This paper presents a wellbore-stability study of the San Andreas Fault Observatory at Depth (SAFOD) research borehole located near Parkfield, California, USA. In the summer of 2005, the SAFOD borehole was drilled successfully through the active trace of the San Andreas Fault (SAF) in an area characterized by fault creep and frequent microearthquakes. In this study, we report how the analysis o...

Some fundamental mechanisms associated with cooling/heating of the rock in the context of drilling and reservoir stimulation in enhanced geothermal systems are described. The role of temperature and pore pressure in wellbore failure and fracture width is considered using analytical and boundary element models. Results indicate that cooling induces a pore pressure drop inside the formation that ...

Wellbore stability analysis based on a new true-triaxial failure criterion i Abstract A main aspect of wellbore stability analysis is the selection of an appropriate rock failure criterion. The most commonly used criterion for brittle failure of rocks is the Mohr-Coulomb criterion. This criterion involves only the maximum and minimum principal stresses, σ 1 and σ 3 , and therefore assumes that ...

Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid. A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. The diffusion coefficient of shale ...

Piedmont tectonic belts are rich of oil and gas resources, however the intense tectonic stress and broken formation may cause great drilling problems in piedmont structures such as borehole collapse, lost circulation and gas cutting. Through analysis of in situ stress properties, bedding structure and mechanical characteristics, wellbore instability mechanism was expounded from rock mechanics, ...

Binary cycle power plants have been used successfully for electricity generation utilizing co-produced fluids from active onshore oil wells. Adapting this process for use on abandoned wells by circulating the binary working fluid down the wellbore has been previously proposed and a selection of fluids evaluated. This work proposes and evaluates an approach using water as the wellbore fluid in c...