Gas extraction technology and application of near horizontal high directional drilling

Huijun, Duan; Wang, Yi; Xiao, Qian; Wang, Jiale; Peng, Dong

doi:10.1016/j.egyr.2022.02.051

Cited by 13 publications

(11 citation statements)

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“…Coal energy is the foundation and pillar of our nation’s energy structure, accounting for approximately 70% of our total energy consumption. − Its significance in our national economy cannot be overstated as the primary energy source supporting industrial production and the daily lives of urban and rural inhabitants. , While our country actively promotes the development and utilization of new and clean energy sources, coal energy will continue to play a crucial role in the short term. − Given the distinctive characteristic of our coal-dominated energy structure, preventing coal mining accidents holds immense importance, particularly the risks of coal and gas outbursts. , The most effective preventive measure is the drilling and extraction of gas, which not only helps to mitigate hazards but also enables the utilization of gas resources, generating additional economic and social benefits for the mines. − Gas extraction from coal seams represents the most effective approach to gas management, with coal seam drilling being the only means of achieving gas extraction . Gas extraction ensures the safe mining of working faces and allows for the acquisition of gas resources, resulting in supplementary economic and social benefits for the mines. − High-gas mines are the primary target for gas extraction in our country, and data indicates that nearly 95% of the coal seams within these high-gas mines are soft .…”

Section: Introductionmentioning

confidence: 99%

Preferred Ratio and Properties of Microfoam Drilling Fluid for Gas Extraction in Soft Coal Seams

Cheng,

Hou,

Luo

et al. 2024

Energy Fuels

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During the gas extraction drilling process, especially the soft coal seam drilling process, due to the constraints of geological conditions, technical conditions, and other factors, it is easy to encounter stuck holes, blowout, lost circulation, and hole collapse, which affect the realization of efficient gas management. In the petroleum industry, microfoam drilling fluid has unique advantages as a drilling and flushing medium. Through the response surface method, this study conducts a preliminary experimental study on the types of foaming agents, foam stabilizers, modified bentonite materials, and filtrate reducers and determines the optimal formula as 3.98% modified bentonite + 0.586% compound foaming agent + 0.776% foam stabilizer + 1% sulfonated phenolic resin + 2% carboxymethyl starch sodium. The performance of the microfoam drilling fluid system is tested. Subsequently, a simulated soft coal seam drilling test is carried out to verify the effectiveness of the developed directional microfoam drilling fluid for protecting coal rock holes. This microfoam drilling fluid system technology can improve the drilling quality of the sealing section of coal seam gas extraction drilling and effectively improve the gas extraction rate of coal mines.

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Section: Introductionmentioning

confidence: 99%

Preferred Ratio and Properties of Microfoam Drilling Fluid for Gas Extraction in Soft Coal Seams

Cheng,

Hou,

Luo

et al. 2024

Energy Fuels

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show abstract

“… 24 For directional long drilling, Liu 25 obtained an exponential relationship between the negative pressure in the extraction drilling hole and the drilling length, using a pressure test device in the extraction drilling hole. Duan 26 designed a directional long-drilling pre-extraction hole. It substantially improved the efficiency of gas extraction.…”

Section: Introductionmentioning

confidence: 99%

Study on Effective Extraction Radius of Directional Long Borehole and Analysis of the Influence Mechanism

et al. 2023

ACS Omega

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To accurately determine the effective extraction radius of directional long drilling, the influence of the negative pressure of the hole mouth, the drilling diameter, and the drilling length of the hole on the effective extraction radius of a directional long drilling hole is simulated by establishing a coal-to-gas gas-structure coupling model considering the Klinkenberg effect. Finally, the reliability of the numerical simulation is verified through field testing in Yuxi Coal Mine. The results reveal that the attenuation of negative pressure in a directional long borehole along a long hole has a significant influence on the gas extraction effect. The radial gas pressure of the extraction drilling hole is distributed in a “V” shape when the negative pressure of the extraction decays along the direction of the hole length. The higher the negative pressure and the longer the diameter of the drilling hole, the higher is the gas extraction effect. The effective extraction radius is exponentially related to the drilled hole depth when the negative pressure of extraction is attenuated along the long hole direction. The negative pressure of the hole and the diameter of the borehole are linearly related to the effective extraction radius at the depth of drilling hole of 430 m. Through field tests, while extracting for 180 days based on the stubble pressing effect, the effective extraction radius of the directional long borehole of the No. 3 coal seam of Yuxi Coal Mine is 5.7 m, and the absolute error between the numerical simulation is 0.1 m. In addition, the gas pressure obtained from different sampling points is consistent with the numerical simulation. The relative error is 0.3–4.1%. The results provide a theoretical basis for the rational layout of directional drilling.

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“…This phenomenon causes the desorption, diffusion, and seepage of coal gas along the depth of the hole under different pressures; it also results in the zoned drainage effect phenomenon (Wang, 12 Lin 13 ), which is one of the main problems that restricts the exploration of the gas flow regularity in coal seams and extraction boreholes. Mastering the dynamic change characteristics of negative pressure along the hole length and determining reasonable gas extraction parameters have been an unmet challenge (Wang, 14 Duan 15 ). Qin 16 believed that the distribution of the negative pressure in an extraction borehole corresponds to a logarithmic relationship.…”

Section: Introductionmentioning

confidence: 99%

Change Characteristics of Negative Drainage Pressure along the Drill Hole: Theoretical Analyses and Field Tests

Liu

Wei

et al. 2022

ACS Omega

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A proper understanding of the change characteristics of negative drainage pressure along a drilling hole is essential since gas drainage parameters are the key parameters that influence the efficiency of gas drainage. In this study, based on the coupling of gas seepage from coal seams and the gas flow along the drilling hole, a theoretical model was established to calculate the gas pressure change law along the drilling hole with different influencing factors. Subsequently, a multibranch method was applied to test the negative pressure at different drilling holes. Finally, a field test was conducted in the Jiulishan coal mine to analyze the changed characteristics of the negative drainage pressure along the drilling hole. The results show that at a constant negative drainage pressure in the borehole, the negative pressure gradually decreased with increasing depth. With an increase in negative drainage pressure at the borehole, the negative pressure loss for every 100 m substantially increased. The gas flux had the most obvious influence on the negative pressure in the drilling hole, and the pressure loss rapidly increased with increasing gas flux. When the diameter of the borehole was small, the negative pressure loss was significant; when the drilling hole was deep, the negative pressure decreased more significantly. This study has important theoretical and practical significance for improving the gas drainage effect.

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Gas extraction technology and application of near horizontal high directional drilling

Cited by 13 publications

References 0 publications

Preferred Ratio and Properties of Microfoam Drilling Fluid for Gas Extraction in Soft Coal Seams

Preferred Ratio and Properties of Microfoam Drilling Fluid for Gas Extraction in Soft Coal Seams

Study on Effective Extraction Radius of Directional Long Borehole and Analysis of the Influence Mechanism

Change Characteristics of Negative Drainage Pressure along the Drill Hole: Theoretical Analyses and Field Tests

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