Sampling a Stimulated Rock Volume: An Eagle Ford Example

Raterman, Kevin T.; Farrell, Helen E.; Mora, Oscar S.; Janssen, Aaron L.; Gomez, Gustavo A.; Busetti, Seth; McEwen, Jamie; Davidson, Michael; Friehauf, Kyle; Rutherford, James; Reid, Ray; Jin, Ge; Roy, Baishali; Warren, Mark

doi:10.15530/urtec-2017-2670034

Cited by 92 publications

(35 citation statements)

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“…Although current fracture diagnostics can rarely resolve the detailed nature of the fractures created during fracture treatment of unconventional hydrocarbon wells (Grechka et al 2017), recent empirical evidence suggests that deviations from planar fracture geometry may exist. Physical 1 3 evidence from cores that were sampled from a hydraulically fractured rock volume indicates that the generated fracture density far exceeds the number of perforation clusters (Raterman et al 2017). The creation of fracture complexity in terms of deflection, offset, and branching is possible at bedding surfaces and other naturally occurring heterogeneities, with preexisting natural fractures not appearing necessary for the creation of complex, distributed fracture systems.…”

Section: Introductionmentioning

confidence: 99%

Drained rock volume around hydraulic fractures in porous media: planar fractures versus fractal networks

Nandlal

Weijermars

2019

Pet. Sci.

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This study applies the Lindenmayer system based on fractal theory to generate synthetic fracture networks in hydraulically fractured wells. The applied flow model is based on complex analysis methods, which can quantify the flow near the fractures, and being gridless, is computationally faster than traditional discrete volume simulations. The representation of hydraulic fractures as fractals is a more realistic representation than planar bi-wing fractures used in most reservoir models. Fluid withdrawal from the reservoir with evenly spaced hydraulic fractures may leave dead zones between planar fractures. Complex fractal networks will drain the reservoir matrix more effectively, due to the mitigation of stagnation flow zones. The flow velocities, pressure response, and drained rock volume (DRV) are visualized for a variety of fractal fracture networks in a single-fracture treatment stage. The major advancement of this study is the improved representation of hydraulic fractures as complex fractals rather than restricting to planar fracture geometries. Our models indicate that when the complexity of hydraulic fracture networks increases, this will suppress the occurrence of dead flow zones. In order to increase the DRV and improve ultimate recovery, our flow models suggest that fracture treatment programs must find ways to create more complex fracture networks.

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Section: Introductionmentioning

confidence: 99%

Drained rock volume around hydraulic fractures in porous media: planar fractures versus fractal networks

Nandlal

Weijermars

2019

Pet. Sci.

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“…Despite the fact that many numerical and small-scale laboratory studies have provided us valuable insight into the interactions between hydraulic fracture and natural fractures, comprehensive field studies of what complex hydraulic fracture really look like are urgently lacking. Raterman et al (2017) presented a cross-study that involves coring multiple sidetracks directly through hydraulic fractures created by the stimulation of an adjacent horizontal well. This type of work is very rare and priceless, and may lead to a paradigm shift in how we envision hydraulic fracture inside SRV; such direct observations are the best benchmarks to validate our hypotheses about hydraulic fracturing in naturally fractured reservoirs.…”

Section: Fig18 the Analogy Between Multi-fracturing Within A Certaimentioning

confidence: 99%

“…Eventually, one dominant fracture will emerge from these narrowly spaced fracture swarms (Wang 2016) and will propagate further by itself until the next moment of unstable fracture propagation occurs. This can possibly explain why fracture swarms are observed in some coring samples while not observed in others (Raterman et al 2017). The advantage of using cohesive zone model is that the dynamic evolution of nucleation growth, and coalescence of microcracks occurs in the process zone ahead of fracture tip can be represented by cohesive zone, so that it is applicable to brittle, quasi-brittle and ductile rocks.…”

Section: Fig18 the Analogy Between Multi-fracturing Within A Certaimentioning

confidence: 99%

“…For instance, core and outcrop data study from 18 shale plays in North America reveals that natural fractures are commonplace and are concentrated where clay content is low (Gale et al 2014). Field study (Raterman et al 2017) by coring rock sample at Eagle Ford reveals that natural fractures are abundant and hydraulic fractures are complex. Studies from a major shale play from Sichuan Basin in China show the existence of both interlaminated and structural fractures, and some fractures are partially or completely filled with calcite (Liang et al 2014;Zeng et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Wang

2019

Journal of Natural Gas Science and Engineering

135

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All reservoirs are fractured to some degree. Depending on the density, dimension, orientation and the cementation of natural fractures and the location where the hydraulic fracturing is done, pre-existing natural fractures can impact hydraulic fracture propagation and the associated flow capacity. Understanding the interactions between hydraulic fracture and natural fractures is crucial in estimating fracture complexity, stimulated reservoir volume (SRV), drained reservoir volume (DRV) and completion efficiency. However, what hydraulic fracture looks like in the subsurface, especially in unconventional reservoirs, remain elusive, and many times, field observations contradict our common beliefs. In this study, a global cohesive zone model is presented to investigate hydraulic propagation in naturally fractured reservoirs, along with a comprehensive discussion on hydraulic fracture propagation behaviors in naturally fractured reservoirs. The results indicate that in naturally fractured reservoirs, hydraulic fracture can turn, kink, branch and coalesce, and the fracture propagation path is quite complex, but it does not necessarily mean that fracture networks can be created, even under low horizontal stress difference, because of strong stress shadow effect and flow-resistance dependent fluid distribution. Perhaps, 'complex fracture', rather than 'fracture networks', is the norm in most unconventional reservoirs.

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“…Recent field study (Palisch et al 2017) using electromagnetic methods to detect electrically conductive proppants distribution reveals that the proppants are unevenly distributed among each cluster and the effective hydraulic fracture length/propped fracture surface area can differ from cluster to cluster in a given stage. Field study (Raterman et al 2017) by examining core samples through the upper section of fractures along a horizontal wellbore indicates that fractures are not evenly distributed spatially and thus reservoir drainage may be non-uniform. So sub-optimal completion, reservoir heterogeneity and premature screen-out may lead to large reservoir volume unstimulated and in turn, impact the rate transient behavior.…”

Section: Fig 1 Top View Of Typical Macroscopic Flow Regimes For Hydrmentioning

confidence: 99%

Discrete fracture networks modeling of shale gas production and revisit rate transient analysis in heterogeneous fractured reservoirs

Wang

2018

Journal of Petroleum Science and Engineering

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To cite this version:Hanyi Wang. Discrete fracture networks modeling of shale gas production and revisit rate transient analysis in heterogeneous fractured reservoirs. AbstractHorizontal wells with multiple hydraulic fractures are necessary stimulation technique for economically developing tight and shale gas reservoirs. In such reservoirs, the conventional well-test techniques are not suitable because of ultralow formation permeability. Rate transient analysis (RTA) is the widely used tool for analyzing these reservoirs for the purpose of reserves estimation, hydraulic fracture stimulation optimization, and development planning. However, the conventional rate transient analysis is based on the models that were derived from idealistic assumptions for homogenous reservoirs. In this article, we first review the industry's common practice for rate transient analysis and discuss why the idealized conceptual model may not be adequate for analyzing production data from shale gas reservoirs. Then, a unified shale gas reservoir model based on Discrete Fracture Networks (DFN) is presented to investigate how each mechanism influences shale gas production and the corresponding rate transient behavior. It is found that shale gas production and rate transient behavior are significantly impacted reservoir heterogeneity, fracture networks, non-Darcy flow, gas adsorption and completion efficiency. Short earlytime linear flow with long transitional flow period is an indication of either existence of abundant complex fracture network or heterogeneous completion with unevenly distributed hydraulic fractures. Consider the nature of non-unique results of RTA, information from other independent sources is required to achieve a consistent and holistic interpretation.

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Sampling a Stimulated Rock Volume: An Eagle Ford Example

Cited by 92 publications

References 0 publications

Drained rock volume around hydraulic fractures in porous media: planar fractures versus fractal networks

Drained rock volume around hydraulic fractures in porous media: planar fractures versus fractal networks

Hydraulic fracture propagation in naturally fractured reservoirs: Complex fracture or fracture networks

Discrete fracture networks modeling of shale gas production and revisit rate transient analysis in heterogeneous fractured reservoirs

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