Wellbore Mechanics and Stability in Shale

Mehrabian, Amin; Nguyen, Vinh Duc; Abousleiman, Younane N.

doi:10.1002/9781119066699.ch11

Cited by 7 publications

(5 citation statements)

References 75 publications

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“…Following Mehrabian et al (2020), the compressive geologic stresses and the related physico-chemical interactions far outweigh the effects of body forces like gravity, so that the following equilibrium equation applies.…”

Section: Force Equilibriummentioning

confidence: 99%

Poroelastic Effects of Chemical Loading in Consolidation of Residual Soils

Irheren,

Onyia,

Okafor

2024

Preprint

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An analytical chemo-hydromechanical model of residual soils was presented in this study. The modeling procedure utilized a unique phenomenological approach, which highlighted some of the macro-mechanical influences responsible for the behavior of residual soils. The macromechanical analysis yielded an extended poroelastic theory. The developed model was applied in solving a typical civil engineering problem of soil consolidation. For a chemical loading treatment, the problem was using requisite boundary conditions. Thereafter, the mathematical software “Mathematica” was used for solving the ensuing diffusion equations using physico-chemical properties typical of a residual soil sample. Even though the chemical loading was instantaneous, it took some time before its effect could be felt everywhere according to the poroelastic theory. From obtained results, the evolution of the generated pore pressure showed increasing segments of the soil returning to their initial state after the passage of the pore pressure front. The vertical displacement showed a slight increase or elevation of the soil surface. The flux of water flow in the soil was initially positive before turning negative, which can be explained by initial successful penetration of the infiltrating liquid until it met increasingly tortuous paths as result of lower permeability. The water volume (per unit area) leaving the soil after chemical loading demonstrated that a portion of the water flux associated with the infiltrating liquid ends up leaving the soil through the sides.

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Section: Force Equilibriummentioning

confidence: 99%

Poroelastic Effects of Chemical Loading in Consolidation of Residual Soils

Irheren,

Onyia,

Okafor

2024

Preprint

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“…Presented a non-linear model that is 'thermo-chemo-poroelastic' to study the effect of distinct types of gradients on the distribution of stress and pore pressure in the wellbore. Pore pressure changes may occur due to cation exchange process presented, through a case study, an approach to incorporate the dual-porosity and permeability proelasticity, and the effects of chemical/thermal gradients into a shale wellbore stability model to get an accurate composition of drilling fluids [23][24][25].…”

Section: Literature Reviewmentioning

confidence: 99%

Reliability of chemical osmosis as a practical method to extract water out of shale and promote shale’s mechanical stability

2023

JOGRR

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Wellbore instability in shale formations is one of the most bothersome problems leading to significant changes in shale’s petrophysical, mechanical, and chemical properties, and could cost billions of dollars annually. Drilling fluid’s ionic composition is one of the factors affecting wellbore stability. This paper investigates the impact of chemical osmosis, ionic diffusion, and diffusion osmosis on the stability of shale, identify the critical salt concentration, and examine the impact of ionic type and concentration on shale stability. Experimental methods include utilization of shale I and II through linear expansion and gravimetric measurement tests using different salts. Results show that the critical salt concentration in shale I and II is 8 w/w%. Chemical osmosis is found to be a reliable method for water extraction out of shale if critical concentration value is not surpassed. Beyond this value, the ionic diffusion and diffusion osmosis in shale I and II were adversely affecting shale’s mechanical and chemical stability. The swelling and gravimetric ions and water uptake tests showed that shale is a leaky semi-permeable membrane, and that chemical osmosis could be jeopardized by ionic transport into shale. However, the water transport impact on changes in the thickness of diffuse double layer of clay needs to be investigated. The impact of temperature on water and ions transportation into shale needs to be examined to reflect in-situ conditions. In this study, the cation type that makes up the salt was varied while the anion type was fixed. Since both cations and anions tend to diffuse into shale in the presence of a concentration gradient, it is recommended to vary the anion type to study the combined impact of cation and anion type on shale stability.

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“…In these depleted fields, new wellbores must be drilled for gas injection operations. Consequently, drilling operation in shale is still a matter of concern [8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Shale often exhibits variation in strength properties along and across the lamination planes. This variation must be taken into consideration when carrying out stability analyses of wellbores [17]. However, the transverse isotropy of shale is not specifically addressed in the indirect approaches.…”

Section: Introductionmentioning

confidence: 99%

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Sensitivity Analysis of Wellbore Mud Pressure towards Anisotropic Shale Properties, Pore Fluid Pressure and Far Field Stresses

Deangeli,

Liu,

Yang

2023

Applied Sciences

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The paper investigates the mud pressure to maintain the stability of wellbores drilled in transversely isotropic shale through sensitivity analyses, carried out with analytical and numerical modeling (FLAC). To this end, we interpreted the anisotropic strength of the Tournemire shale with the Weakness Plane Model (WPM) and the modified Hoek–Brown criterion (HBm). The sensitivity analyses of synthetic case studies indicated a different trend in mud pressure for the two criteria. In some cases, the WPM predicts mud pressures higher than those predicted by the HBm and vice versa. The mud pressures predicted by the HBm resulted in being more sensitive to the increase in the anisotropy of the far field stresses for all the inclinations of the weakness planes. In this context, the WPM predicts some anomalous low mud pressures in a wide range of inclinations of the weak planes. The change in the frictional component of strength decreases with an increase in the pore fluid pressure for both criteria. The mud pressure predicted by the WPM resulted in being more sensitive to the change in frictional strength. The change in trend of the two criteria with change in input data suggests caution in the “a priori” selection of the strength criterion. A simple solution is proposed to predict a safe and reliable mud pressure with a small number of lab tests.

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Wellbore Mechanics and Stability in Shale

Cited by 7 publications

References 75 publications

Poroelastic Effects of Chemical Loading in Consolidation of Residual Soils

Poroelastic Effects of Chemical Loading in Consolidation of Residual Soils

Reliability of chemical osmosis as a practical method to extract water out of shale and promote shale’s mechanical stability

Sensitivity Analysis of Wellbore Mud Pressure towards Anisotropic Shale Properties, Pore Fluid Pressure and Far Field Stresses

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