Experimental study on coal permeability and cracking characteristics under LN2 freeze-thaw cycles

Su, Shanjie; Gao, Feng; Cai, Chengzheng; Du, Menglin; Wang, Zekai

doi:10.1016/j.jngse.2020.103526

Cited by 34 publications

(11 citation statements)

References 18 publications

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“…In the 1970s, Tenneco Oil Company proposed injecting cryogenic fluid into coal and rock fractures to increase natural gas production. − Industrial field tests were successfully conducted by B. W. McDaniel in 1997 and Steve R. Grundman in 1998 and proved that repeated fracturing using LN 2 can increase the production of unconventional oil and gas. − Between the late 1990s and the early 21st century, unconventional oil and gas production met demand from the energy market, and research on LN 2 fracturing stagnated. − In recent years, the share of unconventional oil and gas in global oil and gas production has continued to increase. As a result, LN 2 technology, fracturing mechanism, and influencing factors have once again become the focus of many research studies. − Liquid nitrogen fracturing has many advantages over traditional fracturing technologies.…”

Section: Ln2 Fracturing Technology Developmentmentioning

confidence: 99%

“…167 Freezing and fracturing break down rocks in three ways: volume expansion of freezing pore water creates large compressive stresses on the pore wall; pore water forms ice lenses, which cause the rock to crack; unfrozen pore water generates additional pore pressure under the pressure of the ice. 168 Because particles have different thermal conductivities and thermal expansion coefficients, they also have different shrinkage rates. As a result, the bonding strength between coal particles decreases and shrinkage stress increases.…”

Section: Mechanisms Of Ln 2 Fracturingmentioning

confidence: 99%

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Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

et al. 2022

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Liquid nitrogen (LN 2 ) fracturing is an anhydrous fracturing technology that enhances coal permeability and supports unconventional oil and gas exploitation. In this Review, we provide a systematic review of five aspects of LN 2 fracturing. They are the history of the technology's development, research topics, factors influencing fracturing efficiency, fracturing mechanism, and engineering processes and systems. Liquid nitrogen fracturing transforms coal and rock pore structure through mechanisms such as low temperature, freeze−thaw damage, and gas expansion. It changes coal and rock mechanical properties and improves the pore penetration and efficiency of unconventional oil and gas extraction. However, in-depth studies are still required in many areas. They include theoretical studies of twophase nitrogen flow in coal and rock, development of technical equipment to support field operations, and plans to monitor and evaluate fracturing efficiency. On the basis of the advances in LN 2 fracturing research and the challenges, we conclude that future research should focus on multiphase flow and field equipment and technology.

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Section: Ln2 Fracturing Technology Developmentmentioning

confidence: 99%

Section: Mechanisms Of Ln 2 Fracturingmentioning

confidence: 99%

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

et al. 2022

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“…Methods other than CO 2 substitution and N 2 displacement will have a significant effect on reservoir permeability. 8 One approach is fluid injection, which includes hydraulic, 9 high energy gas, 10 , 11 supercritical CO 2 , 12 , 13 liquid nitrogen, 14 − 16 and steam injection fracturing. 17 , 18 Another approach is the application of external acoustic, 19 − 21 electric, 22 electromagnetic, 23 − 26 or electrochemical fields.…”

Section: Introductionmentioning

confidence: 99%

“…Methods other than CO 2 substitution and N 2 displacement will have a significant effect on reservoir permeability . One approach is fluid injection, which includes hydraulic, high energy gas, , supercritical CO 2 , , liquid nitrogen, − and steam injection fracturing. , Another approach is the application of external acoustic, − electric, electromagnetic, − or electrochemical fields. − Although these methods have achieved enhancements, there are still some limitations, such as water locking damage, construction costs, complex operations, ecological environmental pollution, and even the possibility of inducing earthquakes by hydraulic fracturing. , At present, microwave modification technology has been successfully used for coking, , reduction of energy for pulverization, lignite dehydration, coal desulfurization, low-rank coal pyrolysis, biomass pyrolysis, enhancing floatation, auxiliary rock breaking, heavy oil exploitation, and oil shale exploitation …”

Section: Introductionmentioning

confidence: 99%

Effect of Cyclical Microwave Modification on the Apparent Permeability of Anthracite: A Case Study of Methane Extraction in Sihe Mine, China

Zhang

Kang

et al. 2021

ACS Omega

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The application of cyclical microwave modification for accelerating the extraction of coalbed methane (CBM) from anthracite is limited. In this study, the apparent permeability of anthracite samples before and after each microwave treatment (three in total) for 120 s was measured by a self-built permeability-testing platform. Microcomputed tomography (micro-CT) technology and image-processing technology were employed to analyze the 3D micron-scale pore structures, especially the quantitative characterization of connected pores and throats. After modification, the average apparent permeability increased from 0.6 to 5.8 × 10 –3 μm 2 . The generation, expansion, and connection of micron-scale pores and fractures became more obvious with each treatment. The total porosity increased from 3.5 to 6.2%, the connected porosity increased from 0.9 to 4.8%, and the porosity of isolated pores decreased from 2.5 to 1.4% after three cycles. The number, volume, and surface area of the connected pores as well as the number, radius, and surface area of the throats were significantly increased. In addition, the release of alkyl side chains from the anthracite surface reduced the capacity of the anthracite to adsorb CH 4 and the decomposition of minerals promoted the development and connectivity of pores. As a result, the gas seepage channels have been greatly improved. This work provides a basis for micron-scale pore characterization after cyclical microwave modification and contributes to CBM extraction.

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“…In the 1990s, liquid nitrogen was used as a fracturing fluid for improving oil and gas production, with significant effects. , Liquid nitrogen cooling has a cold impact on the reservoir. The mineral particles and rock cement shrink sharply owing to the sudden temperature drop, reducing the toughness of the rock and increasing its brittleness. − When the temperature drops sharply, a large tensile stress is generated inside the rock, leading to a change in the rock pore throat structure and the generation of microcracks. − In addition, liquid nitrogen will induce the formation of secondary fractures perpendicular to the main fracture, and the secondary fractures will propagate and connect to each other, significantly increasing the permeability of the reservoir. − …”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Changes in Pore Throat Systems Owing to Liquid CO₂ Cooling in Shale Oil Reservoirs

Huang

et al. 2021

Energy Fuels

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The interactions between CO2 and reservoirs under low-temperature cooling conditions can change the pore throat characteristics of the corresponding rocks. In this work, the interaction mechanisms between liquid CO2 cooling and pore throat systems of shale were researched using nuclear magnetic resonance (NMR) technology. Five typical shale core samples were selected and subjected to liquid CO2 cooling experiments under different conditions. Furthermore, the change ranges of the pores were quantitatively calculated based on the NMR T 2 spectra. The results indicate that the overall pore throat system of the shale changes after liquid CO2 cooling. The factors influencing the degree of change are the pore throat structure, liquid CO2 cooling temperature, and cooling time. The degree of change for different pores are related to the relative contents of the pores in the initial state. When the liquid CO2 cooling experiments comprise one, two, and three iterations, the average overall increase in the NMR T 2 spectrum are 2.56, 5.81, and 8.97%, respectively, and the average increase of the smaller pores are 0.77, 0.92, and 1.84%, respectively. The overall pore throat system changes greatly with an increase in the liquid CO2 cooling times, and the degree of change in the smaller pores increases. When the liquid CO2 cooling temperature of core sample A2 ranges from −30 to −20 °C, the increase in the T 2 spectrum is between 3.57 and 2.20%. When the liquid CO2 cooling temperature of core sample B2 is increased from −30 to −20 to −10 °C, the increases in the T 2 spectrum are 2.97, 2.90, and 2.79%, respectively. As the temperature of the liquid CO2 increases, the change in the overall pore throat system is weakened. The smaller pores change more obviously after liquid CO2 cooling within a certain low-temperature range. The degree of change of the larger pores is less affected by temperature.

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Experimental study on coal permeability and cracking characteristics under LN2 freeze-thaw cycles

Cited by 34 publications

References 18 publications

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

Effect of Cyclical Microwave Modification on the Apparent Permeability of Anthracite: A Case Study of Methane Extraction in Sihe Mine, China

Experimental Study on Changes in Pore Throat Systems Owing to Liquid CO₂ Cooling in Shale Oil Reservoirs

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Experimental study on coal permeability and cracking characteristics under LN2 freeze-thaw cycles

Cited by 34 publications

References 18 publications

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

Advances in Liquid Nitrogen Fracturing for Unconventional Oil and Gas Development: A Review

Effect of Cyclical Microwave Modification on the Apparent Permeability of Anthracite: A Case Study of Methane Extraction in Sihe Mine, China

Experimental Study on Changes in Pore Throat Systems Owing to Liquid CO2 Cooling in Shale Oil Reservoirs

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Experimental Study on Changes in Pore Throat Systems Owing to Liquid CO₂ Cooling in Shale Oil Reservoirs