Investigation on Flowback Behavior of Imbibition Fracturing Fluid in Gas–Shale Multiscale Pore Structure

Jiajia Bai (), Guoqing Wang, Qingjie Zhu, Lei Tao and Wenyang Shi
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Jiajia Bai: State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Beijing 100083, China
Guoqing Wang: College of Petroleum Engineering, Changzhou University, Changzhou 213164, China
Qingjie Zhu: College of Petroleum Engineering, Changzhou University, Changzhou 213164, China
Lei Tao: College of Petroleum Engineering, Changzhou University, Changzhou 213164, China
Wenyang Shi: College of Petroleum Engineering, Changzhou University, Changzhou 213164, China

Energies, 2022, vol. 15, issue 20, 1-16

Abstract: To investigate the influence of flowback time and flowback difference on flowback behavior of shale fracturing fluid, we carried out the permeability test experiment of Longmaxi Formation shale under different flowback pressure gradients and analyzed the retention characteristics of water phase in shale pores and fractures after flowback by nuclear magnetic resonance (NMR) instrument. The results indicate that after flowback under the pressure gradient ranges of 0.06~0.18 MPa/cm, the content of retained water phase in shale samples ranges from 9.68% to 16.97% and the retention of fracturing fluid in shale does not decrease with the increase of flowback pressure difference. Additionally, increasing the flowback pressure difference will reduce the shale permeability damage rate, but the permeability damage rate is still above 80%. After the flowback, the water phase mainly stays in the pore space with D < 100 nm, especially in the pore space with 2~10 nm and 10~50 nm. It is extremely difficult for the water phase in the pores with D < 100 nm to flow back out. The experimental results show that the critical flowback pressure gradient for particle migration of rock powder in shale fracture surface is 0.09 MPa/cm. The research results have important guiding significance for shale gas well flowback.

Keywords: shale gas; fracturing fluid flowback; NMR; water phase distribution; gas permeability (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: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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