Effect mechanism of seepage force on the hydraulic fracture propagation

作者

Haiyang Wang Desheng Zhou Yi Zou Peng Zheng
单位

School of Petroleum Engineering, Xi’an Shiyou University Engineering Research Center of Development and Management for Low to Extra-Low Permeability Oil and Gas Reservoirs in West China, Ministry of Education, Xi’an Shiyou University Xi’an University of Science and Technology
摘要

The flow of fluid through the porous matrix of a reservoir rock applies a seepage force to the solid rock matrix. Although the seepage force exerted by fluid flow through the porous matrix of a reservoir rock has a notable influence on rock deformation and failure, its effect on hydraulic fracture (HF) propagation remains ambiguous. Therefore, in this study, we improved a traditional fluid–solid coupling method by incorporating the role of seepage force during the fracturing fluid seepage, using the discrete element method. First, we validated the simulation results of the improved method by comparing them with an analytical solution of the seepage force and published experimental results. Next, we conducted numerical simulations in both homogeneous and heterogeneous sandstone formations to investigate the influence of seepage force on HF propagation. Our results indicate that fluid viscosity has a greater impact on the magnitude and extent of seepage force compared to injection rate, and that lower viscosity and injection rate correspond to shorter hydraulic fracture lengths. Furthermore, seepage force influences the direction of HF propagation, causing HFs to deflect towards the side of the reservoir with weaker cementation and higher permeability.
关键词

Hydraulic fracturing Seepage force Fracture propagation Discrete element method Reservoir heterogeneity
DOI

10.1007/s40789-024-00695-9
引用格式

Wang, H., Zhou, D., Zou, Y. et al. Effect mechanism of seepage force on the hydraulic fracture propagation.Int J Coal Sci Technol 11, 43 (2024).

图表

Schematic diagram of the effect of the seepage force

Darcy steady state seepage experiment simulation

Validation of seepage force simulation results. (L = 5 cm; W = 2.5 cm; ΔL = 1 cm; μ = 1 mPa·s)

$Comparison of numerical simulation result and experimental result of hydraulic fracture propagation under non-uniform pore pressure field$

$Rock specimen model for the hydraulic fracturing simulation$

Fracture propagation at the same time step using different fluid viscosities. (Reservoir permeability:2 mD; injection rate: 2.5 × 10−3 m3/s)

The number of contact bond failure in the rock model under the same time step and different fluid viscosity. (Injection rate: 2.5 × 10−3 m3/s)

Fluid domain pressure distribution field under different fluid viscosities. (Reservoir permeability: 20 mD; Injection rate: 2.5 × 10−3 m3/s)

Ball appliedforce distribution field under different fluid viscosities. (Reservoir permeability: 20 mD; Injection rate: 2.5 × 10−3 m3/s)

Induced stress field around HF under different fluid viscosities. (Reservoir permeability: 20 mD; Injection rate: 2.5 × 10−3 m3/s)

$Simulation results of fracture propagation under the same time step and different injection rates$

Pore pressure distribution around HFs under different injection rates. (Reservoir permeability: 20 mD; Fluid viscosity: 10 mPa·s)

Seepage force distribution around HFs under different injection rates. (Reservoir permeability: 20 mD; Fluid viscosity: 10 mPa·s)

Fracture propagation in heterogeneous cemented reservoirs under different horizontal in-situ stress differences and fluid viscosities. (SH: 20 MPa)

Fracture propagation in heterogeneous permeability reservoirs under different horizontal in-situ stress differences and fluid viscosities. a High permeability fluid domain network, wo = (rmax + r

Table 1

Microscopic parameters	Values
Maximum particle radius (m)	0.00096
Number of particles	30186
Particle density (kg/m³)	2650
Young’s modulus of the parallel bond (GPa)	32.0
Ratio of stiffness of the parallel bond	1.6
Tensile strength of the parallel bond (MPa)	12.0
Cohesion of the parallel bond (MPa)	30.0
Friction angle of the parallel bond(°)	45.0