Experimental investigation of the effects of heterogeneity and geostress difference on the 3D growth and distribution of hydrofracturing cracks in unconventional reservoir rocks

Liu, Peng; Ju, Yang; Ranjith, P.G.; Zheng, Zhixue; Chen, Jialiang

doi:10.1016/j.jngse.2016.08.071

Cited by 106 publications

(47 citation statements)

References 53 publications

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“…In situ monitoring and laboratory experiments have been used to identify the morphologies of hydrofracturing cracks [13][14][15][16][17]. Microseismic and nondestructive testing methods have been used to investigate the hydrofracturing crack morphologies [18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Adaptive Finite Element‐Discrete Element Analysis for Microseismic Modelling of Hydraulic Fracture Propagation of Perforation in Horizontal Well considering Pre‐Existing Fractures

Wang

Yang

2018

Shock and Vibration

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Hydrofracturing technology of perforated horizontal well has been widely used to stimulate the tight hydrocarbon reservoirs for gas production. To predict the hydraulic fracture propagation, the microseismicity can be used to infer hydraulic fractures state; by the effective numerical methods, microseismic events can be addressed from changes of the computed stresses. In numerical models, due to the challenges in accurately representing the complex structure of naturally fractured reservoir, the interaction between hydraulic and pre-existing fractures has not yet been considered and handled satisfactorily. To overcome these challenges, the adaptive finite element-discrete element method is used to refine mesh, effectively identify the fractures propagation, and investigate microseismic modelling. Numerical models are composed of hydraulic fractures, pre-existing fractures, and microscale pores, and the seepage analysis based on the Darcy's law is used to determine fluid flow; then moment tensors in microseismicity are computed based on the computed stresses. Unfractured and naturally fractured models are compared to assess the influences of pre-existing fractures on hydrofracturing. The damaged and contact slip events were detected by the magnitudes, -values, Hudson source type plots, and focal spheres.

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Section: Introductionmentioning

confidence: 99%

Adaptive Finite Element‐Discrete Element Analysis for Microseismic Modelling of Hydraulic Fracture Propagation of Perforation in Horizontal Well considering Pre‐Existing Fractures

Wang

Yang

2018

Shock and Vibration

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“…This kind of feature has also been observed in a recent hydrofracturing experiment [ Liu et al , ] (see Figure ). Figure a shows the hydraulic fracture in an artificial heterogeneous sample, which is more complex than the fracture in homogeneous one (Figure b).…”

Section: Resultsmentioning

confidence: 99%

“…The hydraulic fracture geometry in different rock samples, where (a) artificially heterogeneous and (b) homogeneous samples are from Reference Liu et al []. (c) The fracture geometry in current heterogeneous sample with h s = 0.23.…”

Section: Resultsmentioning

confidence: 99%

Pore‐scale modeling of hydromechanical coupled mechanics in hydrofracturing process

Chen

Wang

2017

JGR Solid Earth

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Hydrofracturing is an important technique in petroleum industry to stimulate well production. Yet the mechanism of induced fracture growth is still not fully understood, which results in some unsatisfactory wells even with hydrofracturing treatments. In this work we establish a more accurate numerical framework for hydromechanical coupling, where the solid deformation and fracturing are modeled by discrete element method and the fluid flow is simulated directly by lattice Boltzmann method at pore scale. After validations, hydrofracturing is simulated with consideration on the strength heterogeneity effects on fracture geometry and microfailure mechanism. A modified topological index is proposed to quantify the complexity of fracture geometry. The results show that strength heterogeneity has a significant influence on hydrofracturing. In heterogeneous samples, the fracturing behavior is crack nucleation around the tip of fracture and connection of it to the main fracture, which is usually accompanied by shear failure. However, in homogeneous ones the fracture growth is achieved by the continuous expansion of the crack, where the tensile failure often dominates. It is the fracturing behavior that makes the fracture geometry in heterogeneous samples much more complex than that in homogeneous ones. In addition, higher pore pressure leads to more shear failure events for both heterogeneous and homogeneous samples.

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“…In fact, rock is a heterogeneous geological material which contains a different scale of natural weaknesses, such as pores, grain boundaries and pre-existing cracks [20]. Increasing evidence from practical stimulations in the field shows that HFs can initiate and propagate in intricate ways that are highly influenced by the heterogeneity of rock reservoirs [21][22][23][24]. In tight glutenite, extensive material heterogeneity exists not only in the single rock, but in between the two types of rock, i.e., the sandstone and gravel create interrock heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

The Fracturing Behavior of Tight Glutenites Subjected to Hydraulic Pressure

Zhang

et al. 2018

Processes

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Tight glutenites are typically composed of heterogeneous sandstone and gravel. Due to low or ultra-low permeability, it is difficult to achieve commercial production in tight glutenites without hydraulic fracturing. Efficient exploitation requires an in-depth understanding of the fracturing behavior of these reservoirs. This paper provides a numerical method that integrates the digital image processing (DIP) technique into a numerical code rock failure process analysis (RFPA). This method could consider the glutenite heterogeneities, including intrarock and interrock heterogeneities, and the practicability is verified through two numerical tests. Two-dimensional (2D) simulations show hydraulic fractures (HFs) can penetrate or deflect to propagate along the gravels, depending on the magnitude of stress anisotropy and gravel strength. Three-dimensional (3D) simulations with the consideration of gravel distribution orientation, gravel size and axial ratio show HFs could propagate past the gravel with no deflection, forming a bypass fracture that is not easy to observe in common laboratory experiments. HFs could also deflect to propagate along the gravels. The impacts of the gravel distribution orientation, gravel size and axial ratio are discussed in detail. The main propagation modes of HFs intersecting the gravels are summarized as: (1) penetrating directly; (2) deflecting to propagate along the gravels to form distorted HFs; (3) propagating to bypass the gravels; (4) a combination of (1) and (2), or (2) and (3).

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Experimental investigation of the effects of heterogeneity and geostress difference on the 3D growth and distribution of hydrofracturing cracks in unconventional reservoir rocks

Cited by 106 publications

References 53 publications

Adaptive Finite Element‐Discrete Element Analysis for Microseismic Modelling of Hydraulic Fracture Propagation of Perforation in Horizontal Well considering Pre‐Existing Fractures

Adaptive Finite Element‐Discrete Element Analysis for Microseismic Modelling of Hydraulic Fracture Propagation of Perforation in Horizontal Well considering Pre‐Existing Fractures

Pore‐scale modeling of hydromechanical coupled mechanics in hydrofracturing process

The Fracturing Behavior of Tight Glutenites Subjected to Hydraulic Pressure

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