Inventory of Shale Formations in the US, Including Geologic, Geochemical, Hydrological, Mechanical, and Thermal Characteristics

Dobson, Patrick; Houseworth, James

doi:10.2172/1156579

Cited by 3 publications

(1 citation statement)

References 47 publications

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“…In the US, the properties of clay/shale formations are currently being investigated as potential feasible host rock formations for nuclear waste disposal [13] and generic (non-site specific) PA model simulations are developed and tested [14]. PFLOTRAN [15] is a state-of-the-art massively parallel subsurface flow and reactive transport code that is being applied for such PA modeling exercises.…”

Section: Introductionmentioning

confidence: 99%

Estimation of stress and stress-induced permeability change in a geological nuclear waste repository in a thermo-hydrologically coupled simulation

Sasaki

Rutqvist

2021

Computers and Geotechnics

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Geologic disposal is a promising solution for a safe permanent isolation of accumulated high-level nuclear waste from nuclear powerplants. The behavior of host rock is highly coupled thermally, hydromechanically, and chemically. Numerical simulations of such coupled phenomena for the extremely long term (> 100,000 years) and large length scale (> 1 km) of geologic disposal remain to be computationally challenging. In this study, a methodology has been developed to approximate stress and stress-induced permeability change in host rock using only thermo-hydrological (TH) variables. A coupled thermo-hydromechanical (THM) simulation is carried out using TOUGH-FLAC simulator to model THM behaviors of a generic nuclear waste repository, in order to evaluate the performance of the developed methodology, which is implemented in a coupled TH simulation. Results show that stress and permeability change estimated by the developed methodology in the TH-coupled simulation match those calculated in the THM-coupled simulation over the simulated timeframe of over 10,000 years. Details about errors in stress and permeability estimates accrued by the developed methodology are discussed in this paper. The developed methodology will help incorporate stress-induced permeability change into existing TH simulators for the long-term radionuclide transport in geologic disposal.

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Section: Introductionmentioning

confidence: 99%

Estimation of stress and stress-induced permeability change in a geological nuclear waste repository in a thermo-hydrologically coupled simulation

Sasaki

Rutqvist

2021

Computers and Geotechnics

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Unconventional Reservoirs: Contact Area and Fracture Network Resulting from Perforations in Shale. A Comparative Study of Different Shale Targets and Shaped Charge Designs Optimized for Hydraulic Fracturing

Loehken,

McNelis,

Yosefnejad

et al. 2024

Day 2 Wed, February 07, 2024

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After decades of a continuous improvement of the plug and perf technology for horizontal wells and especially the shaped charges employed, operators nowadays have the choice between a variety of shaped charge designs. As a guidance to choose the optimal charge, this snapshot examines the influence of shale rock type and shaped charge design on the tunnel created in the reservoir rock during perforation. Tests were conducted in an API Section II Test environment, simulating in-situ downhole conditions. Specifically, the investigation focused on the characteristics of the contact surface and the induced fracture network resulting from different perforation charges, each with its own distinctive tunnel geometry. Three different shaped charge designs were tested on various shale targets. This included equal entrance hole charges, maximum formation contact, and oriented perforation tailored charges. To assess the impact of the formation rock on the results, test shots were made on Marcellus, Mancos, and Lotharheiler, which is similar to the Haynesville or Eagle Ford, shale cores. The analysis included CT scans to identify tip fractures and to examine the shape of the tunnel as well as conventional core analysis. Additionally, newly formed fractures within the rock and on the surface of the perforation tunnel were identified. The test results indicate that both the charge type and the rock type significantly influence the tunnel geometry and fracture network. Although all charges created roughly the same entrance hole diameter in the casing, variations in tunnel length and contact surface as well as in the newly created fractures were observed. Notably, the shape of the tunnel deviated strongly from the theoretical assumed cylindrical or conical tunnel. Doglegs, as well as cavities were detected at many tunnel tips, which change the overall stress field at the tunnel wall. To determine which rock parameters are relevant, the cores underwent analysis in an external laboratory to assess their petrophysical properties for further correlation analysis. From a practical perspective shale rock proved to be a challenging target rock due to its high anisotropy and significant differences in rock strength between targets of the same formation. Additionally, the target cores were prone to cracking during the rock preparation process. Therefore, this study should be considered as a snapshot and conclusions drawn from this set of tests should be approached cautiously and account for these circumstances. Our study provides insights into the dependency of the perforation result on the type of shale and charge design. Depending on the combination of the perforation technique and the characteristics of the rock formation, distinct fracture networks and tip deviations are formed. This improved understanding will help to identify the best perforation strategy tailored to the specific reservoir rock's unique properties.

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Probabilistic Evaluation of Geomechanical Risks in CO2 Storage: An Exploration of Caprock Integrity Metrics Using a Multilaminate Model

Lee,

Mohamed,

Lee

et al. 2023

Energies

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The probabilistic uncertainty assessment of geomechanical risk—specifically, caprock failure—attributable to CO2 injection, as presented in a simplified hypothetical geological model, was the focus of this study. Our approach amalgamates the implementation of a multilaminate model, the creation of a response surface model in conjunction with the Box–Behnken sampling design, the execution of associated numerical modeling experiments, and the utilization of Monte Carlo simulations. Probability distributions to encapsulate the inherent variability (elastic and mechanical properties of the caprock and reservoir) and uncertainty in prediction estimates (vertical displacement, total strain, and F value) were employed. Our findings reveal that the Young modulus of the caprock is a key factor controlling equivalent total strain but is insufficient as a stand-alone indicator of caprock integrity. It is confirmed that the caprock can accommodate significant deformation without failure, if it possesses a low Young’s modulus and high mechanical strength properties, such as the friction angle and uniaxial compressive strength. Similarly, vertical displacement was found to be an unreliable indicator for caprock integrity, as caprock failure can occur across a broad spectrum of vertical displacements, particularly when both the Young modulus and mechanical strength properties have wide ranges. This study introduces the F value as the most dependable indicator for caprock failure, although it is a theoretical attribute (the shortest distance between the Mohr circle and the nearest failure envelope used to measure the sensitivity to failure) and not physically measurable in the field. Deviatoric stress levels were found to vary based on stress regimes, with the maximum levels observed under extensive and compressive stress regimes. In conjunction with the use of the response surface method, this study demonstrates the efficacy of the multilaminate framework and the Mohr–Coulomb constitutive model in providing a simplified, yet effective, probabilistic model of the mechanical behavior of caprock failure, reducing mathematical and computational complexities.

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Inventory of Shale Formations in the US, Including Geologic, Geochemical, Hydrological, Mechanical, and Thermal Characteristics

Cited by 3 publications

References 47 publications

Estimation of stress and stress-induced permeability change in a geological nuclear waste repository in a thermo-hydrologically coupled simulation

Estimation of stress and stress-induced permeability change in a geological nuclear waste repository in a thermo-hydrologically coupled simulation

Unconventional Reservoirs: Contact Area and Fracture Network Resulting from Perforations in Shale. A Comparative Study of Different Shale Targets and Shaped Charge Designs Optimized for Hydraulic Fracturing

Probabilistic Evaluation of Geomechanical Risks in CO2 Storage: An Exploration of Caprock Integrity Metrics Using a Multilaminate Model

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