scholarly journals Simulation of Hydraulic Fracture in Unsaturated Soils with High Degree of Saturation

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Tielin Chen ◽  
Liangyi Zhang ◽  
Dingli Zhang
Keyword(s):  
Crack Initiation ◽  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Unsaturated Soils ◽  
Numerical Approach ◽  
Degree Of Saturation ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Critical Model ◽  
High Degree

A numerical simulation approach of hydraulic fracture process, considering the couplings of the stress distribution, the fluid flow of the water-air mixture, the compression and dissolution of air, and the element damage evolution, has been developed to investigate the mechanisms of crack initiation and propagation in porous media during hydraulic fracturing. The concept of homogenized pore fluid has been adopted to represent the water air mixture. A large number of numerical analysis on hydraulic fracturing in clay with incipient injection slot have been carried out to study the mechanism of hydraulic fracturing in unsaturated soil with the characteristic of critical model I type of crack loading using stress intensity factorKIc. The results provide a numerical picture depicting the mechanisms of crack initiation and propagation during hydraulic fracturing. The numerical results are in good agreement with the experimental results, which confirms the adequacy and the power of the numerical approach.

scholarly journals Mechanisms of Crack Initiation and Propagation in Dense Linear Multihole Directional Hydraulic Fracturing

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Jiangwei Liu ◽  
Changyou Liu ◽  
Qiangling Yao
Keyword(s):  
Rock Mass ◽  
Crack Initiation ◽  
Hydraulic Fracturing ◽  
Principal Stress ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation ◽  
Coal Rock

Artificially fracturing coal-rock mass serves to form break lines therein, which is related to the distribution of cracked boreholes. For this reason, we use physical experiments and numerical simulations to study the crack initiation and propagation characteristics of dense linear multihole drilling of fractured coal-rock mass. The results indicate that only in the area between the first and last boreholes can hydraulic fracturing be controlled by dense linear multihole expansion along the direction of the borehole line; in addition, no directional fracturing occurs outside the drilling section. Upon increasing parameters such as the included angle θ between the drilling arrangement line and the maximum principal stress σ1 direction, the drilling spacing D, the difference Δσ in principal stress, etc., the effect of directional fracture is gradually weakened, and the hydraulic fractures reveal three typical cracking modes: cracking along the borehole line, bidirectional cracking (along the borehole line and perpendicular to the minimum principal stress σ3), and cracking perpendicular to σ3. Five propagation modes also appear in sequence: propagating along borehole line, step-like propagation, S-shaped propagation, bidirectional propagation (along the borehole line and perpendicular to σ3), and propagation perpendicular to σ3. Based on these results, we report the typical characteristics of three-dimensional crack propagation and discuss the influence of the gradient of pore water pressure. The results show clearly that crack initiation and propagation are affected by both the geostress field and the pore water pressure. The pore water pressure will exhibit a circular-local contact-to-integral process during crack initiation and expansion. When multiple cracks approach, the superposition of pore water pressure at the tip of the two cracks increases the damage to the coal rock, which causes crack reorientation and intersection.

scholarly journals Crack initiation and propagation in coalbed gas reservoir during hydraulic fracturing

Sadhana ◽  
2019 ◽  
Vol 44 (2) ◽  
Author(s):  
Tingting Jiang ◽  
Haiwang Ye ◽  
Gaofeng Ren ◽  
Jianhua Zhang ◽  
Yubiao Li ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Hydraulic Fracturing ◽  
Crack Initiation And Propagation ◽  
Gas Reservoir ◽  
Coalbed Gas ◽  
Initiation And Propagation ◽  
Coalbed Gas Reservoir
Sign in / Sign up

Export Citation Format

Share Document