Hydraulic fracture energy budget: Insights from the laboratory

Abstract

In this paper we present results from a series of laboratory hydraulic fracture experiments designed to investigate various components of the energy budget. The experiments involved a cylindrical sample of Westerly granite being deformed under various triaxial stress states and fractured with distilled water, which was injected at a range of constant rates. Acoustic emission sensors were absolutely calibrated, and the radiated seismic energy was estimated. The seismic energy was found to range from 7.02E−8% to 1.24E−4% of the injection energy which is consistent with a range of values for induced seismicity from field‐scale hydraulic fracture operations. The deformation energy (crack opening) of the sample during hydraulic fracture propagation was measured using displacement sensors and ranged from 18% to 94% of the injection energy. Our results support the conclusion that aseismic deformation is a significant term in the hydraulic fracture energy budget.

Microscale Characterization of Fracture Growth and Associated Energy in Granite and Sandstone Analogs: Insights Using the Discrete Element Method

“…Our results show that fracture energy ( W frac ) accounts for a small fraction of input energy, similar to energy budget estimations from field, laboratory observations, and numerical studies (Fulton & Rathbun, ; Goodfellow et al, ; Herbert et al, ; Pittarello et al, ). Additionally, we show that the fraction of input energy partitioned into fracture growth is a function of rock strength and confining pressure and is influenced by microscale processes.…”

Aseismic Motions Drive a Sparse Seismicity During Fluid Injections Into a Fractured Zone in a Carbonate Reservoir

“…For instance, De Barros et al () found that more than 99.99% of the deformation is aseismic performing similar injection experiments in shale materials. At the laboratory scale (i.e., centimeter), Goodfellow et al () performed hydraulic fracture experiments on granite samples under different triaxial stress and investigated the energy budget. Using acoustic emission sensors, they estimated that the seismic energy represented 4 to 8% of the injection energy, indicating that aseismic deformation is a significant term in the total energy budget.…”

“…The dotted line represents the theoretical prediction from McGarr (). Data are from Buijze et al (), De Barros et al (), Goodfellow et al (), Maxwell (), McGarr (), and this study.…”

“…Aseismic motion was also observed in controlled in situ fluid injection experiments at meter scale in limestone (Guglielmi et al, ) or in shale (De Barros et al, ). At the laboratory scale, Goodfellow et al () performed fluid injection experiments on granite samples under triaxial stresses and showed that most of the deformation is aseismic during the fluid pressurization.…”

Normalized Radiated Seismic Energy From Laboratory Fracture Experiments on Opalinus Clayshale and Barre Granite

“…Recent laboratory studies have shown that there is significant similarity between the lab and field scales on key seismic parameters; for example, Yoshimitsu et al () found that the physical processes at these scales were highly similar in that the seismic moment is inversely proportional to the cube of the corner frequency. Among hydraulic fracture experiments, Goodfellow et al () suggest that the seismic energy radiated as a proportion of the injection energy during HF scales is consistent between the laboratory and the field scales at around to and that the seismic moment of the recorded microseisms are log‐proportional to the injected fluid volume across scales. The radiated seismic energy approach has since been employed by researchers such as Jestin et al () to study the seismicity of tensile fractures propagating through material interfaces, where they found that seismic efficiency increases with the square root of crack velocity.…”