Review ArticleA review of laboratory studies and theoretical analysis for the interaction mode between induced hydraulic fractures and pre-existing fractures
Introduction
Hydraulic fracturing technique has been extensively used to increase the permeability of oil and gas reservoirs, which can sharply enhance oil and gas production, especially in unconventional reservoirs (e.g., shale, tight sandstone, and coalbed methane). More than one million wells in the United States have used hydraulic fracturing to enhance productions since the 1940s (King, 2012). To create complex fractures in reservoirs, the fracturing fluid (either water or a water-based fluid with various additives) pumps into reservoirs at a predetermined rate. The entire hydraulic fracturing processes are as follows. As the fracturing fluid pumps down the well, the wellbore pressure sharply increases (in Fig. 1). When the pressure surpasses the rock strength, the reservoir begins to crack, corresponding to a fracture initiation pressure (Pin). After the initiation, the pressure increases to its maximum value, which is named breakdown pressure (Pb). Then, the pressure drops to the propagation pressure (Pprop), which is the steady portion of the pressure curve. As the pumping stops, the pressure instantly drops to a low value. The transition point is called shut-in pressure (Ps) or instantaneous shut-in pressure (ISIP). The fluid leaks off from the fracture surface, the fracture opening width decreases, and the pressure decreases slowly. The fluid pressure inside the fracture eventually reaches equilibrium with the minimum in situ stress. At this point, the hydraulic fracture closes, which corresponds to the fracture closure pressure (Pc). Finally, the pressure decreases to the pore pressure due to fluid leaking off from the fracture and the borehole.
In general, the propagation of the induced hydraulic fracture is along the direction of the maximum confining stress (Zhang et al., 2019c; Wu et al., 2020; Zhao et al., 2020). However, if a pre-existing fracture (e.g. natural fracture, bedding plane, flaw, joint or fault) is near or along the path of the induced hydraulic fracture growth, the propagation direction of the induced hydraulic fracture may be diverted (Zhang et al., 2018a, b). The existence of pre-existing fracture may benefit to improve the stimulated reservoir volume (SRV), or impede the induced hydraulic fracture propagation. It is affected by in situ stress state, geometry and mechanical properties of pre-existing fracture, injection rate and fluid viscosity, etc. (Xu et al., 2020; Yew and Weng, 2014). Many studies have been carried out to study the interaction mechanisms through numerical modelling, laboratory test and theoretical analysis. Comprehensive reviews of numerical modelling used for simulation of hydraulic fracturing and investigation the interaction process can be found in recent published papers (Dahi Taleghani et al., 2016; Kolawole and Ispas, 2019b; Lecampion et al., 2018; Xu et al., 2018; Zhang et al., 2019e). Therefore, the present study is focused on the interaction studies of laboratory test and theoretical analysis.
The objective of the present study is to review the current state-of-the-art hydraulic fracturing studies, discuss advantages, practicality and drawbacks of different methods, and summarize the key findings regarding the interaction mode between the induced hydraulic fractures and pre-existing fractures. Laboratory studies on the interaction mode between the induced hydraulic fracture and a single pre-existing fracture, multiple pre-existing fractures (parallel pre-existing fractures, random pre-existing fractures, and bedding planes) are discussed based on a comprehensive literature review in Section 2. In Section 3, the theoretical criterion for the interaction mode based on different mechanical theories (e.g., linear elasticity theory and fracture mechanics theory) are discussed in detail. Recommendations for further researches are discussed and proposed in section 4. Finally, conclusions are drawn in Section 5.
Section snippets
Hydraulic fracturing in laboratory
Researchers have observed a considerable number of pre-existing fractures in rocks through several techniques, including borehole televiewer (Hickman et al., 1999), geologic sketches (Warpinski and Teufel, 1984), and coring (Warpinski et al., 1993; Gale et al., 2014). These pre-existing fractures significantly influence the stress state. The stress state induced by the pre-existing fracture controls the behaviours and the geometry of induced hydraulic fractures (Warpinski and Teufel, 1984).
Criteria of the interaction mode
To evaluate the fracturing processes and distinguish the failure nature of the pre-existing fractures during the hydraulic fracturing, some researchers have proposed a series of theoretical criteria to predict the interaction mode (in Table 3). Blanton (1982; 1986), and Warpinski and Teufel (1984) proposed a criterion to discuss the interaction mode based on the approaching angle and differential stress. Renshaw and Pollard (1995) proposed a criterion considering crossing an unbounded
Field applications
In the field, there is not so much data that can be obtained like in laboratory tests. The fracturing curve is the main data that can be used to evaluate the fracturing morphology and fracture behaviour (Jiang et al., 2019a; Tan et al., 2020; Zhang et al., 2019a). When a hydraulic fracture propagates in a homogenous rock, the fracturing curve does not have a large pressure fluctuation. As an induced hydraulic fracture encounters a pre-existing fracture (e.g., induced hydraulic fracture arrested
Conclusions and future researches
In the present study, the development of hydraulic fracturing in laboratory was comprehensively reviewed and investigated. The main factors affecting the interaction mode between the induced hydraulic fractures and pre-existing fractures were discussed. The interaction mode is mainly controlled by the confining stress, approaching angle, mechanical properties of pre-existing fractures, injection rate and fluid viscosity. The interaction mode in specimens containing a single pre-existing
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (Grant Nos. 51978541, 41941018, and 51839009), China Postdoctoral Science Foundation (Grant No. 2019M662711), and State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology (Grant No. SKLGDUEK1901).
References (137)
- et al.
Experimental study on hydraulic fracturing of soft rocks: influence of fluid rheology and confining stress
J. Petrol. Sci. Eng.
(2006) - et al.
A criterion for identifying hydraulic fractures crossing natural fractures in 3D space
Petrol. Exp. Devel.
(2014) - et al.
Reactivation mechanism of natural fractures by hydraulic fracturing in naturally fractured shale reservoirs
J. Nat. Gas Sci. Eng.
(2015) - et al.
Overview of numerical models for interactions between hydraulic fractures and natural fractures: challenges and limitations
Comput. Geotech.
(2016) - et al.
The effect of natural fracture dip and strike on hydraulic fracture propagation. Int. J. Rock Mech
MIN (Minim. Invasive Neurosurg.)
(2015) - et al.
Interpretation of hydraulic fracturing breakdown pressure
J. Rock Mech. Min. Sci. Geomech. Abstr
(1993) - et al.
Comprehensive study of fracture flow characteristic and feasibility of hybrid volume stimulation technique in tight fractured carbonate gas reservoir
J. Petrol. Sci. Eng.
(2019) - et al.
Experimental study of hydraulic fracturing for shale by stimulated reservoir volume
Fuel
(2014) - et al.
ISRM suggested methods for rock stress estimation-part 3: hydraulic fracturing (HF) and/or hydraulic testing of pre-existing fractures (HTPF). Int. J. Rock Mech
MIN (Minim. Invasive Neurosurg.)
(2003) - et al.
Experimental and numerical study on the non-planar propagation of hydraulic fractures in shale
J. Petrol. Sci. Eng.
(2019)
CT-based 3D reconstruction of the geometry and propagation of hydraulic fracturing in shale
J. Petrol. Sci. Eng.
Experimental and numerical study on hydraulic fracture propagation in coalbed methane reservoir
J. Nat. Gas Sci. Eng.
Propagation behavior of hydraulic fracture across the coal-rock interface under different interfacial friction coefficients and a new prediction model
J. Nat. Gas Sci. Eng.
Adaptive finite element-discrete element method for numerical analysis of the multistage hydrofracturing of horizontal wells in tight reservoirs considering pre-existing fractures, hydromechanical coupling, and leak-off effects
J. Nat. Gas Sci. Eng.
Interaction analysis of propagating opening mode fractures with veins using the discrete element method. Int. J. Rock Mech
MIN (Minim. Invasive Neurosurg.)
Effect of water infiltration, injection rate and anisotropy on hydraulic fracturing behavior of granite
Rock Mech. Rock Eng.
Laboratory hydraulic fracturing of granite: acoustic emission observations and interpretation
Eng. Fract. Mech.
Multi-scale modeling of shale laminas and fracture networks in the Yanchang formation, Southern Ordos Basin, China
Eng. Geol.
Influence of vugs in fractured-vuggy carbonate reservoirs on hydraulic fracture propagation based on laboratory experiments
J. Struct. Geol.
Practical considerations for diagnostic fracture injection test (DFIT) analysis
J. Petrol. Sci. Eng.
Comprehensive before-closure model and analysis for fracture calibration injection falloff test
J. Petrol. Sci. Eng.
Laboratory hydraulic fracturing test on large-scale pre-cracked granite specimens
J. Nat. Gas Sci. Eng.
Monitoring hydraulically-induced fractures in the laboratory using acoustic emissions and the fluorescent method, Int. J. Rock Mech
Min. Sci.
An experimentally verified criterion for propagation across unbounded frictional interfaces in brittle, linear elastic materials
J. Rock Mech. Min. Sci. Geomech. Abstr
Fracture mechanics approach to hydraulic fracturing stress measurements
Fract. Mech. Rock
Theoretical overview of hydraulic fracturing break-down pressure
J. Nat. Gas Sci. Eng.
Poroelastic effects in the determination of the maximum horizontal principal stress in hydraulic fracturing tests-a proposed breakdown equation employing a modified effective stress relation for tensile failure
J. Rock Mech. Min. Sci. Geomech. Abstr
Analysis of hydraulic fracture initiation and vertical propagation behavior in laminated shale formation
Fuel
Experimental investigation of the effect of natural fracture size on hydraulic fracture propagation in 3D
J. Struct. Geol.
Interaction between cemented natural fractures and hydraulic fractures assessed by experiments and numerical simulations
J. Petrol. Sci. Eng.
Borehole yield and hydraulic fracture initiation in poorly consolidated rock strata-part I. impermeable media. J. Rock Mech
Min. Sci. Geomech. Abstr
Quantitative Seismology
Distinct element modeling of hydraulically fractured Lac du Bonnet granite
J. Geophys. Res. Sol. Earth
Hydraulic and mechanical responses of porous sandstone during pore pressure-induced reactivation of fracture planes: an experimental study. Rock Mech
Rock Eng.
Experimental hydraulic fracture propagation in a multi-fractured medium
An experimental study of interaction between hydraulically induced and pre-existing fractures
Propagation of hydraulically and dynamically induced fractures in naturally fractured reservoirs
Body force equivalents for seismic dislocations
Bull. Seismol. Soc. Am.
Laboratory hydraulic fracturing test on a rock with artificial discontinuities
Experimental study on fracturing features in naturally fractured reservoir
Acta Petrolei. Sinica.
Interaction between Hydraulic Fracture and Natural Fracture - a New Prediction Model by Adaptive Neuro-Fuzzy Inference System (ANFIS)
Hydraulic fracture propagation across a weak discontinuity controlled by fluid injection
Injection-sensitive mechanics of hydraulic fracture interaction with discontinuities. Rock Mech
Rock Eng.
Effects of Stress, Pore Pressure and Pore Fluid on Bulk Strain, Velocity, and Permeability in Rocks
Analysis of Hydraulic Fracture Propagation in Fractured Reservoirs: an Improved Model for the Interaction between Induced and Natural Fractures
Hydraulic fracture propagation in the presence of planes of weakness. SPE 4852
Mechanism of fracture initiation and propagation using a tri-axial hydraulic fracturing test system in naturally fractured reservoirs
Eur. J. Environ. Civ. Eng.
Introduction to moment tensor inversion of microseismic events
Lead. Edge
Moment tensor inversion of induced microseisnmic events: evidence of non-shear failures in the−4<M<−2 moment magnitude range
Geophys. Res. Lett.
Shear and tensile earthquakes caused by fluid injection
Geophys. Res. Lett.
Cited by (37)
The critical pressures for crack closure, crack reopening and crack instability in hydraulic fracturing
2024, International Journal of Rock Mechanics and Mining SciencesVisualization of hydraulic fracture interacting with pre-existing fracture
2023, Petroleum ScienceMutual impact of true triaxial stress, borehole orientation and bedding inclination on laboratory hydraulic fracturing of Lushan shale
2023, Journal of Rock Mechanics and Geotechnical EngineeringGeneration mechanism and influencing factors of fracture networks during alternate fracturing in horizontal wells
2023, Theoretical and Applied Fracture Mechanics