Two new shaped coal pillars designed to protect the subsurface pipeline in the gas-coal integrated mining field

Abstract

In the gas-coal integrated mining field, the conventional design method of pipeline coal pillars leads to a large amount of coal pillars being unrecovered and overlooks the pipeline’s safety requirements. Considering the coal pillar recovery rate and pipeline’s safety requirements, two new shaped coal pillar design approaches for subsurface pipelines were developed. Firstly, the deformation limitations for measuring pipeline safety are categorized into two: no deformation is permitted, and deformation is acceptable within elastic limits. Subsequently, integrating the key stratum theory (KST) and cave angle, a fishbone-shaped coal pillar design approach that does not permit pipeline deformation is established. Meanwhile, combined with the ground subsidence and the pipeline’s elastic deformation limit, a grille-shaped coal pillar design approach that accepts deformation pipelines within elastic limits is established. Those two new approaches clarify parameters including mined width, coal pillar width and mined length. Finally, the case study shows that the designed mined width, coal pillar width and mined length of the fishbone-shaped coal pillar are 90, 80, and 130 m, while those of the grille-shaped are 320, 370, and 640 m. Compared with the conventional method, the fishbone-shaped and grille-shaped coal pillar design approaches recovered coal pillar resources of 2.65×10⁶ and 5.81×10⁶ t on the premise of meeting the pipeline safety requirements, and the recovery rates increased by 20.5% and 45.0%, with expenditures representing only 56.46% and 20.02% of the respective benefits. These new approaches provide managers with diverse options for protecting pipeline safety while promoting coal pillar recovery, which is conducive to the harmonic mining of gas-coal resources.

Keywords

Subsurface pipeline / Coal pillar recovery rate / Safe requirement / Fishbone-shaped coal pillar / Grille-shaped coal pillar / Gas-coal integrated mining field

Acknowledgments

This research was funded by the National Natural Science Foundation of China (No. 52225402) and Inner Mongolia Research Institute, China University of Mining and Technology - Beijing (IMRI23003).

References

[1] Chen P, Xian BZ, Li MJ, Liang XW, Wu QR, Zhang WM, Wang JH, Wang Z, Liu JP. A giant lacustrine flood-related turbidite system in the Triassic Ordos Basin, China: Sedimentary processes and depositional architecture. Sedimentology 2021; 68(7):3279-306.

[2] Yuan L, Zhang T, Zhao YX, Ren B, Hao XJ, Xu C. Precise coordinated mining of coal and associated resources: A case of environmental coordinated mining of coal and associated rare metal in Ordos basin. J China Univ Min Technol 2017; 46(3):449-59. in Chinese.

[3] Ren JD, Zhao YX, Sun ZB. Failure characteristics of buried pipelines in subsidence areas under the influence of multi-adjustable factors during coal mining: A case study of Ordos. China Gas Sci Eng 2024;121:205178.

[4] Emery J, Canbulat I, Zhang CG. Fundamentals of modern ground control management in Australian underground coal mines. Int J Min Sci Technol 2020; 30(5):573-82.

[5] Tsinidis G, Di Sarno L, Sextos A, Furtner P. A critical review on the vulnerability assessment of natural gas pipelines subjected to seismic wave propagation. Part 1: Fragility relations and implemented seismic intensity measures. Tunn Undergr Space Technol 2019;86:279-96.

[6] Wang W, Ren JD, Wang FB, Dong M, Luo Y, Miao CG. Study on the mining mode of “gas corridor” in Erdos basin. Metal Mine 2019;520:23-31. in Chinese.

[7] Ren JD, Zhao YX, Wang W, Guo JH, Sun ZB, Liu SM. Optimal design of a protective coal pillar with a buried pipeline in a thick loose layer in western China: Methodology and case study. Rock Mech Rock Eng 2023; 56 (4):2879-96.

[8] Luo SX, Sha JH, Lv GX. The study on the overlapping mineral rights in the Ordos basin. Chin Min Magazine 2012;21:201-4. in Chinese.

[9] Wang Y, Yang WL, Deng J, Wu BL, Li ZY, Wang MZ. Accumulation system of cohabitating multi-energy minerals and their comprehensive exploration in Sedimentary Basin: A case study of Ordos Basin, NW China. Acta Geol Sin 2014;88:815-24. in Chinese.

[10] Cui AY. Study and discussion on coordinated development of coal and natural das resources in Erdos region. Coal Eng 2015;47:122-5. In Chinese.

[11] Dong M, Wang W. Research on coordinated exploitation for resources overlap area of oil-gas and coal in Ordos Basin. Chin Energy Environ Prot 2017;39:101-4. In Chinese.

[12] Ren JD, Zhao YX, Sun ZB, Wang W, Liu S. Investigation on protective coal pillar optimization and multi-parameter evolution characteristics of buried pipeline in gas-coal superposition area. Rock Soil Mech 2023;44:2679-95. in Chinese.

[13] Zou CN, Yang Z, Tao SZ, Yuan XJ, Zhu RK, Hou LH, Wu ST, Sun L, Zhang GS, Bai B, Wang L, Gao X, Pang Z. Continuous hydrocarbon accumulation over a large area as a distinguishing characteristic of unconventional petroleum: The Ordos Basin, North-Central China. Earth Sci Rev 2013;126:358-69.

[14] Zhang Q, Wang ZJ, Zhang JX, Jiang HQ, Wang YB, Yang K, Tian XG, Yuan LF. Integrated green mining technology of “coal mining-gangue washingbackfilling- strata control-system monitoring”: Taking Tangshan Mine as a case study. Environ Sci Pollut Res Int 2022; 29(4):5798-811.

[15] Wang F, Jiang BY, Chen SJ, Ren MZ. Surface collapse control under thick unconsolidated layers by backfilling strip mining in coal mines. Int J Rock Mech Min Sci 2019;113:268-77.

[16] Xu JM, Zhu WB, Xu JL, Wu JY, Li YC. High-intensity longwall mining-induced ground subsidence in Shendong coalfield, China. Int J Rock Mech Min Sci 2021;141:104730.

[17] He MC, Wang Q, Wu QY. Innovation and future of mining rock mechanics. J Rock Mech Geotech Eng 2021; 13(1):1-21.

[18] Obregon C, Mitri H. Probabilistic approach for open pit bench slope stability analysis: A mine case study. Int J Min Sci Technol 2019; 29(4):629-40.

[19] Qian MG, Shi PW, Xu JL Mining Pressure and Strata Control. 2rd ed. Xuzhou: China University of Mining and Technology Press; 2010.

[20] He CC, Lu WY, Zha WH, Wang F. A geomechanical method for predicting the height of a water-flowing fractured zone in a layered overburden of longwall coal mining. Int J Rock Mech Min Sci 2021;143:104798.

[21] Guo WB, Zhao GB, Lou GZ, Wang SR. A new method of predicting the height of the fractured water-conducting zone due to high-intensity longwall coal mining in China. Rock Mech Rock Eng 2019; 52(8):2789-802.

[22] Hucka VJ, Tu JH, Das BM. Computer analysis of the effect of mine subsidence on pipelines. Montréal: Canadian Institute. Min Metall 1989;82:42-5.

[23] Wang YJ, He MC, Yang J, Wang Q, Liu JN, Tian XC, Gao YB. Case study on pressure-relief mining technology without advance tunneling and coal pillars in longwall mining. Tunn Undergr Space Technol 2020;97:103236.

[24] Cui XM, Zhao YL, Wang GR, Zhang B, Li CY. Calculation of residual surface subsidence above abandoned longwall coal mining. Sustainability 2020; 12 (4):1528.

[25] Ghasemi E, Shahriar K. A new coal pillars design method in order to enhance safety of the retreat mining in room and pillar mines. Saf Sci 2012; 50(3):579-85.

[26] Zhang Z, Li Z, Xu G, Gao XJ, Liu QJ, Li ZJ, Liu JC. Lateral abutment pressure distribution and evolution in wide pillars under the first mining effect. Int J Min Sci Technol 2023; 33(3):309-22.

[27] Brook M, Hebblewhite B, Mitra R. Coal mine roof rating (CMRR), rock mass rating (RMR) and strata control: Carborough Downs Mine, Bowen Basin. Australia Int J Min Sci Technol 2020; 30(2):225-34.

[28] Parmar H, Yarahmadi Bafghi A, Najafi M. Impact of ground surface subsidence due to underground mining on surface infrastructure: The case of the Anomaly No. 12 Sechahun, Iran. Environ Earth Sci 2019; 78(14):409.

[29] Guo WB. Coal Mining Damage and Protection.3rd ed. Beijing: Emergency Management Press; 2019.

[30] Butchibabu B, Khan PK, Jha PC. Geophysical investigations for stability and safety mitigation of regional crude-oil pipeline near abandoned coal mines. J Geophys Eng 2021; 18(1):145-62.

[31] Kalisz P. Impact of mining subsidence on natural gas pipeline failures. IOP Conf Ser: Mater Sci Eng 2019;471:042024.

[32] Hao M, Nie Y. Hazard identification, risk assessment and management of industrial system: process safety in mining industry. Saf Sci 2022;154:105863.

[33] Watkins E, Karacan CÖ, Gangrade V, Schatzel S. Assessing gas leakage potential into coal mines from shale gas well failures: Inference from field determination of strata permeability responses to longwall-induced deformations. Nat Resour Res 2021; 30(3):2347-60.

[34] Mercx WP, van den Berg AC, Hayhurst CJ, Robertson NJ, Moran KC. Developments in vapour cloud explosion blast modeling. J Hazard Mater 2000; 71(1-3):301-19.

[35] Wang X. Hazard assessment of natural gas pipeline leakage and diffusion. Master’s dissertation. Harbin: Harbin Institute of Technology: 2010.

[36] Li XW, Chai YJ. Determination of pillar width to improve mining safety in a deep burst-prone coal mine. Saf Sci 2019;113:244-56.

[37] Chen SJ, Wang HL, Wang HY, Guo WJ, Li XS. Strip coal pillar design based on estimated surface subsidence in Eastern China. Rock Mech Rock Eng 2016; 49 (9):3829-38.

[38] Lei WL, Yu L, Bai SY, Chen YF, Zhao F, Zheng C, Huang X, He JY, Zhou HL. Parameter design and effectiveness evaluation of wide strip mining of extra thick coal seams under dense buildings. Sci Rep 2024; 14(1):10037.

[39] Xu JM. Movement law of the overlying strata above large mining height longwall face-end with shallow cover and its effect on ground deformation. Master’s dissertation. Xuzhou: China University of Mining and Technology; 2017.

[40] Yi MS. Study and application of key strata theory in shallow seam of shendong mining area. Doctoral dissertation. Xuzhou: China University of Mining and Technology; 2008.

[41] Wang F. Structure of “key strata and arch structure in unconsolidated layers” and Its application. Doctoral dissertation. Xuzhou: China University of Mining and Technology; 2016.

[42] Ju JF, Xu JL. Surface stepped subsidence related to top-coal caving longwall mining of extremely thick coal seam under shallow cover. Int J Rock Mech Min Sci 2015;78:27-35.

[43] Kang L, Yao AL, Guan HP, Liu P. Safety influence analysis of subsidence trough on oil & gas pipeline in steeply inclined coal-mining area. J Safety Sci Techno 2013;9:102-6. In Chinese.