through the augmentation of injection mass and the expansion of production well spacing. However, it was reduced by higher injection temperatures and wider primary fracture apertures. Using response surface design, the optimal parameters were found to be an injection temperature of 24 °C, an injection mass of 30 kg/s, a primary fracture aperture of 6.192 mm, and a production well spacing of 200 m. These parameters facilitated a reservoir heating efficiency of 0.322, a reservoir flow efficiency of 0.514, and a geothermal economic ratio of 1.026 × 10−20. The proposed metric and results would offer a concise and informative analysis of the market potential of EGS.

Influence of Dilution and Effusion Flows in Generating Variable Inlet Profiles for a High-Pressure Turbine

Abstract The elevated flow temperatures and pressures exiting gas turbine combustors affect the efficiency and durability of the high-pressure turbine stage. Understanding the effects that result from the upstream dilution and effusion flow interaction in creating the combustor exit profiles is important to advancing gas turbines. Understanding how common combustor features, such as dilution jets and effusion cooling, interact based on computational predictions guided the design of a non-reacting profile simulator capable of producing a wide range of non-uniform temperature profiles representative of those entering high-pressure turbines. The mechanical design of a new simulator device, which will be experimentally tested in the future, is presented in this paper along with computational predictions of flow and thermal fields. The simulator was designed for modular installation into the Steady Thermal Aero Research Turbine (START), which is a continuous-duration, steady-state turbine facility that houses a single-stage test turbine. Features of the simulator included interchangeable liner panels with multiple rows of dilution jets and wall effusion cooling to study various hole diameters and patterns. The dilution jets generate elevated turbulence intensities and tailor the temperature profiles in the radial and circumferential directions. The air mass flow distribution and source flow temperatures are independently controlled. To aid in the simulator design, computational fluid dynamics (CFD) simulations using Reynolds-averaged Navier–Stokes modeling were conducted with a two-level Design of Experiments (DOE) approach to determine a number of engine-representative target profiles with temperature shapes that are mid-radius peaked, outer-diameter peaked, inner-diameter peaked, and uniform. A sensitivity analysis of the CFD DOE results determined which factors significantly affected the profile shape so that the target profiles could be produced. The analysis indicated that the main contributor to the temperature profile shape at near-wall vane radial span locations of 0–15% and 85–100% was the injection temperature of the effusion flow. The main contributor at radial span locations of 15–40% and 60–85% was the injection temperature of the third-row dilution jets, and at the mid-radius location of 40–60% vane radial span, the main contributor was the diameter of the first-row dilution holes.

Harnessing the heat below: Efficacy of closed-loop systems in the cooper basin, Australia

Transitioning to renewable energy is vital for combating climate change and reducing CO2 emissions. Geothermal energy, sourced from the earth's crust, presents a promising alternative. While shallow geothermal energy extraction grows steadily, tapping into deep Hot Dry Rock reservoirs poses challenges. Sustainable utilization of deep geothermal energy is crucial for large-scale electricity generation. Australia's Habanero enhanced geothermal system (EGS) projects faced obstacles due to complex fracture networks. Borehole heat exchangers (BHEs) offer a solution, circulating a working fluid without direct contact with geofluids. This study assesses coaxial BHEs' feasibility in the Habanero reservoir using a 2D axisymmetric model (2D-AM), comparing it with a simpler 1D depth-integrated model (1D-DIAM). Both models yield similar outcomes. Additionally, results indicated that the production temperature of the coaxial BHE exponentially decreased from 250 °C to 100 °C within 10 h, rendering energy recovery for electricity generation unsuitable after 10 h of operation. The study proposes an energy recovery cycle of 10 h followed by a 110-h shutdown. Injection temperatures and flow rates significantly impact production efficiency, while steel casing's thermal conductivity has minimal influence on heat exchanger performance.

Examining the factors that impact the formation of barite scale in water injection operations: experimental study and quantification of scale formation

Barium sulfate (BaSO4) scale formation in oilfield operations is a significant problem that leads to severe operational challenges, including reduced production efficiency and increased maintenance costs. Understanding the factors that influence BaSO4 scale formation, such as injection rate and temperature, is crucial for developing effective mitigation strategies. In this study, we systematically investigated the effects of injection rate and temperature on BaSO4 scale formation using a series of controlled laboratory experiments. The injection rates varied between 1 and 5 mL/min and temperatures between 25 and 75 °C, simulating realistic field conditions. Our findings indicate that higher injection rates and elevated temperatures significantly increase the amount of BaSO4 scale formed. Specifically, the scale formation increased from 15.2 mg/L at 1 mL/min and 25 °C to 22.3 mg/L at 5 mL/min and the same temperature. Similarly, at a constant injection rate of 3 mL/min, the scale formation increased from 18.1 mg/L at 25 °C to 26.5 mg/L at 75 °C. The study employed Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) to analyze the crystal morphology and structure of the formed scales. SEM images revealed a transition from dendritic structures at lower temperatures and slower injection rates to spherical crystals at higher temperatures and faster injection rates. XRD patterns indicated variations in crystallinity and phase purity corresponding to the experimental conditions. Our results align with previous studies that report increased nucleation rates and reduced solubility of BaSO4 at higher temperatures and injection rates. These findings highlight the critical role of controlling operational parameters to mitigate scale formation in oil and gas operations. By optimizing injection rates and temperatures, it is possible to reduce scale deposition, thereby improving production efficiency and reducing maintenance costs. This study provides valuable insights for the development of scale management strategies and underscores the importance of a comprehensive understanding of the physicochemical factors affecting BaSO4 scale formation.

Comprehensive analysis of thermal performance and low-grade energy charging efficiency of pipe-embedded building envelopes enhanced with single-level tree-shaped fin structures

Pipe-embedded walls (CnPWs) are structural and energy composite building components that can resist external disturbances by forming stealth thermal shielding layers. To tackle the mismatch between the heat charging rate and heat diffusion rate during energy charging processes, as well as the unsatisfactory robustness of stealth thermal shielding layers, the single-level tree-shaped metal finnd pipe-embedded walls (TfPWs) are proposed. To verify the effectiveness of TfPWs and obtain dynamic performances, a simulation study is conducted on 8 risk variables in 4 pairs through the validated numerical model. Results showed that the improved design was effective in obtaining more robust thermal shielding layers in auxiliary energy supply mode, the effect gained prominence as both the injection temperature and pipe spacing were augmented. In room heat load reduction mode, favorable benefits arise when pipe spacing exceeds 400 mm. The maximum increase rate of total injected energy under different reduction ratios of external insulation layer was 11.83%–31.91 %, while the maximum extra total heat loss was 5.33 %. Secondly, the trunk fins and branch fins played different roles in minimizing the excessive heat accumulation surrounding pipes, and the vertical and horizontal sizes of heat accumulation region mainly increased with the increase in trunk fin size and branch fin size respectively. Meanwhile, the utilization efficiency of fin material was higher when trunk fin size was smaller, and parameter combinations with trunk fin size of 0.2b and branch fin size of 0.4a/0.6a could achieve a better balance between material input and performance increase. Thirdly, the improvement effect of single left branch fin schemes was close to that of double branch fin schemes and significantly better than that of single right branch fin schemes. It was recommended to use single left branch fin schemes with an inclination angle of 60°. Finally, even if the reduction ratio of external insulation layer in different cities increased to 80 %, the inside surface temperature of TfPWs was still greater than room air. Taking CnPWs with standard external insulation layer as references, the TfPWs applied in Harbin, Beijing, and Shanghai could achieve similar or better results even when the reduction ratio of external insulation layer increased to 60 %, while TfPWs applied in Guangzhou could exhibit better performance even when the reduction ratio of external insulation layer increases to 80 %.

Optimizing the heat extraction performance in the Qingfeng Karst geothermal reservoir

Faults are typically associated with hydrothermal reservoirs and may control the heat extraction of geothermal reservoirs. However, in Karst geothermal reservoirs, the dissolution of soluble rocks results in pronounced spatial porosity and permeability anisotropy (PPA), potentially weakening the dominant role of faults. The question arises: which plays a dominant role, PPA or faults? Should geothermal exploitation strategies be adjusted under the interaction of both factors? In this study, we proposed a coupled Thermal-Hydraulic-Geothermal Wellbore (THG) numerical simulation model to streamline the integration of non-isothermal flow and heat transfer processes within a 3D wellbore. Utilizing this model, we analyzed the influence of faults compared to PPA and assessed the geothermal well doublet's heat extraction performance, including thermal breakthrough time, temperature losses along the wellbore wall, and recovery factor (Rg). There are specific geothermal reservoir development conditions leading to the latest thermal breakthrough time and the maximum Rg. The results of contribution rates highlight the influence of injection rate in determining Rg. It is crucial to note that thermal breakthrough time does not necessarily increase with injection temperatures. A more suitable definition for thermal breakthrough time in the Karst geothermal reservoir has also been identified. This study provides an essential reference value for the efficient development of similar Karst geothermal reservoirs.

Thermal recovery of heavy oil reservoirs: Modeling of flow and heat transfer characteristics of superheated steam in full-length concentric dual-tubing wells

Accurately predicting the flow and heat transfer characteristics of superheated steam (SHS) in the wellbore is essential for efficiently developing heavy oil reservoirs. However, few studies have examined SHS flow in full-length concentric dual-tubing wells (CDTWs). In this paper, firstly, based on fluid dynamics and thermodynamics theories, a mathematical model for SHS flow in vertical and horizontal wellbores is proposed. Then, this model is solved using a finite difference method for spatial discretization and an iterative technique. Finally, model verification, type curve analysis, and sensitivity analysis are conducted sequentially. The results indicate that SHS temperature and pressure are independent variables, and the effect of friction energy on temperature is greater than its impact on pressure. The injection rate has a critical value, and the critical injection rates of the main controlling factors affecting the pressure drop and temperature drop of SHS in the vertical tubing are different. When the injection rate is below the critical value, the gravitational force of the SHS helps maintain high enthalpy. The SHS should be transported to the well bottom as quickly as possible. To enhance the uniform heating effect of the reservoir and improve heat utilization efficiency, a relatively small injection rate, high injection pressure, and low injection temperature are recommended. The uniformity of SHS pressure and temperature distribution in the horizontal annulus positively correlates with the uniformity of the reservoir's heat absorption rate. Achieving more uniform SHS pressure and temperature profiles in the horizontal annulus benefits the uniform heating of the reservoir.

Experimental Study on Factors Influencing the Efficiency of Hot Water Injection in Offshore Heavy Oil Reservoirs

Abstract In response to the problem of low final recovery rate in conventional water flooding development of offshore heavy oil, the Bohai LD5 heavy oil field was taken as the target area. Through one-dimensional oil displacement efficiency experiments, the influence of crucial injection and production parameters on oil displacement efficiency, such as temperature, injection rate, injection production ratio, timing of hot water flooding, and injection medium, was studied. The key injection and production parameters were optimized, and the main controlling factors affecting the efficiency of hot water flooding after water flooding were identified through data analysis. Propose an optimization approach for thermal injection media and quantitatively evaluate the oil recovery efficiency under different injection and production parameters. Research has shown that for the Bohai LD5 heavy oil field, the optimal combination of injection and production parameters is: an injection rate of 2mL/min, injection temperature of 110°C, and timing of conversion to flooding at a recovery rate of 20% to 30% (water content of 55% to 70%). The hot water composite flue gas has the best oil recovery effect, considering both oil recovery efficiency and on-site construction conditions. The degree of influence of various factors on the efficiency of hot water flooding is as follows: temperature>timing of hot water flooding (recovery degree)>injection rate. Under low temperature (within 110 °C) conditions, temperature is the main factor affecting the efficiency of hot water flooding. The overall recovery rate of different injection media shows a trend of hot water composite>hot water>cold recovery.

Moulding of SS316L surgical component using palm-stearin feedstock: Rheological analysis, process window and parametric optimisation

Metal injection moulding of a thin surgical component using a palm-stearin based SS316L feedstock was investigated. The study first determined the optimal solids loading of the feedstock, followed by examining its sensitivity to the shear rate and temperature, to ensure its pseudo-plastic behaviour. After developing the Mouldability index, a process window was established based on the experiments to present appropriate injection parameters. Using the analysis of variance, the significance and mutual coupling of each parameter was evaluated. The study found that the impact of injection speed was greater than other parameters, while holding pressure showed little effect. The verified optimised injection parameters to maximise the green density were found to be an injection temperature of 155 °C, an injection speed of 80 mm/s, a holding pressure of 83 bar, a holding time of 9 s, and an injection pressure of 132 bar, resulting in a green part density of 4.892 g/cm3.

Two-Dimensional Physical Model Experimental Study on Sweep Efficiency of Offshore Heavy Oil Hot Water Flooding

Abstract The conventional water flooding approach for the development of ordinary heavy oil faces challenges such as high injection-production mobility, rapid increase in water cut, and low final recovery. By using the temperature-sensitive properties of heavy oil, the viscosity can be effectively reduced, and the flow capacity within porous media can be enhanced by increasing the temperature of injected water. Onshore hot water flooding is primarily used to exploit the remaining oil potential during the later stages of steam stimulation, while offshore is used to enhance efficiency during the mid to late stages of water flooding. The key to the success of hot water flooding technology lies in the improvement of the sweep coefficient. Firstly, a two-dimensional physical experiment model is designed in accordance with the geological and reservoir characteristics of the target oilfield, based on the principle of similarity. Secondly, parameters that quantitatively characterize the development law of the plane temperature field, such as the effective sweep coefficient, regular factor, and plane expansion speed of the high-temperature region, are studied. Then, through two-dimensional experiments, the effects of injection medium, formation rhythm, and timing of hot water injection on sweep efficiency and temperature field development were discussed. Finally, on the basis of two-dimensional experiments, the effects of heat injection temperature, timing of heat injection, hot water injection speed, and high permeability strip on the improvement of sweep efficiency were quantitatively analyzed by numerical simulation. The results show that compared with hot water flooding, hot water composite flooding can increase the effective sweep coefficient from 15.05 % to 28.71 %. The anti-rhythm is helpful to the upward expansion of the high temperature zone, which can increase the oil displacement efficiency by 1.5 %. Water channeling can be effectively controlled by injecting hot water with low water cut. The increase of heat injection temperature is helpful to increase the proportion of high temperature heating area. The higher the injection speed, the greater the expansion speed of the heating chamber. The research results provide a direction for the development of heavy oil conventional water flooding to improve oil recovery in offshore heavy oil.