ABSTRACT

A regional geochemical study of the carbonate Slave Point Formation from a wide area of the subsurface of western Canada was made in an attempt to relate chemical variation to facies change. Both core and drill cuttings from petroleum wells were used as samples. The resulting data showed that chemical variation was subtle enough that a knowledge of sampling and analytical errors was essential for the proper interpretation of the data.

This paper is an attempt to evaluate such errors by examining the effects of within-station variation, selective sampling during drilling, contamination, and analytical error. These various factors, which bias or add variance to the data, do not affect all elements equally. Least affected are the elements that are carried principally in solid solution within the dominant carbonate mineral of the rock. Therefore, for the Slave Point Formation, these elements are more reliable as indicators of facies change than are those elements that are held in the terrigenous fraction or within secondary minerals.