Discrete element modeling of cyclic rate fluid injection at multiple locations in naturally fractured reservoirs

Yoon, Jeoung Seok; Zimmermann, Günter; Zang, Arno

doi:10.1016/j.ijrmms.2014.12.003

Cited by 62 publications

(39 citation statements)

References 28 publications

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“…Dissimilar to recent studies by Zang et al (2013) and Yoon et al (2014Yoon et al ( , 2015aYoon et al ( , 2015b, the model investigated in this study contains a large fault zone. Not only the seismic events computed from bond breakages, but also the seismic events by fracture slip are taken into account and compared with field observations.…”

Section: Introductionmentioning

confidence: 82%

“…Better understanding of the fault behaviour by nearby fluid injection and its implication on controlling induced seismicity and mitigation of larger magnitude events can be achieved by conducting more simulation runs with varying geological conditions and operational parameters, e.g., cyclic rate injection as was done by Zang et al (2013) and Yoon et al (2015aYoon et al ( , 2015b. Cumulative frequency…”

Section: Discussionmentioning

confidence: 99%

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Discrete element modeling of fluid injection–induced seismicity and activation of nearby fault

et al. 2015

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Enhanced geothermal systems, shale gas, and geological carbon sequestration all require underground fluid injection in high-pressure conditions. Fluid injection creates fractures, induces seismicity, and has the potential to reactivate nearby faults that can generate a large magnitude earthquake. Mechanisms of fluid injection-induced seismicity and fault reactivation should be better understood to be able to mitigate larger events triggered by fluid injection. This study investigates fluid injection, induced seismicity, and triggering of fault rupture using hydromechanical-coupled discrete element models. Results show that a small amount of fluid pressure perturbation can trigger fault ruptures that are critically oriented and stressed. Induced seismicity by rock failure shows in general higher b-values (slope of magnitude-frequency relation) compared to seismicity triggered by the fault fracture slip. Numerical results closely resemble observations from geothermal and shale-gas fields and demonstrate that discrete element modeling has the potential to be applied in the field as a tool for predicting induced seismicity prior to in situ injection.Key words: induced seismicity, fault reactivation, large-magnitude events, triggered seismicity, magnitude-frequency relation b-value.Résumé : Les systèmes géothermiques améliorés, l'extraction du gaz de schiste et la séquestration du carbone géologique nécessitent l'injection de fluides à haute pression dans le sous sol. Ce type d'injection génère des fractures, cause des secousses sismiques et peut réactiver des failles avoisinantes, lesquelles peuvent provoquer des tremblements de terre de forte magnitude. Il serait utile de mieux comprendre les mécanismes des séismes induits par l'injection de fluides et ceux de la réactivation de failles, et ce afin d'être en mesure de prévenir les événements graves causés par l'injection de fluide. Dans le présent article, on étudie l'injection de fluides, la sismicité induite et le déclenchement de ruptures de failles à l'aide de modèles couplés hydromécaniques basés sur la méthode des éléments discrets. Les résultats montrent qu'une légère perturbation de la pression du fluide injecté peut déclencher des ruptures d'orientation critique soumises à des contraintes. La sismicité induite par la rupture de roches est généralement caractérisée par des valeurs de b (pente de la fonction de relation entre la magnitude et la fréquence) par rapport à celles observées dans le cas de la sismicité déclenchée par le cisaillement de rupture des failles. Les résultats numériques se rapprochent beaucoup des observations faites sur les sites géothermiques ou d'extraction de gaz de schiste et montrent que la modélisation basée sur la méthode des éléments discrets pourrait être utilisée sur ces sites comme outil servant à prédire la sismicité induite avant l'injection de fluides in situ. [Traduit par la Rédaction] Mots-clés : sismicité induite, réactivation de failles, incidents de forte magnitude, sismicité déclenchée, valeur de b: pente ...

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Section: Introductionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Discrete element modeling of fluid injection–induced seismicity and activation of nearby fault

et al. 2015

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“…Eshiet et al (2013) employed PFC 2D to model the pressure development and the subsequent fracturing and/or cavity propagation of bulk rock and sand, respectively, considering fluid flow based on the Navier-Stokes equation of an incompressible fluid with contact density. Yoon et al (2015aYoon et al ( , 2015b investigated the fluid injection-induced seismicity in a reservoir for developing an enhanced geothermal system in deep underground using discrete element modelling.…”

Section: Introductionmentioning

confidence: 99%

Hydraulic fracturing process by using a modified two-dimensional particle flow code - method and validation

Zhou

Zhang

Han

2017

PCFD

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Hydraulic fracturing had been proved as a very useful tool for unconventional oil and gas development, where the fracturing fluid is injected into tight reservoirs under high pressure to enhance the permeability of rock mass. Although hydraulic fracturing theory, numerical modelling, and laboratory experiments develops fast, knowledge is still limited when the geological conditions are complex. This paper presents a numerical method -particle flow code (PFC) -and validates its power for hydraulic fracturing modelling in complex conditions. Firstly, the bonded particle method (BPM) and fluid-mechanical coupling mechanism are introduced; secondly, Darcy's flow in circular particles is simulated; thirdly, a series of numerical simulations is carried out to validate its suitability for hydraulic fracturing modelling; finally, the laminated reservoir will be modelled by BPM. The modelling results show good agreement with classical analytical solution and laboratory test results, which demonstrates that the BPM is a useful and strong tool for understanding the fracturing behaviour of reservoir rocks.Keywords: bonded particle model; modified fluid-mechanical couple mechanism; Darcy's flow; hydraulic fracturing; validation of pressure breakdown simulation.Reference to this paper should be made as follows: Zhou, J., Zhang, L. and Han, Z. (2017) 'Hydraulic fracturing process by using a modified two-dimensional particle flow code -method and validation

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“…The modelling work of Rutqvist et al [23] found that shear and tensile failure occur simultaneously and that, when a fault is present, events are larger than the small microseismic events generated by the hydraulic fracturing process. Yoon et al [24] modelled the response of a geothermal reservoir, using Discrete Element Modelling, to fluid injection and found that cyclic pumping rather than a constant pump rate decreased the occurrence of induced seismicity.…”

Section: Introductionmentioning

confidence: 99%

A sensitivity analysis of the effect of pumping parameters on hydraulic fracture networks and local stresses during shale gas operations

Westwood

Toon

Cassidy

2017

Fuel

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The shale gas industry has significant impact on economies around the world, however, it is not without risk. One of the primary concerns is felt seismicity and recent earthquakes, caused by fault reactivation related to hydraulic fracturing operations, have escalated uncertainty about hydraulic fracturing methods. Mitigating these risks is essential for restoring public confidence in this controversial industry. We investigate the effect that changing two operational parameters (flow rate and pumping time) and differential pressure has on the flow distance, fracture network area and the minimum lateral distance that hydraulic fracturing should occur from a pre-existing fault in order not to reactivate it (lateral respect distance); thus reducing the risk of felt seismicity. Sensitivity analyses are conducted using a Monte Carlo approach. The lateral respect distance is obtained from calculations of the Coulomb stress change of the rock surrounding the injection stage, for four stress threshold values obtained from the literature. Results show that the flow rate has the smallest rate of change for fracture area (3700 m 2 per 0.01 m 3 /s) and flow distance (8.3 m per 0.01 m 3 /s). We find that differential pressure has the largest impact on stimulated fracture area, when less than 2 MPa, at 31,029 m 2 /MPa. The pumping time has the most significant effect on the flow distance (48 m/hr) and the stress threshold value the most significant effect on the lateral respect distance. This study suggests that to reduce the lateral distance, a compromise is required between flow distance and fracture area. The results obtained by this research provide invaluable guidance for operational practice in determining the potential area of the induced fracture network and generated stress field under realistic hydraulic fracturing conditions, an important aspect for risk assessments.

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Discrete element modeling of cyclic rate fluid injection at multiple locations in naturally fractured reservoirs

Cited by 62 publications

References 28 publications

Discrete element modeling of fluid injection–induced seismicity and activation of nearby fault

Discrete element modeling of fluid injection–induced seismicity and activation of nearby fault

Hydraulic fracturing process by using a modified two-dimensional particle flow code - method and validation

A sensitivity analysis of the effect of pumping parameters on hydraulic fracture networks and local stresses during shale gas operations

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