Failure of Inclined Boreholes

Bradley, W.B.

doi:10.1115/1.3446925

Cited by 424 publications

(125 citation statements)

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“…1) and may thus be related to the rock anisotropy (Table 2). Babcock, 1978Guenot, 1989Brown, 1978Schafer, 1980 Hubbert andWillis, 1957;Haimson and Fairhurst, 1967;Haimson, 1978Morin et al, 1990Guenot, 1987Dart and Zoback, 1989Hottman et al, 1979Bell and Gough, 1979;Zoback et al, 1985Guenot, 1989Cheatham, 1984Teufel, 1983;Bradley, 1979Babcock, 1978Dart andZoback, 1989 Plumb andCox, 1987;Plumb and Hickman, 1985Guenot, 1989Gaylord, 1983 Table 1) and azimuth (AzCmax) of the pad that corresponds to the larger measured diameter for each of the five passes, labeled from pi to p5. Azimuth is with respect to magnetic north.…”

Section: Discussionmentioning

confidence: 99%

Constraints on the Geometry and Fracturing of Hole 894G, Hess Deep, from Formation MicroScanner Logging Data

Célérier¹,

Macleod²,

Harvey³

1996

Proceedings of the Ocean Drilling Program, 147 Scientific Results

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Ocean Drilling Program Hole 894G, sited on a small horst within Hess Deep, was drilled in lower oceanic crust that was generated at the East Pacific Rise and then rifted by the propagating Cocos/Nazca divergent plate boundary. Difficult drilling conditions in fractured gabbros resulted in a washed-out hole.Despite these unfavorable circumstances, open-hole logs from the Formation MicroScanner (FMS) tool string provide strong constraints on the fracture orientations and suggest a few directions of preferential enlargement. These results were obtained because five logging passes were recorded to compensate for the expected low data quality by redundancy and because the now classical analysis of FMS data has been adapted to this situation of multiple passes and washed out borehole.An east enlargement direction is thought to be related to the east-west strike of the dense network of fractures observed both in cores and on the FMS resistivity images, and an east-northeast enlargement direction may be the result of drill pipe wear along the borehole plunge direction. Additional east-southeast to south-southeast and north-northeast enlargements may reflect the influence of either the Nazca-Galapagos or the Cocos-Nazca plate boundary state of stress, respectively. However, the interpretation of these poorly defined directions remains uncertain.The analysis of the FMS resistivity images shows mainly east-west striking and southward dipping fractures and very few north-south trending features. This suggests a strong Cocos-Nazca control on brittle deformation in the Hess Deep. The distribution of orientation of the fractures identified on the FMS images is very similar to that obtained from core veins reoriented relative to paleomagnetic north. Matching the two sets requires that the remanent magnetization direction points north-northwest. The preferred interpretation of this result is a vertical-axis component of tectonic rotation of 30° to 40° counterclockwise.

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Section: Discussionmentioning

confidence: 99%

Constraints on the Geometry and Fracturing of Hole 894G, Hess Deep, from Formation MicroScanner Logging Data

Célérier¹,

Macleod²,

Harvey³

1996

Proceedings of the Ocean Drilling Program, 147 Scientific Results

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“…So it is necessary to correct the fracture pressure for tectonic stress in calculations. Bradley developed an equation in which stress anisotropy due to horizontal stress variation can be modelled (Brandley 1979). Quantifying horizontal tectonic stress for wildcat well location is almost impossible without P-wave and S-wave velocity data or leak-off test data.…”

Section: Fracture Pressure Predictionmentioning

confidence: 99%

Design of safe well on the top of Atharamura anticline, Tripura, India, on the basis of predicted pore pressure from seismic velocity data

Brahma

Sircar

2018

J Petrol Explor Prod Technol

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Pore pressure prediction is an essential part of wildcat well planning. In India, Tripura sub-basin is characterised by huge anticlines, normal faults and abnormally pressured formations. These factors push the wildcat well planning in this area into wide margin of uncertainty. Pore pressures were predicted from seismic velocities by using modified Eaton's method over the synclinal and flank part of Atharamura to understand the pressure succession towards the anticline. These predicted pore pressures on the flank part lead to a reasonable match when plotted with offset well-measured pore pressures. To reduce the uncertainty, fracture pressures were established by various methods such as Hubbert and Willis method and Matthews and Kelly method from predicted pore pressures. But the fracture pressures were predicted with available horizontal stress correlations due to lack of Poisson's ratio curve for the study area. The mud pressure required to drill the well is calculated using median line principle, and hence drilling mud window is established by assuming virtual tight conditions. The plot of equivalent circulation density versus depth suggests that well can be drilled with two casing policy. But it is found that adding one more casing pipe will ensure the safety of well. Casing pipes were designed on the basis of collapse pressure, burst pressure and tensile load. Finally, a well plan which includes pore pressure, fracture pressure, drilling mud policy, casing policy and kick tolerance graph were proposed to give clear picture on well planning on the top of the anticline in pore pressure point of view.

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“…They introduced poroelasticity theory in order to study the effects of fluid flow on wellbore stability because this flow induces additional normal stresses. Bradford and Cook (1994) developed a semi-analytical elastoplastic model [19]. This model applies to vertical wells subjected to isotropic in-situ stress and pore pressure fields that predict the onset of sanding.…”

Section: Coupling Fluid Flow and Induced Stressesmentioning

confidence: 99%

“…Kirsch's solution is based on assumptions such as a twodimensional, elastic and non-porous medium. Further studies by Bradley [19] based on Fairhurst's works [20] included the effect of mud pressure in calculating the drilling induced stresses. In this work, however, plane strain condition and omission the flow of fluid near wellbore and its impact on induced stresses were the two major assumption.…”

Section: Coupling Fluid Flow and Induced Stressesmentioning

confidence: 99%

The effect of Non-Darcy Flow on Induced Stresses Around a Wellbore in an anisotropic in-situ stress field

2017

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After drilling a well, the stresses will be altered and the induced stresses present the new state of stress. These induced stresses which result in geomechanical problems. The studies indicate that the flow of hydrocarbon into the wellbore influences the induced stresses. Darcy equation has been used in the past; however, the laminar flow assumption embedded in this equation cannot correctly model the flow of fluid when a nonDarcy flow dominates near a wellbore. Example of such situation includes the gas wells.In this study, analytical equations are developed to incorporate the effect of nonDarcy flow on the induced stresses around a wellbore. These equations developed based on Forchheimer flow equation. Then the simplified solutions were presented by considering the second term of Forchheimer flow equation. It was found that the difference between the results from Darcy and nonDarcy flow models is proportional to the drawdown pressure.Further studies included numerical simulation of non-Darcy fluid flow in a typical reservoir.Comparison of the results with the analytical models indicated that the magnitude of stresses in non-Darcy flow is larger than of Darcy flow.Finally, sensitivity of the reservoir properties on the induced stresses in the non-Darcy flow regime was investigated.

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Failure of Inclined Boreholes

Cited by 424 publications

References 0 publications

Constraints on the Geometry and Fracturing of Hole 894G, Hess Deep, from Formation MicroScanner Logging Data

Constraints on the Geometry and Fracturing of Hole 894G, Hess Deep, from Formation MicroScanner Logging Data

Design of safe well on the top of Atharamura anticline, Tripura, India, on the basis of predicted pore pressure from seismic velocity data

The effect of Non-Darcy Flow on Induced Stresses Around a Wellbore in an anisotropic in-situ stress field

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