Changes

==Recognizing anomalies==

==Recognizing anomalies==

[[file:surface-geochemical-exploration-for-petroleum_fig18-4.png|thumb|{{figure number|1}}Illustration of the value of geochemical grids over geochemical traverses for anomaly recognition. Copyright: Geo-Microbial Technologies, Inc.]]

[[file:surface-geochemical-exploration-for-petroleum_fig18-4.png|300px|thumb|{{figure number|1}}Illustration of the value of geochemical grids over geochemical traverses for anomaly recognition. Copyright: Geo-Microbial Technologies, Inc.]]

Defining background values adequately is an essential part of anomaly recognition and delineation; Matthews<ref name=ch18r26 /> suggests that as many as 80% of the samples collected be obtained outside the area of interest. This is a good recommendation for reconnaissance and prospect evaluation surveys. However, for very small targets such as pinnacle reefs or channel sandstones, optimum results are obtained when numerous samples are collected in a closely spaced grid pattern, (100–160-m sample interval or less) over the feature of interest.<ref name=ch18r41>Schumacher, D., Hitzman, D., C., Tucker, J., Roundtree, B., 1997, Applying high-resolution surface geochemistry to assess reservoir compartmentalization and monitor hydrocarbon drainage, in Kruizenga, R., J., Downey, M., W., eds., Applications of Emerging Technologies: Unconventional Methods in Exploration for Oil and Gas V: Dallas, Texas, Southern Methodist Univ. Press, p. 309–322.</ref>

Defining background values adequately is an essential part of anomaly recognition and delineation; Matthews<ref name=ch18r26 /> suggests that as many as 80% of the samples collected be obtained outside the area of interest. This is a good recommendation for reconnaissance and prospect evaluation surveys. However, for very small targets such as pinnacle reefs or channel sandstones, optimum results are obtained when numerous samples are collected in a closely spaced grid pattern, (100–160-m sample interval or less) over the feature of interest.<ref name=ch18r41>Schumacher, D., Hitzman, D., C., Tucker, J., Roundtree, B., 1997, Applying high-resolution surface geochemistry to assess reservoir compartmentalization and monitor hydrocarbon drainage, in Kruizenga, R., J., Downey, M., W., eds., Applications of Emerging Technologies: Unconventional Methods in Exploration for Oil and Gas V: Dallas, Texas, Southern Methodist Univ. Press, p. 309–322.</ref>