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A platform for research: civil engineering, architecture and urbanism
Stochastic Optimization of In Situ Horizontal Stress Magnitudes Using Probabilistic Model of Rock Failure at Wellbore Breakout Margin
https://orcid.org/0000-0001-5718-9156
Abstract Constraining the relationship between the borehole breakout width and rock compressive strength in a vertical borehole is fundamental for determining the magnitudes of the principal in situ horizontal stresses. However, the deterministic relationship yields indeterminate solutions for the two unknown stresses. This paper describes a new method incorporating probabilistic distributions of rock strength and breakout width in a vertical wellbore section for the simultaneous determination of the magnitudes of both stresses. This method optimizes the complete set of in situ principal stresses by minimizing the misfit between a probabilistic model and the measured data of wellbore breakouts. The breakout model is established based on the Weibull distribution of rock strength at the margins of the breakout for a uniform set of far-field stresses. The inverse problem is solved by choosing the best-fit set of far-field stresses in a stress polygon using a grid search algorithm. This process also enables one to evaluate the statistical reliability in terms of sensitivity and uncertainty. The stochastic optimization process is demonstrated using borehole images and sonic logging data obtained from the Integrated Ocean Drilling Program (IODP) Hole C0002A, a vertical hole near the seaward margin of the Kumano basin offshore from the Kii Peninsula, southwest Japan.
Stochastic Optimization of In Situ Horizontal Stress Magnitudes Using Probabilistic Model of Rock Failure at Wellbore Breakout Margin
https://orcid.org/0000-0001-5718-9156
Abstract Constraining the relationship between the borehole breakout width and rock compressive strength in a vertical borehole is fundamental for determining the magnitudes of the principal in situ horizontal stresses. However, the deterministic relationship yields indeterminate solutions for the two unknown stresses. This paper describes a new method incorporating probabilistic distributions of rock strength and breakout width in a vertical wellbore section for the simultaneous determination of the magnitudes of both stresses. This method optimizes the complete set of in situ principal stresses by minimizing the misfit between a probabilistic model and the measured data of wellbore breakouts. The breakout model is established based on the Weibull distribution of rock strength at the margins of the breakout for a uniform set of far-field stresses. The inverse problem is solved by choosing the best-fit set of far-field stresses in a stress polygon using a grid search algorithm. This process also enables one to evaluate the statistical reliability in terms of sensitivity and uncertainty. The stochastic optimization process is demonstrated using borehole images and sonic logging data obtained from the Integrated Ocean Drilling Program (IODP) Hole C0002A, a vertical hole near the seaward margin of the Kumano basin offshore from the Kii Peninsula, southwest Japan.
Stochastic Optimization of In Situ Horizontal Stress Magnitudes Using Probabilistic Model of Rock Failure at Wellbore Breakout Margin
https://orcid.org/0000-0001-5718-9156
Abstract Constraining the relationship between the borehole breakout width and rock compressive strength in a vertical borehole is fundamental for determining the magnitudes of the principal in situ horizontal stresses. However, the deterministic relationship yields indeterminate solutions for the two unknown stresses. This paper describes a new method incorporating probabilistic distributions of rock strength and breakout width in a vertical wellbore section for the simultaneous determination of the magnitudes of both stresses. This method optimizes the complete set of in situ principal stresses by minimizing the misfit between a probabilistic model and the measured data of wellbore breakouts. The breakout model is established based on the Weibull distribution of rock strength at the margins of the breakout for a uniform set of far-field stresses. The inverse problem is solved by choosing the best-fit set of far-field stresses in a stress polygon using a grid search algorithm. This process also enables one to evaluate the statistical reliability in terms of sensitivity and uncertainty. The stochastic optimization process is demonstrated using borehole images and sonic logging data obtained from the Integrated Ocean Drilling Program (IODP) Hole C0002A, a vertical hole near the seaward margin of the Kumano basin offshore from the Kii Peninsula, southwest Japan.
Stochastic Optimization of In Situ Horizontal Stress Magnitudes Using Probabilistic Model of Rock Failure at Wellbore Breakout Margin
Song, Insun (author) / Chang, Chandong (author)
2018
Article (Journal)
English
Local classification TIB:
560/4815/6545
BKL:
38.58
Geomechanik
/
56.20
Ingenieurgeologie, Bodenmechanik
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