Optimal Water Injection Research Articles

Numerical analysis of water injection in coal seams under mining influence

This study investigates the diffusion characteristics and optimization of borehole water injection in the 3# coal seam of Licun Coal Mine under mining influence. The distribution of stress and permeability ahead of working face using FLAC3D combined COMSOL Multiphysics. The influence of distances between the borehole along with the diameters of the boreholes on the stress distribution around the borehole is studied. Additionally, the diffusion characteristics of coal seam water injection are analyzed under various parameters. The study found that borehole proximity to the working face significantly enhances stress relief and permeability, while borehole diameter has a minor impact. Simulation results from COMSOL Multiphysics indicated that increasing injection pressure significantly improves seepage velocity and wetting range, though borehole diameter effects remain negligible. Optimal water injection parameters were identified, suggesting that the most effective water injection occurs at a borehole 3 m from the working face, with a diameter of 0.11 m and an injection pressure of 10 MPa, achieving saturation within 48 h. This research contributes to the theoretical and practical understanding of optimizing borehole water injection in complex geological settings and thick coal seams.

Research on the water flooding front based on dynamic and static data inversion – a case study

To clarify the movement of the water flooding front in fluvial reservoirs, this research takes the BZ oilfield as an example. By considering the equivalent flow resistance theory for oil–water two-phase flow, the horizontal micro-element equivalent method and the strong heterogeneity of fluvial facies reservoir comprehensively, a calculation model for a non-piston water flooding front in a horizontal well pattern was established. First, five horizontal injection–production well groups in the BZ oilfield were taken as examples to calculate the water breakthrough time for the oil wells. The calculation results are in good agreement with the actual production performance. In detail, the advancing speed of the water flooding front in the high-permeability strip was 0.8–1.6 m/day, and the speed in the low-permeability strip was 0.12–0.35 m/day. When water is seen in the oil well, the advancing speed in the low-permeability strip is reduced, resulting in uneven displacement and the formation of non-dominant potential areas. In addition, the water flooding front advancing distance was simulated to be 300–450 m by establishing a reservoir numerical simulation model, which is close to the result of the proposed model, indicating that the calculation method is reliable. This research is of great significance for predicting the water breakthrough time of horizontal production wells, judging the weak affected area on the mainstream line, and optimizing water injection and tapping reservoir potential in good time.

Optimizing Water-Cut and Boosting Oil Recovery: Geological Insights from Mishrif Reservoir, Buzurgan Oil Field

This study utilizes streamline simulation to model fluid flow in the complex subsurface environment of the Mishrif reservoir in Iraq's Buzurgan oil field. The reservoir faces challenges from high-pressure depletion and a substantial increase in water cut during production, prompting the need for innovative reservoir management. The primary focus is on optimizing water injection procedures to reduce water cuts and enhance overall reservoir performance. Three waterflooding tactics were examined: normal conditions without injectors or producers, normal conditions with 30 injectors and 80 producers and streamline simulation using the frontsim simulator. Three main strategies were employed to streamline water injection in targeted areas. Over a 22-year forecasting period and employing seven Strategies, streamline simulation were optimized both oil and water outputs. The hybrid Strategy-7 as mixed between all three outperformed Strategy-1 that was gave highest optimization result for only one strategy, yielding the highest cumulative oil production of 1281 million stock tank barrels, the highest oil recovery factor of 24.1%, and a minimal of 2.5% water cut. This study underscores the importance of streamline simulation in managing reservoirs under challenging subsurface conditions, highlighting that a thoughtful integration of streamlining tactics can significantly improve reservoir performance even enhancing oil recovery and addressing water-related issues. The findings contribute valuable insights for optimizing waterflooding strategies in similar globally geological contexts.

Method for predicting the injection pressure for horizontal wells in fractured tight sandstone reservoirs

Hydraulic fracturing and horizontal well drilling are the key technologies for increasing the production of continental tight sandstone reservoirs. Taking the typical fractured tight sandstone in the Yuan-287 block of the Ordos Basin as an example, a reservoir geologic model is established based on the stratigraphic correlation of 206 wells. The model and 3D paleostress field are combined to predict fracture parameters such as fracture density and strike. Using reservoir breakdown pressure (RBP) monitoring data and other data such as reservoir physical and mechanical parameters, tectonic fracture characteristics, and in situ stress parameters, a quantitative evaluation model of the RBP, which predicts the 3D distribution of RBP, is established via stepwise regression, and the factors controlling the RBP are analyzed. The rock P-wave velocity, horizontal minimum principal stress, and fracture density are found to be three key parameters that control the breakdown pressure of this tight sandstone reservoir. By comparing the fracture opening pressure of subsurface tectonic fractures with the RBP, a new method for predicting the optimal water injection pressure of this reservoir is developed. This work provides a valuable evaluation model for accelerating the efficient development of continental tight sandstone reservoirs.

Applications of Oxyhydrogen, Direct Water Injection, and Early-Intake Valve Closure Technologies on a Petrol Spark Ignition Engine—A Path towards Zero-Emission Hydrogen Internal Combustion Engines

This study investigates the performance of a 4-MIX engine utilizing hydrogen combustion in pure oxygen, water injection, and the application of the early-intake valve closure (EIVC) Miller cycle. Transitioning from a standard petrol–oil mix to hydrogen fuel with pure oxygen combustion aims to reduce emissions. Performance comparisons between baseline and oxyhydrogen engines showed proportional growth in the energy input rate with increasing rotational speed. The oxyhydrogen engine exhibited smoother reductions in brake torque and thermal efficiency as rotational speed increased compared to the baseline, attributed to hydrogen’s higher heating value. Water injection targeted cylinder and exhaust temperature reduction while maintaining a consistent injected mass. The results indicated a threshold of around 2.5 kg/h for the optimal water injection rate, beyond which positive effects on engine performance emerged. Investigation into the EIVC Miller cycle revealed improvements in brake torque, thermal efficiency, and brake specific fuel consumption as early-intake valve closure increased. Overall, the EIVC model exhibited superior energy efficiency, torque output, and thermal efficiency compared to alternative models, effectively addressing emissions and cylinder temperature concerns.

Experimental study on the impact of “IDS + JFCS” complex wetting agent on the characteristics of coal bodies

As China's coal mines have transitioned to deep mining, the ground stress within the coal seams has progressively increased, resulting in reduced permeability and poor wetting ability of conventional wetting agents. Consequently, these agents have become inadequate in fulfilling the requirements for preventing washouts during deep mining operations. In response to the aforementioned challenges, a solution was proposed to address the issues by formulating a composite wetting agent. This composite wetting agent combines a conventional surfactant with a chelating agent called tetrasodium iminodisuccinate (IDS). By conducting a meticulous screening of surfactant monomer solutions, the ideal formulation for the composite wetting agent was determined by combining the monomer surfactant with IDS. Extensive testing, encompassing evaluations of the composite solution's apparent strain, contact angle measurements, and alterations in the oxygenated functional groups on the coal surface, led to the identification of the optimal composition. This composition consisted of IDS serving as the chelating agent and fatty alcohol polyoxyethylene ether (JFCS).Subsequent assessment of the physical and mechanical performance of the coal briquettes treated with the composite wetting agent revealed notable enhancements. These findings signify significant advancements in the field and hold promising implications. Following the application of the composite wetting agent, notable reductions were observed in the dry basis ash and dry basis full sulfur of coal. Additionally, the water content within the coal mass increased significantly, leading to a substantial enhancement in the wetting effect of the coal body. This enhanced wetting effect effectively mitigated the coal body’s inclination towards impact, thereby offering technical support for optimizing water injection into coal seams and preventing as well as treating impact ground pressure.

Design of water nozzle shape and structure optimization for eccentric injection mandrel in water injection wells

AbstractInjection mandrel is one of the key components to control the water injection rate of each layer in the layered injection process in the oilfield. The imbalance between the layers can be changed by an optimized injection mandrel to control the appropriate injection rate. This study introduces an approach to optimize water injection in oilfields, focusing on a new eccentric injection mandrel with adjustable flat nozzles. Firstly, computational fluid dynamics (CFD) simulations were carried out using FLUENT software to model and analyze the flow characteristics of the injection mandrel. The simulation results were validated through experimental comparisons, demonstrating excellent consistency. Secondly, the nozzle shapes were identified and optimized. The semicircle nozzle demonstrating superior regulation performance due to its smallest differential pressure and a robust linear relationship between flow rate and opening degree. Finally, orthogonal tests are designed for three influencing factors of the eccentric injection mandrel: number of injection holes, injection hole diameter, and nozzle shape. The simulation results show that the number of injection holes is 36, the diameter of injection holes is 3.2 mm, and the eccentric injection mandrel has relatively better performance. After optimization, the differential pressure between the inlet and outlet is reduced by 57.14%, and the average shear stress on the fluid is reduced by 3.88%. This innovative methodology, employing CFD simulations and orthogonal tests, offers precise water injection rate control, reducing water wastage, and optimizing energy consumption in water injection systems.

Study on the wall-approaching film formation characteristics of water injected in a single screw steam compressor

To investigate the wall-approaching film formation (WAFF) mechanism of water injected during the compression process of single screw compressor, then to realize reasonable control of water injection parameters, a numerical simulation of water and steam two-phase flow inside the compression chamber during the compression process was carried out. The WAFF characteristics of water injected inside the compression chamber and the influence laws of the key parameters such as water injection angle (IA), injection velocity (IV), injection mass flow rate (IMFR), screw rotor rotational speed (SRRS) and injection hole spatial position (IHSP) on the WAFF characteristics were analyzed. The results show that the water injected into the chamber forms a water film by approaching the wall. With the increase of IA and IV, the effective water film average thickness (EWF-AT) and surface area (EWF-SA) show an increasing trend. In the process of IMFR growth, EWF-AT and EWF-SA exhibit maximum values. Considering the goal of minimizing the injection power consumption, the IA of 70°, IV of 30 m·s−1 and IMFR of 0.3 kg·s−1 were determined as the optimal water injection parameters. Selecting the appropriate IMFR, SRRS and IHSP will effectively increase EWF-AT and EWF-SA, then to prevent leakage.

Optimizing water injection system facilities based on the digital model

Optimizing water injection system facilities based on the digital model

A new hybrid rate optimization method to enhance oil recovery from Brugge field using streamline-driven injection efficiencies

BackgroundOptimization of waterflooding projects traditionally focuses on optimizing rate control of injector/producer wells to enhance recovered oil from reservoirs. In such projects, a complex, constrained, multi-variable problem is optimized to enhance the oil recovery performance of reservoirs. MethodsStreamline-based rate optimization has been applied as a robust method to find the optimal water injection strategy. The present study aims to optimize injector/producer wells rates using streamline-driven injection efficiencies. A heuristic algorithm (the so-called weights algorithm) was used in previous works. This study proposes a new hybrid particle swarm optimization (PSO)-weights method. The weights algorithm oil recovery results are dependent on the initial guesses to start searching the domain. PSO global search ability provides a proper set of initial guesses for the weights algorithm. Significant findingsThe hybrid method is implemented to optimize two reservoir models. First, the PSO-weights algorithm is applied on a 2-D homogenous model with 13 wells; after optimization, injectors/producers’ computed rate converged to known optimal rates. Second, the proposed algorithm has been tested to optimize the Brugge field and successfully afforded it quickly. The field oil production rate (FOPR) and the total field oil production (FOPT) results indicate an improvement in oil production. In addition, less trapped oil in saturation contours in different reservoir layers is reported.

Study on water seepage law of confined coal body and optimization of water injection parameters

To optimize water injection parameters, it is necessary to understand the water seepage characteristics of coal and establish an evaluation method for the coal seam water injection effect. Using low-field nuclear magnetic resonance (NMR) technology and a peripheral loading pressure experimental system, real-time Carr-Purcell-Meiboom-Gill sequence tests were conducted on coal samples under different water injection schemes. The dynamic migration characteristics of pressurized water in coal under a constant water injection pressure and injection flow were studied. The results showed that under a fixed water injection pressure, the change in water content with injection time was in concordance with first-order kinetics, indicating that the process is controlled by diffusion. Combined with the fitting results of the wetting rate constant and water injection pressure, the best water injection pressure was obtained. Moderate water injection flow, an increase in water injection volume, and an extension of the water injection time can improve the wetting effect. Under constant water pressure, water seepage in the coal includes two processes: the rapid migration of free water to the pore fractures of coal and the spontaneous water absorption process in the coal. Under constant water flow, the water seepage process in the coal is consistent with the Boltzmann equation. Based on the time constant and inflection point of the time growth obtained by the Boltzmann equation, the seepage process was divided into the water inflow, water transportation, and water adsorption stages. The peak area of the adsorbed water is proportional to the mass of coal moisture. This relationship can realize the mutual conversion between the NMR water signal quantity and moisture content in coal.

The performance of streamline simulation technique to mimic the waterflooding management process in oil reservoirs

Multiple simulation techniques are often used to predict the performance of waterflooding and to plan the infill drilling techniques via a process called waterflooding management. However, such simulation techniques usually suffer from many drawbacks and shortages. Therefore, the waterflooding process management is in an evitable need for a robust technique, which can predict the optimal water injection rates and the incremental oil production in a cost-effective manner.In this study, the streamline simulation technique (SST) was used to visualize and analyze the fluid flow patterns in order to investigate the validity of this technique for improving waterflooding management process. In addition, the feasibility of SST in waterflooding management was clearly tested by setting new injection strategies to improve the sweep efficiency via estimating the injector-producer relationship as well as the water injection efficiency. Furthermore, the advantages of streamline simulation visualization in determining the best infill drilling locations, which production wells could be converted to injection wells, and optimizing water injection rates based on monitoring and trials were investigated. The results of this research indicated that the streamline simulation technique is capable to efficiently model and predict the waterflooding process. The SST is computationally efficient and fast in terms of providing flow visualization among injectors and producers, estimating an allocation factor for injection system, and optimizing the locations of new injectors/producers’ wells to increase the sweep efficiency. In addition, the SST could provide a deep understanding with visualization to the waterflooding process and how to improve the waterflooding in oil reservoirs. In this work, through the comparison of various waterflooding scenarios, we discovered the best solution that eliminated the need for optimization algorithms with high computational requirements. This approach relies on areas exhibiting low streamline densities to enable streamlined prediction of infill well locations, thereby reducing simulator processing time. Consequently, this method represents an effective first step in the process of identifying approximate infill well locations, and its efficacy can be enhanced by integrating optimization methods.

Study of direct water injection on knock suppressing and engine performance of a gasoline engine

Turbocharger technology has become an essential method for the internal combustion engine to improve fuel economy. However, too high a boost pressure leads to too high a temperature in the combustion chamber at the end of the compression stroke, which can cause knocking or worsen abnormal combustion. Water injection technology plays a role in cooling the intake air and components in the cylinder, which can control the combustion process and suppress knock. This work focused on the influence of direct water injection (DWI) on knock suppression and efficiency improvement using a small turbocharged gasoline engine, investigating the fuel-saving potential of DWI and the optimal strategy of DWI for different engine operating conditions. Taking knock intensity (KI) as the evaluation index, KI decreases from 0.052 to 0.04 MPa, and knock limit spark angle (KLSA) increases with increasing water injection. This work shows that the DWI strategy plays a critical role in earlier spark timing, optimized combustion phase, and improved efficiency. Fuel consumption decreases by 11.55% with the optimal DWI strategy at an operating condition of 2000 rpm and a brake mean effective pressure (BMEP) of 1.3 MPa. Moreover, the optimal water injection timing is at −180°CA under various engine loads. Due to the stronger knock tendency under higher load conditions, the knock suppression is less effective for the same amount of water, so more water injection mass is necessary for higher efficiency.

An Algorithm to Optimize Water Injection Temperature for Thermal Recovery of High Pour Point Oil

With the advancement of conventional water displacement technology, cold damage may affect the vicinity of high pour point oil wells to a certain extent. Thus, the optimization of thermal recovery parameters of high pour point oil is of great significance to the oil field. In this study, a comprehensive model of the temperature distribution of the wellbore fluid was constructed, and the function of f(tD) was introduced to participate in the calculation of the thermal resistance of the formation. The temperature distribution along the wellbore was calculated and simulated under different conditions. The results show that the surface water injection temperature of 60.8℃ could ensure the desired water temperature reaching the target layer, and the injection temperature of 60.4°C could meet the needs of efficient development after considering the design of the 750-m insulated tubing. The final thermal recovery parameter optimization system could provide a theoretical reference for the thermal recovery design of the same type of reservoir.

Optimization of the Algorithm for Increasing Injection Rate in Water Injection Wells for Pressure Optimization in P Oilfield

In today’s society, with the continuous growth of energy demand, Bohai Oilfield, as an important offshore oil resource base in China, is facing increasingly severe challenges while contributing to national energy security. In order to improve the quality of water injection in the oilfield and gradually achieve efficient and stable production, Bohai Oilfield has launched a water injection well pressure optimization project, focusing on improving the efficiency and quality of water injection in the water injection wells, in order to achieve the optimal water injection plan. In practical work, P Oilfield continues to promote the development of water injection well pressure optimization projects, emphasizing practical exploration and continuous optimization of work plans. However, during the project implementation process, there were some problems, one of which was that the statistics of cumulative injection volume were not scientific enough, resulting in a more comprehensive and accurate presentation of the actual results of pressure optimization work. In the context of continuous improvement work, after careful analysis and research, P Oilfield has decided to optimize the cumulative injection rate algorithm to guide the oilfield’s water injection work in a more refined way, ensuring sufficient and good water injection, and enhancing the oilfield’s production efficiency and comprehensive competitiveness.

Capacitance Resistance Clustered Model for Mature Peripheral Waterflood Performance Prediction & Optimization

Optimizing water injection rate distribution in waterflooding operations is a vital reservoir management aspect since water injection capacities may be constrained due to geographic location and facility limitations. Traditionally, numerical grid-based reservoir simulation is used for waterflood performance evaluation and prediction. However, the reservoir simulation approach can be time-consuming and expensive with the vast amount of wells data in mature fields.
 Capacitance Resistance Model (CRM) has been widely used recently as a data-driven physics-based model for rapid evaluation in waterflood projects. Even though CRM has a smaller computation load than numerical reservoir simulation, large mature fields containing hundreds of wells still pose a challenge for model calibration and optimization. In this study, we propose an alternative solution to improve CRM application in large-scale waterfloods that is particularly suitable for peripheral injection configuration. Our approach attempts to reduce CRM problem size by employing a clustering algorithm to automatically group producer wells with an irregular peripheral pattern. The selection of well groups considers well position and high throughput well (key well). We validate our solution through an application in a mature peripheral waterflood field case in South Sumatra. Based on the case study, we obtained up to 18.2 times increase in computation speed due to parameter reduction, with excellent history match accuracy.

Integrated Design Technology of Geological Engineering for Pressure Flooding and Water Injection in Low Permeability Reservoirs: Take the Reservoir of Keshang Formation in Wu2 East Area as an Example

The objective factors of low permeability reservoir determine that there is obvious starting pressure gradient in waterflooding development, and the injection pressure is high. Conventional waterflooding has the technical bottleneck of “no injection and no flooding.” It highlights the development contradictions such as serious under-injection, rapid production decline and difficult production of reserves. Pressurized water injection is a new technology of unconventional water injection to enhance oil recovery, which can improve the production degree of low permeability reservoir reserves and solve the problem of water injection difficulty. In order to ensure the reliability of scheme design and the success rate of field implementation, the key technologies of unconventional oil and gas reservoir geological engineering integration are applied for the first time, including 3D geological modeling technology, geomechanics modeling technology, complex fracture network simulation technology of geological engineering integration and numerical simulation technology, and a fine 3D dynamic and static model covering all elements of geology and engineering is objectively established. Through numerical simulation research, the optimal water injection parameters of pressure flooding are determined, and the implementation effect of the optimal scheme is predicted, which provides a scientific basis for field implementation.

Intelligent Oil Production Stratified Water Injection Technology

As the driving energy to deal with the decrease of interlayer pressure caused by continuous oil production, the layered water injection technology has the characteristics of inhibiting the decrease of oil production and slowing down the increase of oil/gas ratio. In engineering, water injection technology is often used to improve the properties of crude oil, such as excessive viscosity, weak liquidity, and depleted storage, to avoid the formation of dead oil. Injecting appropriate amount of water into different production horizons can effectively maintain the formation water injection pressure, improve the sustainable development speed of the oilfield, ensure the oil production and effectively control the production cost. It is of great value to petroleum engineering and has been widely concerned by the industrial and academic circles at home and abroad. With the continuous development of oilfields over the years, most oilfields have become high-water-cut oilfields. Through the existing layered water injection technology, there are defects such as high labor cost, low operating efficiency, and long commissioning cycle. The ratio of water injection cost to constant increase gradually decreases, and the technical shortcomings become more and more obvious, which is difficult to meet production needs. It is urgent to study and optimize water injection technology scheme to meet oilfield production and technology iteration. In recent years, electronic technology, communication technology, automatic control technology, and other advanced production technology applied to geological exploration, logging technology fields such as engineering, oilfield development is towards integration and intelligent direction, which makes the advanced control and real-time communication intelligent power precision, and the layered water injection technology is possible. This paper summarizes the development history and status quo of oil recovery stratified water injection technology at home and abroad and points out that there are technical bottlenecks and development limitations in the development of water injection technology at present. Focusing on the current hot spots of intelligent oil recovery stratified water injection technology, the advantages and disadvantages of various intelligent water injection technology are compared and analyzed. It provides a certain theoretical reference value for the theoretical research and engineering application of intelligent stratified water injection technology to the equipment design and production of oilfield production and oil recovery technology research institutes and technology and equipment manufacturers.

Control Strategy Development for Optimized Operational Flexibility From Humidified Microgas Turbine: Saturation Tower Performance Assessment

Abstract Waste heat recovery through cycle humidification is considered as an effective tool to increase the operational flexibility of micro gas turbines (mGTs) in cogeneration in a decentralized energy system (DES) context. Indeed, during periods with low heat demand, the excess thermal power can be reintroduced in the cycle under the form of heated water/steam, leading to improved electrical performance. The micro humid air turbine (mHAT) has been proven to be the most effective route for cycle humidification; however, so far, all research efforts focused on optimizing the mHAT performance at nominal electrical load, in the absence of any thermal load. Nevertheless, in a DES context, the thermal and electrical load of the mGT need to be changed depending on the demand, requiring both optimal nominal and part load performances. To address this need, in this paper, we present the first step toward the development of a control strategy for a Turbec T100 mGT-mHAT test rig. First, using experimental data, the global performance, depending on the operating point as well as the humidity level, has been assessed. Second, the performance of the saturation tower, i.e., the degree of saturation (relative humidity) of the working fluid leaving this saturator, is analyzed to assess the optimal water injection system control parameter settings. Results show that optimal mHAT performance can only be obtained when the working fluid leaving the saturation tower is fully saturated, but does not contain a remaining liquid fraction. Under these conditions, a maximal amount of waste heat is transferred from the water to the mGT working fluid in the saturation tower. From these data, some general observations can be made to optimize the performance, being maximizing injection pressure and aiming for a water flow rate of ≈5m3/h. Besides these general recommendations, having a specific control matrix, that allows setting the saturation tower control parameters for any set of operational setpoint and the inlet conditions would lead to optimized performance. Therefore, future work involves the development of a control matrix, using advanced data postprocessing for noise reduction and accuracy improvement, as well as an experimental validation of this methodology on the actual test rig.

Exploring the potential of water injection (WI) in a high-load diesel engine under different fuel injection strategies

Water injection (WI) is a promising technology in diesel engines. However, the joint effects of WI and fuel injection strategy have not been investigated well. Furthermore, the comparison between WI and exhaust gas recirculation (EGR) requires further clarification. This study aims to identify the optimal way of WI and its benefits for a high-load diesel engine operated with various fuel injection strategies. Therefore, four schemes, i.e., diesel single injection strategy with/without WI and diesel double injection strategy with/without WI, were optimized by employing numerical simulation. The optimal water injection timing for single injection strategy is near −108°CA ATDC, while it is 8–20°CA before the first diesel injection for double injection strategy. Water mass is the most decisive parameter, and the optimal water masses are 10%–35% and 29%–51% of the fuel mass, respectively. When WI is employed alone without introducing EGR, NOx can be reduced by 30% and 90% respectively. Compared with EGR, the main superiority of WI is reduced NOx emissions without sacrificing fuel economy until the water mass reaches 50% of the fuel mass. For single injection strategy, the cooling effect of WI is the dominant factor, while for double injection strategy, the dilution effect becomes prominent.