scholarly journals Analysis of Application Parameters of Hydraulic Slotting Technology in Jointed Coal Reservoirs

2019 ◽  
Vol 9 (24) ◽  
pp. 5536
Author(s):  
Zhaolong Ge ◽  
Shaojie Zuo ◽  
Yingwei Wang ◽  
Youchang Lyu ◽  
Xinyan Feng
Keyword(s):  
Coal Seam ◽  
Rotation Speed ◽  
Experimental Testing ◽  
Water Pressure ◽  
High Water ◽  
Fracture Network ◽  
Field Application ◽  
Water Jet ◽  
Jet Impact ◽  
Complex Fracture Network

Hydraulic slotting technology is typically used in coal mines to enhance permeability and prevent gas outbursts. Because a coal seam contains many cleats and joints, this study investigated the influence of conventional application parameters on the hydraulic slotting effect by numerical simulation and experimental testing. The cleats in the coal generated stress concentration and initiated with the water jet impact, which promoted the formation of a complex fracture network. The optimized arrangement included angles with an inclination of 20–45° between the borehole and the coal seam strike. The water jet pressure and rotation speed determined the shape of the slot. A high water jet pressure and low rotation speed promoted the formation of cracks at the end of the slot and strengthened the permeability-enhancing effect. Coal fragments could more easily peel off from the sides of the seam and block the borehole. The high water pressure and low rotation speed application parameters were optimized without blocking the borehole. Results obtained by field application revealed that the gas extraction flow after optimization was 1.3 times that of conventional hydraulic slotting. An appropriate angle between the cleats and borehole can more effectively increase the permeability of the coal seam and results in higher gas drainage flow. The results of this study can be useful as guidelines for field applications of hydraulic slotting technology.

Test Study of Water-Resisting Ability of Coal Seam Floor Rock Mass

2013 ◽  
Vol 734-737 ◽  
pp. 854-857
Author(s):  
Cheng Fan ◽  
Xue Qing Jing
Keyword(s):  
Coal Seam ◽  
Water Pressure ◽  
Final Analysis ◽  
Test Site ◽  
High Water ◽  
Scientific Basis ◽  
Test Method ◽  
Floor Rock ◽  
Test Study ◽  
Water Blocking

According to Yang Zhuang coal mine engineering background and the actual situation, reasonable to determine the test site and experimental programs in this paper, and detailed description of the test method, and the final analysis of the coal seam floor water blocking capability, The results show that In low water pressure, the pressure of injection water in the hole with the water in the aperture of little contact, and in high water pressure will produce a good hydraulic connection. The study provides a theoretical foundation and scientific basis for the actual engineering improves safety.

A Study on Erosion of Alumina Wafer in Abrasive Water Jet Machining

2014 ◽  
Vol 1017 ◽  
pp. 228-233 ◽  
Author(s):  
Yong Wang ◽  
Hong Tao Zhu ◽  
Chuan Zhen Huang ◽  
Jun Wang ◽  
Peng Yao ◽  
...  
Keyword(s):  
Process Parameters ◽  
Water Pressure ◽  
Abrasive Particle ◽  
Particle Diameter ◽  
Water Jet ◽  
Abrasive Waterjet ◽  
Abrasive Water Jet ◽  
Alumina Ceramics ◽  
Abrasive Water Jet Machining ◽  
Jet Impact

Abrasive water jet machining is considered as a promising technique in hard and brittle material processing. This paper studies the erosion performance of the alumina ceramics in the different process parameters. In the erosion experiments, alumina ceramics wafers were eroded by the abrasive waterjet machining. The single factor experiments were carried out to understand the effect of different process parameters (jet impact angle, standoff distance, water pressure, abrasive particle diameter) on the material removal rate (MRR), the removal depth and surface roughness (Ra). The experimental results can provide guidance for alumina ceramics abrasive water jet cutting and polishing.

scholarly journals Rock-Breaking Properties Under the Rotatory Impact of Water Jets in Water Jet Drilling

2019 ◽  
Vol 9 (24) ◽  
pp. 5417 ◽  
Author(s):  
Zhaolong Ge ◽  
Lei Wang ◽  
Man Wang ◽  
Zhe Zhou ◽  
Songqiang Xiao ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Rotation Speed ◽  
Impact Angle ◽  
Rock Breaking ◽  
Water Jet ◽  
Drill Bit ◽  
Rock Breakage ◽  
Jet Impact ◽  
Tension State ◽  
Optimum Water

Water jet drilling is widely used to develop coalbed methane reservoirs. The water jet drill bit is the core component, and a self-rotating bit is an economical bit because of its high rock-breaking efficiency and low energy consumption. Because the important parameters concerning the rock-breaking efficiency of these drill bits are unclear, this study carried out rock-breaking experiments on water jet rotation under different conditions of drill bit rotation speed, jet pressure, and jet impact angle. How the rock was fractured and eroded under these different conditions was analyzed. The results show that the volume of rock broken under rotary jet erosion increases exponentially with increasing jet pressure. The rock-breaking depth is the most important factor that influences the volume of rock broken, whereas the diameter of the area broken is a secondary factor. There is an optimum water jet rotation speed for the most efficient rock breakage, and this rotation speed is positively correlated with jet pressure. There is also an optimum water jet impact angle for rock breaking, and, in our experiments, this angle was 10°. The rotary impact of the water jet causes the rock to be in a three-way tension state, and this reduces the water cushion effect and jet reflection. This study can be used as a reference and guide for optimizing the design of self-rotating water jet bits and the determination of reasonable drilling parameters.

scholarly journals Investigation of Process Parameters in High-Speed Die-less Water Jet Spin-Forming of Copper Sheets

2021 ◽  
Author(s):  
Mehrdad Asadi ◽  
Mohsen Loh-Mousavi ◽  
Ali Heidari ◽  
Kamran Amini
Keyword(s):  
Surface Quality ◽  
High Speed ◽  
Rotation Speed ◽  
High Water ◽  
Water Jet ◽  
Wall Angle ◽  
Relative Water ◽  
Lathe Machine ◽  
Metal Spinning

Abstract A new forming method called high speed water jet spin-forming was developed. This new forming method is a combination of water jet incremental forming and sheet metal spinning without any mandrel. The forming speed has been significantly increased by spinning of the sheet using a lathe machine. The effects of the forming parameters such as water jet pressure, rotation speed and relative water jet diameter on formability and surface quality of deformed copper parts were investigated. The experimental results indicate that the water jet pressure and the sheet rotation speed have a significant effect on the final depth, wall angle, and surface smoothness. It was also concluded that the final depth exponentially increases as the sheet rotational speed reduced. In addition, when the water jet pressure is low, sheet rational speed does not play a significant role in the final depth of the specimen. Furthermore, it has been determined from the results that high water jet pressure plays an important role in improving the surface quality and wrinkling at different rotational speeds, and as the pressure is increased, the wrinkling decreases and thus the surface quality is improved.

scholarly journals Calculation Model of High-Pressure Water Jet Slotting Depth for Coalbed Methane Development in Underground Coal Mine

2019 ◽  
Vol 9 (23) ◽  
pp. 5250 ◽  
Author(s):  
Jianguo Zhang ◽  
Yingwei Wang ◽  
Zhaolong Ge ◽  
Songqiang Xiao ◽  
Hanyun Zhao ◽  
...  
Keyword(s):  
High Pressure ◽  
Rotation Speed ◽  
Initial Period ◽  
Calculation Model ◽  
Water Jet ◽  
Nozzle Diameter ◽  
Coal Seams ◽  
Jet Impact ◽  
Pressure Water ◽  
High Pressure Water Jet

In underground coal mines, high-pressure water jet slotting is effective at improving coal seams’ permeability. The slotting depth determines the effect of pressure relief and permeability enhancement in coal seams. However, there is no effective and feasible way of determining the slotting depth; thus, the operational parameters and borehole layout are unknown. This study determined the effects of key parameters, including the nozzle diameter, jet pressure, rotation speed, and slotting time, on the slotting depth. A water jet slotting depth calculation model was established and verified according to the slotting experiments under different operational conditions. The slotting depths were investigated based on the results of field slotting experiments. The results revealed that there exists an optimal nozzle diameter for a higher jet impact velocity. The slotting depth linearly increased with the jet pressure and decreased as a power function with the increase of the jet translation speed. The slotting depth increased with the slotting time, but the growth rate gradually decreased and tended to be stable. As the rotation speed increased, the slotting depth became greater at the initial period and the limit depth was reached faster. Laboratory and field slotting experiments were conducted to verify the model, and the experimental results are approximately in agreement with the theoretical predictions. The results of this study can be useful as guidelines for the hydraulic parameter selection of water jet slotting and for optimizing the layout of coal gas drainage boreholes.

Development and Experimental Research on a Formula of Water Inrush Coefficient

2013 ◽  
Vol 448-453 ◽  
pp. 3901-3907
Author(s):  
Gan Tian
Keyword(s):  
High Pressure ◽  
Coal Seam ◽  
Water Resistance ◽  
Water Pressure ◽  
Water Inrush ◽  
High Water ◽  
Residual Pressure ◽  
Simulation Experiments ◽  
Pressure Water ◽  
High Water Pressure

Based on analysis of water inrush coefficients developed and applied in deep coal mining with high water pressure, the author proposes that there are some defects of water inrush coefficients in calculation and application. By simulation experiments on the water resistance properties of the aquiclude in a coal seam floor, the author arrived at the distribution and digital characteristics of residual pressure in the course of high-pressure water rising in the water-resisting floor. The formula for a water inrush coefficient has been further revised.

scholarly journals A New Method to Improve the Fracturing Effect of Coal Seams by Using Preset Slots and Induced Stress Shadows

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Li Li ◽  
Lei Zhou ◽  
Honglian Li ◽  
Binwei Xia ◽  
Junping Zhou
Keyword(s):  
Coal Seam ◽  
Hydraulic Fracturing ◽  
Fracture Network ◽  
Coal Bed ◽  
Hydraulic Fractures ◽  
Large Area ◽  
Multiple Fractures ◽  
Complex Fracture ◽  
Induced Stress ◽  
Complex Fracture Network

Efficient extraction of coal bed methane before coal mining is essential to eliminate the risk of coal-gas outbursts. However, stimulation technologies should be implemented to enhance the conductivity of the coal seam. In this study, we propose a novel method to create a complex fracture network in underground coal mines with the integration of multiple hydraulic slotting and hydraulic fracturing. In this method, hydraulic slots are used to direct hydraulic fractures and initialize branch fractures, while hydraulic fracturing is used to extend the fractures. Given the mutually exclusive and attractive propagation of multiple fractures, a relatively evenly distributed fracture network can be generated. The results show that (1) the dynamically induced stress shadows of hydraulic fractures can cause exclusive and attractive propagation of multiple hydraulic fractures; (2) a preset slot that deviates from the principal stress can direct hydraulic fractures to a certain extent and generate branch fractures; and (3) with a staggered distribution of preset slots, a relatively large volume of the coal seam in both the minimum and maximum horizontal stress directions can be stimulated, creating a complex fracture network including many vertical branch fractures and a large area of horizontally layered directional fractures.

Erosive Wear Of Natural Gas Pipes Due To High Velocity Jet Impact: Physical Examination And Experimental Study

2012 ◽  
Author(s):  
Z. A. Majid ◽  
R. Mohsin ◽  
M. Z. Yusof
Keyword(s):  
High Pressure ◽  
Carbon Steel ◽  
High Speed ◽  
Experimental Testing ◽  
Water Jet ◽  
Gas Jet ◽  
Water Pipe ◽  
Pipe Surface ◽  
Jet Impact ◽  
Pressure Water

A sequential failure of API 5L X42 (NPS8) carbon steel and SDR 17 medium density polyethylene (MDPE) pipes towards the high pressure water pipe was studied. Pipe’s failed specimen was physically examined and experimental testing was conducted by using high speed water jetting facility towards a similar NPS8 pipe specimen. High pressure water jet impact from leaked water pipe forms highly erosive water–soil slurry and this caused severely damaged on NPS8 carbon steel pipe surface. Thus, causing substantial losses of pipe coating materials and subsequent rapid thinning of pipe body occurred. Furthermore, weaker ground support causes instability to the MDPE pipe and leads to vertical descend towards high speed gas jet region exerted from failed NPS8 pipe. High impact gas jet physically hit the MDPE pipe at its opposite direction causing its rapid erosion. Key words: Liquid impact erosion; gas jet impact; solid particle impact; water jet impact

scholarly journals Analysis on the Shape and Impact Pressure of the High-Pressure Water Jet during the Hydraulic Flushing Cavity Technique

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Shouqing Lu ◽  
Chengfeng Wang ◽  
Wei Wang ◽  
Mingjie Li ◽  
Dongti Zhang
Keyword(s):  
High Pressure ◽  
Rotation Speed ◽  
Water Pressure ◽  
Water Jet ◽  
Impact Pressure ◽  
Coal Seams ◽  
Soft Coal ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
The Impact

A large proportion of minable coal seams in China belong to low-permeability soft coal seams. Such coal seams suffer serious coal and gas outburst hazards and endure a high incidence of major disasters in coal mines. The adoption of the high-pressure water jet (HPWJ) hydraulic flushing cavity can effectively promote the gas drainage efficiency and volume and eliminate the hidden danger of gas disasters. Nevertheless, the shape and impact pressure of rotating HPWJ are rarely researched. In this study, on the basis of the numerical simulation, the axial and radial stress distributions of HPWJ and the energy-gathering effect of a conical-cylindrical combined nozzle were analyzed. It is concluded that the submerged condition will accelerate the attenuation of jet velocity and reduce the impact strength of the jet. The jet diffusion angle grows with the increases in the nozzle diameter and water pressure, and 24° is the optimal contraction angle. Finally, the influences of factors such as the rotation speed on the shape and impact pressure of HPWJ were explored, and the results show that the rotation speed should be controlled within 90 r/min. The research findings lay the foundation of the study on the mechanism of coal crushing by HPWJ and provide technical support for the research and development of drilling and flushing integrated equipment.

Sign in / Sign up

Export Citation Format

Share Document