Changes

Core orientation is the process by which the original ''in situ'' position or orientation of a core cylinder is determined. Typically, a mark, groove, or line is placed on the surface of the core and the ''in situ'' azimuth of the marking is determined with respect to geographic north.

Core orientation is the process by which the original ''in situ'' position or orientation of a core cylinder is determined. Typically, a mark, groove, or line is placed on the surface of the core and the ''in situ'' azimuth of the marking is determined with respect to geographic north.

Cores are oriented to facilitate measurement of directional properties in the rock. Most routinely, orientation is used to measure large scale features such as bedding, cross-bedding, fractures, flow textures, and stylolites<ref name=pt03r40>Pettijohn, F. J., Potter, P. E., Siever, R., 1973, Sand and sandstone: New York, Springer-Verlag, 618 p.</ref>. In recent years, oriented core has been used to establish the directions of downhole stress and strain fields<ref name=pt03r46>Teufel, L. W., Hart, C. M., Sattler, A. R., Clark, J. A., 1984, Determination of hydraulic fracture azimuth by geophysical, geological, and oriented core methods at the multi-well experiment site, Rifle, Colorado: Sandia National Laboratories Paper SAND 84-0380, Society of Petroleum Engineers Paper No. 13226, 15 p.</ref>; Smith et al., 1984{{missing ref}}; <ref name=pt03r31>Lacy, L. L., 1984, Comparison of hydraulic fracture orientation techniques: Society of Petroleum Engineers Paper No. 13225, 12 p.</ref>.

Cores are oriented to facilitate measurement of directional properties in the rock. Most routinely, orientation is used to measure large scale features such as bedding, cross-bedding, fractures, flow textures, and stylolites.<ref name=pt03r40>Pettijohn, F. J., Potter, P. E., Siever, R., 1973, Sand and sandstone: New York, Springer-Verlag, 618 p.</ref> In recent years, oriented core has been used to establish the directions of downhole stress and strain fields.<ref name=pt03r46>Teufel, L. W., Hart, C. M., Sattler, A. R., Clark, J. A., 1984, Determination of hydraulic fracture azimuth by geophysical, geological, and oriented core methods at the multi-well experiment site, Rifle, Colorado: Sandia National Laboratories Paper SAND 84-0380, Society of Petroleum Engineers Paper No. 13226, 15 p.</ref><ref name=Smith el al._1985>Smith, M. B., N.-K. en, G. G. Sorrells, and L. W. Teufel, 1985, A comprehensive fracture diagnostics experiment, Part II, Comparison of seven fracture azimuth measurements: Society of Petroleum Engineers Paper No. 13894, 16 p.</ref><ref name=pt03r31>Lacy, L. L., 1984, Comparison of hydraulic fracture orientation techniques: Society of Petroleum Engineers Paper No. 13225, 12 p.</ref>

Core orientation techniques fall broadly into two categories: mechanical and core-based.

Core orientation techniques fall broadly into two categories: mechanical and core-based.