Experimental and Theoretical Study on Dynamic Hydraulic Fracture

Abstract

Hydraulic fracturing is vital in the stimulation of oil and gas reservoirs, whereas the dynamic process during hydraulic fracturing is still unclear due to the difficulty in capturing the behavior of both fluid and fracture in the transient process. For the first time, the direct observations and theoretical analyses of the relationship between the crack tip and the fluid front in a dynamic hydraulic fracture are presented. A laboratory-scale hydraulic fracturing device is built. The momentum-balance equation of the fracturing fluid is established and numerically solved. The theoretical predictions conform well to the directly observed relationship between the crack tip and the fluid front. The kinetic energy of the fluid occupies over half of the total input energy. Using dimensionless analyses, the existence of equilibrium state of the driving fluid in this dynamic system is theoretically established and experimentally verified. The dimensionless separation criterion of the crack tip and the fluid front in the dynamic situation is established and conforms well to the experimental data. The dynamic analyses show that the separation of crack tip and fluid front is dominated by the crack profile and the equilibrium fluid velocity. This study provides a better understanding of the dynamic hydraulic fracture.

Numerical Modeling Study on Mineral Alteration and Sealing Performance for CO2 Geological Sequestration with Enhancing Water Recovery in Hydraulic Fractured Shale Reservoirs

“…Deformation of the formation will occur because of CO 2 injection. Considering the existence of shale the bedding plane, natural fractures, and faults [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53], the deformation behavior and the effect on fluid transport will be extremely complicated. The reactivation potential of faults does exist, Lithosphere which may provide a leak path for CO 2 to escape the storage formation [54][55][56].…”

Experimental study of multi-timescale crack blunting in hydraulic fracture

“…a Specimen and b hydraulic fracturing device. The experimental setup is largely the same as the device and specimen described by Dong et al (2019aDong et al ( , 2020) (Dong et al 2019a). It is worth noting that according to Eqs.…”

“…In the previous study, the tip of the hydraulic fracture is often considered as "dry zone". The relationship between the fluid front and the crack tip in dynamic hydraulic fracture was studied by Dong et al (2019a). In the quasi-static hydraulic, the crack tip is often considered dry due to the viscosity of the fracturing fluid.…”

Stick‐slip like behavior in shear fracture propagation including the effect of fluid flow

“…Recently, several authors have argued that the propagation of fractures in porous materials is not smooth, but stepwise 26–29 . This stepwise propagation is observed in experiments with pressurized fractures, 30–33 resulting in pressure oscillations at the inlet. Stepwise fracture propagation has also been argued to be one of the sources of intermittent earthquakes 34 .…”