Effects of microfractures on permeability in carbonate rocks based on digital core technology

Abstract

Carbonate reservoirs develop many different types of microfractures that play an important role in increasing the effective reservoir space and permeability. Thus, the qualitative and quantitative characterisation of the effect of microfractures on permeability in rocks is essential. In this study, a quantitative method for evaluating the impact of different microfracture parameters on carbonate rock permeability was proposed. Lattice Boltzmann simulations were carried on two carbonate digital cores with different types of artificially added microfractures. Based on the simulation results, a partial least squares regression analysis was used to investigate the impact of microfractures on the permeability of the cores. Increases in the fracture length, aperture, and density were found to linearly increase the permeability of the carbonate rocks, and as the fracture length increased to penetrate the whole core, an exponential increase in permeability was observed. Additionally, the effect of microfractures on the digital core permeability was more significant in cores with high permeability compared to that in low-permeability cores. Although both fractures and matrix permeability contribute to the permeability of the digital cores, the former were found to have a greater effect on the permeability.

Cited as: Liu, C., Zhang, L., Li, Y., Liu, F., Martyushev, D. A., Yang, Y. Effects of microfractures on permeability in carbonate rocks based on digital core technology. Advances in Geo-Energy Research, 2022, 6(1): 86-90. https://doi.org/10.46690/ager.2022.01.07

References

Akhavan, A., Shafaatian, S. -M. -H., Rajabipour, F. Quantifying the effects of crack width, tortuosity, and roughness on water permeability of cracked mortars. Cement and Concrete Research, 2012, 42(2): 313-320.

Blunt, M. J., Bijeljic, B., Dong, H., et al. Pore-scale imaging and modelling. Advances in Water Resources, 2013, 51: 197-216.

Geladi, P., Kowalski, B. R. Partial least-squares regression: A tutorial. Analytica Chimica Acta, 1986, 185: 1-17.

Guerriero, V., Mazzoli, S., Iannace, A., et al. A permeability model for naturally fractured carbonate reservoirs. Marine and Petroleum Geology, 2013, 40: 115-134.

Jones, Jr., F. O. A laboratory study of the effects of confining pressure on fracture flow and storage capacity in carbonate rocks. Journal of Petroleum Technology, 1975, 27(1): 21-27.

Ju, Y., Zhang, Q., Zheng, J., et al. Fractal model and lattice Boltzmann method for characterization of non-darcy flow in rough fractures. Scientific Reports, 2017, 7: 41380.

Neuman, S. P. Multiscale relationships between fracture length, aperture, density and permeability. Geophysical Research Letters, 2008, 35(22): L22402.

Nie, X., Zhang, C., Wang, C., et al. Variable secondary porosity modeling of carbonate rocks based on μ-CT images. Open Geosciences, 2019, 11(1): 617-626.

Pradipto, Purqon, A. Accuracy and numerical stabilty analysis of lattice Boltzmann method with multiple relaxation time for incompressible flows. Journal of Physics: Conference Series, 2017, 877: 012035.

Rong, Y., Pu, W., Zhao, J., et al. Experimental research of the tracer characteristic curves for fracture-cave structures in a carbonate oil and gas reservoir. Journal of Natural Gas Science and Engineering, 2016, 31: 417-427.

Sagar, B., Runchal, A. Permeability of fractured rock: Effect of fracture size and data uncertainties. Water Resources Research, 1982, 18(2): 266-274.

Wang, X., Yin, H., Zhao, X., et al. Microscopic remaining oil distribution and quantitative analysis of polymer flooding based on CT scanning. Advances in Geo-Energy Research, 2019, 3(4): 448-456.

Wang, Z., Li, H., Lan, X., et al. Formation damage mechanism of a sandstone reservoir based on micro-computed tomography. Advances in Geo-Energy Research, 2021, 5(1): 25-38.

Yang, H., Zhang, L., Liu, R., et al. Thermal conduction simulation based on reconstructed digital rocks with respect to fractures. Energies, 2019, 12(14): 2768.