... stress, called the s h springline, where the highest stress concentration occurs. Hence, stress-induced breakouts have been utilized as a reliable indicator of the in situ stress direction. Breakouts in crystalline and carbonate rocks were found to be typically broad at the borehole wall and short...

... ratio pore pressure inversion technique Aadnøy in-situ stress state horizontal stress stress state borehole wall inclination pressure gradient Fracture angle fracture position stress field azimuth fracture fracture equation fracture trace angle image log equation ARMA/NARMS 04-481...

... ABSTRACT: Drilling of a borehole in fluid saturated rocks exerts significant influence on its surrounding reservoir. As have been observed extensively, stresses, pressure and/or thermal loadings on the borehole wall will lead to great change of stress field in the rock. As a result...

...-bit penetration rate increases shortened the breakout length under the same far-field stress conditions. Heavier drilling-fluids were found to improve borehole stability by yielding shorter breakouts due to a thin "mud cake" deposited on the borehole wall and along the breakout. Despite the varying...

... are affixed. The packer is inflated to touch the borehole wall, and then pressure is increased step-wise and the resultant strains recorded. Initially, the circumferential strain developed around the borehole is radially symmetric. However, this becomes strongly asymmetric once the cracks begin to open. Thus...

.... This phenomenon was most likely due to the crack extension growing deeper from the borehole wall. At another point, during a re-open procedure, two AE bursts were recorded. The pressure at the end of the first burst corresponds to the reopening pressure, while that at the start of the second burst corresponds...

... caused by the effective stress concentration near the borehole wall due to the far-field stress, and this concentration can be affected by diffusive fluid flow. Extensive studies have been conducted to investigate the coupled fluid-stress effect and one may refer to Rice and Cleary [1976], Detournay...

... ABSTRACT: Observations of joint persistence and connectivity are made by comparison of digital borehole wall images of fractures, fluid conductivity logs and hydraulic injections test results. The fractures were found to be generally impersistent across vertical boreholes about 8 m apart. Many...

... is known and breakout dimensions are logged. Reservoir Characterization reservoir geomechanics Upstream Oil & Gas borehole breakout Herrick Alabama limestone numerical simulation breakout dimension Zoback horizontal stress MPa borehole wall episodic failure compressive strength...