Model for Fracturing Fluids Entering Soft–Hard Coal Interbedded Strata and Its Application
Publication: International Journal of Geomechanics
Volume 24, Issue 10
Abstract
The effectiveness of hydraulic fracturing is determined by the location of fracture initiation and the propagation. Previous research paid more attention to the control effect of geostress and construction-related parameters on the fracturing and propagation of fractures induced by hydraulic fracturing but ignored the important influence of fracturing fluid flow distribution when soft coal and hard coal interbed. In view of this, a model for the amount of fracturing fluids entering soft–hard coal interbedded strata was established. Meanwhile, the relationship among the strength differences between soft and hard coals, the perforation aperture, the coal seam thickness, the thickness ratio of hard coal, and the ratio of fracturing fluids entering hard coal was analyzed. The effect of the ratio of fracturing fluids flowing into hard coal on fracturing and gas production was discussed. On this basis, the fracturing construction suggestions under different thickness ratios of soft and hard coals were proposed. The results reveal that fracturing fluids always preferentially enter the soft coal with a lower strength, which causes an increased frictional resistance of fracturing fluid migration in soft coal, resulting in the redistribution of fracturing fluids entering coal seams and finally achieving the distribution balance. The strength differences between soft and hard coals, the perforation aperture, and seam thickness are negatively correlated with the proportion of fracturing fluids flowing into hard coal. The thickness of hard coal is positively correlated with that of hard coal; when the reservoir gas production potential is similar and the proportion of fracturing fluids entering hard coal does not exceed 30%, stable daily gas production is unlikely to exceed 800 m3/day; when the proportion of fracturing fluids entering hard coal exceeds 70%, daily gas production exceeds 1,000 m3/day. The results provide theoretical support for optimizing hydraulic fracturing schemes when soft and hard coals are interbedded.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
All data, models, or codes generated or used during the study are available from the corresponding author by request.
Acknowledgments
This study was supported by National Natural Fund Projects (42072189) and the Program for Innovative Research Team (in Science and Technology) in Universities of Henan Province, China (Grant No. 21IRTSTHN007) and Collaborative Innovation Center of Coal Work Safety and Clean High-Efficiency Utilization.
Author contributions: Xiaoming Ni: Writing—Reviewing and Editing. Jin Yan: Conceptualization, Methodology, Writing—Original draft preparation. Yafei Zhang: Investigation, Visualization. Ruize Niu: Conceptualization, Supervision. Wensheng Wang: Visualization, Investigation.
References
Baocun, Z., T. Shuheng, and Z. Jiazan. 2009. “Mechanics characteristics of coal and its roof and floor rock and the effects of hydraulic fracturing on coal reservoir.” J. China Coal Soc. 34 (6): 756–760.
Biao, F., H. Liu, S. Zhang, J. Zhang, and X. Wang. 2011. “A numerical study of parameter influences on horizontal hydraulic fracture.” Eng. Mech. 28 (10): 228–235.
Chase, M. 2020. “Evaluating limited entry perforating & diverter completion techniques with ultrasonic perforation imaging & fiber optic DTS warmbacks.” In Proc., SPE Hydraulic Fracturing Technology Conf. and Exhibition. Richardson, TX: Society of Petroleum Engineers.
Chen, M., F. Pang, and Y. Jin. 2000. “Experiments and analysis on hydraulic fracturing by a large-size triaxial simulator.” Chin. J. Rock Mech. Eng. 19 (S1): 868–872.
Chen, Z., and X. Liao. 2022. “A workflow of fracture geometry diagnostics of unconventional wells with complex fracture networks coupling fracture mapping and well testing.” J. Pet. Sci. Eng. 208: 109310. https://doi.org/10.1016/j.petrol.2021.109310.
Chen, Z., X. Liao, W. Yu, and X. Zhao. 2018. “Transient flow analysis in flowback period for shale reservoirs with complex fracture networks.” J. Pet. Sci. Eng. 170: 721–737. https://doi.org/10.1016/j.petrol.2018.05.032.
Deisman, N., M. Khajeh, and R. J. Chalaturnyk. 2013. “Using geological strength index (GSI) to model uncertainty in rock mass properties of coal for CBM/ECBM reservoir geomechanics.” Int. J. Coal Geol. 112: 76–86. https://doi.org/10.1016/j.coal.2012.10.015.
Feng, Q., L. Jinhua, C. Yidong, L. Dameng, and S. Fengrui. 2023. “Mechanical property evaluation of coal bed and favorable area prediction of coalbed methane (CBM) development based on well logging: A case study of No. 3 coal bed in Zhengzhuang Block, southern Qinshui Basin.” Coal Geol. Explor. 51 (4): 46–56.
Fengshan, H. 2007. “Method of geological strength index (GSI) for the estimation of strength and mechanical parameters of jointed rock mass.” J. Dalian Univ. 28 (6): 48–51.
Guo, X., H. Song, K. Wu, and J. Killough. 2018. “Pressure characteristics and performance of multi-stage fractured horizontal well in shale gas reservoirs with coupled flow and geomechanics.” J. Pet. Sci. Eng. 163: 1–15. https://doi.org/10.1016/j.petrol.2017.12.038.
Hoek, E., and P. Marinos. 2007. “A brief history of the development of the Hoek‒Brown failure criterion.” Soils Rocks 2 (11): 1–13.
Hou, B., M. Chen, B.-W. Zhang, Y. Sang, W. Cheng, and P. Tan. 2015. “Propagation of multiple hydraulic fractures in fractured shale reservoir.” Chin. J. Geotech. Eng. 37 (6): 1041–1046.
Jianchun, G., Y. Lijun, Z. Jinzhou, and R. Yong. 2005. “Modified model and application of calculating perforation pressure loss during hydraulic fracturing.” Nat. Gas Ind. 25 (5): 69–71.
Jiang, Y., W. Liang, T. Cai, X. Zhang, J. Yan, and S. Yue. 2023. “Fracture growth and acoustic emission response in natural coal‒rock blocks with different stress, fracturing medium and injection rates.” Geoenergy Sci. Eng. 220: 111228.
Jiaosheng, Y., W. Yibing, L. Anqi, C. Zhenghong, C. Yanpeng, and Z. Yushi. 2012. “Experimental study on propagation mechanism of complex hydraulic fracture in coal-bed.” J. China Coal Soc. 37 (1): 73–77.
Jinzhou, Z. H., C. H. Xiyu, L. I. Yongming, F. U. Bin, and X. U. Wenjun. 2017. “Numerical simulation of multi-stage fracturing and optimization of perforation in a horizontal well.” Pet. Explor. Dev. 44 (1): 119–126. https://doi.org/10.1016/S1876-3804(17)30015-0.
Li, C., W. Liang, D. Hou, H. Yao, and X. Song. 2020a. “Study on crack morphology and formation mechanism of water an ScCO2 cracking coals.” J. Rock Mech. Eng. 39 (4): 761–772.
Li, C. L., Z. B. Yang, H. S. Sun, Y. Y. Ma, Z. G. Zhang, Y. Y. Li, and G. Li. 2020b. “Construction of a logging interpretation model for coal structure from multi-coal seams area.” J. China Coal Soc. 45 (2): 721–730.
Li, M., W. Lv, J. Liu, Z. Sun, F. Zhou, and B. Wang. 2022. “Effect of perforation friction on 3D in-stage multiple fracture propagation: A numerical study.” Eng. Fract. Mech. 267: 108415. https://doi.org/10.1016/j.engfracmech.2022.108415.
Liu, D., Y. Wang, X. Ni, C. Tao, J. Fan, X. Wu, and S. Zhao. 2020. “Classification of coal structure combinations and their influence on hydraulic fracturing: A case study from the Qinshui Basin, China.” Energies 13 (17): 4559. https://doi.org/10.3390/en13174559.
Liu, W., H. Liu, S. Wang, and K. Dong. 2023. “A multi-fracture balanced extension control method for horizontal wells in anisotropic shale.” Eng. Fract. Mech. 281: 109102. https://doi.org/10.1016/j.engfracmech.2023.109102.
Long, G., and G. Xu. 2017. “The effects of perforation erosion on practical hydraulic-fracturing applications.” SPE J. 22 (2): 645–659. https://doi.org/10.2118/185173-PA.
Ni, X., Z. Zhao, Y. Wang, and L. Wang. 2020. “Optimisation and application of well types for ground development of coalbed methane from no. 3 coal seam in Shizhuang south block in Qinshui basin, Shanxi province, China.” J. Pet. Sci. Eng. 193: 107453. https://doi.org/10.1016/j.petrol.2020.107453.
Ni, X. M., X. B. Su, and Y. K. Li. 2010. “Study of the key technologies of the hydraulic fracturing used in multilayer coal seam.” J. China Univ. Min. Technol. 39 (5): 728–732.
Peng, W., M. Xian-biao, L. Jin-bin, and D. Chun-zhi. 2009. “Study of the borehole hydraulic fracturing and the principle of gas seepage in the coal seam.” Procedia Earth Planet. Sci. 1 (1): 1561–1573. https://doi.org/10.1016/j.proeps.2009.09.241.
Song, H., S. Du, J. Yang, Y. Zhao, and M. Yu. 2022. “Evaluation of hydraulic fracturing effect on coalbed methane reservoir based on deep learning method considering physical constraints.” J. Pet. Sci. Eng. 212: 110360. https://doi.org/10.1016/j.petrol.2022.110360.
Tao, Y. Q., D. Liu, J. Xu, and F. Zhang. 2019. “Experimental study on hydraulic fracturing propagation in coal/rock with large size and complex stress.” J. Min. Saf. Eng. 36 (2): 405–412.
Ugueto, G., F. Todea, and T. Daredia. 2019. “Can you feel the strain? DAS strain fronts for fracture geometry in the BC Montney, Groundbirch.” In Proc., SPE Annual Technical Conf. and Exhibition. Richardson, TX: Society of Petroleum Engineers.
Wang, Y., D. Liu, and Y. Cai. 2017. “Study of coal structures quantitative identification and distribution law in Gujiao Block, Northern Qinshui Basin.” In Proc., Int. Field Exploration and Development Conf. Chengdu, China: Shaanxi Petroleum Society.
Wu, K., J. Olson, M. T. Balhoff, and W. Yu. 2017. “Numerical analysis for promoting uniform development of simultaneous multiple-fracture propagation in horizontal wells.” SPE Prod. Oper. 32 (1): 41–50. https://doi.org/10.2118/174869-PA.
Wu, K., and J. E. Olson. 2016. “Mechanisms of simultaneous hydraulic-fracture propagation from multiple perforation clusters in horizontal wells.” SPE J. 21 (3): 1000–1008. https://doi.org/10.2118/178925-PA.
Wu, Y., L. Cheng, J. Killough, S. Huang, S. Fang, P. Jia, R. Cao, and Y. Xue. 2021. “Integrated characterization of the fracture network in fractured shale gas Reservoirs—Stochastic fracture modeling, simulation and assisted history matching.” J. Pet. Sci. Eng. 205: 108886. https://doi.org/10.1016/j.petrol.2021.108886.
Yang, C.-X., L.-P. Yi, Z.-Z. Yang, and X.-G. Li. 2022a. “Numerical investigation of the fracture network morphology in multi-cluster hydraulic fracturing of horizontal wells: A DDM-FVM study.” J. Pet. Sci. Eng. 215: 110723. https://doi.org/10.1016/j.petrol.2022.110723.
Yang, L., S. Wu, K. Gao, and L. Shen. 2022b. “Simultaneous propagation of hydraulic fractures from multiple perforation clusters in layered tight reservoirs: Non-planar three-dimensional modelling.” Energy 254: 124483. https://doi.org/10.1016/j.energy.2022.124483.
Yang, Y., X. Li, X. Yang, and X. Li. 2022c. “Influence of reservoirs/interlayers thickness on hydraulic fracture propagation laws in low-permeability layered rocks.” J. Pet. Sci. Eng. 219: 111081. https://doi.org/10.1016/j.petrol.2022.111081.
Yong, Q. 2021. “Strategic thinking on research of coal measure gas accumulation system and development geology.” J. China Coal Soc. 46 (8): 2387–2399.
Yu, B., C. Liu, W. Chen, J. Lu, and Y. Liu. 2022. “Experimental study on deformation and fracture characteristics of coal under different true triaxial hydraulic fracture schemes.” J. Pet. Sci. Eng. 216: 110839. https://doi.org/10.1016/j.petrol.2022.110839.
Yuan ZG, Wang HT, Hu GZ, Fan XG, Liu NP. 2012. “Numerical simulation of hydraulic fracturing of crossing borehole and its engineering application.” J. China Coal Soc. 37 (S1): 109–114.
Zhao, H., X. Li, H. Zhen, X. Wang, and S. Li. 2023. “Study on H-shaped fracture propagation and optimization in shallow dull-type coal seams in the Hancheng block, China.” J. Pet. Sci. Eng. 221: 111226.
Zhao, J., J. Zhao, Y. Hu, T. Huang, and J.-J. Liu. 2019. “Study on stress field distribution of hydraulic fracturing.” Nat. Gas Geosci. 30 (12): 1677–1683.
Zhaobiao, Y. A., L. I. Yangyang, Q. I. Yong, S. Hansen, P. Zhang, Z. Zhang, W. Congcong, L. Cunlei, and C. Changxiao. 2019. “Development unit division and favorable area evaluation for joint mining coalbed methane.” Pet. Explor. Dev. 45 (3): 559–568.
Zheng, S., M. Lin, W. Jiang, X. Qiu, and Z. Chen. 2022. “New method of in situ high-resolution experiments and analysis of fracture networks formed by hydraulic fracturing.” J. Pet. Sci. Eng. 217: 110849. https://doi.org/10.1016/j.petrol.2022.110849.
Zhu, G., S. Dong, and Z. Pan. 2021. “Simulation model of dynamic stress in reservoir under unsteady excitation of hydraulic fracturing.” J. China Coal Soc. 46 (S1): 149–156.
Zhu, Y., H. Zhou, C. Q. Zhang, and T. Lv. 2019. “Brittle inequality of Hoek‒Brown criterion and its applicability limit to GSI.” Chin. J. Rock Mech. Eng. 38 (Suppl. 2): 3412–3419.
Information & Authors
Information
Published In
International Journal of Geomechanics
Volume 24 • Issue 10 • October 2024
Copyright
© 2024 American Society of Civil Engineers.
History
Received: Nov 15, 2023
Accepted: Mar 28, 2024
Published online: Jul 18, 2024
Published in print: Oct 1, 2024
Discussion open until: Dec 18, 2024
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.