Analysis of Pore Pressure and Stress Distribution around a Wellbore Drilled in Chemically Active Elastoplastic Formations

Roshan, Hamid; Rahman, Sheik S.

doi:10.1007/s00603-011-0141-x

Cited by 30 publications

(12 citation statements)

References 28 publications

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“…The effects of temperature on solute transfer, pore pressure and stresses around a borehole have been previously investigated (Roshan and Rahman 2011). Therefore, focus is made on the effect of temperature coupling terms on pore pressure and stresses (see Eqs.…”

Section: Effect Of Temperature Coupling Terms On Pore Pressure and Stmentioning

confidence: 99%

“…Another mechanism, which has an effect on pore pressure, is thermal osmosis. This mechanism also affects the hydration/dehydration rate of water-active rocks (Ghassemi and Diek 2002;Roshan and Rahman 2011). Sánchez et al (2010) investigated thermal osmotic flow and its effect on hydration of clay barriers in the framework of thermo-hydro-mechanical analysis.…”

Section: Introductionmentioning

confidence: 99%

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A Non-Isothermal Constitutive Model for Chemically Active Elastoplastic Rocks

Roshan

Oeser

2011

Rock Mech Rock Eng

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Hydration/dehydration of water-active rocks under non-isothermal conditions is encountered in many industries, in particular the drilling industry. Water-active rocks can adsorb water on their basal crystal surfaces on both the external, and, in the case of expanding lattice clays, the inter-layer surfaces. There are two main mechanisms in which the instability may occur for a structure built in water-active rocks. First mechanism is the change in stresses resulted from mechanical, hydraulic, chemical and thermal interaction, which we formulate based on the concept of non-equilibrium thermodynamics. Second mechanism illustrates the change in mechanical properties of the rock due to physic-chemical interaction between the rock and exposed fluid. We postulate the later mechanism in terms of chemically active plastic deformation by using the modified Cam Clay model. The complete governing equations for non-isothermal chemo-poro-elastoplastic rock are therefore presented. A three-dimensional finite element model is then developed to solve the obtained governing equations. From the numerical results, it was found that the effect of temperature coupling term on stress cannot be ignored when non-isothermal conditions are encountered. However, this effect is almost trivial on pore pressure. It was also revealed that the effect of change in the shale's mechanical properties on stability due to physic-chemical interaction is as important as change in stresses due to mechanical, hydraulic, chemical and thermal interactions.

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Section: Effect Of Temperature Coupling Terms On Pore Pressure and Stmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Non-Isothermal Constitutive Model for Chemically Active Elastoplastic Rocks

Roshan

Oeser

2011

Rock Mech Rock Eng

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“…The interaction between the drilling fluids with formation fluid will cause pressure variation around the wellbore, which results in time dependent stresses changes locally [3]. Therefore, in this paper the interaction between geomechanics and formation fluid [4] is taken into consideration to analyze time dependent rocks deformation around the wellbore.…”

Section: Introductionmentioning

confidence: 99%

“…Another study shows that the two main effects causing collapse failure are as follows: (1) poroelastic influence of equalized pore pressure at the wellbore wall and (2) the thermal diffusion between wellbore fluids and formation fluids [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…Numerous scientists presented powerful models to simulate the effect of poroelastic, thermal, and chemical effects by varying values of formation pore pressure, rock failure situation, and critical mud weight [3,6]. These models mentioned that controlling the component of the water present in the drilling fluid results in controlling the wellbore stability.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Wellbore Stability during Underbalanced Drilling Operation

Azim

2017

Journal of Applied Mathematics

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The wellbore stability analysis during underbalance drilling operation leads to avoiding risky problems. These problems include (1) rock failure due to stresses changes (concentration) as a result of losing the original support of removed rocks and (2) wellbore collapse due to lack of support of hydrostatic fluid column. Therefore, this paper presents an approach to simulate the wellbore stability by incorporating finite element modelling and thermoporoelastic environment to predict the instability conditions. Analytical solutions for stress distribution for isotropic and anisotropic rocks are presented to validate the presented model. Moreover, distribution of time dependent shear stresses around the wellbore is presented to be compared with rock shear strength to select appropriate weight of mud for safe underbalance drilling.

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Large‐scale experiments of the borehole instability on shale formation influenced by drill pipe rotation

Sun

Meng

Dai

et al. 2019

Energy Science & Engineering

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Wellbore instability happens mostly in the shale formation. Early researches have studied thoroughly on the physicochemical and mechanical mechanism that causes instability. However, only a few works have considered the influence of field drilling operations, such as drill pipe rotation. In this paper, a true triaxial cell is used to simulate the downhole field situations, and a drill pipe rotation device is innovatively designed and implemented into the true triaxial cell. Using this facility, the influence of drill pipe rotation on shale instability has been performed. Different rotation speed, weight on bit, drilling fluid pressure, and microcracks on borehole have been considered. The enlargement of the wellbore is quantitatively plotted and compared.Results show that the drill pipe rotation contributes to a more enlargement of the wellbore, and a higher rotation speed causes a more severe collapse. The drill string weight on bit also contributes to the enlargement of the wellbore, with a larger weight on bit induces a larger diameter of the collapsed wellbore. Compared with the rotation speed and weight on bit, the influence of drilling fluid density is relatively less significant. However, the influence of microcracks caused by hitting of drilling tools is profound. For a cracked shale formation, the wellbore diameter can be enlarged for more than 40%. Then, the variation of borehole collapse with time and depth under drill pipe rotation influence is analyzed. In all of these four factors, the significant sequence is microcracks > weight on bit > rotation speed > drilling fluid pressure.In all the collapse phenomena, the collapse is more severe in the minimum horizontal stress direction. This is explained by the analysis of the stress distribution in the whole circumferential angle (360°) of the wellbore. Overall, this work fills the gap of the influence of drilling operations on wellbore instability. K E Y W O R D Sborehole enlargement, drill pipe rotation, true triaxial cell, wellbore instability 2896 | SUN et al.

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Analysis of Pore Pressure and Stress Distribution around a Wellbore Drilled in Chemically Active Elastoplastic Formations

Cited by 30 publications

References 28 publications

A Non-Isothermal Constitutive Model for Chemically Active Elastoplastic Rocks

A Non-Isothermal Constitutive Model for Chemically Active Elastoplastic Rocks

Simulation of Wellbore Stability during Underbalanced Drilling Operation

Large‐scale experiments of the borehole instability on shale formation influenced by drill pipe rotation

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