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

2020 ◽  
Author(s):  
Leandra M. Weydt ◽  
Ángel Andrés Ramírez-Guzmán ◽  
Antonio Pola ◽  
Baptiste Lepillier ◽  
Juliane Kummerow ◽  
...  
Keyword(s):  
Geothermal Field ◽  
Heat Extraction ◽  
Rock Properties ◽  
Triaxial Tests ◽  
Petroleum Reservoir ◽  
Thin Sections ◽  
Rock Property ◽  
Rock Samples ◽  
Core Samples ◽  
Reservoir Assessment

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.

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

2021 ◽  
Vol 13 (2) ◽  
pp. 571-598 ◽  
Author(s):  
Leandra M. Weydt ◽  
Ángel Andrés Ramírez-Guzmán ◽  
Antonio Pola ◽  
Baptiste Lepillier ◽  
Juliane Kummerow ◽  
...  
Keyword(s):  
Geothermal Field ◽  
Heat Extraction ◽  
Rock Properties ◽  
Triaxial Tests ◽  
Petroleum Reservoir ◽  
Rock Property ◽  
X Ray ◽  
Rock Samples ◽  
Core Samples ◽  
Reservoir Assessment

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 is 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 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, grant agreement no. 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 analog 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 the Los Humeros and Acoculco calderas and 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, and heat capacity, as well as ultrasonic 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, the bulk modulus, the shear modulus, fracture toughness, cohesion and the friction angle. In addition, X-ray diffraction (XRD) and X-ray fluorescence (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; https://doi.org/10.25534/tudatalib-201.10), comprising 34 parameters determined on more than 2160 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.

scholarly journals Effect of Thermal Exposure on Oil Shale Saturation and Reservoir Properties

2020 ◽  
Vol 10 (24) ◽  
pp. 9065
Author(s):  
Aliya Mukhametdinova ◽  
Polina Mikhailova ◽  
Elena Kozlova ◽  
Tagir Karamov ◽  
Anatoly Baluev ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Thermal Exposure ◽  
Rock Properties ◽  
Reservoir Properties ◽  
Rock Samples ◽  
The Core ◽  
Core Samples ◽  
Before And After ◽  
Porosity And Permeability

The experimental and numerical modeling of thermal enhanced oil recovery (EOR) requires a detailed laboratory analysis of core properties influenced by thermal exposure. To acquire the robust knowledge on the change in rock saturation and reservoir properties, the fastest way is to examine the rock samples before and after combustion. In the current paper, we studied the shale rock properties, such as core saturation, porosity, and permeability, organic matter content of the rock caused by the combustion front propagation within the experimental modeling of the high-pressure air injection. The study was conducted on Bazhenov shale formation rock samples. We reported the results on porosity and permeability evolution, which was obtained by the gas pressure-decay technique. The measurements revealed a significant increase of porosity (on average, for 9 abs. % of porosity) and permeability (on average, for 1 mD) of core samples after the combustion tube experiment. The scanning electron microscopy showed the changes induced by thermal exposure: the transformation of organic matter with and the formation of new voids and micro and nanofractures in the mineral matrix. Low-field Nuclear Magnetic Resonance (NMR) was chosen as a primary non-disruptive tool for measuring the saturation of core samples in ambient conditions. NMR T1–T2 maps were interpreted to determine the rock fluid categories (bitumen and adsorbed oil, structural and adsorbed water, and mobile oil) before and after the combustion experiment. Changes in the distribution of organic matter within the core sample were examined using 2D Rock-Eval pyrolysis technique. Results demonstrated the relatively uniform distribution of OM inside the core plugs after the combustion.

scholarly journals Empirical relations of rock properties of outcrop and core samples from the Northwest German Basin for geothermal drilling

2014 ◽  
Vol 2 (1) ◽  
pp. 21-37 ◽  
Author(s):  
D. Reyer ◽  
S. L. Philipp
Keyword(s):  
Tensile Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Sedimentary Rocks ◽  
Rock Properties ◽  
Rock Samples ◽  
Core Samples ◽  
Empirical Relations ◽  
Static Young’S Modulus ◽  
German Basin

<p><strong>Abstract.</strong> Information about geomechanical and physical rock properties, particularly uniaxial compressive strength (UCS), are needed for geomechanical model development and updating with logging-while-drilling methods to minimise costs and risks of the drilling process. The following parameters with importance at different stages of geothermal exploitation and drilling are presented for typical sedimentary and volcanic rocks of the Northwest German Basin (NWGB): physical (<i>P</i> wave velocities, porosity, and bulk and grain density) and geomechanical parameters (UCS, static Young's modulus, destruction work and indirect tensile strength both perpendicular and parallel to bedding) for 35 rock samples from quarries and 14 core samples of sandstones and carbonate rocks. <br><br> With regression analyses (linear- and non-linear) empirical relations are developed to predict UCS values from all other parameters. Analyses focus on sedimentary rocks and were repeated separately for clastic rock samples or carbonate rock samples as well as for outcrop samples or core samples. Empirical relations have high statistical significance for Young's modulus, tensile strength and destruction work; for physical properties, there is a wider scatter of data and prediction of UCS is less precise. For most relations, properties of core samples plot within the scatter of outcrop samples and lie within the 90% prediction bands of developed regression functions. The results indicate the applicability of empirical relations that are based on outcrop data on questions related to drilling operations when the database contains a sufficient number of samples with varying rock properties. The presented equations may help to predict UCS values for sedimentary rocks at depth, and thus develop suitable geomechanical models for the adaptation of the drilling strategy on rock mechanical conditions in the NWGB.</p>

Anisotropic Geomechanical Rock Properties Modelling for Unconventional Shale Gas Formation

2021 ◽  
Author(s):  
Ikhwanul Hafizi Musa ◽  
Chee Phuat Tan ◽  
Junghun Leem ◽  
Iftikhar Altaf ◽  
Zahidah Md Zain ◽  
...  
Keyword(s):  
Elastic Properties ◽  
Shale Gas ◽  
Velocity Shear ◽  
Rock Properties ◽  
Triaxial Tests ◽  
Sonic Velocity ◽  
Confining Stress ◽  
Geomechanical Properties ◽  
Core Samples ◽  
Using Data

Abstract Geomechanical rock properties correlations and modeling approach for conventional reservoirs are inappropriate and unsuitable for unconventional shale gas reservoirs where the shale formation is strong and has very low porosity. These correlations are critical in the development of 1D and 3D geomechanical models which are used for various field applications including drilling optimization, hydraulic fracturing design and operation, and field management. The study investigates various geomechanical rock properties and their relationships to one another using data extracted from rock mechanics testing conducted on shale core samples. For rock elastic properties correlations, dynamic elastic properties determined from compressional sonic velocity, shear sonic velocity and density are plotted against laboratory-measured static elastic properties obtained from triaxial tests. Steps were taken to further refine the properties correlations by separating the data from vertical and horizontal core samples, using data from tests conducted at in-situ confining stress condition, and focusing on data only taken from Field A and nearby fields. Similar steps were also taken to develop the correlations for rock strength properties. Correlations for the shale anisotropic elastic properties were also developed based on ratio of horizontal and vertical elastic properties. Blind tests were conducted on three wells in Field A using the new rock properties correlations which showed good matching of the predicted geomechanical properties with the new correlations and core measured test data.

The role of freezing-thaw cycling in rock samples topography evolution and rock cliff retreat

2021 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun ◽  
...  
Keyword(s):  
Freezing Point ◽  
Meteorological Data ◽  
Test Chamber ◽  
Monitoring Program ◽  
Dynamic Environment ◽  
Rock Properties ◽  
Rock Surface ◽  
Physical Weathering ◽  
Rock Samples

&lt;p&gt;Freezing-thaw weathering is recognized as one of the most significant factors in the fatigue of rock mass in areas where the temperature periodically fluctuates around the freezing point.&amp;#160;&lt;br&gt;A one-year monthly SfM monitoring program from December 19, 2019, to January 7, 2021, was done to detect rockfall activity on a rockslide cliff composed of marl-sandstone at La Cornalle, Switzerland. More than one hundred rockfall events were detected during this period with the volumes varied from 0.005m&lt;sup&gt;3&lt;/sup&gt; to 4.85m&lt;sup&gt;3&lt;/sup&gt;.&amp;#160;&lt;br&gt;We texture all the rockfalls on the 3D SfM model. It is shown that most of them are mainly located in three areas: &amp;#160;the top of the cliff, the foot of the cliff, and the medium-left part of the cliff. The common feature of these three parts is that the layers are more or less overhanging with dense fractures around them. At the same time, the meteorological data collected by a weather station on site is correlated with the rockfall events to figure out the relationship between each other. Actually, about 30% of total rockfall volume fell during winter on this site. The triggering factor of rockfall during winter is related to freezing-thaw cycling. This kind of weathering can be understood as an interplay between rock properties and its dynamic environment.&lt;br&gt;In order to make clear the role of freezing-thaw played on the rockfall generation, an on-site 24h monitoring measurement program that consists of two crack meters, one rock thermal sensor, and thermal camera monitoring is installed in January 2021. Those datasets will help to understand how the crack grows with the changing temperature. In addition, freezing-thaw cycling laboratory experiments for the rock samples taken from different areas of the cliff will be done with an environmental test chamber. The topography of the rock samples before and after the experiments will be acquired by a 3D handheld scanner. This work will benefit to reveal the rock surface evolution during the freezing-thaw cycling in a dynamic environment with varied humidity and number of cycles.&amp;#160;&lt;br&gt;In conclusion, the combination of on-site measurements and laboratory freezing-thaw experiments will provide a good basis for a better understanding of the rockfall triggering mechanism led by physical weathering.&lt;/p&gt;

scholarly journals X-Ray CT analyses, models and numerical simulations – a comparison with common analytical methods of an experimental CO<sub>2</sub> study

2016 ◽  
Author(s):  
Steven Henkel ◽  
Dieter Pudlo ◽  
Frieder Enzmann ◽  
Viktor Reitenbach ◽  
Daniel Albrecht ◽  
...  
Keyword(s):  
High Resolution ◽  
Numerical Simulations ◽  
Analytical Methods ◽  
Rock Properties ◽  
Similar Data ◽  
Sample Material ◽  
Thin Sections ◽  
Deutschland Gmbh ◽  
Before And After ◽  
Reservoir Sandstones

Abstract. An essential part of the collaborative research project H2STORE ("hydrogen to store"), which is founded by the German government, was a comparison of various analytical methods to characterize reservoir sandstones from different stratigraphic units. In this context Permian, Triassic and Tertiary reservoir sandstones were analysed. Rock core materials, provided by RWE Gasspeicher GmbH (Dortmund), GFD Suez E&amp;P Deutschland GmbH (Lingen), E.ON Gas Storage GmbH (Essen) and RAG Rohöl-Aufsuchungs Aktiengesellschaft (Wien), was processed by different laboratory techniques; thin sections were prepared, rock fragments were crushed, cubes of 1 cm edge length and plugs of 5 cm in length were sawn from macroscopic homogenous cores. With this prepared sample material, polarized light microscopy and scanning electron microscopy – coupled with image analyses, specific surface area measurements (BET), He-porosity and N2-permeability measurements and high resolution micro-computer-tomography (µ-CT), which were used for numerical simulations were conducted. All these methods were applied to most of the same sample material, before and after static CO2 experiments under reservoir conditions. A major concern in comparing the results of these methods is an appraisal of the reliability of the given porosity, permeability and mineral specific reactive (inner) surface areas data. The CO2 experiments are modifying the petrophysical as well the mineralogical/geochemical rock properties. These changes are detectable by all applied analytical methods. Nevertheless, a major outcome of the high resolution µ-CT analyses and proceeded numerical data simulations results in quite similar data sets and data interpretations maintained by the different standard methods; even regarding only CT-single scan of the rock samples. Moreover, this technique is not only time saving, but also none destructive. This is an important point, if only minor sample material is available and a detailed comparison before and after the experimental tests on micro meter, pore scale of specific rock features is envisaged.

scholarly journals Crystal Size and Orientation Patterns in the Wisconsin-Age Ice from Dye 3, Greenland

1988 ◽  
Vol 10 ◽  
pp. 109-115 ◽  
Author(s):  
C.C. Langway ◽  
H. Shoji ◽  
N. Azuma
Keyword(s):  
Crystal Size ◽  
Ice Core ◽  
Ice Crystal ◽  
Axis Orientation ◽  
Measuring Device ◽  
Thin Sections ◽  
Core Samples ◽  
Physical Measurements ◽  
Ice Crystal Size ◽  
Velocity Measuring

Crystal size and c-axis orientation patterns were measured on the Dye 3, Greenland, deep ice core in order to investigate time-dependent changes or alterations in the physical character of the core as a function of time after recovery. The physical measurements were expanded to include depth intervals not previously studied in the field. The recent study focused on core samples located between 1786 m and the bottom of the ice sheet at 2037 m.Manual c-axis measurements were made on 23 new thin sections using a Rigsby-type universal stage. A new semi-automatic ultrasonic wave-velocity measuring device was developed in order to compare the results with the earlier manual measurements and to study an additional 114 ice-core samples in the Wisconsin-age ice. Crystal-size measurements were made on specimen surfaces by inducing evaporation grooves at crystal boundaries and measuring linear intercepts. The ultrasonically measured test samples were subsequently cleaned and analyzed by ion chromatography in order to measure impurity concentration levels of Cl−, NO3− and SO42− and study their effects on crystal growth and c-axis orientation.

Induced‐polarization response of zeolitic conglomerate and carbonaceous siltstone

Geophysics ◽  
1982 ◽  
Vol 47 (1) ◽  
pp. 71-88 ◽  
Author(s):  
P. H. Nelson ◽  
W. H. Hansen ◽  
M. J. Sweeney
Keyword(s):  
Electrical Response ◽  
Induced Polarization ◽  
Phase Response ◽  
Electrical Measurements ◽  
Intimate Contact ◽  
Thin Sections ◽  
Field Surveys ◽  
Core Samples ◽  
Rock Types ◽  
Geologic Materials

Three case studies investigating induced‐polarization (IP) responses of a zeolite‐bearing conglomerate and of two carbonaceous siltstones are presented. The IP response of these noneconomic geologic materials can either mask or mimic the response from sulfide mineralization which is sought by electrical field surveys. The nonsulfide rock types which produced unusually high responses on IP field surveys were sampled by core drilling for chemical, mineralogical, and electrical laboratory study. The electrical response of core samples was measured in a four‐electrode sample holder over the 0.03–1000 Hz range. Geologic description of the core, petrographic examination of thin sections, mineral identification by x‐ray diffraction (XRD), and chemical analysis of samples supplemented the electrical measurements. A surface phase response of 20 mrad was obtained from field surveys over the Gila conglomerate at an Arizona location. Core samples of the Gila were examined in thin section, and clast surfaces were found to be coated with a thin layer of zeolites. These zeolites project into pore spaces in the conglomerate, and thus are in intimate contact with formation waters. A series of laboratory experiments suggests that zeolites cause most of the observed IP response. Phase responses as high as 100 mrad were measured with field surveys over siltstone and limestone sequences in western Nevada. Samples recovered from the Luning and Gabbs‐Sunrise formations include siltstones containing small amounts of amorphous carbon. These siltstones are very conductive electrically, and the high‐phase response is attributed to polarization of the carbon‐pore water interface. Low porosity in these carbonaceous siltstones enhances the phase response.

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