Changes

Careful examination and recording of information from continuous cores provide critical data for stratigraphic correlation, environmental interpretation, and wireline log calibration. Core plugs provide samples for analysis of [[porosity]], [[permeability]], fluid saturation, and a host of compositional and textural studies. Recommendations for the well site and laboratory handling of cores as well as sedimentological analyses are described by Siemers et al.<ref name=pt05r145>Siemers, C. T., Tillman, R. W., Williamson, C. R., eds., 1981, Deep-water clastic sediments—a core workshop: SEPM Core Workshop, n. 2, 416 p.</ref> and Miall.<ref name=pt05r109>Maness, M., Price, J. G. W., 1977, Well formation characterization by residual hydrocarbon analysis: Annual Meeting of the Society of Petroleum Engineers, Denver, CO, Oct. 9–12, SPE 6860.</ref>

Careful examination and recording of information from continuous cores provide critical data for stratigraphic correlation, environmental interpretation, and wireline log calibration. Core plugs provide samples for analysis of [[porosity]], [[permeability]], fluid saturation, and a host of compositional and textural studies. Recommendations for the well site and laboratory handling of cores as well as sedimentological analyses are described by Siemers et al.<ref name=pt05r145>Siemers, C. T., Tillman, R. W., Williamson, C. R., eds., 1981, Deep-water clastic sediments—a core workshop: SEPM Core Workshop, n. 2, 416 p.</ref> and Miall.<ref name=pt05r109>Maness, M., Price, J. G. W., 1977, Well formation characterization by residual hydrocarbon analysis: Annual Meeting of the Society of Petroleum Engineers, Denver, CO, Oct. 9–12, SPE 6860.</ref>

Continuous cores have some advantages over outcrop exposures for environmental interpretation.<ref name=pt05r166>Weimer, R. J., Tillman, R. W., 1980, Tectonic influence on deltaic shoreline facies, Fox Hills Sandstone, west-central Denver basin: Colorado School of Mines Professional Contribution, n. 10, 131 p.</ref> These advantages include the following:

Continuous cores have some advantages over outcrop exposures for environmental interpretation.<ref name=pt05r166>Weimer, R. J., Tillman, R. W., 1980, Tectonic influence on deltaic shoreline facies, Fox Hills Sandstone, west-central Denver basin: Colorado School of Mines Professional Contribution, n. 10, 131 p.</ref> These advantages include the following:

These advantages, however, are offset by the lack of a three-dimensional view and the inability to observe lateral facies changes and large-scale sedimentary features directly.

These advantages, however, are offset by the lack of a three-dimensional view and the inability to observe lateral facies changes and large-scale sedimentary features directly.

A graphic log format, which visually expresses a stratigraphic succession, is strongly recommended for describing continuous cores. Such logs should reflect the following:

A graphic log format, which visually expresses a stratigraphic succession, is strongly recommended for describing continuous cores. Such logs should reflect the following:

* Fracturing

* Fracturing

* [[Porosity]]

* [[Porosity]]

[[file:core-description_fig1.png|thumb|left|{{figure number|1}}Idealized graphic log. Explanation for some symbols used for sedimentary structures, lithologies, fossils, and contacts are given. Grain size of sillclclastic rocks and Dunham's)<ref name=pt05r50>Dunham, R. J., 1962, Classification of carbonate rocks according to depositional texture, in Ham, W. E., ed., Classification of Carbonate Rocks: AAPG Memoir 1, p. 108–121.</ref> classification of limestones are indicated in the column on the left. All sedimentary structures are depicted graphically as accurately as possible. Porosity amounts in percent can be scaled as needed. (Modified from <ref name=pt05r32>Casey, J. M., 1980, Depositional systems and basin evolution of the Late Paleozoic Taos trough, northern New Mexico: Ph. D. Dissertation, The University of Texas at Austin, 236 p.</ref><ref name=pt05r28 />.)]]

[[file:core-description_fig1.png|thumb|left|{{figure number|1}}Idealized graphic log. Explanation for some symbols used for sedimentary structures, lithologies, fossils, and contacts are given. Grain size of sillclclastic rocks and Dunham's)<ref name=pt05r50>Dunham, R. J., 1962, Classification of carbonate rocks according to depositional texture, in Ham, W. E., ed., Classification of Carbonate Rocks: AAPG Memoir 1, p. 108–121.</ref> classification of limestones are indicated in the column on the left. All sedimentary structures are depicted graphically as accurately as possible. Porosity amounts in percent can be scaled as needed. (Modified from <ref name=pt05r32>Casey, J. M., 1980, Depositional systems and basin evolution of the Late Paleozoic Taos trough, northern New Mexico: Ph. D. Dissertation, The University of Texas at Austin, 236 p.</ref><ref name=pt05r28 />.)]]