Daniel Vogler

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Vogler

First Name

Daniel

ORCID

0000-0002-0974-9240

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Publications 1 - 10 of 36

Simulation of hydro-mechanically coupled processes in rough rock fractures using an immersed boundary method and variational transfer operators
von Planta, Cyrill; Vogler, Daniel; Xiaoqing, Chen; et al. (2019)
Computational Geosciences
Simulating hydro-mechanical processes in intersecting rough fractures with a fictitious domain method
von Planta, Cyrill; Vogler, Daniel; Chen, Xioqing; et al. (2019)
AGU Fall Meeting Abstracts
Flow-through Drying during CO Injection into Brine-filled Natural Fractures: A Tale of Effective Normal Stress
Grimm Lima, Marina; Javanmard, Hoda; Vogler, Daniel; et al. (2021)
International Journal of Greenhouse Gas Control
Injecting supercritical CO2 (scCO2) into brine-filled fracture-dominated reservoirs causes brine displacement and possibly evaporite precipitations that alter the fracture space. Here, we report on isothermal laboratory experiments on scCO2-induced flow-through drying in a naturally fractured granodiorite specimen under effective normal stresses of 5-10 MPa, where two drying regimes are identified. A novel approach is developed to delineate the evolution of brine saturation and relative permeability from fluid production and differential pressure measurements. Under higher compressive stresses, the derived relative permeability curves indicate lower mobility of brine and higher mobility of the scCO2 phase. The derived fractional flow curves also suggest an increase in channelling and a decrease in brine sweep efficiencies under higher compressive stresses. Finally, lowering compressive stresses seems to promote less water evaporation. Our experimental results assist in understanding the injectivity of single fractures and eventually of fracture networks during subsurface applications that involve scCO2 injection into saline formations.
Thermo-Fluid-Structure Interaction Based on the Fictitious Domain Method: Application to Dry Rock Simulations
Hassanjanikhoshkroud, Nasibeh; Nestola, Maria G.C.; Zulian, Patrick; et al. (2020)
Proceedings of the 45th Workshop on Geothermal Reservoir Engineering
Simulating plasma formation in pores under short electric pulses for plasma pulse geo drilling (Ppgd)
Ezzat, Mohamed; Vogler, Daniel; Saar, Martin O.; et al. (2021)
Energies
Plasma Pulse Geo Drilling (PPGD) is a contact-less drilling technique, where an electric discharge across a rock sample causes the rock to fracture. Experimental results have shown PPGD drilling operations are successful if certain electrode spacings, pulse voltages, and pulse rise times are given. However, the underlying physics of the electric breakdown within the rock, which cause damage in the process, are still poorly understood. This study presents a novel methodology to numerically study plasma generation for electric pulses between 200 and 500 kV in rock pores with a width between 10 and 100 µm. We further investigate whether the pressure increase, induced by the plasma generation, is sufficient to cause rock fracturing, which is indicative of the onset of drilling success. We find that rock fracturing occurs in simulations with a 100 µm pore size and an imposed pulse voltage of approximately 400 kV. Furthermore, pulses with voltages lower than 400 kV induce damage near the electrodes, which expands from pulse to pulse, and eventually, rock fracturing occurs. Additionally, we find that the likelihood for fracturing increases with increasing pore voltage drop, which increases with pore size, electric pulse voltage, and rock effective relative permittivity while being inversely proportional to the rock porosity and pulse rise time.
Fictitious domain methods for HM-processes in fractures
von Planta, Cyrill; Vogler, Daniel; Chen, Xiaqing; et al. (2019)
SCCER-SoE Science Report 2019
Modelling of hydro-mechanical processes in heterogeneous fracture intersections using a fictitious domain method with variational transfer operators
von Planta, Cyrill; Vogler, Daniel; Chen, Xiaoqing; et al. (2020)
Computational Geosciences
Fluid flow in rough fractures and the coupling with the mechanical behaviour of the fractures pose great difficulties for numerical modeling approaches due to complex fracture surface topographies, the non-linearity of hydro-mechanical processes and their tightly coupled nature. To this end, we have adapted a fictitious domain method to enable the simulation of hydro-mechanical processes in fracture intersections. The main characteristic of the method is the immersion of the fracture, modelled as a linear elastic solid, in the surrounding computational fluid domain, modelled with the incompressible Navier-Stokes equations. The fluid and the solid problems are coupled with variational transfer operators. Variational transfer operators are also used to solve contact within the fracture using a dual mortar approach and to generate problem-specific fluid meshes. With respect to our applications, the key features of the method are the usage of different finite element discretizations for the solid and the fluid problem and the automatically generated representation of the fluid-solid boundary. We demonstrate that the presented methodology resolves small-scale roughness on the fracture surface, while capturing fluid flow field changes during mechanical loading. Starting with 2D/3D benchmark simulations of intersected fractures, we end with an intersected fracture composed of complex fracture surface topographies, which are in contact under increasing loads. The contributions of this article are as follows: (1) the application of the fictitious domain method to study flow in fractures with intersections, (2) a mortar-based contact solver for the solid problem, (3) generation of problem-specific grids using the geometry information from the variational transfer operators.
Impact of Effective Normal Stress on Capillary Pressure in a Single Natural Fracture
Grimm Lima, Marina; Schädle, Philipp; Vogler, Daniel; et al. (2019)
Proceedings of the European Geothermal Congress 2019
On the applicability of connectivity metrics to rough fractures under normal stress
Javanmard, Hoda; Saar, Martin O.; Vogler, Daniel (2022)
Advances in Water Resources
Rough rock fractures have complex geometries which result in highly heterogeneous aperture fields. To accurately estimate the permeability of such fractures, heterogeneity of the aperture fields must be quantified. In this study heterogeneity of single rough rock fractures is for the first time parametrized by connectivity metrics, which quantify how connected the bounds of a heterogeneous field are. We use 3000 individual realizations of synthetic aperture fields with different statistical parameters and compute three connectivity metrics based on percolation theory for each realization. The sensitivity of the connectivity metrics with respect to the determining parameter, i.e the cutoff threshold, is studied and the correlation between permeability of the fractures and the computed connectivity metrics is presented. The results show that the Θ connectivity metric predicts the permeability with higher accuracy. All three studied connectivity metrics provide better permeability estimations when a larger aperture value is chosen as the cutoff threshold. Overall, this study elucidates that using connectivity metrics provides a less expensive alternative to fluid flow simulations when an estimation of fracture permeability is desired.
Impact of Temperature on the Performance of Plasma-Pulse Geo-Drilling (PPGD)
Ezzat, Mohamed; Börner, Jascha; Kammermann, Benedikt; et al. (2024)
Rock Mechanics and Rock Engineering
Advanced Geothermal Systems (AGS) may in principle be able to satisfy the global energy demand using standard continental-crust geothermal temperature gradients of 25–35 ∘C/km. However, conventional mechanical rotary drilling is still too expensive to cost-competitively provide the required borehole depths and lengths for AGS. This highlights the need for a new, cheaper drilling technology, such as Plasma-Pulse Geo-Drilling (PPGD), to improve the economic feasibility of AGS. PPGD is a rather new drilling method and is based on nanoseconds-long, high-voltage pulses to fracture the rock without mechanical abrasion. The absence of mechanical abrasion prolongs the bit lifetime, thereby increasing the penetration rate. Laboratory experiments under ambient-air conditions and comparative analyses (which assume drilling at a depth between 3.5 and 4.5 km) have shown that PPGD may reduce drilling costs by approximately 17–23%, compared to the costs of mechanical drilling, while further research and development are expected to reduce PPGD costs further. However, the performance of the PPGD process under deep wellbore conditions, i.e., at elevated temperatures as well as elevated lithostatic and hydrostatic pressures, has yet to be systematically tested. In this paper, we introduce a standard experiment parameter to examine the impact of deep wellbore conditions on PPGD performance, namely the productivity (the excavated rock volume per pulse) and the specific energy (the amount of energy required to drill a unit volume of rock). We employ these parameters to investigate the effect of temperature on PPGD performance, with temperatures increasing up to 80 ∘C, corresponding to a drilling depth of up to approximately 3 km.

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Daniel Vogler

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