Sample Types and Typical Analyses

A geochemist may work with actual rock/oil/gas samples, or may be looking at data previously generated by others (e.g., vendor/regional studies). A geochemist may also work with an internal lab, or an external vendor.

Samples
Samples may arrive for analysis. Site (e.g. well name, lat/long, etc.) and sample (e.g. depth, lithology info, etc.) information are typically logged into a lab management system or database. All of the site and sample descriptive information in GWIS are handled in the Info_Site and Info_Sample tables.

Rocks
Rock samples are most typically well cuttings (rock chips from drilling a well, composited over, say, 20 ft. intervals, e.g.), cores (chunks of rock taken from a coring tool in the well bore), sidewall cores (samples taken from the sidewall of a well bore), outcrops (chunk of rock hacked off with a hammer from a hillside), or seafloor samples (sediment collected from the sea bottom, e.g. piston, drop, or gravity cores).

A geochemist will typically request several types of analyses on rock samples. For analytical purposes, a rock may be divided into several parts. The whole rock consists of an inorganic component (i.e., rock/mineral matter) and an organic component, including insoluble (kerogen), and soluble (bitumen) organic matter.

The fractions into which a rock sample are typically divided, and the analysis types requested on each fraction are shown (see Fig. 1).

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