Quantitative clay typing and lithological evaluation of subsurface formations

A method for investigating, through logging, an earth formation traversed by a borehole comprising:

• (a) determining, by logging the said borehole, the concentrations of at least two index elements in said formation;
• (b) determining the quantity of at least two dominant minerals of said formation by operating with an element-mineral transform on said at least two elemental concentrations wherein said dominant minerals are identified by a multivariate statistical analysis on elemental and mineralogical data;
• and
• (c) generating a tangible record of said values of said dominant attributes.

A method for investigating, through logging, an earth formation transversed by a borehole comprising:

• (a) determining, by logging the said borehole, the concentrations of at least one index element for at least one depth of said borehole in said formation;
• (b) determining, for at least one depth of said borehole, the quantity of at least one dominant mineral in said formation by operating with an element-mineral transform operation on said index elemental concentrations, wherein said dominant minerals are identified by a multivariate statistical analysis on elemental and mineralogical data;
• and
• (c) from said determined elemental concentrations and mineral quantities, characterizing at least one of said quantified minerals at at least one borehole depth.

A method for investigating, through logging, an earth formation traversed by a borehole comprising:

• (a) identifying the elements and minerals likely to be found in said formation,
• (b) associating said identified elements and minerals with factors;
• (c) identifying said factors as at least dominant mineral components;
• (d) constructing an element-mineral transform matrix between at least said identified dominant mineral factors and index elements;
• (e) determining, by logging said borehole, the elemental concentrations of said index elements at least one depth of said borehole in said formation;
• and
• (f) quantifying at least said dominant minerals for at least one depth of said borehole by inputting said index elemental concentrations into said element-mineral transform matrix.