Tracking the development of seismic fracture network by considering the fault rupture method

2020 ◽  
Author(s):  
Taghi Shirzad ◽  
Stanisław Lasocki ◽  
Beata Orlecka‐Sikora
Keyword(s):  
Maximum Amplitude ◽  
Clean Energy ◽  
Velocity Model ◽  
Fracture Network ◽  
P Wave ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
The European Union ◽  
Fault Rupture ◽  
Horizon 2020

<p> In Enhanced Geothermal Systems pressurized injections play a role in developing fracture networks and enhancing the water transmissivity. However, the fractures may also coalesce into undesired pathways for fluid migration to enable the fluids to reach pre-existing faults. The properties of observed seismicity can shed some light on the fracture network development and from the standpoint of the possibility to form such undesired pathways. However, to reach this goal the seismic events should be well parameterized. In particular, the information on fault plane mechanisms is essential, which is often not readily accessible. In this study, we use the rupturing process with an accurate P-wave velocity model, which is obtained by the first arrival P-wave tomography approach, to compensate for an eventual lack of source mechanisms of micro-events. For this purpose, four characteristics of the sources (final/average displacement on the fault, the dimension of fault, rupture velocity and particle velocity) can be considered. A 3D model is defined around the hypocenter of each event, so that the size of this model directly depends on the event magnitude. After calculating the arrival time of the selected phase (e.g., P, S, p or s) for each station, all waveforms are then aligned, and stacked by different stacking (e.g., phase weight, N<sup>th</sup>-root) methods. By considering the maximum amplitude of the stacked waveform which is stimulated by each grid, the rupturing plane and the average velocity of rupturing can be obtained. This information of source can be replaced by the double-couple mechanism to investigate the fractures linking and tracking.</p><p>This work was supported under the <em>S4CE</em>: "Science for Clean Energy" project, which has received funding from the European Union’s Horizon 2020 research and innovation program, under grant agreement No 764810.</p>

scholarly journals Slates: a potential rock type to extract geothermal energy from the underground?

2020 ◽  
Author(s):  
Johannes Herrmann ◽  
Erik Rybacki ◽  
Wenxia Wang ◽  
Harald Milsch ◽  
Bianca Wagner ◽  
...  
Keyword(s):  
Geothermal Energy ◽  
Rock Type ◽  
Metamorphic Rocks ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
The European Union ◽  
Fracture Permeability ◽  
Horizon 2020 ◽  
Rock Types ◽  
Confining Pressures

<p>Commonly used host rock reservoirs for Enhanced Geothermal Systems (EGS) are composed of granite, as they display highly conductive and sustainable fracture networks after stimulation. However, considering the large amount of metamorphic rocks in Europe’s underground, these rock types may also show a large potential to extract geothermal energy from the subsurface. Within the framework of the European Union’s Horizon 2020 initiative ‘MEET (Multi-Sites EGS Demonstration)’, we are conducting fracture permeability experiments at elevated confining pressures, p<sub>c</sub>, temperatures, T, and differential stresses, </p>

An integrated approach to assess both risk and impacts related with geo-resources exploration and exploitation

2021 ◽  
Author(s):  
Maria Vittoria Gargiulo ◽  
Alexander Garcia ◽  
Ortensia Amoroso ◽  
Paolo Capuano
Keyword(s):  
Life Cycle ◽  
Probabilistic Approach ◽  
Energy Resource ◽  
Clean Energy ◽  
Integrated Approach ◽  
The European Union ◽  
Horizon 2020 ◽  
Risk Sources ◽  
New Perspective

<p>To the welfare of both economy and communities, our society widely exploits geo-resources. Nevertheless, with benefits come risks and even impacts. Understanding how a given project intrinsically bares such risks and impacts is of critical importance for both industry and society. In particular, it is fundamental to distinguish between the specific impacts related to exploiting a given energy resource and those shared with the exploitation of other energy resources. In order to do so, it is useful to differentiate impacts in two categories: routine impacts – caused by ordinary routine operations, investigated by Life-cycle assessment with a deterministic approach – and risk impacts – caused by incidents due to system failure or external events, investigated by risk assessments with a probabilistic approach. The latter category is extremely interesting because it includes low probability/high consequences events, which may not be completely independent or unrelated, causing the most disastrous and unexpected damages. For this reason, it is becoming more and more crucial to develop a strategy to assess not only the single risks but also their possible interaction and to harmonize the result obtained for different risk sources. Of particular interest for this purpose is the Multi-Hazard/Multi-Risk Assessment.</p><p>The aim of our work is to present an approach for a comprehensive analysis of impacts of geo-resource development projects. Routine operations as well as risks related to extreme events (as e.g.,seismic or meteorological) are linked using a Multi-Hazard Risk (MHR) approach built upon a Life-Cycle analysis (LCA). Given the complexity of the analysis, it is useful to adopt a multi-level approach: (a) an analysis of routine operations, (b) a qualitative identification of risk scenarios and (c) a quantitative multi-risk analysis performed adopting a bow-tie approach. In particular, after studying the two tools, i.e. LCA and MRA, we have implemented a protocol to interface them and to evaluate certain and potential impacts.</p><p>The performance of the proposed approach is illustrated on a virtual site (based on a real one) for geothermal energy production. As a result, we analyse the outcome of the LCA, identify risk-bearing elements and events, to finally obtain harmonised risk matrices for the case study. Such approach, on the one hand, can be used to assess both deterministic and stochastic impacts, on the other hand, can also open new perspective in harmonizing them. Using the LCA outputs as inputs of the MRA can allow the analyst to focus on particular risk pathways that could otherwise seem less relevant but can open new perspective in the risk/impact evaluation of single elements, as we show in this case study.</p><p>This work has been supported by S4CE ("Science for Clean Energy") project, funded from the European Union’s Horizon 2020 - R&I Framework Programme, under grant agreement No 764810 and by PRIN-MATISSE (20177EPPN2) project funded by Italian Ministry of Education and Research.</p>

Modeling fluid flow through complex fracture network in geological media by using hierarchical hydraulic properties

2020 ◽  
Author(s):  
Kyung Won Chang ◽  
Gungor Beskardes ◽  
Chester Weiss
Keyword(s):  
Fluid Flow ◽  
Surrounding Medium ◽  
Computational Cost ◽  
Energy Resource ◽  
Fracture Network ◽  
Fractured Media ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Hydraulic Stimulation ◽  
Complex Fracture

<p>Hydraulic stimulation is the process of initiating fractures in a target reservoir for subsurface energy resource management with applications in unconventional oil/gas and enhanced geothermal systems. The fracture characteristics (i.e., number, size and orientation with respect to the wellbore) determines the modified permeability field of the host rock and thus, numerical simulations of flow in fractured media are essential for estimating the anticipated change in reservoir productivity. However, numerical modeling of fluid flow in highly fractured media is challenging due to the explosive computational cost imposed by the explicit discretization of fractures at multiple length scales. A common strategy for mitigating this extreme cost is to crudely simplify the geometry of fracture network, thereby neglecting the important contributions made by all elements of the complex fracture system.</p><p>The proposed “Hierarchical Finite Element Method” (Hi-FEM; Weiss, Geophysics, 2017) reduces the comparatively insignificant dimensions of planar- and curvilinear-like features by translating them into integrated hydraulic conductivities, thus enabling cost-effective simulations with requisite solutions at material discontinuities without defining ad-hoc, heuristic, or empirically-estimated boundary conditions between fractures and the surrounding formation. By representing geometrical and geostatistical features of a given fracture network through the Hi-FEM computational framework, geometrically- and geomechanically-dependent fluid flow properly can now be modeled economically both within fractures as well as the surrounding medium, with a natural “physics-informed” coupling between the two.</p><p>SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.</p>

scholarly journals Hydraulic Fracturing in Enhanced Geothermal Systems—Field, Tectonic and Rock Mechanics Conditions—A Review

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5725
Author(s):  
Rafał Moska ◽  
Krzysztof Labus ◽  
Piotr Kasza
Keyword(s):  
Hydraulic Fracturing ◽  
Fracture Network ◽  
Hydraulic Fractures ◽  
Enhanced Geothermal Systems ◽  
Seismic Velocities ◽  
Geothermal Systems ◽  
Principal Stresses ◽  
Pumping Rate ◽  
Work Related ◽  
Stimulation Method

Hydraulic fracturing (HF) is a well-known stimulation method used to increase production from conventional and unconventional hydrocarbon reservoirs. In recent years, HF has been widely used in Enhanced Geothermal Systems (EGS). HF in EGS is used to create a geothermal collector in impermeable or poor-permeable hot rocks (HDR) at a depth formation. Artificially created fracture network in the collector allows for force the flow of technological fluid in a loop between at least two wells (injector and producer). Fluid heats up in the collector, then is pumped to the surface. Thermal energy is used to drive turbines generating electricity. This paper is a compilation of selected data from 10 major world’s EGS projects and provides an overview of the basic elements needed to design HF. Authors were focused on two types of data: geological, i.e., stratigraphy, lithology, target zone deposition depth and temperature; geophysical, i.e., the tectonic regime at the site, magnitudes of the principal stresses, elastic parameters of rocks and the seismic velocities. For each of the EGS areas, the scope of work related to HF processes was briefly presented. The most important HF parameters are cited, i.e., fracturing pressure, pumping rate and used fracking fluids and proppants. In a few cases, the dimensions of the modeled or created hydraulic fractures are also provided. Additionally, the current state of the conceptual work of EGS projects in Poland is also briefly presented.

Stress-based tomography: potential, open-questions and future developments

2020 ◽  
Author(s):  
Peter Bayer ◽  
Mohammad Javad Afshari Moein ◽  
Márk Somogyvári ◽  
Lisa Ringel ◽  
Mohammadreza Jalali
Keyword(s):  
Rock Mass ◽  
Imaging Techniques ◽  
Fracture Network ◽  
Great Depth ◽  
Heterogeneous Structure ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Fracture Networks ◽  
Future Developments ◽  
Open Questions

<p>Fracture network characterization is critical for many subsurface engineering problems in petroleum, mining, nuclear waste disposal and Enhanced Geothermal Systems (EGS). Due to limited exposure, direct measurement of fracture network properties at great depth is not possible and geophysical imaging techniques cannot resolve the fractures. Therefore, tomographic imaging techniques have been proposed and applied to reconstruct the structural discontinuities of rock mass. Stress-based tomography is a novel concept aiming at probabilistic imaging of the fracture network using the stress perturbations along deep boreholes. Currently, this approach has only been successfully tested on two-dimensional fracture networks. However, its great potential to unravel the heterogeneous structure of fractured rocks at great depth motivates further scientific effort. Here, we present the potential, open questions, current challenges and necessary future developments in order to apply this methodology to image three-dimensional multiscale structure of the rock mass in the field. Other tomographic approaches such as tracer and hydraulic tomography invert tracer breakthrough curves (BTCs) and pressure response in an observational well. We suggest a joint and comparative tomographic analysis in a Bayesian inversion framework to reconstruct Discrete Fracture Networks (DFN). This is expected to provide a new view of the strengths of each tomographic variant.</p>

scholarly journals Crustal-scale reflection imaging and interpretation by passive seismic interferometry using local earthquakes

2016 ◽  
Vol 4 (3) ◽  
pp. SJ29-SJ53 ◽  
Author(s):  
Yohei Nishitsuji ◽  
Shohei Minato ◽  
Boris Boullenger ◽  
Martín Gomez ◽  
Kees Wapenaar ◽  
...  
Keyword(s):  
Receiver Function ◽  
P Wave ◽  
Seismic Interferometry ◽  
Enhanced Geothermal Systems ◽  
Geothermal Systems ◽  
Decomposition Scheme ◽  
Local Earthquakes ◽  
Basin Scale ◽  
Passive Seismic ◽  
Reflection Imaging

We have developed an application of passive seismic interferometry (SI) using P-wave coda of local earthquakes for the purpose of crustal-scale reflection imaging. We processed the reflection gathers retrieved from SI following a standard seismic processing in exploration seismology. We applied SI to the P-wave coda using crosscorrelation, crosscoherence, and multidimensional deconvolution (MDD) approaches for data recorded in the Malargüe region, Argentina. Comparing the results from the three approaches, we found that MDD based on the truncated singular-value decomposition scheme gave us substantially better structural imaging. Although our results provided higher resolution images of the subsurface, they showed less clear images for the Moho in comparison with previous seismic images in the region obtained by the receiver function and global-phase SI. Above the Moho, we interpreted a deep thrust fault and the possible melting zones, which were previously indicated by active-seismic and magnetotelluric methods in this region, respectively. The method we developed could be an alternative option not only for crustal-scale imaging, e.g., in enhanced geothermal systems, but also for lithospheric-scale as well as basin-scale imaging, depending on the availability of local earthquakes and the frequency bandwidth of their P-wave coda.

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