A numerical approach for modeling thermo-poro-elastic deformation sources in volcanic and hydrothermal regions.

Mapping Intimacies ◽

10.5194/egusphere-egu21-8282 ◽

2021 ◽

Author(s):

Massimo Nespoli ◽

Maria Elina Belardinelli ◽

Maurizio Bonafede

Keyword(s):

Pore Pressure ◽

Homogeneous Medium ◽

Numerical Approach ◽

Deformation Source ◽

Campi Flegrei ◽

Temperature Changes ◽

Magmatic Body ◽

Temperature Diffusion ◽

Realistic Representation ◽

Source Models

The Thermo-Poro-Elastic (TPE) inclusions contribute to deformation and stress in volcanic and hydrothermal areas. Differently from other deformation source models (e.g. magma chambers), the TPE sources effects are due to pore-pressure and temperature changes of the fluid within the inclusion. So that the TPE inclusions can allow large deformations even in those volcanic environments in which there is no evidence of a shallow magmatic body. This kind of sources also provides large deviatoric stresses, promoting different types of focal mechanisms both inside and around them. With respect to a previous work, we propose a numerical model that allows for a more realistic representation of TPE sources: we can represent inclusions with an arbitrary geometry and we take into account the elastic stratification of the crust, thanks to a modified version of the EDGRN/EDCMP code. We can also represent the case of a depth dependent distribution of pore pressure and temperature changes within inclusions, as expected during the transient stage of fluid propagation and temperature diffusion. We found that elastic layering and transient changes of the TPE source can promote both normal and thrust earthquakes in its interior. For the 1982-84 unrest episode at Campi Flegrei the inversion of geodetic data leads to a lower misfit between modeled and measured deformation data, with respect to a homogeneous medium and the retrieved geometry and location of the thermo-poro-elastic are in good agreement with the observed distribution of seismicity.

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Deformation driven magma ascent in stratified magma reservoirs: an experimental study

10.5194/egusphere-egu21-1397 ◽

2021 ◽

Author(s):

Amy Ryan ◽

Mark Zimmerman ◽

Lars Hansen

Keyword(s):

Pore Pressure ◽

Seismic Waves ◽

Soda Lime ◽

High Viscosity ◽

Magma Ascent ◽

Campi Flegrei ◽

Soda Lime Glass ◽

Borosilicate Glasses ◽

Magma Intrusion ◽

Magma Reservoirs

Mature volcanic systems (e.g., Yellowstone, USA; Campi Flegrei, Italy) are fed by stratified magma reservoirs &#8211; small bodies of eruptible, crystal-poor silicic magma are suspended within a larger volume of non-eruptible, crystal-rich mush. Lavas erupted from these systems record geochemical evidence for long-term (103 to 105 years) deep storage followed by short (<1 to 103 years) residences in shallow chambers prior to eruption. Evidence for protracted magma ascent is frequently absent, suggesting deep-seated magmas rise quickly in reservoirs despite the high viscosity and low permeability of crystal-rich mushes. We hypothesize that deformation of a reservoir (by intrusion of new magma, passing seismic waves, tectonic stresses, etc.) allows low viscosity magmas to intrude high viscosity mush, creating mechanical instabilities that focus magma migration and facilitate rapid magma ascent through the reservoir.To test this hypothesis, we are conducting high-temperature and high-pressure deformation experiments in a gas-medium, Paterson apparatus. Samples consist of a disk of soda lime glass (&#8220;magma&#8221;) stacked in series with a disk of a composite (&#8220;mush&#8221;) composed of borosilicate glass and fine quartz sand (44-106 &#956;m). The mush has a crystal fraction of 80%. The stacked magma and mush disks are overlain by permeable ceramics. Sample assemblies are heated to 900&#176;C (above the glass transition temperatures for soda lime and borosilicate glasses) and pressurized to 200 MPa confining pressure. At 900&#176;C the magma viscosity is 104 Pa s and the mush viscosity is ~1012-1014 Pa s. Following heating and pressurization, samples either dwell at high P-T conditions for extended time or are subjected to axial compression (strain rates of 10-5-10-3 s-1; shortening up to 50% of the length of the mush disk) or pore pressure gradients (a pressure difference across the sample of 10-150 MPa, equivalent to 2-30 MPa/mm over the length of the mush disk). After dwelling or deformation, samples are rapidly quenched and decompressed, cut in longitudinal sections and polished. Polished samples are analyzed in an SEM to collect back-scatter electron images and compositional maps. BSE images can be used to look for melt structures (e.g., viscous channels, dikes) that form in the mush during deformation. The compositions of magma (soda lime) and mush (borosilicate) melts are different, therefore compositional maps can be used to look for their respective spatial distributions. In static experiments, no magma intrudes the mush. We expect deformation to facilitate magma intrusion and that the volume of intruding magma will increase with increasing strain rate, strain and pore pressure gradient. These experiments will shed light on the role deformation plays in instigating magma ascent in stratified magma reservoirs.

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Prediction of Microelectronic Substrate Warpage Using Homogenized Thermomechanical Finite Element Models

Advances in Electronic Packaging, Parts A, B, and C ◽

10.1115/ipack2005-73122 ◽

2005 ◽

Author(s):

Parsaoran Hutapea ◽

Joachim L. Grenestedt ◽

Mitul Modi ◽

Michael Mello ◽

Kristopher Frutschy

Keyword(s):

Finite Element ◽

Effective Properties ◽

Isothermal Condition ◽

Numerical Approach ◽

Thermomechanical Properties ◽

Temperature Changes ◽

Numerical Predictions ◽

Homogenization Approach ◽

Simple Bounds ◽

Complex Features

High-density microelectronic substrates, used in organic CPU packages, are comprised of several polymer, fiber-weave, and copper layers and are filled with a variety of complex features such as traces, micro-vias, Plated-Through-Holes (PTH), and adhesion holes. When subjected to temperature changes, these substrates may warp, driven by the mismatch in Coefficients of Thermal Expansion (CTE) of the constituent materials. This study focused on predicting substrate warpage in an isothermal condition. The numerical approach consisted of three major steps: estimating homogenized (effective) thermomechanical properties of the features; calculating effective properties of discretized layers using the effective properties of the features; and assembling the layers to create 2D Finite Element (FE) plate models and to calculate warpage of the whole substrates. The effective properties of the features were extracted from 3D unit cell FE models, and closed-form approximate expressions were developed using the numerical results, curve fitting, and some simple bounds. The numerical approach was applied to predict warpage of production substrates, analyzed, and validated against experimentally measured stiffness and CTEs. In this paper, the homogenization approach, numerical predictions, and experimental validation are discussed.

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Numerical models for ground deformation and gravity changes during volcanic unrest: simulating the hydrothermal system dynamics of a restless caldera

Solid Earth ◽

10.5194/se-7-557-2016 ◽

2016 ◽

Vol 7 (2) ◽

pp. 557-577 ◽

Cited By ~ 13

Author(s):

A. Coco ◽

J. Gottsmann ◽

F. Whitaker ◽

A. Rust ◽

G. Currenti ◽

...

Keyword(s):

Mechanical Properties ◽

Pore Pressure ◽

Hydrothermal System ◽

Ground Deformation ◽

Numerical Models ◽

Gravity Data ◽

Ground Surface ◽

Campi Flegrei ◽

Hazard Evaluation ◽

Gravity Changes

Abstract. Ground deformation and gravity changes in restless calderas during periods of unrest can signal an impending eruption and thus must be correctly interpreted for hazard evaluation. It is critical to differentiate variation of geophysical observables related to volume and pressure changes induced by magma migration from shallow hydrothermal activity associated with hot fluids of magmatic origin rising from depth. In this paper we present a numerical model to evaluate the thermo-poroelastic response of the hydrothermal system in a caldera setting by simulating pore pressure and thermal expansion associated with deep injection of hot fluids (water and carbon dioxide). Hydrothermal fluid circulation is simulated using TOUGH2, a multicomponent multiphase simulator of fluid flows in porous media. Changes in pore pressure and temperature are then evaluated and fed into a thermo-poroelastic model (one-way coupling), which is based on a finite-difference numerical method designed for axi-symmetric problems in unbounded domains.Informed by constraints available for the Campi Flegrei caldera (Italy), a series of simulations assess the influence of fluid injection rates and mechanical properties on the hydrothermal system, uplift and gravity. Heterogeneities in hydrological and mechanical properties associated with the presence of ring faults are a key determinant of the fluid flow pattern and consequently the geophysical observables. Peaks (in absolute value) of uplift and gravity change profiles computed at the ground surface are located close to injection points (namely at the centre of the model and fault areas). Temporal evolution of the ground deformation indicates that the contribution of thermal effects to the total uplift is almost negligible with respect to the pore pressure contribution during the first years of the unrest, but increases in time and becomes dominant after a long period of the simulation. After a transient increase over the first years of unrest, gravity changes become negative and decrease monotonically towards a steady-state value.Since the physics of the investigated hydrothermal system is similar to any fluid-filled reservoir, such as oil fields or CO2 reservoirs produced by sequestration, the generic formulation of the model will allow it to be employed in monitoring and interpretation of deformation and gravity data associated with other geophysical hazards that pose a risk to human activity.

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Probabilistic Flow Modelling Approach for Kick Tolerance Calculations

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology ◽

10.1115/omae2017-61391 ◽

2017 ◽

Author(s):

Dalila Gomes ◽

Knut Steinar Bjørkevoll ◽

Johnny Frøyen ◽

Kjell Kåre Fjelde ◽

Dan Sui ◽

...

Keyword(s):

Monte Carlo ◽

Pore Pressure ◽

Flow Model ◽

Transient Flow ◽

Probabilistic Approach ◽

Numerical Approach ◽

Free Form ◽

Maximum Pressure ◽

Fracture Pressure ◽

Calculation Process

During drilling, there must be an evaluation of the maximum pressure that the formation can handle during a well kill scenario. This will depend on various parameters like fracture pressure, pore pressure, kick volume and several other factors. The depth of the next planned hole section will depend on if a kick of a certain size can be handled safely. This evaluation is often referred to as performing kick tolerances. When starting to drill a section, one will take a leak off test to get an indication of the fracture pressure at the last set casing shoe and this will be important information for the kick tolerance results. For HPHT wells the margin between pore and fracture pressures will be small, and one often has to resort to using transient flow models to perform the kick tolerances. However, there are many uncertain parameters that are affecting the results. Some examples here are pore pressure, type of kick and kick distribution. There is a need for trying to incorporate the uncertainty in the calculation process to give a better overview of possible outcomes. This approach has become more and more popular, and one example here is reliability based casing design. This paper will first describe the kick tolerance concept and its role in well design planning and operational follow up. An overview of all parameters that can affect the results will be given. In water based mud, the gas kick will be in free form yielding higher maximum casing shoe pressures compared to the situation when oil based mud is used where the kick can be fully dissolved. Then it will be shown how both an analytical and a transient flow model can be used in combination with the use of Monte Carlo simulations to generate a probabilistic kick tolerance calculation showing possible outcomes for maximum casing shoe pressure for different kick volumes. Here uncertain input parameters that can affect the calculation result will be drawn from statistical distributions and propagated through the flow model to estimate the casing shoe pressure. Multiple runs will be needed in the Monte Carlo simulation process to generate a distribution of the maximum casing shoe pressure. This will demand a rapid and robust flow model. The resulting maximum casing shoe pressure distribution will then be compared against the uncertainty in the fracture pressure at the last set casing shoe to yield a probability for inducing losses. The numerical approach for predicting well pressures and a schematic of the total calculation process will be given. Emphasis will also be put on discussing how this should be presented to the engineer with respect to visualization and communication. It will also be shown that one of the strengths of the probabilistic approach is that it is very useful for performing sensitivity analysis such that the most dominating factors affecting the calculation results can be identified. In that way, it can help in interpreting and improving the reliability of the kick tolerance simulation results.

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Caldera’s Breathing: Poroelastic Ground Deformation at Campi Flegrei (Italy)

Frontiers in Earth Science ◽

10.3389/feart.2021.702665 ◽

2021 ◽

Vol 9 ◽

Author(s):

Micol Todesco

Keyword(s):

Pore Pressure ◽

Ground Deformation ◽

Campi Flegrei ◽

Driving Mechanism ◽

Extensive Literature ◽

Magma Intrusion ◽

Volcanic System ◽

Scientific Debate ◽

Fluid Content ◽

History Of

Ground deformation at Campi Flegrei has fuelled a long-term scientific debate about its driving mechanism and its significance in hazard assessment. In an active volcanic system hosting a wide hydrothermal circulation, both magmatic and hydrothermal fluids could be responsible, to variable degrees, for the observed ground displacement. Fast and large uplifts are commonly interpreted in terms of pressure or volume changes associated with magma intrusion, while minor, slower displacement can be related to shallower sources. This work focuses on the deformation history of the last 35 years and shows that ground deformation measured at Campi Flegrei since 1985 is consistent with a poroelastic response of a shallow hydrothermal system to changes in pore pressure and fluid content. The extensive literature available for Campi Flegrei allows constraining system geometry, properties, and conditions. Changes in pore pressure and fluid content necessary to cause the observed deformation can then be calculated based on the linear theory of poroelasticity. The predicted pore pressure evolution and fluid fluxes are plausible and consistent with available measurements and independent estimates.

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Effects of Host-rock Fracturing on Elastic-deformation Source Models of Volcano Deflation

Scientific Reports ◽

10.1038/s41598-017-10009-6 ◽

2017 ◽

Vol 7 (1) ◽

Cited By ~ 12

Author(s):

Eoghan P. Holohan ◽

Henriette Sudhaus ◽

Thomas R. Walter ◽

Martin P. J. Schöpfer ◽

John J. Walsh

Keyword(s):

Elastic Deformation ◽

Host Rock ◽

Deformation Source ◽

Rock Fracturing ◽

Source Models

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Inflating Source Imaging and Stress/Strain Field Analysis at Campi Flegrei Caldera: The 2009–2013 Unrest Episode

Remote Sensing ◽

10.3390/rs13122298 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2298

Author(s):

Raffaele Castaldo ◽

Pietro Tizzani ◽

Giuseppe Solaro

Keyword(s):

Shear Stress ◽

Strain Field ◽

Volumetric Strain ◽

Temporal Distribution ◽

Deformation Source ◽

Field Analysis ◽

Campi Flegrei ◽

Fe Model ◽

Stress Strain ◽

Source Imaging

In this study, we analyze the 2009–2013 uplift phenomenon at Campi Flegrei (CF) caldera in terms of temporal and spatial variations in the stress/strain field due to the effect of an inflating source. We start by performing a 3D stationary finite element (FE) modeling of X-band COSMO-SkyMed DInSAR and GPS mean velocities to retrieve the geometry and location of the deformation source. The modeling results suggest that the best-fit source is a three-axis oblate spheroid ~3 km deep, which is mostly elongated in the NE–SW direction. Furthermore, we verify the reliability of model results by calculating the total horizontal derivative (THD) of the modeled vertical velocity component; the findings emphasize that the THD maxima overlap with the projection of source boundaries at the surface. Then, we generate a 3D time-dependent FE model, comparing the spatial and temporal distribution of the shear stress and volumetric strain with the seismic swarms beneath the caldera. We found that low values of shear stress are observed corresponding with the shallow hydrothermal system where low-magnitude earthquakes occur, whereas high values of shear stress are found at depths of about 3 km, where high-magnitude earthquakes nucleate. Finally, the volumetric strain analysis highlights that the seismicity occurs mainly at the border between compression and dilatation modeled regions, and some seismic events occur within compression regions.

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A numerical approach for the formation of chlorite and sulphide-bearing greisen: a study based on the Navalcubilla system (Spanish Central System)

Mineralogical Magazine ◽

10.1180/minmag.1997.061.408.03 ◽

1997 ◽

Vol 61 (408) ◽

pp. 639-654

Author(s):

Fernando Tornos

Keyword(s):

Hydrothermal Alteration ◽

Granitic Rock ◽

Numerical Approach ◽

Base Metals ◽

Central System ◽

Temperature Changes ◽

Ore Minerals ◽

Acid Fluid ◽

High Concentrations ◽

Spanish Central System

AbstractThe formation of sulphide and cassiterite-bearing chlorite-rich greisens in the Navalcubilla granite has been modelled theoretically. Numerical simulation on the reaction of a hydrothermal fluid with a granitic rock predicts assemblages very similar to those found in nature, with progressive formation of muscovite, quartz, chlorite, microcline and plagioclase zones. The hydrothermal alteration of the rock produces a neutralization of the inflowing acid fluid, a drop in the fS2 and, to a lesser degree, an increment in fO2. During hydrothermal alteration, fS2 and fO2 change abruptly between metasomatic zones, but chlorite seems to control their major changes. Scheelite and cassiterite are concentrated in the internal zones, while sulphides are related to the more external zones. Fluid-rock reactions seem to be very effective for precipitating cassiterite and scheelite, even from very Sn and W-poor fluids. Appreciable amounts of sulphides are only expected in systems with high concentrations of base metals. Boiling and simple cooling of the fluids acidifies and oxidizes them but chemical changes are not strong enough to induce significant precipitation of ore minerals, at least when the temperature changes are small. Continued circulation of fluids along fractures with previously precipitated quartz + wolframite produces replacement of wolframite by scheelite and sulphides.

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