Laboratory-scale hydraulic fracturing dataset for benchmarking of enhanced geothermal system simulation tools

Abstract

Against this background, a large-sample triaxial setup was developed at RWTH Aachen University under a project funded by BMWi (Federal Ministry of Economics and Technology). The planning and construction of the testing facility, including the analytical and numerical validation of the final experimental procedure, is thoroughly discussed in 2,3. The setup allows for experiments on rocks with size 30 cm × 30 cm × 45 cm under defined and controlled boundary conditions, yielding reproducible and repeatable datasets, well-suited for code benchmarking. In this paper we present hydraulic stimulation datasets from experiments where the borehole axis was parallel to the minimum horizontal stress direction and therefore the plane of crack propagation was parallel to the maximum horizontal stress direction. Investigated rock samples represent the reservoir rock types of a potential EGS site in Mexico. The datasets represent hydraulic stimulation responses in quasi-homogenous and extremely heterogeneous crystalline rock types, such as, a very fine-grained granite and a coarse-grained marble, respectively. Additionally, a dense network of 32 acoustic sensors, comprising of 28 GmuG standard ultrasonic sensors (http://www.gmugmbh.de/prod.html) and 4 Glaser amplitude-calibrated sensors 4,5 , was used to track the fracture propagation in real time. The validation dataset includes fluid injection rate, pressure in the injection interval, confining stresses, mechanical and petrophysical properties of the rock specimens, properties of the injection fluid, mechanical details of the experimental setup , and acoustic emission data. Additionally, we provide a Python-based code which can be used for processing the seismic data and visualizing of the experimental results. Methods The main components of the experimental setup , sample requirements and experimental protocol are described separately in the following subsections .

Verification of Coupled Hydraulic Fracturing Simulators Using Laboratory-Scale Experiments

“…Then, the events are localized in space using the average P-wave velocity determined in the previous step. The detailed seismic data processing and event localization workflow is discussed in Deb et al (2020).…”

“…The experiments were performed on samples of size 30 cm × 30 cm × 45 cm . The experimental data are reported in Deb et al 2020. The dataset is unique due to the large sample sizes, detailed characterization of the experimental set-up and the accurate knowledge of the initial notch size, the boundary conditions, and the geometry of the induced fracture.…”

A holistic review on hydraulic fracturing stimulation laboratory experiments and their transition to enhanced geothermal system field research and operations

“…A benchmark test for verifying existing or new hydraulic stimulation codes was also performed based on a laboratory fracturing test, using igneous and metamorphic rock samples [60], [84]. Fracture growth and propagation were monitored by acoustic emissions and visually by ink injection.…”

Are Engineered Geothermal Energy Systems a Viable Solution for Arctic Off-Grid Communities? A Techno-Economic Study

“…Additionally, an artificial neural network-genetic algorithm-based displacement back analysis has been proposed by Zhang et al [91] to estimate fracture stiffness, in situ stresses and elastic parameters from borehole displacements during drilling. Laboratory tests are also an important component to enhance the understanding of joint behavior (e.g., [92][93][94][95][96][97][98][99]). However, care must be taken due to scaling effects.…”