Automatic Calibration of a Geomechanical Model from Sparse Data for Estimating Stress in Deep Geological Formations

2021 ◽  
Author(s):  
O. Andersen ◽  
M. Kelley ◽  
V. Smith ◽  
S. Raziperchikolaee
Keyword(s):  
Stress Field ◽  
Stress Tensor ◽  
Co2 Storage ◽  
Measurement Data ◽  
Automatic Calibration ◽  
Storage Site ◽  
Tensor Fields ◽  
Geomechanical Model ◽  
Fully Automatic

Summary In this study, we demonstrate geomechanical modeling with fully automatic parameter calibration to estimate the full geomechanical stress fields of a prospective US CO2 storage site, based on sparse measurement data. The goal is to compute full stress tensor field estimates (principal stresses and orientations) that are maximally compatible with observations within the constraints of the model assumptions, thereby extending point-wise, incomplete partial stress measurement to a simulated full formation stress field, as well as a rough assessment of the associated error. We use the Perch site, located in Otsego Country, Michigan, as our case study. Input data consists of partial stress tensor information inferred from in-situ borehole tests, geophysical well logs and processing of seismic data. A static earth model of the site was developed, and geomechanical simulation functionality of the open-source MATLAB Reservoir Simulation Toolbox (MRST) used to model the stress field. Adjoint-based nonlinear optimization was used to adjust boundary conditions and material properties to calibrate simulated results to observations. Results were interpreted through a Bayesian framework. The focus of this article is to demonstrate how the fully automatic calibration procedure works and discuss the results obtained but does not attempt a detailed analysis of the stress field in the context of the proposed CO2 storage initiatives. Our work is part of a larger effort to non-invasively determine in-situ stresses in deep formations considered for CO2 storage. Guided by previously published research on geomechanical model calibration, our work presents a novel calibration approach supporting a potentially large number of linear or nonlinear calibration parameters, in order to produce results optimally agreeing with available measurements and thus extend partial point-wise estimates to full tensor fields compatible with the physics of the site.

scholarly journals Uncertainties in geomechanical models – exhaustive vs. feasible approach

2021 ◽  
Vol 1 ◽  
pp. 187-188
Author(s):  
Moritz Ziegler ◽  
Oliver Heidbach
Keyword(s):  
Standard Deviation ◽  
Stress State ◽  
Stress Tensor ◽  
In Situ Stress ◽  
Rock Properties ◽  
Geomechanical Model ◽  
Rock Property ◽  
Stress Changes ◽  
Stress States

Abstract. The stress state is a key component for the safety and stability of deep geological repositories for the storage of nuclear waste. For the stability assessment and prediction over the repository lifetime, the stress state is put in relation to the rock strength. This assessment requires knowledge of both the future stress changes and the current in situ stress state. Due to the limited number of in situ stress data records, 3D geomechanical models are used to obtain continuous stress field prediction. However, meaningful interpretation of the stress state model requires quantification of the associated uncertainties that result from the geological, stress and rock-property data. This would require thousands of simulations which in a high-resolution model is called an exhaustive approach. Here we present a feasible approach to reduce computation time significantly. The exhaustive approach quantifies uncertainties that are due to variabilities in stress data records. Therefore, all available data records within a model volume are used individually in separate simulations. Due to the inherent variability in the available data, each simulation represents one of many possible stress states supported by data. A combination of these simulations allows estimation of an individual probability density function for each component of the stress tensor represented by an average value and a standard deviation. If weighting of the data records can be performed, the standard deviation can usually be reduced and the significance of the model result is improved. Alternatively, a range of different stress states supported by the data can be provided with the benefit that no outliers are disregarded, but this comes at the cost of a loss in precision. Both approaches are only feasible since the number of stress data records is limited. However, it is indicated that large uncertainties are also introduced by variabilities in rock properties due to natural intra-lithological lateral variations that are not represented in the geomechanical model or due to measurement errors. Quantification of these uncertainties would result in an exhaustive approach with a high number of simulations, and we use an alternative, feasible approach. We use a generic model to quantify the stress state uncertainties from the model due to rock property variabilities. The main contributor is the Young's module, followed by the density and the Poisson ratio. They affect primarily the σxx and σyy components of the stress tensor, except for the density, which mainly affects the σzz component. Furthermore, a relative influence of the stress magnitudes, the tectonic stress regime and the absolute magnitude of rock properties is observed. We propose to use this information in a post-computation assignment of uncertainties to the individual components of the stress tensor. A range of lookup tables need to be generated that compile information on the effect of different variabilities in the rock properties on the components of the stress tensor in different tectonic settings. This allows feasible quantification of uncertainties in a geomechanical model and increases the significance of the model results significantly.

Full Potential Electronic Structure Calculations and the Concept of Stress Fields and Energy Densities for Total Energy Calculations

1991 ◽  
Vol 253 ◽  
Author(s):  
P. Ziesche
Keyword(s):  
Energy Density ◽  
Stress Field ◽  
Stress Tensor ◽  
Particle Density ◽  
Local Stress ◽  
Full Potential ◽  
Many Body ◽  
Tensor Fields ◽  
Defect Energies ◽  
Total Energies

ABSTRACTWith the availability of reliable full atomic cell orbitals the possibility arises to calculate pressure or stress, restoring or relaxation driving Hellmann -Feynman forces, and total energies (especially of defects) alternatively and directly via stress tensor fields and energy densities, two local quantities. Although quantum mechanical stress field and energy density can not be defined uniquely, there is a recent interest in these quantities, because integrals with physical meaning are gauge invariant.The mentioned fields can be defined (i) for the full many-body description with the exact one-particle density matrix and pair distribution function as well as (ii) for the Kohn-Sham one-particle description with LDA or beyond (gradient expansion approximation). If the local stress field for a special system once is constructed, then the global stress tensor and /or forces on nuclei can be calculated via the stress theorem and the force theorem by means of unit cell surface integrals. The energy density can be derived from the terms of the stress field by taking the trace and can be used to calculate defect energies without bothering about the thermodynamic limit.

CHARACTERISING THE FULL STRESS TENSOR BASED ON OBSERVATIONS OF DRILLING-INDUCED WELLBORE FAILURES IN VERTICAL AND INCLINED BOREHOLES LEADING TO IMPROVED WELLBORE STABILITY AND PERMEABILITY PREDICTION

1998 ◽  
Vol 38 (1) ◽  
pp. 466 ◽  
Author(s):  
C.A. Barton ◽  
D.A. Castillo ◽  
D. Moos ◽  
P. Peska ◽  
M.D. Zoback
Keyword(s):  
Stress Field ◽  
Stress Tensor ◽  
Image Data ◽  
In Situ Stress ◽  
Wellbore Stability ◽  
Efficient Production ◽  
Sand Production ◽  
Inclined Boreholes ◽  
In Situ Stress Field

To minimise wellbore failures in unstable environments, knowledge of the complete stress tensor is crucial to designing optimally-stable borehole trajectories, selecting suitable mud weights, and determining appropriate casing points. Understanding how the in situ stress field interacts with the drilling and production of a well enables one to design for maximum stability and to facilitate intersecting the greatest population of hydraulically-conductive fractures for efficient production. Knowledge of the in situ stress field is also important to reduce uncertainties in sand production prediction to allow more aggressive completion designs and production schedules.A new interactive software system, Stress and Failure of Inclined Boreholes (SFIB) (Peska and Zoback, 1995a) is used to demonstrate how observations of drilling-induced compressive and tensile wellbore failures from acoustic and electrical images in vertical and inclined boreholes can be integrated with routinely-collected drilling data (leak-off and drill stem tests) to construct a well-constrained stress tensor. These techniques can also exploit wellbore image data to constrain in situ rock strength in vertical and inclined wells. This paper illustrates how to apply this knowledge to limit wellbore instability, design optimally stable wellbores, develop constraints that help mitigate problems associated with sand production, and optimise productivity of fractured reservoirs.In addition to mapping drilling-induced wellbore features, image data can also be used to determine the distribution, orientation, and apparent aperture of natural fractures and fault systems. With knowledge of the orientations and magnitudes of the in situ stresses it is possible to identify the subset of fractures that are likely to be hydraulically conductive.Examples of recent applications in the North Sea, Gulf of Mexico, California, and Puerto Rico illustrating how this integrated approach can be used in a variety of tectonic settings.

Measurement and the Distribution Law of In Situ Stresses at Deep Depth of Hongyang Coal Mine

2013 ◽  
Vol 671-674 ◽  
pp. 65-68
Author(s):  
Hong Man Xia ◽  
Jiong Wang ◽  
Yang Liu ◽  
Jie Wen Pang ◽  
Dong Qiao Liu ◽  
...  
Keyword(s):  
Stress Field ◽  
Coal Mine ◽  
Stress Measurement ◽  
Measurement Data ◽  
Tectonic Stress ◽  
In Situ Stress ◽  
Distribution Law ◽  
In Situ Stress Measurement ◽  
In Situ Stress Field

There are many in situ stress measurement methods nowadays, the ISRM suggested two methods for in situ stresses measurement: overcoring methods and the hydraulic fracturing methods. In order to study the distribution law of in situ stress field in the deep position of Hongyang coal mine, 3 points of in situ stress measurement were carried out in underground roadways at the -870 m level adopting the overcoring method. The KX-81 type gauge was used to measure the 3 points of in-situ stress. According to the analysis and calculation of the measurement data, the result showed that the in situ stress field in Hongyang coal mine at the depth of -870m was dominated by horizontal tectonic stress.

Applied Risk and Consequence Analysis for CO2 Storage Projects – the Captain X Storage Site, Offshore UK (Acorn)

2019 ◽  
Author(s):  
Niklas Heinemann ◽  
Hazel Robertson ◽  
Juan Alcalde ◽  
Alan James ◽  
Saeed Ghanbari ◽  
...  
Keyword(s):  
Co2 Storage ◽  
Storage Site ◽  
Consequence Analysis

Towards a Multiphysical Model and Inversion of the Ketzin CO2 Storage Site Full Operational Period

2019 ◽  
Author(s):  
Bernd Wiese ◽  
Wolfgang Weinzierl ◽  
Cornelia Schmidt-Hattenberger
Keyword(s):  
Co2 Storage ◽  
Storage Site ◽  
And Inversion

scholarly journals Driving stress and seismotectonic implications of the 2013 Mw5.8 Awaji Island earthquake, southwestern Japan, based on earthquake focal mechanisms before and after the mainshock

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Kazutoshi Imanishi ◽  
Makiko Ohtani ◽  
Takahiko Uchide
Keyword(s):  
Stress Field ◽  
Stress Tensor ◽  
Nankai Trough ◽  
Source Region ◽  
Local Scale ◽  
Southwest Japan ◽  
Stress Tensor Inversion ◽  
Earthquake Fault ◽  
Reverse Faulting ◽  
Before And After

Abstract A driving stress of the Mw5.8 reverse-faulting Awaji Island earthquake (2013), southwest Japan, was investigated using focal mechanism solutions of earthquakes before and after the mainshock. The seismic records from regional high-sensitivity seismic stations were used. Further, the stress tensor inversion method was applied to infer the stress fields in the source region. The results of the stress tensor inversion and the slip tendency analysis revealed that the stress field within the source region deviates from the surrounding area, in which the stress field locally contains a reverse-faulting component with ENE–WSW compression. This local fluctuation in the stress field is key to producing reverse-faulting earthquakes. The existing knowledge on regional-scale stress (tens to hundreds of km) cannot predict the occurrence of the Awaji Island earthquake, emphasizing the importance of estimating local-scale (< tens of km) stress information. It is possible that the local-scale stress heterogeneity has been formed by local tectonic movement, i.e., the formation of flexures in combination with recurring deep aseismic slips. The coseismic Coulomb stress change, induced by the disastrous 1995 Mw6.9 Kobe earthquake, increased along the fault plane of the Awaji Island earthquake; however, the postseismic stress change was negative. We concluded that the gradual stress build-up, due to the interseismic plate locking along the Nankai trough, overcame the postseismic stress reduction in a few years, pushing the Awaji Island earthquake fault over its failure threshold in 2013. The observation that the earthquake occurred in response to the interseismic plate locking has an important implication in terms of seismotectonics in southwest Japan, facilitating further research on the causal relationship between the inland earthquake activity and the Nankai trough earthquake. Furthermore, this study highlighted that the dataset before the mainshock may not have sufficient information to reflect the stress field in the source region due to the lack of earthquakes in that region. This is because the earthquake fault is generally locked prior to the mainshock. Further research is needed for estimating the stress field in the vicinity of an earthquake fault via seismicity before the mainshock alone.

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