Injection Pressure Research Articles

Development and Application of a Chelating Acid for Water Injection Wells of Chang 6 Reservoir of An-Sai Oilfield

Abstract Ansai oilfield is a typical low permeability, low pressure, low yield and serious heterogeneity oilfield. Chang 6 play of Triassic YanChang Formation is a typical ultra-low permeability reservoir. The average porosity of the reservoir is 10 % ~ 14 %, and the average permeability is (0.2 ~ 4.0) × 10−3 μm2. The absolute content of clay minerals in the reservoir is relatively high, with an average content of 18.61 %. The main components are kaolinite, chlorite, illite and illite/montmorillonite interlayer. Due to the reservoir blockage caused by scaling, water sensitivity and formation particle migration in the process of water injection, high injection pressure and under injection wells is increasing dramatically. In view of the above challenges, a fit-for-purpose acid, which contains organic acids and chelating agents, was developed for injection pressure reduction and injection enhancement. It has the characteristics of strong dissolution, good retarding and corrosion inhibition performance. Corrosion rate is 0.5632 g / (m2·h) for J55 steel in 24h, and the core permeability increases by 74.57 % after acid flooding. It has been applied in field test of 3 wells in Chang 6 layer of Ansai oilfield since March 2024. The average daily injection volume increased by 37.87 %, and the validity period was more than 180 days.

Study on the friction characteristics of a self-lubricating linear compressor using vapor injection{fr}Étude des caractéristiques de frottement d'un compresseur linéaire auto-lubrifié utilisant l'injection de vapeur.

The self-lubricating linear compressor with aerostatic bearings has good prospect for the scenario which has difficulties of oil returning. This study presents a novel oil-free linear compressor and establishes a frictional damping model by using equivalent circuit approach to evaluate the mechanical performance of the compressor. The changes in friction damping characteristics of VISLLC under different piston strokes and injection pressure are analyzed. The flow resistance coefficients within the porous medium and gas gap are obtained by experimental tests and modeling analysis. Simulation results indicate that the equivalent frictional damping coefficient can be reduced by 36.1 % comparing with that of the non-injection and the efficiency can improved the by 17.2 %. The frictional damping coefficient in the porous bearing thickness of 0.9 mm at 600 kPa injection pressure is 3.64 N∙s∙m−1.

Study on the Effect of Nitrogen Bubble Foam Flooding in Deep Heavy Oil Reservoirs with Edge And Bottom Water

Abstract The oil recovery rate is low, the degree of recovery is low and the water content rises fast after water flooding in deep edge and bottom water heavy oil reservoir in Lukeqin oilfield. In order to explore the method to improve the production effect, the integrated foam system of high temperature and high pressure resistant viscosity reduction and oil displacement is optimized. On the basis of clarifying the mechanism of improving the production effect of nitrogen foam flooding for deep heavy oil, taking the west area of Lukeqin oilfield as the research object, the parameter optimization design of nitrogen foam flooding for deep edge and bottom water heavy oil is carried out, such as injection section plug, gas-liquid ratio and injection-recovery ratio. The optimization results are as follows: the injected nitrogen foam slug is 0.2pv, the gas-liquid ratio is 1-1.2, and the injection production ratio is 1:1. The pilot test of 4 well groups was carried out on the site. After foam flooding, the injection pressure was increased by 5.2mpa, the daily oil production of the oil well was increased by 43T / D, the water cut was decreased by 45%, the accumulated oil production was increased by 32000 tons, and the oil recovery was expected to be increased by more than 10%. The purpose of improving the development efficiency of this type of oil reservoir was achieved. Using this optimization technology for scheme design and field implementation, the oil enhancement effect is remarkable and improves the benefit of deep thick oil development, which can provide technical support for the development of similar domestic reservoirs.

Effect of engine parameters on the mixture distribution, performance and emission characteristics of a gasoline direct injection engine with baffles – A numerical analysis

Baffles inside the combustion chamber of internal combustion (IC) engines improve in-cylinder mixture distribution, performance, and emission characteristics. However, the effect of engine operating parameters on these aspects of the engine with baffles (EWB) remains underexplored. In this study, using computational fluid dynamics (CFD), the effects of fuel injection pressure (FIP), engine speed and load in a spray-guided, gasoline direct injection engine (GDI) are analysed and compared with the conventional engine. For the analysis, injection pressures of 30, 50, 80, and 120 bar; engine speeds of 1000, 2000, and 3000 rev/min.; and overall equivalence ratios of 0.7, 0.9, and 1.2 are considered, keeping the fuel injection timing constant. Results show that, EWB outperforms the conventional engine under various conditions considered. Also, it is found that the performance of EWB at an FIP of 30 bar is comparable to that of the base engine at an FIP of 80 bar. Additionally, the EWB exhibits better thermal efficiency across all the engine speeds and load conditions. Moreover, the HC and CO emissions of the EWB are found to be lower in most engine operating conditions. However, NOx emissions are marginally higher than those of the base engine.

Interwell channeling and sealing technology in Changqing CCUS block

Abstract In the Changqing Oilfield’s CCUS (Carbon Capture, Utilization, and Storage) project, a novel fracture-based inter-well gas migration sealing technology was developed to address the challenges of reduced production and even shutdown of oil and water wells due to inter-well migration. This was particularly crucial in the context of low fracture pressure-bearing capacity below 40 MPa, the absence of precedents in inter-well gas migration sealing techniques, and the difficulty in accurately estimating the fracture communication volume. The technology is grounded in multi-segment plug water blocking techniques, utilizing geological and well-network data to simulate the gas volume within fractures, thereby determining the precise quantity of plugging agent required. To meet the long-term sealing needs, the technology not only incorporates corrosion-resistant gel in the multi-segment plugs but also integrates water-dispersive cement slurry and CO2 corrosion-resistant cement slurry to enhance the durability of the seal. The injection parameters were optimized based on the pressure-bearing characteristics of the formation to prevent pressure leakage. Field tests indicated that the injection pressure increased by 4 MPa after the application of this technology. Despite the occurrence of gas migration during the plugging process, the close approximation between the designed injection volume of 350 cubic meters and the actual required volume of 326 cubic meters suggests that the technique could achieve its intended effectiveness with further adjustments. This technology provides new insights for handling similar inter-well migration issues in CCUS projects and serves as a reference for other similar endeavors.

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.

Investigation of the GCI main injection: experimental-numerical analysis of gasoline spray impact at reference engine conditions

This work deals with the experimental and numerical investigation of ultra-high pressure gasoline injection against heated walls in order to characterize the fuel evaporation and distribution in gasoline compression ignition combustion chambers. Spray-wall impingement tests have been conducted in a quiescent vessel and recorded by means of the Mie scattering technique. The test conditions have been set in line with those of a reference benched GCI engine, leading to 500 bar and 700 bar for the injection pressure, 298 K, 423 K, 493 K for the wall temperature, 20 mm and 30 mm for the injector-wall distance. The same test matrix has been reproduced by means of CFD three-dimensional simulations using a proper setting of the wall-impingement model and the joint use of CFD-FEM approaches for the vapour-wall heat exchange. The time evolution of the rebound spray has been recorded and then postprocessed leading to the width and the thickness of the cloud. The CFD results are in line with the experimental ones both in terms of the overall time evolution and punctual values, proving a good accuracy of the simulation in predicting the rebound/adhered fuel mass split and the local distribution of the fuel after the impingement. Given the reliability of the simulations, insights on the numerical wall film mass and evaporated mass have been provided in order to clarify the effect of increasing pressure, temperature, and distance.

Multi-scale flow atomization characteristics of Jatropha biodiesel swirl liquid film breakup

The characteristics of the spray and droplets produced by liquid film breakup are crucial for understanding the atomization process in industrial furnace atomizers. This study employed high-speed camera technology to capture images of Jatropha biodiesel (JB) spray at various pressures and Ohnesorge numbers (Oh). Image processing methods were employed to analyze the evolution morphology and proper orthogonal decomposition (POD) of fuel swirl spray, revealing the instability, breakup length, spray cone angle, fractal characteristics of the liquid film breakup zone, and droplet distribution characteristics. The results indicated that the JB jet evolution progressed through stages: cylindrical jet, torsion liquid film, open swirl, complete swirl, and fully developed mode. The evolution and disintegration of the liquid film exhibited a complex structure with ligaments, perforations, and droplet separation. Flow disturbances induced the Klystron effect, characterizing microscopic droplet motion. As spray pressure increased, the growth rate of the disturbance wave increased, the breakup length decreased, the atomization cone angle enlarged, and the fractal dimension (FD) of the liquid film breakup zone increased. The droplet size distribution followed a log-normal distribution, with a substantial increase in the number of small droplets as injection pressure increased. This study provides valuable insights into the multi-scale flow atomization of biodiesel in industrial furnace, and is of great significance for the design, operation, and optimization of spraying systems in various industrial applications.

Investigation of fuel temperature and injection timing effects on ammonia direct injection in an optical engine

This work investigates the effects of fuel temperature and injection timing on ammonia direct injection in an optical engine using a multi-hole injector. Flash-boiling may occur over various engine-relevant conditions due to ammonia’s high vapor pressure. This phenomenon impacts spray characteristics and, in severe cases, facilitates cavitation inside the nozzle. Both fuel temperature and injection timing (i.e., ambient conditions during injection) impact the intensity of flash-boiling during fuel injection. Therefore, this work varies fuel temperature (from 320K to 388K) and injection timing (from −60CADaTDC (crank angle degrees after top dead center) to −6CADaTDC) to assess their impact on injection mass flux, discharge coefficients, and macroscopic spray characteristics using an ammonia injection pressure of 200bar. For this purpose, the injection mass is measured by analyzing exhaust gas compositions during engine operation with ammonia injections but without combustion. In addition, diffuse background illumination (DBI) images capture the liquid phase of the fuel spray to characterize spray behavior. The findings reveal that increasing fuel temperature decreases ammonia’s injection mass by up to 12.8% but has little impact on discharge coefficients for late injection timings and high in-cylinder pressures. However, discharge coefficients decrease by up to 17.4% (from 0.58 to 0.48) for early injection timings if fuel temperatures are high. The individual sprays of the 6-hole GDI injector may collapse into a uniform spray at high-density conditions without flash-boiling or under strongly flash-boiling conditions. The findings clarify the impact of ammonia’s high vapor pressure on injection mass and prove the relevance of different spray collapse mechanisms in ammonia direct injection engines.

Research and Practice on EOR Development Strategy of Water Drive Followed by Gas Drive in Fractured Carbonate Reservoir in Bohai Sea

Abstract Focusing on the issues of high comprehensive water cut and low recovery degree following water flooding in the CFD 2-2 carbonate buried hill reservoir in the Bohai Sea, the productivity variation law, water cut rising characteristics and development effect of horizontal wells were analyzed based on different types of reservoir classification systems. The reservoir numerical simulation model of dual media coupling of matrix and fracture is established, and the analysis is done on the matrix and fracture production state, the distribution pattern of the residual oil, and the primary governing parameters.. The physical simulation experiment of water flooding to gas flooding is carried out. In conjunction with the distribution characteristics of fractures and matrix residual oil in low, middle and upper tiers of the framework, the development strategy of nitrogen injection pressure water cone in low water-flooded area, nitrogen flooding in middle inter-well residual oil enrichment area and nitrogen huff and puff in high well point residual oil enrichment area is put forward. The recovery rate is increased by 5-8 %, which successfully enhances the high water cut stage development effect, and provides reference for similar oilfield development.

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.

Research on the Mechanism of Nanoparticle materials in Oil Displacement and its Application

Abstract The application of nanoparticles in the field for enhanced oil recovery (EOR) is a new technology, which has attracted widespread concern. However, there is a lack of systematic research on the types and mechanisms. In order to clarify the types and characteristics of the material, oil displacement mechanism and its effect on oil and water flow, this paper systematically sorted out the classification of nanoparticle materials used in the field of petroleum development, and analysed its percolation and oil displacement mechanism. Numerical simulation and field data analysis were carried out to study the applications of two types of nanomaterials in improving reservoir water injection and oil displacement efficiency quantitatively. The results show that the main mechanism of nanoparticle flooding is to change reservoir wettability, reduce oil-water interfacial tension, modify the mobility ratio between water and oil phases, and reduce asphaltene precipitation. Lipophilic and hydrophobic nanoparticle may reduce injection pressure, and increases significantly injection in low permeability reservoirs, and the average water injectability of 6 wells is increased by 177.76%. The displacement efficiency of hydrophilic and oleophobic nanoparticles can be increased by 14.78%. This paper reveals the oil displacement mechanism of nanoparticle materials and establishes a new method to quantitatively predict the oil displacement effect of nanoparticle materials, which provides a basis and reference for the application of oilfield.

An integrated dynamic modeling workflow for acid gas and CO2 geologic storage screening in saline aquifers with faults: A case study in Western Canada

This study investigates the feasibility of storing the acid gas produced from the oil and gas facilities in Southern Saskatchewan into the Basal Sand aquifer using a coupled wellbore-aquifer-compositional reservoir model. The simulations investigate the pressure change around the fault in proximity of the primary storage location incorporating the influence of reservoir permeability, fault transmissibility, and wellbore configuration, on the factors critical to safe and efficient storage, such as plume migration, pressure changes, and CO2 storage capacity. A compositional fluid model created using an equation of state was integrated into the reservoir model. Simultaneous incorporation of fault transmissibility, phase solubility, water salinity, temporal in-situ hysteresis and structural trapping, and in-situ compositional tracking of individual gas components is considered as the main novelty of this work. The main challenge of the study was the lack of available data to characterize the aquifer. To this end, a comprehensive workflow of reservoir studies and modeling was applied to reduce the uncertainties and evaluate the site selection. The Basal sand scoping models reveal that the aquifer is expected to handle the required disposal volume given its extent. The injected acid gas plume migrates laterally and preferentially towards the northwest, away from the fault, owing to the aquifer's geological structure. CO2 remains entirely in the supercritical state, offering storage advantages due to its lower volume. The reservoir permeability significantly impacts the pressure patterns with lower permeability formations triggering higher wellhead injection pressures. Substantial pressure increases around the sealing fault can be observed. Pressure changes of 110 kPa (16 psi) to over 400 kPa (58 psi) were observed at the fault segment after 20 years of continuous gas injection for the expected range of reservoir properties. Mitigation strategies to minimize the increase in fault pressure entail relocating the injection site away from the fault or utilizing a horizontal well trajectory and using an observation well near the fault for monitoring any pressure buildup and slippage.

An Analytical Solution for Characterizing Mine Water Recharge of Water Source Heat Pump in Abandoned Coal Mines

Due to tremendous mining operations, large quantities of abandoned mines with considerable underground excavated space have formed in China during the past decades. This provides huge potential for geothermal energy production from mine water in abandoned coal mines to supply clean heating and cooling for buildings using heat pump technologies. In this study, an analytical model describing the injection pressure of mine water recharge for water source heat pumps in abandoned coal mines is developed. The analytical solution in the Laplace domain for the injection pressure is derived and the influences of different parameters on the injection pressure are investigated. This study indicates that a smaller pumping rate results in a smaller injection pressure, while smaller values of the hydraulic conductivity and the thickness of equivalent aquifer induce larger injection pressures. The well distance has insignificantly influenced the injection pressure at the beginning, but a smaller well distance leads to a larger injection pressure at later times. Additionally, the sensitivity analysis, conducted to assess the behavior of injection pressure with concerning changes in each input parameter, shows that the pumping rate and the hydraulic conductivity have a large influence on injection pressure compared with other parameters.

English

English

Experimental study on the heat storage characteristics of rock bed heat storage system with different packing structure

Establishing energy storage systems can provide an effective solution to the challenges posed by the variability and intermittency of renewable energy sources. Among the available options for energy storage, rock-packed bed thermal energy storage systems are widely favored for their performance, cost-effectiveness, and reliability. The more compact the rock packing, the more adequate the heat exchange of the system; however, poorer permeability increases fluid friction losses and pressure drop, which is detrimental to heat transport within the system. The permeability and heat exchange of the system jointly determines its thermal energy storage performance. This study proposes a composite packing scheme utilizing intact rock slabs and broken rock to enhance the thermal energy storage performance of the packed bed. This approach aims to augment heat exchange efficiency and elevate energy storage density while maintaining the bed's commendable permeability. Heat injection and heat extraction experiments of rock beds were conducted to study the heat storage characteristics of the rock-packed bed thermal storage system under different packing structure. In addition, this study investigates the effect of different injection pressures on the storage and release of heat in the system. The results show that the volume of the pore space of the filled bed, serving as the primary domain for gas flow and gas-rock heat exchange, is a decisive factor affecting the packed bed's permeability and heat exchange performance. When the porosity of the packed bed increased from 5.5 % to 9.9 %, its permeability increased from 1.42 × 10−13 m2 to 3.20 × 10−13 m2, yet the thermal exchange efficiency declined from 67.2 % to 65.3 %. Reasonably arranging intact rock slabs and broken rock fill can alter the path of heat transfer within the packed bed, thereby effectively enhancing its heat storage and release performance. For the same pore volume conditions, the heat exchange efficiency of the packed bed is increased by about 10 % by increasing the number of layers of broken rock fill. Additionally, high gas injection pressures can facilitate heat storage and release processes, but it does not mean that this is more efficient. The research findings can guide the selection of packing and injection schemes in packed bed thermal energy storage systems.

A new track for high-efficiency marine diesel engines: Initiative air jet and post-split injection combined

In pursuit of adequate mixing with a high volume of fuel injection, a re-intake scheme is proposed to promote the diffusion of combustibles and flames by using the disturbance of high-pressure air jets after the pressure peak. The results indicate that during the power stroke, an additional air jet enhances combustion by penetrating the spray and disturbing the flame front. The high-pressure air jet's obstruction of the atomization of local sprays achieves a longer combustion duration, while intensifying the vortex and temperature at the cylinder center, which enhances the evaporation of fuel near the nozzle. However, excessively high fuel injection pressure brings in more cold air, causing a temperature drop. It is necessary to have sufficient flame expansion before re-intake to eliminate the impact on pressure. By adjusting the re-intake pressure and timing, the air jet, when it reaches half the cylinder diameter, can exert its maximum advantage. By introducing post-injection and increasing the pressure of the first fuel injection, the air-spray impingement duration is extended, thereby improving thermal efficiency. This work, at 190 MPa injection pressure without changing the duration, and combined with a 5°CA re-intake, achieved a 1.82 % increase in thermal efficiency.

Injection Techniques to Reduce Adverse Effects of Subcutaneous Low-Molecular-Weight Heparin Among Patients With Cardiovascular Diseases: A Scoping Review.

To systematically review the existing literature and address the following research question: What are the most effective techniques used to minimise adverse effects resulting from subcutaneous injections of low-molecular-weight heparin among patients with cardiovascular diseases? A scoping review. A comprehensive search was conducted across multiple databases, including CINAHL, PubMed, EMBASE and the Cochrane Library, from 1 February 2014 to 31 January 2024. Participants were aged 18 years or older, diagnosed with venous thromboembolism or arterial thromboembolism and had prescribed subcutaneous injections of low-molecular-weight heparin. The collected data were analysed following the Joanna Briggs Institute approach, and it was organised and categorised based on the main objectives of the review. Twenty studies were eligible, including 1 best practice project, 7 randomised controlled trials and 9 quasi-experimental studies. The techniques under investigation encompassed various aspects, including the injection site, injection duration (e.g., 30 s vs. 10 s), injection method (e.g., needle insertion angle), duration of needle withdrawal after injection, pressure application time and cold pressure. Preliminary evidence suggests that techniques such as using the abdominal site and slower injection rates may help reduce adverse effects. However, the optimal parameters for injection duration, waiting time, pressure and cold application, including the duration of these applications, remain uncertain due to limitations in sample size and heterogeneity in interventions and outcome measures across the studies. Ensuring the accurate administration of low-molecular-weight heparin is of utmost importance as it plays a critical role in decreasing mortality rates and minimising substantial healthcare costs linked to complications arising from incorrect administration. The findings from the current review have significantly contributed to strengthening the evidence base in this field, providing more robust and reliable information. This review emphasises the significance of implementing standardised subcutaneous injection techniques for low-molecular-weight heparin in patients with cardiovascular disease in order to reduce complications and enhance patient outcomes. This study followed the applicable guidelines established by the PRISMA 2020 statement. The PRISMA checklist for systematic reviews was utilised for reporting purposes. There is no patient or public contribution to declare. OSF registries: osf.io/phk72.

Analysis of dynamic characteristics and influencing factors of CO2 low-permeability coal reservoir sequestration

ABSTRACT Abandoned coal seams can be an important carrier for CO2 geological storage. Considering the gas seepage-diffusion and physical adsorption coupling characteristics in the process of CO2 adsorption and storage in coal and rock, a two-dimensional model of coupled flow-solidity for geological storage of CO2 in low-permeability reservoir with double voids was established by introducing the Zhang Hongbin model algorithm and adding the Klinkenberg effect and the compression effect of the rock skeleton in coal reservoirs in the controlling equation for rock deformation. The coupled flow-solid model was solved by using the PDE equation of COMSOL Multiphics program, and the simulation results difference between the new model and the traditional model in terms of sequestration dynamics were compared. The dynamic characteristic of reservoir gas pressure, formation stress, permeability and sequestration density in the process of CO2 geologic sequestration and injection were analyzed, and the influences of injection pressure and injection well diameter on the amount of CO2 sequestration were explored. The results show that the new model is more reasonable for calculating reservoir gas pressure and permeability compared with the Palmer-Mansoori model (PM model), and can simulate the free-state seepage movement of CO2 in the fracture system as well as its physical adsorption process compared with the single-heavy pore medium model. With continuous CO2 injection, the maximum sequestration density was raised to a limit value of about 1000 kg/m3 after 1 year. The date of reaching the limit of the sequestration volume was advanced by about 45 d when the positive pressure of the injected gas was increased from 10 kPa to 50 kPa. This model can reproduce the main parameters including, when affecting the effect, and realize the calculation of parameters such as CO2 density reaching the limit value, sealing limit day, sealing limit amount, which can provide a theoretical basis for further deep understanding of CO2 geological sealing law and scientific development of gas injection scheme.

Threshold Determination for Effective Water Injection in Coal Seams: Insights from Numerical Simulation

Coal seam water injection is the most basic and effective dust control technology used on the coal mining face. Numerical simulations are helpful for predicting the humidity range of coal seam water injection. The results can provide guidance for the field design of coal seam water injection process parameters. In order to understand the influence of coal seam water injection pressure and water injection time on the coal seam wetting effect, this paper uses the Fluent 17.0 software system to study the process parameters of the coal seam water injection seepage process under different conditions. It is found that in the process of coal seam water injection, with the increase in water injection pressure and the prolongation of water injection time, there is a specific threshold value for the change in coal seam permeability. Only when the water injection pressure and time increase to the threshold value will the permeability of the coal seam be significantly enhanced and the wetting effect improved. The pressure threshold of the mine is 15 MPa–20 MPa, and the time threshold is the first 42 h.