Research on Stress Sensitivity of Fractured Carbonate Reservoirs Based on CT Technology

Yongfei Yang, Zhihui Liu, Zhixue Sun, Senyou An, Wenjie Zhang, Pengfei Liu, Jun Yao and Jingsheng Ma
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Yongfei Yang: Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, China
Zhihui Liu: Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, China
Zhixue Sun: Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, China
Senyou An: Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, China
Wenjie Zhang: Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, China
Pengfei Liu: Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, China
Jun Yao: Research Centre of Multiphase Flow in Porous Media, China University of Petroleum (East China), Qingdao 266580, China
Jingsheng Ma: Institute of Petroleum Engineering, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, UK

Energies, 2017, vol. 10, issue 11, 1-15

Abstract: Fracture aperture change under stress has long been considered as one of primary causes of stress sensitivity of fractured gas reservoirs. However, little is known about the evolution of the morphology of fracture apertures on flow property in loading and unloading cycles. This paper reports a stress sensitivity experiment on carbonate core plugs in which Computed Tomography (CT) technology is applied to visualize and quantitatively evaluate morphological changes to the fracture aperture with respect to confining pressure. Fracture models were obtained at selected confining pressures on which pore-scale flow simulations were performed to estimate the equivalent absolute permeability. The results showed that with the increase of confining pressure from 0 to 0.6 MPa, the fracture aperture and equivalent permeability decreased at a greater gradient than their counterparts after 0.6 MPa. This meant that the rock sample is more stress-sensitive at low effective stress than at high effective stress. On the loading path, an exponential fitting was found to fit well between the effective confining pressure and the calculated permeability. On the unloading path, the relationship is found partially reversible, which can evidently be attributed to plastic deformation of the fracture as observed in CT images.

Keywords: CT; digital core; fracture opening; stress sensitivity; pore-scale simulations (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2017
References: View complete reference list from CitEc
Citations: View citations in EconPapers (9)

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