ALBERT

Description: In geosciences 3D geomechanical-numerical models are used to estimate the in-situ stress state. In such a model each geological unit is populated with the rock properties Young’s module, Poisson ratio, and density. Usually, each unit is assigned a single set of homogeneous properties. However, variable rock properties are observed and expected within the same geological unit. Even in small volumes large variabilities may. The Python script HIPSTER (Homogeneous to Inhomogeneous rock Properties for Stress TEnsor Research) provides an algorithm to include inhomogeneities in geomechanical-numerical models that use the solver Abaqus®. The user specifies the mean values for the rock properties Young's module, Poisson ratio and density, and their variability for each geological unit. The variability of the material properties is individually defined for each of the three rock properties in each geological layer. For each unit HIPSTER generates a normal or uniform distribution for each rock property. From these distributions for each single element HIPSTER draws individual rock properties and writes them to a separate material file. This file defines different material properties for each element. The file is included in the geomechanical-numerical analysis solver deck and the numerical model is solved as usual. The HIPSTER script files and example files are provided for download at http://github.com/MorZieg/hipster. Table 0-1 Structure of the GitHub repository gives an overview of the repository and files including a short explanation.

Description: In geosciences the discretization of complex 3D model volumes into finite elements can be a time-consuming task and often needs experience with a professional software. Es-pecially outcropping or out-pinching geological units, i.e. geological layers that are rep-resented in the model volume, pose serious challenges. Changes in the geometry of a model may occur well into a project at a point, when re-meshing is not an option any-more or would involve a significant amount of additional time to invest. In order to speed up and automate the process of discretization, Apple PY (Automatic Portioning Preventing Lengthy manual Element assignment for PYthon) separates the process of mesh-generation and unit assignment. It requires an existing uniform mesh together with separate information on the depths of the interfaces between geological units (herein called horizons). These two pieces of information are combined and used to assign the individual elements to different units. The uniform mesh is created with a standard meshing software and contains no or only very few and simple structures. The mesh has to be available as an Abaqus input file. The information on the horizons depths and lateral variations in the depths is provided in a text file. Apple PY compares the ele-ment location and depth with that of the horizons in order to assign each element to a corresponding geological unit below or above a certain horizon.

Description: The distribution of data records for the maximum horizontal stress orientation SHmax in the Earth’s crust is sparse and very unequally. To analyse the stress pattern and its wavelength and to predict the mean SHmax orientation on regular grids, statistical interpolation as conducted e.g. by Coblentz and Richardson (1995), Müller et al. (2003), Heidbach and Höhne (2008), Heidbach et al. (2010) or Reiter et al. (2014) is necessary. Based on their work we wrote the Matlab® script Stress2Grid that provides several features to analyse the mean SHmax pattern. The script facilitates and speeds up this analysis and extends the functionality compared to the publications mentioned before. This script is the update of Stress2Grid v1.0 (Ziegler and Heidbach, 2017). It provides two different concepts to calculate the mean SHmax orientation on regular grids. The first is using a fixed search radius around the grid points and computes the mean SHmax orientation if sufficient data records are within the search radius. The larger the search radius the larger is the filtered wavelength of the stress pattern. The second approach is using variable search radii and determines the search radius for which the standard deviation of the mean SHmax orientation is below a given threshold. This approach delivers mean SHmax orientations with a user-defined degree of reliability. It resolves local stress perturbations and is not available in areas with conflicting information that result in a large standard deviation. Furthermore, the script can also estimate the deviation between plate motion direction and the mean SHmax orientation.

Description: The MT repository contains geophysical data sets collected in field experiments from all over the world. The acronym MT stands for magnetotelluric, a geophysical method used to probe the Earth's deep interior for its electrical conductivity distribution through electromagnetic (EM) induction. MT is based on EM fields generated by natural processes in the Earth's atmosphere and magnetosphere. But the repository also contains data from Controlled Source Electromagnetic (CSEM) projects, for which man-made EM sources are used. The principle form of data in the repository are time-series of EM field components acquired with heterogeneous sets of sensors, recording instruments, and sampling rates. It is the main purpose of this archive or repository to provide the links between the data and their physical meaning by means of metadata. To achieve this, the repository is organized as a combination of data files and associated meta-data in a well defined folder (directory) structure, with the data files being sorted into subfolders. Meta-data are provided as XML (Extensible Markup Language) formatted file.

Description: In geosciences 3D geomechanical-numerical models are used to estimate the in-situ stress state. In such a model each geological unit is populated with the rock properties Young’s module, Poisson ratio, and density. Usually, each unit is assigned a single set of homogeneous properties. However, variable rock properties are observed and expected within the same geological unit. Even in small volumes large variabilities may. The Python script HIPSTER (Homogeneous to Inhomogeneous rock Properties for Stress TEnsor Research) provides an algorithm to include inhomogeneities in geomechanical-numerical models that use the solver Abaqus®. The user specifies the mean values for the rock properties Young's module, Poisson ratio and density, and their variability for each geological unit. The variability of the material properties is individually defined for each of the three rock properties in each geological layer. For each unit HIPSTER generates a normal or uniform distribution for each rock property. From these distri-butions for each single element HIPSTER draws individual rock properties and writes them to a separate material file. This file defines different material properties for each element. The file is included in the geomechanical-numerical analysis solver deck and the numerical model is solved as usual.

Description: The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides real-time seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. Like all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.

Description: The GEOFON program consists of a global seismic network (GE Network), a seismological data centre (GEOFON DC) and a global earthquake monitoring system (GEOFON EQinfo). These three pillars are part of the MESI research infrastructure of the Helmholtz Centre Potsdam - GFZ German Research Centre for Geosciences aiming at facilitating scientific research. GEOFON provides real-time seismic data, access to its own and third party data from the archive facilities as well as global and rapid earthquake information. The GEOFON Seismological Software can be considered a fourth cross-cutting module of the GEOFON Program. Data, services, products and software openly distributed by GEOFON are used by hundreds of scientists and data centres worldwide. Its earthquake information service is accessed directly by tens of thousands of visitors. The SeisComP software package is the flagship software provided to the community, which is geared for seismic observatory and data centre needs and used extensively to support our internal operations. Like all other MESI (Modular Earth Science Infrastructure) modules GEOFON has the majority of users outside the GFZ as well as an external advisory committee that provides advice to the GFZ Executive Board and to the GEOFON team. This report describes the main activities carried out within the three GEOFON pillars and the software development group.

Description: Radial Jet Drilling (RJD) is a technique to stimulate wells by creating small-diameter laterals from vertical or deviated wells using hydraulic jets. The laterals, also called radials, can be up to 100 m in length. To analyze under which sub-surface conditions the radials improve the well performance most, a step-wise approach is followed in which first the performance of a single stimulated well is analyzed and in a second step, the performance of a doublet system is analyzed. Finally, case studies that are more detailed are simulated. For the single well case, a good first estimate of radial stimulation performance for different reservoir conditions can be obtained from (semi-) analytical solutions. These results show that the anisotropy in the permeability and the thickness of the reservoir influence the relative increase in productivity/injectivity most. The permeability influences in particular the absolute performance of the stimulated well. Many aspects not included in the semi-analytical solution also influence the performance of the radial stimulation: - Since the radials are open hole, stability for friable rocks or deep reservoirs is unlikely. This depends on the in-situ stress conditions. Collapsed radials probably have much lower performance or no effect at all. - The uncertainty in the radial path and diameter decreases the expected benefits from radials significantly depending on the type of reservoir. For example for a layered reservoir, the expected increase may be tens of percent lower. - Due to the small diameter (0.02-0.05 m) and rough surface of the radials and the high rates of geothermal wells, viscous pressure drop due to flow in the radials has to be taken into account for prediction of performance. For example for a radius of 0.04 m and well rate of 3600 m3/d, expected increase in performance is halved when taking into account pressure drop. - Heterogeneity in the permeability has a strong impact on the performance of the radials. Performance of individual radials depends in first approximation on the local permeability. However, this is difficult to capture in general terms. - Near well bore damage (positive skin) and prior stimulation (negative skin) have a large impact on the expected increase due to stimulation. In case the radials can be used to by-pass near well damage, performance can be much higher than predicted using the analytical equations. - Heterogeneity due to fault and/or fractures, voids, sharp transitions or layering all make potential success more uncertain and predictability lower due to potential issues with jetting. Whether increased performance for a single well can be translated to similar increased performance of a doublet depends on the doublet settings and subsurface conditions. For a fixed doublet distance or field size, an increase in rate due to improved performance of the wells will result in a reduced field life. The increased well performance can also be used to lower pumping cost at a fixed rate and thus improve performance of the doublet. It was found, that for most subsurface systems, the impact of the radials on production temperature was minor (for constant rate). Only for some fractured systems, short-circuiting can be increased due to radials. Overall, the ideal candidate for radial stimulation is a reservoir which is not too deep, in homogeneous, competent rock with a well with near well bore damage or in a not too deep anisotropic reservoir in which the main well is not drilled beneficially compared to the main direction of permeability.