Drilling in South America : A Wellbore Stability Approach for Complex Geologic 
Conditions

Willson, S.M.; Last, N.C.; Zoback, M.D.; Moos, D.

doi:10.2523/53940-ms

Cited by 5 publications

(2 citation statements)

References 8 publications

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“…Vernik and Zoback (1990) analytically showed that there are four sectors around the wellbore that could satisfy the failure in the weak plane, which have been observed in the image log as two double-lobed BOs (Kowan et al, 2021). However, no double-lobed BOs have been observed in the current study since the BO morphology is highly controlled by the angle between the wellbore inclination and weak plane geometry (Okland & Cook, 1998;Willson et al, 1999). The angle between the normal of the weak plane and the wellbore axis is denoted as β n .…”

Section: Relations Between Metamorphic Texture Anisotropy and Breakoutsmentioning

confidence: 60%

Heterogeneity Versus Anisotropy and the State of Stress in Stable Cratons: Observations From a Deep Borehole in Northeastern Alberta, Canada

Wang

Schmitt

Chan³

2023

JGR Solid Earth

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Geophysical logs collected from a deep borehole drilled into the North American Craton in Northeastern Alberta shed valuable light on the state of stress in stable cratons. Observed breakout (BO) azimuths rotate between three depth intervals, ranging from 100° at 1,650–2,000 m to 173° at 2,000–2,210 m, and finally to 145° at the bottom. No apparent fractures that might have disturbed the stress field were found. Two potential causes of these rotating BOs can be either a heterogeneous stress field or elastic and strength anisotropy of the formation. The latter interpretation is favored since observed BO azimuths are strongly controlled by rock metamorphic textures, as validated by their close correlations with dip directions of foliation planes and polarization directions from dipole sonic logs. Monte Carlo realizations further demonstrate that anisotropic metamorphic rocks subjected to a uniform horizontal stress direction could result in the observed azimuth‐rotating BOs. Stress magnitudes inferred from this analysis, which incorporates rock anisotropy and weak foliation failure planes, suggest a normal faulting regime and a maximum horizontal compressive direction consistent with that in the overlying Western Canadian Sedimentary Basin (NE‐SW) and the motion of the North American plate. The inferred stress magnitudes are low and Mohr‐Coulomb analyses demonstrate that the formation is not near the critical condition for slip on weak planes. However, more detailed investigations should be conducted since Monte Carlo calculations indicate that analyses from BO widths, particularly when a conventional Kirsch‐based formula is employed, are highly nonunique, allowing for large variations in potential stress states.

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Section: Relations Between Metamorphic Texture Anisotropy and Breakoutsmentioning

confidence: 60%

Heterogeneity Versus Anisotropy and the State of Stress in Stable Cratons: Observations From a Deep Borehole in Northeastern Alberta, Canada

Wang

Schmitt

Chan³

2023

JGR Solid Earth

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“…The stress state in the earth's crust controls stress concentration around a wellbore and therefore plays a critical role in wellbore instability, well stimulation operations, fluid flow in fractured reservoirs, and sand production (Bell 1996;Willson et al 1999). Knowledge of the stress state is not only important in the petroleum industry, but it is also vital in geotechnical applications and other solid earth sciences.…”

Section: Introductionmentioning

confidence: 99%

Determination of minimum and maximum stress profiles using wellbore failure evidences: a case study—a deep oil well in the southwest of Iran

Molaghab

Taherynia

Aghda

et al. 2017

J Petrol Explor Prod Technol

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The main objective of this paper is estimating the horizontal stresses and calibration of the log-derived horizontal stress profiles in deep oil wells according to their wall failure evidences, including both compressive (breakouts) and tensile failures (drilling-induced tensile fractures). Estimation of the horizontal stress profiles using well logs is one of the standard methods in the oil industry. Another method for estimating horizontal stresses is analyzing failure evidences in the wellbore wall. By integrating these two methods, a practical strategy was followed in this research to determine the horizontal stress profiles. By this strategy, minimum and maximum horizontal stress profiles are determined in such a way that the stress concentration at the wellbore wall at the tensile fracture identified depths, exceeds the formation tensile strength, while at the breakouts identified depths it exceeds the compressive strength of the formation. An advantage of this procedure is that does not require to measure in situ stresses. Also, due to the presence of a large number of breakouts and the induced fractures detected in different zones of a deep wellbore, log-derived stress profile calibration is done using the stress state in different zones that causes to increase the accuracy and reliability of the obtained horizontal stress profile. The proposed solution was applied to determine the horizontal stress profiles in a deep oil well in the southwest of Iran as a real case.

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Geomechanics of Gas Shales

Rasouli

2015

Fundamentals of Gas Shale Reservoirs

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Drilling in South America : A Wellbore Stability Approach for Complex Geologic Conditions

Cited by 5 publications

References 8 publications

Heterogeneity Versus Anisotropy and the State of Stress in Stable Cratons: Observations From a Deep Borehole in Northeastern Alberta, Canada

Heterogeneity Versus Anisotropy and the State of Stress in Stable Cratons: Observations From a Deep Borehole in Northeastern Alberta, Canada

Determination of minimum and maximum stress profiles using wellbore failure evidences: a case study—a deep oil well in the southwest of Iran

Geomechanics of Gas Shales

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