... 20GPa in some rocks. We have also found that the residual strain is relevant to the increase in the rock stiffness under repeated load. This relationship seems to be similar among different rock types. Upstream Oil & Gas crack closure loading Reservoir Characterization volumetric strain...

... problems in advance. Rock in situ has been subjected to the three principal stresses for a long time, and is in a saturated state of strain. (Hereafter, the saturated state of strain is defined as the state in which residual strain is sufficiently generated and in which no further strain can be recognized...

... tests. The primary orientation is 337ø-348øT, and a secondary alignment from 045 -060 T. This mechanical anisotropy is correlated with the fabric of the rock. The primary fracture orientation is aligned with the maximum residual strain direction in the bedding plane as determined by overcoring...

..., microfracture orientation, crystallographic orientation, grain dimensional ori- entation, and residual strain. Thin sections were cut parallel and perpendicular to the bedding plane and examined microscopically. In some cases sections were cut from two depths within the same well to determine vertical...

... the residual strains are not relaxed (as they might be had their origin been re- lated to the natural thermal history of the rock), but rather they re locally augmented until the elastic limit is reached and intragranular tensile fractures occur preferrentially at high angles to the greatest elongation...

... Upstream Oil & Gas grain size gage Reservoir Characterization Rock mechanics Existence stress field principal direction residual strain granite reservoir geomechanics microresidual stress rosette stiffness self-equilibrating unit mechanism strain gage residual strain field...

... to the weight per unit area of the overburden. In fact, vertical dilatational strains associated with stresses of more than 100 times the present overburden pressure have been measured by strain-relief methods on outcrops 1,2 . The notion of residual strain (stress) or latent stress 3 seems unassailable...