Abstract: A method for determining total clay content of an earth formation based on elemental concentration logs obtained from a logging tool. This method avoids the need for obtaining an aluminum concentration measurement. First, the concentrations of a plurality of elements in the formation are determined without measuring an aluminum concentration. Then, at least the silicon, calcium, and iron concentrations are combined in accordance with a function determined by regression analysis to produce an estimate of the total clay content.

Abstract: A method and apparatus for analyzing a sample to determine its mineral composition. The invention combines X-ray diffraction with Fourier transform infrared spectroscopy to provide a complete spectrum including molecular vibrations, probed by FTIR scans and lattice spacing measured by X-ray diffraction in a single representation. This FX spectrum provides a more complete and accurate mineralogy than either of the techniques alone. In addition, new techniques for independent X-ray diffraction analysis and FTIR analysis are described.

Abstract: Methods are disclosed which provide for determining in situ the characteristics of hydrocarbons including oil API gravity in a formation traversed by a borehole. The vanadium content in the formation is determined from a logging tool. The total vanadium content is then systematically separated into an oil vanadium content and a formation matrix or clay vanadium content. From the oil vanadium content and a determination of formation bulk density, porosity and oil saturation, the vanadium concentration of the oil is derived in parts per million, from which the API gravity is determined.

Abstract: Methods are disclosed which provide for quantifying and characterizing the mineral content of a formation as a function of depth. Elemental data derived from logging tools are input into an element-mineral transform operation, preferably a matrix which is constructed using multivariate statistical analysis on previously available data, to determine the quantity of at least one or more dominant minerals in the formation. From the mineral quantity information and the elemental log data, the formation minerals are further characterized. Information regarding the character and quantities of formation minerals is further used to obtain improved determinations of formation characteristics such as the cation exchange capacity and water saturation, and the grain density and formation porosity, as well as to obtain an increased understanding of the formation such as the depositional environment of the formation.

Abstract: Method for finding in situ the characteristics of oil are provided. The methods generally comprise logging the borehole to determine the total formation content of at least one element such as vanadium, sulfur or nickel associated with oil quality and determining how much of the total content is due to the occurrence of the element in the minerals of the earth formation and how much is due to the occurrence of the element in the oil. From the determination of how much of the element is in the oil, a characteristic of the oil at a depth in said borehole is found. In order to determine how much of the element is in the minerals of the earth formation, an equation relating the element to the minerals is required as well as a knowledge of which minerals are at the particular depth in the formation and in what quantities. The equation relating the minerals and element is obtained via a multiple regression analysis on elemental and mineralogical data.

Abstract: Methods for determining the permeability of an earth formation traversed by a borehole are provided and comprise: logging the borehole to determine indications of at least a plurality of elements in the formation; determining the mineralogical content of the formation from the elemental indications; determining the porosity of the formation; and determining the permeability of the formation as a function of the determined mineralogical content and porosity. The mineralogical content of the formation is preferably determined according to a transform which relates elemental concentrations of the formation to mineral weight percentages.

Abstract: Methods are disclosed which provide for quantifying and characterizing the mineral content of a formation as a function of depth. Elemental data derived from logging tools are input into an element-mineral transform operation, to determine the quantity of at least one or more dominant minerals in the formation including minerals distinguishable by degree of crystallinity. From the mineral quantity information and the elemental log data, the formation minerals are further characterized. Information regarding the character and quantities of formation minerals is further used to obtain improved determinations of formation characteristics such as the cation exchange capacity and water saturation, and the grain density and formation porosity, as well as to obtain an increased understanding of the formation such as the depositional environment of the formation.

Abstract: Methods are disclosed which provide for quantifying and characterizing the mineral content of a formation as a function of depth. Elemental data derived from logging tools are input into an element-mineral transform operation, preferably a matrix which is constructed using multivariate statistical analysis on previously available data, to determine the quantity of at least one or more dominant minerals in the formation. From the mineral quantity information and the elemental log data, the formation minerals are further characterized. Information regarding the character and quantities of formation minerals is further used to obtain improved determinations of formation characteristics such as the cation exchange capacity and water saturation, and the grain density and formation porosity, as well as to obtain an increased understanding of the formation such as the depositional environment of the formation.