Local earthquake tomography at the Los Humeros geothermal field, Mexico

Toledo, Tania; Jousset, Philippe; Gaucher, Emmanuel; Maurer, Hansruedi; Krawzcyzk, Charlotte; Calo, M.; Figueroa, Angel

doi:10.5194/egusphere-egu2020-9865

Cited by 5 publications

(1 citation statement)

References 38 publications

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“…Likewise, it is planned to create a local structural model for Acoculco, which will be transformed into an integrated numerical THM model including the previously determined fracture geometries and rock properties to model different reservoir operation scenarios and to evaluate the treatment efficiency (Hofmann et al, 2020). The results of the petrophysical properties and volcanological studies are being used to interpret results of electric resistivity surveys (Benediktsdóttir et al, 2020), local earthquake tomography (Toledo et al, 2020) or gravity and magnetotelluric surveys (Cornejo et al, 2020). Besides the many advantages described above, a number of limiting factors have to be considered prior to using this data set for modeling the Los Humeros and Acoculco geothermal systems.…”

Section: Discussionmentioning

confidence: 99%

Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico)

Weydt¹,

Ramírez-Guzmán²,

Pola³

et al. 2020

Preprint

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Abstract. Petrophysical and mechanical rock properties are key parameters for the characterization of the deep subsurface in different disciplines such as geothermal heat extraction, petroleum reservoir engineering or mining. They are commonly used for the interpretation of geophysical data and the parameterization of numerical models and thus are the basis for economic reservoir assessment. However, detailed information regarding petrophysical and mechanical rock properties for each relevant target horizon are often scarce, inconsistent or distributed over multiple publications. Therefore, subsurface models are often populated with generalized or assumed values resulting in high uncertainties. Furthermore, diagenetic, metamorphic and hydrothermal processes significantly affect the physiochemical and mechanical properties often leading to a high geological variability. A sound understanding of the controlling factors is needed to identify statistical and causal relationships between the properties as a basis for a profound reservoir assessment and modeling. Within the scope of the GEMex project (EU-H2020, GA Nr. 727550), which aims to develop new transferable exploration and exploitation approaches for enhanced and super-hot unconventional geothermal systems, a new workflow was applied to overcome the gap of knowledge of the reservoir properties. Two caldera complexes located in the northeastern Trans-Mexican Volcanic Belt – the Acoculco and Los Humeros caldera – were selected as demonstration sites. The workflow starts with outcrop analogue and reservoir core sample studies in order to define and characterize the properties of all key units from the basement to the cap rock as well as their mineralogy and geochemistry. This allows the identification of geological heterogeneities on different scales (outcrop analysis, representative rock samples, thin sections and chemical analysis) enabling a profound reservoir property prediction. More than 300 rock samples were taken from representative outcrops inside of the Los Humeros and Acoculco calderas, the surrounding areas and from exhumed fossil systems in Las Minas and Zacatlán. Additionally, 66 core samples from 16 wells of the Los Humeros geothermal field and 8 core samples from well EAC1 of the Acoculco geothermal field were collected. Samples were analyzed for particle and bulk density, porosity, permeability, thermal conductivity, thermal diffusivity, heat capacity, as well as ultra-sonic wave velocities, magnetic susceptibility and electric resistivity. Afterwards, destructive rock mechanical tests (point load tests, uniaxial and triaxial tests) were conducted to determine tensile strength, uniaxial compressive strength, Young’s modulus, Poisson’s ratio, bulk modulus, shear modulus, fracture toughness, cohesion and friction angle. In addition, XRD and XRF analyses were performed on 137 samples to provide information about the mineral assemblage, bulk geochemistry and the intensity of hydrothermal alteration. An extensive rock property database was created (Weydt et al. 2020, http://dx.doi.org/10.25534/tudatalib-201.2), comprising 34 parameters determined on more than 2,160 plugs. More than 31,000 data entries were compiled covering volcanic, sedimentary, metamorphic and igneous rocks from different ages (Jurassic to Holocene), thus facilitating a wide field of applications regarding resource assessment, modeling and statistical analyses.

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Section: Discussionmentioning

confidence: 99%

Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico)

Weydt¹,

Ramírez-Guzmán²,

Pola³

et al. 2020

Preprint

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A collection of 3D geomodels of the Los Humeros and Acoculco geothermal systems (Mexico)

et al. 2022

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This paper aims at sharing 3D geological models that were constructed at different scales in two Mexican geothermal areas as part of the European-Mexican GEMex project. The project was devoted to investigate superhot resources in Los Humeros and enhanced geothermal systems in Acoculco, both areas located in eastern Mexico. To build confidence in the resultant datasets and to potentially inform the development of models in similar contexts, the methodology is also described. The models integrate the main geological and geothermal features of the study areas and served as a framework for subsequent calculations and simulations. Preliminary models were based on data available at the beginning of the project, and were updated several times as new geological, geochemical, and geophysical field-data were obtained. The construction of the geomodels was performed in a collaborative and interdisciplinary way, using an existing software, and ultimately enabled a consensus interpretation and representation to be reached by the several disciplinary experts involved.

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Imaging the Deep Structures of Los Humeros Geothermal Field, Mexico, Using Three-Component Seismic Noise Beamforming

Löer

Toledo

Norini

et al. 2020

Seismological Research Letters

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We present a 1D shear-velocity model for Los Humeros geothermal field (Mexico) obtained from three-component beamforming of ambient seismic noise, imaging for the first time the bottom of the sedimentary basement ∼5 km below the volcanic caldera, as well as the brittle-ductile transition at ∼10 km depth. Rayleigh-wave dispersion curves are extracted from ambient seismic noise measurements and inverted using a Markov chain Monte Carlo scheme. The resulting probability density function provides the shear-velocity distribution down to 15 km depth, hence, much deeper than other techniques applied in the area. In the upper 4 km, our model conforms to a profile from local seismicity analysis and matches geological structure inferred from well logs, which validates the methodology. Complementing information from well logs and outcrops at the near surface, discontinuities in the seismic profile can be linked to geological transitions allowing us to infer structural information of the deeper subsurface. By constraining the extent of rocks with brittle behavior and permeability conditions at greater depths, our results are of paramount importance for the future exploitation of the reservoir and provide a basis for the geological and thermodynamic modeling of active superhot geothermal systems, in general.

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Local earthquake tomography at the Los Humeros geothermal field, Mexico

Cited by 5 publications

References 38 publications

Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico)

Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico)

A collection of 3D geomodels of the Los Humeros and Acoculco geothermal systems (Mexico)

Imaging the Deep Structures of Los Humeros Geothermal Field, Mexico, Using Three-Component Seismic Noise Beamforming

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