Injection Flow Research Articles

Numerical simulation of oil shale in-situ exploration productivity comparison between steam injection and electrical heating

Oil shale is an important alternative resource to the conventional oil and gas because of its rich reserves. The in-situ heating exploitation is the most promising method to produce oil from the oil shale, mainly including electrical heating and steam injection heating. However, to the best of our knowledge, a comprehensive comparison between these two kinds of heating methods is still absent, thus the comparison is necessarily conducted to provide suggestions on how to select heating modes for the oil shale in-situ exploitation. On this basis, a systematic comparison is presented between in-situ steam heating and electrical heating, including physical and process parameters, and then sensitivity analysis and optimization on key parameters are carried out. Simulation results show that steam injection heating is superior to electrical heating in output, energy consumption and production cycle. The flow rate and temperature of the injected steam and the specific heat capacity of oil shale are sensitive to productivity. The production will be increased with larger injection flow rate and temperature. The thermal conductivity and porosity are less sensitive to the mining efficiency compared to the injection flow rate and temperature. At the same time, different well pattern structures also have an impact on productivity, and the hexagonal well pattern has better productivity benefits than the triangular and quadrilateral well patterns. In the simulation case of this paper, the most conducive parameters for exploitation were derived as injection flow rate 0.20 kg/s, injection temperature 650 °C, specific heat capacity 1.5 kJ/(kg⋅K), thermal conductivity 0.5 W/(m⋅K), porosity 0.05. These results are expected to provide theoretical suggestions for improving the productivity efficiency of oil shale in-situ exploitation.

Injection Flow Rate Threshold Preventing Atypical In-Cavity Pressure during Low-Pressure Powder Injection Molding

Controlling injection parameters is paramount when it comes to producing high-quality green parts using powder injection molding. This work combines experimental and numerical approaches to study the impact of injection parameters on mold in-cavity pressure and on the overall quality of green parts produced by low-pressure powder injection molding. The properties of two low-viscosity feedstocks (formulated from a water-atomized stainless-steel powder and wax-based binder system) were measured and implemented in an Autodesk Moldflow numerical model to quantify the molding pressures, which were finally validated using experimental real-scale injections. The results confirmed that an increase in mold temperature, an increase in feedstock temperature, and a decrease in solid loading decrease the mold in-cavity pressure, which was correlated with the feedstock viscosity. As a key result, real-scale injections confirmed that a minimum flow rate was required to avoid atypical high in-cavity pressure leading to several visual defects such as weld lines, flow marks, cracks, sinks, and incomplete filling. Due to differences in its thermal transfer properties, this flow rate threshold value decreases as the feedstock solid loading increases. For injection speeds higher than this value, the injection pressure measured experimentally was linearly correlated with the injection flow rate.

Experimental and Simulation Investigation on Ball-Sealer Transport and Diversion Performance Aided by Machine Learning Method

Summary Ball-sealer diversion has been proven to be an effective and economical way to increase fractures and fracturing volume in multistage hydraulic fracturing and matrix acidizing treatments. However, designing and implementing a successful ball-sealer diversion treatment is still challenging. Typically, operators rely on empirical data to determine diversion parameters and need an understanding of accurate ball transport and diversion behaviors. A model for optimizing operating parameters, including fluid and ball properties, and predicting the diversion performance of ball sealers before treatment is needed for designing the fracturing process. In this work, we systematically investigated ball-sealer diversion using experimental and numerical methods. The resolved model of computational fluid dynamics (CFD) and discrete element method (DEM) is first developed to simulate the transport of a large ball in a horizontal wellbore with side holes. The experimental results validated the numerical model. The effects of the ball position in the pipe, flow ratio of the hole to pipe, injection flow rate, and ball density on the diversion performance were studied under field parameters. The results show that the ball sealer easily misses the heel-side perforation due to the inertial effect and travels to the toe side due to the large inertia and turbulent flow. The ball position and flow rate ratio are crucial for the diversion performance. There is a threshold value of the ball position under the specific condition, and the ball successfully turns to the perforation only when the threshold distance is met. A ball sealer closer to the perforation will have a larger probability of blocking the hole than the ball at the other side of the wellbore. The larger the flow rate ratio, the more the drag force on the ball, and the ball can successfully divert to the perforation despite the ball being far from the hole. The injection flow rate and ball density negatively correlate with the diversion performance due to the large inertia and gravity. The best classification result with the F1 score of 87.0% in the prediction set was achieved using the random forest (RF) algorithm. It provides new insight into developing ball sealers and adjusting fracturing parameters based on machine learning (ML) methods.

Effects of inflow velocity on transverse jet injection in a supersonic cavity combustor

The flow, mixing, and combustion mechanisms in the wide range scramjet engine are complex and far from clear. In the present work, the mixing flow of a sonic transverse jet injection in a supersonic cavity combustor is numerically investigated at two typical inflow velocities. The basic flow structures, unsteady flow dynamics, average flow structures, and several significant mixing performance parameters are well captured and compared based on high-resolution large eddy simulation. The simulation results show that separation shock induced by the jet is gradually merged with the bow shock at low Mach inflow so that the curved shock flow patter is produced. In addition, smaller large-scale coherent structures at the windward side and slower large-scale vortex transport are observed at low Mach inflow. At low Mach inflow, moreover, much narrower range of jet species mass fraction distributions and more upstream large-scale vortices breakdown and dissipation can be observed. The low Mach inflow generates weaker pair of counter-rotating vortices and some trailing counter-rotating vortices, which primarily leads to the weaker jet/cavity interaction. The baroclinic term effects are considerably weaker at low Mach inflow in the near field. In view of mixing efficiency and flammability efficiency, the effect of the cavity in enhancing mixing is more evident at low Mach inflow.

Investigation of nozzle geometry and wall roughness effects on diesel injector flow

The flow and design of fuel injector nozzles have a considerable influence on the spray and combustion characteristics of a diesel engine. In-cylinder combustion, atomization, and primary breakdown are all highly influenced by the cavitation and turbulence in the fuel injector nozzle. In this paper, the effect of the nozzle geometry parameters, wall roughness parameters, and pressure difference on the swirl number, mass flow rate, turbulent kinetic energy, and vapor volume fraction is explored. U-type nozzle hole geometry, a well-known benchmark for the injector nozzle flow, is used to evaluate mesh independence and model validation. Large-eddy simulations are performed to provide a precise presentation of the flow structures and turbulent eddies inside the nozzle. Multiphase flow is studied using the mixture model, whereas cavitation is studied using the Schnerr–Sauer model based on the Rayleigh–Plesset equation. We find that the wall roughness parameters have an exciting impact on the discharge coefficient, swirl number, and vapor volume fraction. Due to the non-monotonic dependence of nozzle flow characteristics on the pressure difference and the wall roughness parameters, we can always find such values of these input parameters that render optimal nozzle flow characteristics. In this way, these parameters provide good control of spray formation and consequently on the quality and rate of combustion in the diesel engine.

Drawing 3D fluid patterns in beverages using a robotic nozzle

Existing three-dimensional (3D) printing technologies assume the production of solid structures on a platform, regardless of whether they are edible. In contrast, we establish a technology that enables the construction of a 3D structure made of liquid into a liquid matrix, where both liquids are edible as beverages. The blur caused by the diffusion of ink is suppressed by a constituent particle size design without resorting to macroscopic plasticity, whereas sedimentation or floating is prevented by tuning the mass density. Mixing by the drawing motion is suppressed by the design of the robotic nozzle motion, where the dynamic positioning and orientation of the nozzle are controlled alongside the injection flow rate of the edible ink. As a demonstration, we draw a complex 3D structure of a fish in tea within 40 s, and the pattern maintained apparent clarity over several hours.

The thermal-fluid-mechanical (TFM) coupling method based on discrete element method (DEM) and the application of CO2 fracturing analysis

Due to the challenges of the complex temperature, fluid and mechanical coupling phenomenon during CO2 fracturing, a new thermal-fluid-mechanical (TFM) coupling method is proposed by using PFC2D fish code. This method utilizes the PFC2D fish code and combines the heat transfer difference algorithm with Cundall's fluid-mechanical coupling algorithm to establish a TFM model for CO2 fracturing. Subsequently, the validation of the TFM coupling model is conducted using the analytical solution provided by the plane strain Khristianovic Geertsma-de Klerk (KGD) model. The reservoir temperature variation, pore pressure and crack propagation are studied considering many involved factors, such as injection fluid temperature, injection flow rate, in-situ stress and formation temperature. Crack number and length would increase with the increasing temperature difference between fracturing CO2 and reservoir temperature. The breakdown pressure reduces when there are large injection flow rate or temperature differences between fracturing CO2 and reservoir temperature, which can be optimized in the CO2 fracturing operation. Even CO2 fracturing could create complex fracture network, we must pay attention to the in-situ stress distribution and injection flow rate. Our simulation suggests that pore pressure and heat could prevent the fracture from initiating and propagating in the direction of the minimum principal stress, and the temperature influencing has contributed to the extra pressure increment in the pore domain, which could not be ignored in CO2 fracturing. From the above research, it is expected to offer a novel method to simulate the complex TFM coupling phenomenon and enhance our understanding of CO2 fracturing.

Numerical analysis and economic evaluation of pinnate horizontal well for supercritical CO2-based enhanced geothermal system

Supercritical carbon dioxide (scCO2) is considered an alternative heat carrier for enhanced geothermal system due to its superior thermophysical property. Extensive investigations have been conducted to improve the heat extraction performance of scCO2-based EGS. However, few investigations have focused on the response mechanism of thermal reservoir for the scCO2-based EGS with fully coupled thermal-hydraulic-mechanical (THM) method. The evaluation differences between THM and TH coupling model are still not clear for the scCO2-based EGS. To further improve the heat extraction performance of scCO2-based EGS, a pinnate horizontal well (PHW) EGS is proposed in present work. Three-dimensional (3D) model with fully coupled thermal-hydraulic-mechanical (THM) is established considering the in-situ stress, which is used to evaluate the geothermal energy utilization and economic performance of PHW EGS. The effects of injection-production parameters, reservoir properties and fracture parameters on the heat extraction performance of PHW are probed. The results revealed that reservoir permeability shows a descending tendency while fracture aperture experiences a significant increase, when the effects of in-situ stress are taken into account. If the in-situ stress is ignored, the production temperature and maximum useful work will be overestimated by about 13 K and 16.4%, respectively. PHW EGS is characterized by the low pump consumption, high system efficiency and net revenue. Compared with doublet EGS, pump power is decreased by 58.1%, the system efficiency is boosted by 2.6 times, and the net revenue is increased by 35.3% at the terminal stage. It has been proved that the heat extraction performance is evidently affected by the injection flow rate and temperature of working fluid, initial reservoir permeability, initial aperture and maximum closure. Appropriate operation strategy can effectively improve the performance of PHW EGS. In addition, the optimized average electricity price, accumulative income and net revenue of PHW EGS can reach to 0.251 CNY/(kW·h), 9.27 × 108 CNY and 6.65 × 108 CNY after 40 years of operation, respectively.

Optimization and Performance Evaluation of an Atomized Acid System for the Expansion of Carbonate Gas Injection

The conventional liquid acid has several shortcomings in the acidizing process of fractured-vuggy carbonate reservoirs, including high filtration loss, fast reaction rate, high friction resistance, and difficult flowback. To address these issues, a new atomizing acid acidizing technology is proposed, combining the gas injection development practice from the fractured-vuggy carbonate reservoir in the Tahe oilfield. The laboratory experiments were conducted to optimize the type and concentration of atomized acid, iron ion stabilizer, corrosion inhibitor, and atomization stabilizer. The acid atomization rate was evaluated under different combinations of gas and liquid injection flows using a self-made atomized acid well migration simulator, and the best atomization scheme was selected. Furthermore, a kinetic experiment for the acid–rock reaction was carried out to evaluate the retarding performance of the atomized acid. The optimized formula for the atomizing acid system consists of 15~25% hydrochloric acid, 0.005% atomizing stabilizer (AEO-7), 1% iron ion stabilizer (EET), 1.5% corrosion inhibitor (EEH-160), and water. The optimal gas and acid injection scheme is gas injection at 2m3/min and acid injection at 10 mL/min, which maintains an atomization rate of over 80% after the acid mist migrates through the wellbore. Compared with gelling acid, the acid–rock reaction rate of atomized acid is 8.5, 9.1, and 10.6 times slower under acid concentrations of 15%, 20%, and 25% respectively. The retarding effect of atomized acid is superior, facilitating etching and initiating underdeveloped gas drive channels and thereby increasing the probability of gas communication with new reservoirs. The research findings presented in this paper establish a theoretical foundation for the practical implementation of the atomized acid acidizing process in the field.

Rock damage evolution in the production process of the enhanced geothermal systems considering thermal-hydrological-mechanical and damage (THM-D)

Hot dry rocks (HDRs) geothermal relies mainly on enhanced geothermal systems (EGS) for production. During production, the evolution of rock stress distribution will cause damage to the rock, especially near fractures. The application of damage mechanics in the geothermal field has mostly focused on the process of hydraulic fracturing, with limited reports on damage research related to long-term water injection development. According to previous experimental studies, the effect of rock damage is significant and cannot be ignored. Therefore, based on a thermal-hydrological-mechanical and damage (THM-D) coupling model, it studies the rock damage evolution features and its role in changes in rock physical properties. It also analyzed the effects of the initial temperature, injection flow, fracture curvature/number, and stress difference on damage evolution. Results indicate that the damage area and degree continue to increase with time, but the growth rate becomes slower. There are two methods of damage evolution: the new damage caused by the expansion of the low-temperature region is throughout the process, and the original damage is aggravated in the later stages. Damage will cause changes such as reduced Young's modulus (negative feedback) and increased permeability (positive feedback) of the rock matrix, which in turn affect the damage evolution. More, damage increases with the initial rock temperature, injection mass flow, and stress difference increase, and the impact of the fracture curvature is small. The damage of complex fracture reservoirs is more pronounced than that of single fracture reservoirs. This study provides a tool for analyzing the impact of damage on the production performance of HDRs. The investigation of relevant patterns is expected to offer guidance for production strategies.

Active Fluidic Control of a Nozzle Guide Vane Throat

Abstract Experiments were conducted to validate the building blocks of a fluidically controlled variable area turbine concept that uses injected high-pressure air to effectively reduce the choke area of the turbine inlet. Preliminary results from a simple quasi-1D converging-diverging nozzle, with an injection flow slot upstream of the throat, showed a 2.2:1 ratio between throttled mass flowrate and injected mass flowrate at a constant nozzle pressure ratio. The penetration of the injection flow and corresponding reduction in the primary flow streamtube were successfully visualized using a shadowgraph technique. Building on this success, a representative single passage nozzle guide vane transonic flowpath was constructed to demonstrate feasibility beyond the quasi-1D converging-diverging nozzle. Both secondary slot blowing from the vane pressure surface and vane suction surface just upstream of the passage throat again successfully reduced primary flow. In addition, fluidic vortex generators were used on the adjacent suction surface to reduce total pressure loss and further throttle the primary flow. Implications for the application of this active flow control technology to a variable area turbine are considered.

Heat Transfer and Film Cooling in an Aggressive Turbine Center Frame

Abstract This article investigates the heat transfer coefficient and the film cooling effectiveness in a turbine center frame (TCF). The TCF is a duct connecting the high-pressure turbine (HPT) to the low-pressure turbine (LPT) and is equipped with nonturning airfoils (struts). The TCF is operated in a product-representative 1.5-stage test turbine setup working under Mach number similarity. Upstream of the TCF, an unshrouded HPT is operated with four individually adjustable purge flow injections through the forward and aft cavities on the hub and tip of the rotor. The heat transfer coefficient and the purge film cooling effectiveness are measured on the hub and the nonturning struts of the aerodynamically aggressive TCF using infrared thermography and tailor-made heating foils. To further extend the film cooling investigation, the seed gas concentration technique, in conjunction with the heat-mass transfer analogy, is used as a second film cooling measurement technique. Seeding the HPT cavities with different foreign gases reveals every individual purge flow's contribution to the global film cooling effectiveness in the TCF. In addition, the seed gas technique extends the investigated area for film cooling to the optically inaccessible shroud of the TCF. The heat transfer in the TCF was found to be dominated by secondary flow features of the upstream HPT. Longitudinal streaks of alternating high and low heat transfer were found on the hub connected to the number and the position of the upstream HPT vanes. A similar pattern was found in the film cooling effectiveness, where the film cooling streaks were situated between the high heat transfer streaks. The film cooling coverage on the shroud was found to be even, symmetric, and superior to the hub cooling performance, with around 10% less usage of purge mass flow.

Investigation on preventive inerting approach of coal spontaneous combustion in gob considering adsorption effect.

Coal spontaneous combustion in the gob poses a significant threat to coal mining operations. Designing optimal process parameters for nitrogen injection to prevent and control fires efficiently is crucial. To achieve this, a multi-field coupling equation was established, considering the adsorption of coal to gas. The model's accuracy was verified on-site, and the effects of nitrogen injection at different locations and flow rates were simulated. The optimal injection parameters were determined by analyzing temperature and inerting time. The results showed that the coal spontaneous combustion hazardous zone in the gob tested on-site was consistent with the simulation from the perspective of physisorption. Nitrogen injection had three stages: gas expansion, rapid oxygen dilution, and complete inerting. The nitrogen injection effect presented a nonlinear change in injection location and flow rate. The optimal nitrogen injection location for the Tingnan Coal Mine in Shaanxi was determined to be 90 m behind the working face on the inlet side, with an optimal flow rate of 800 m3/min. This study focused on gas adsorption and offered valuable insights for creating high-efficiency fire-fighting techniques that involve inserting in the gob.

Experimental analysis of boron dilution transient flow mixing characteristics based on planar laser induced fluorescence measurement

In Reactor Pressure Vessels (RPV), flow mixing between high and low concentration coolants will cause uneven distribution of boric acid. Severe cases will lead to boron dilution transient and re-criticality safe operation accident. Therefore, accurate measurement of coolant flow mixing characteristics and boron concentration distribution in RPV and study of the mechanism affecting the mixing process are of great significance to improve reactor operation safety. Based on the structural characteristics of large advanced pressurized water reactor pressure vessel, a large-scale visual experimental device was built by 1:6 scale modular design. Optical path correction scheme is used to solve the problem of optical path distortion existing in PLIF technology, and improved ratio calibration method is used to reduce the experimental error of concentration field distribution measurement. Flow mixing process and boron concentration field distribution in pressure vessel under single loop conditions were obtained based on plane laser induced fluorescence technique (PLIF). The influence of Reynolds number on boron diffusion behavior was studied. The experimental results show that during single loop operation, the localized eddy current formed in the left area of the lower head will result in a high concentration retention zone and a V-shaped boric acid concentration distribution in the core. With the increase of the ratio of cold tube flow to injection flow, the time when the high concentration coolant reaches the core hardly changes with the boric acid solution flow rate. The mixing diffusion behavior of boron concentration is the best when the ratio of injection to Reynolds number in the cold tube is at a certain value.

Multiscale Fractal Characterization of Pore–Fracture Structure of Tectonically Deformed Coal Compared to Primary Undeformed Coal: Implications for CO2 Geological Sequestration in Coal Seams

The tectonically deformed coal (TDC) reservoirs with abundant gas resources and low permeability are expected to become one of the target coal seams for carbon dioxide geological storage-enhanced coalbed methane recovery (CO2-ECBM). The pore–fracture structure plays a crucial role in determining the effectiveness of CO2 storage. Fractal analysis provides a valuable approach to quantitatively describe the complex and heterogeneous pore–fracture structures across various scales in coal matrixes. Accordingly, the TDC samples in the Huainan–Huaibei coalfield and primary-undeformed coal (PUC) samples in the Qinshui Basin were selected for pore–fracture structure parameter tests using the mercury intrusion porosimetry (MIP) and low–temperature nitrogen adsorption (LNA) methods. Their multiscale pore–fracture parameters were analyzed using different fractal methods based on pore diameter. According to the fractal results, a multiscale classification standard for pore–fracture structures was devised in this study that is suitable for the controlling gas migration process. A parameter of 8 nm is set as the separating pore diameter for gas migration and storage. It was observed that the connectivity of migration pores (>8 nm) in TDC samples was stronger compared to PUC samples, reflected in larger pore volumes and smaller fractal dimensions. However, its complex development of seepage pores (150–300 nm) may hinder the flow of CO2 injection. As for the storage pores (<8 nm), the fractal dimension of the 2–8 nm pores in TDC was found to be similar to that of PUC but with larger pore volumes. The fractal dimension of the filling pores (<2 nm) in TDC samples was relatively lower, which facilitates efficient gas volume filling. Therefore, the pore–fracture structure of the TDC samples is found to be more advantages for CO2 injection and storage compared to the PUC. This suggests that TDC reservoirs holds promising geological potential for CO2-ECBM implementation.

Professor Manuel Miró, a researcher with an extensive and prestigious academic career, kindly spoke to BrJAC

Manuel Miró received his M.Sc. (1998) and Ph.D. (2002) in Chemistry from the University of the Balearic Islands, Spain. He has conducted post-doctoral research in several universities, including the Technical University of Berlin, Technical University of Denmark and University of Natural Resources and Applied Life Sciences. He is currently Full Professor in Analytical Chemistry at the University of the Balearic Islands (since September 2017); Guest Professor at Charles University (Czech Republic) (since 2014); and member of the IUPAC Chemistry and Environment Division (Subcommittee on Chemical and Biophysical Processes in the Environment). He has completed and consolidated four teaching periods (each of 5 years) and three research periods (each of 6 years). Dr. Miró is the Reviews Editor of the journal Analytica Chimica Acta (Elsevier, IF: 6.91, the second highest IF across scientific journals for general analytical chemistry) and Associate Editor of the Encyclopedia of Analytical Science, 3rd Edition, Elsevier, positions that he has held since 2007 and 2016, respectively. His publication record shows over 220 refereed publications, including 14 book chapters and a foreword, with an h-index of 42 and over 5600 citations. He has published 24 articles in the prestigious journal ‘Analytical Chemistry’ from the American Chemical Society and is the corresponding author of 110 articles. Dr. Miró has delivered 70 oral presentations (60 as plenary, keynote, or invited lecturer) at international conferences on analytical chemistry, sample preparation, nanotechnology, environmental chemistry, and automation based on flow methodology. He has also presented over 180 poster communications in international conferences and symposiums. He has supervised 10 Ph.D. students in national and international universities (Technical University of Denmark, Mahidol University and Chiang Mai University in Thailand, University of the Balearic Islands in Spain, and Federal University of Bahia in Brazil). He has been actively engaged in 34 national and international research projects (e.g., University of Melbourne in Australia and Charles University in Czech Republic), including 16 as the Principal Investigator. Dr. Miró’s research interests are focused on the development of on-line sample processing strategies for isolation and/or preconcentration of trace levels of environmental pollutants, exploiting 3D printing in the generation of various flow injections, including 3D-printed µFIA and Lab-on-a-Valve mesofluidic platforms, in conjunction with modern analytical instrumentation.

Cadmium and copper transport in alluvial soils in the Brazilian semiarid region: column percolation and modeling

ABSTRACT Regarding the Brazilian textile industry, part of the northeast region stands out as the second-largest textile manufacturing hub in the country. Despite its importance, this industrial activity has been bringing relevant environmental concerns regarding the disposal of textile effluents, especially from industrial laundries. This waste contains many chemicals and among them are various types of heavy metals. To assess environmental risks associated with heavy metals, pollutant transfer needs to be investigated. This study evaluated the retention and mobility of heavy metals Cd and Cu in alluvial soil, through soil column tests. The up-flow column percolation tests were performed using a nonreactive tracer (KBr) at a concentration of 0.3 mol L -1 and injecting a metallic solution containing Cu and Cd at 100 and 60 mg L -1 , respectively. The injection flow rate was 0.75 mL min -1 . The hydro-dispersive parameters were obtained by modeling the observed breakthrough curves with the convection-dispersion equation (CDE) and the two-region model, also referred to as the MIM (Mobile-IMmobile waters) model. The transport parameters were obtained from the two-site model (TSS). All elution curves were fitted to the models with the CXTFIT 2.0 program. The Two-Site Sorption Model was the best for the case studied, with R 2 of 0.985 and 0.995 for Cu and Cd, respectively. The values of R were considerably higher than the unit, presenting an average of 2.138 for Cu and 1.907 for Cd. This indicates a delay of these contaminants when leaving the column, which is caused by the interaction of these chemical compounds with the soil. The values obtained for parameter D were 3.469 for Cu and 5.205 for Cd. Thus, the metals in this study present a risk of groundwater contamination for the local alluvial aquifers. The main reason for that is the physicochemical features of the soil, such as high sand content (85 %) and low OM content (2.1 %). The results also indicated greater retention and less mobility for Cu than for Cd, pointing to a greater risk for Cd.

BCH modelling studies on biocementation process in mitigating leaks from a CO2 sequestrated aquifer

BCH modelling studies on biocementation process in mitigating leaks from a CO2 sequestrated aquifer

Optimal parameter adjustment of catalytic combustion heaters for oil shale in-situ conversion of low calorific value gases

Oil shale resources are huge, and in order to develop and utilize them rationally, it is crucial to research heaters suitable for downhole in-situ conversion mining. Compared with the problems of short life and multi-stage energy utilization of downhole electric heaters, combustion heaters have advantages such as high thermal efficiency and low cost. The heater uses low calorific value industrial waste gas as the fuel for gas injection, which reduces carbon emissions and environmental pollution and saves gas injection costs. In this paper, we propose to apply catalytic combustion of low calorific value industrial waste gas to generate high temperature exhaust gas suitable for mining, and establish the relationship between gas injection flow rate, combustion chamber parameters and gas injection duration by mathematical methods. The effect of the downhole high-pressure environment on the catalytic combustion characteristics of low calorific gas was simulated and the formula for calculating the content of low calorific gas in the exhaust gas was modified. The results show that the determination of the relational equation solves the problem of excessive axial volume in the design process of downhole heaters. Under high pressure conditions downhole, the exhaust gas temperature and low calorific gas conversion rate are significantly improved. The catalyst ignition temperature ranged from 973 K to 1073 K. Increasing the downhole pressure to 5 MPa increased the conversion of low calorific value gas from 74.56% to 88.22%. The gas injection rate and calorific value range can be calculated by correcting the equation for the content of low calorific gas in the exhaust gas. The conclusion of the study provides a reference basis for the selection of catalytic combustion process parameters for low calorific industrial waste gas, and also provides an important theoretical basis for the construction of the downhole test prototype.

Application of Remote Wireless Intelligent Layered Water Injection Technology in Dagang Oilfield

A remote wireless intelligent layered water injection technolo-gy is proposed to address the problems of traditional layered water in-jection well testing in oil fields, such as the inability to achieve continu-ous dynamic monitoring of injection parameters, high failure rate, and low success rate of testing and commissioning. The technology consists of a host computer client, a server, a surface controller, and an under-ground intelligent water distributor. The underground intelligent water distributor takes the injected water as the carrier, and uses the fluctua-tion of the water injection pressure in the tubing for signal transmission to realize two-way communication between the ground controller and the downhole intelligent water distributor. The underground intelligent water distributor integrates high-precision pressure gauges, controllable water nozzles, and calculation and control modules to form an intelli-gent control system, realizing the reception of ground down transmitted commands or data, the calculation and control of water injection flow rate of water nozzles, and the storage and upload of underground data. Remote wireless intelligent layered water injection technology has been applied in 43 wells, with a success rate of 100%. The maximum depth is 3897m, and the maximum wellbore inclination is 56.07°. This tech-nology realizes remote control of water injection wells, intelligent au-tomatic measurement and adjustment, real-time data monitoring, and automatic early warning functions, laying a foundation for the con-struction of “Digital Intelligence” oilfield.