Abstract: A method for estimating a distribution of pore sizes of a fluid filled rock formation penetrated by a borehole, the method includes: processing nuclear magnetic resonance (NMR) data to determine a distribution of diffusion coefficients and a distribution of relaxation time constants for at least one depth in the borehole; plotting the distribution of diffusion coefficients and the distribution of relaxation time constants as a cross-plot for the at least one depth; identifying a water line on the cross-plot, each point on the water line having substantially the same value for the diffusion coefficient; and estimating the distribution of pore sizes from the distribution of relaxation time constants plotted along the water line.

Abstract: A method for estimating a distribution of pore sizes of a fluid filled rock formation penetrated by a borehole, the method includes: processing nuclear magnetic resonance (NMR) data to determine a distribution of diffusion coefficients and a distribution of relaxation time constants for at least one depth in the borehole; plotting the distribution of diffusion coefficients and the distribution of relaxation time constants as a cross-plot for the at least one depth; identifying a water line on the cross-plot, each point on the water line having substantially the same value for the diffusion coefficient; and estimating the distribution of pore sizes from the distribution of relaxation time constants plotted along the water line.

Abstract: A method for estimating a distribution of pore sizes of a fluid filled rock formation penetrated by a borehole, the method including: processing nuclear magnetic resonance (NMR) data to determine a distribution of diffusion coefficients and a distribution of relaxation time constants for at least one depth in the borehole; plotting the distribution of diffusion coefficients and the distribution of relaxation time constants as a cross-plot for the at least one depth; identifying a water line on the cross-plot, each point on the water line having substantially the same value for the diffusion coefficient; and estimating the distribution of pore sizes from the distribution of relaxation time constants plotted along the water line.

Abstract: A method for estimating a distribution of pore sizes of a fluid filled rock formation penetrated by a borehole, the method including: processing nuclear magnetic resonance (NMR) data to determine a distribution of diffusion coefficients and a distribution of relaxation time constants for at least one depth in the borehole; plotting the distribution of diffusion coefficients and the distribution of relaxation time constants as a cross-plot for the at least one depth; identifying a water line on the cross-plot, each point on the water line having substantially the same value for the diffusion coefficient; and estimating the distribution of pore sizes from the distribution of relaxation time constants plotted along the water line.

Abstract: A method and apparatus for measuring the caliber of a borehole while drilling utilizes a borehole compensated downhole measuring system in both a compensated and a non-compensated manner. A transmitter of the measuring system generates a signal which is received by at least one spaced receiver with the time/phase relationship of the transmission and reception of the signal at each receiver being indicative of the borehole caliber.

Abstract: A gamma ray density sub and method useful for measurement-while-drilling applications utilizing a gamma ray source and detector located on the rotating sub and computation of the product of the counting rates obtained from at least three locations in the formation sample, the locations being located in a azimuthally symmetric pattern about the sub therefore indicating the average density location in the formation sample surrounding a borehole traversing an earth formation. The sub is able to measure the density of the sample, independent of the location of the sub within the borehole and the chemical composition of the interfering materials lying between the formation sample and the detectors.

Abstract: A gamma ray density sub and method useful for measurement-while-drilling applications utilizing three pairs of gamma ray sources and detectors located symmetrically about the axis of the sub and computation of the product of the counting rates obtained from the three detectors to indicate the average density of a formation sample surrounding a borehole traversing an earth formation. The sub is able to measure the density of the sample, independent of the location of the sub within the borehole and the chemical composition of the interfering materials lying between the formation sample and the detectors.

Abstract: A system for detecting changes in drilling fluid density downhole during a drilling operation includes a radiation source and detector which are arranged in the outer wall of a drill string sub to measure the density of drilling fluids passing between the source and detector. Radiation counts detected downhole are transmitted to the surface by telemetry methods or recorded downhole, where such counts are analyzed to determine the occurrence of fluid influx into the drilling fluid from earth formations. Changes in the density of the mud downhole may indicate the influx of formation fluids into the borehole. Such changes in influx are determinative of formation parameters including surpressures which may lead to the encountering of gas kicks in the borehole. Gas kicks may potentially result in blowouts, which of course are to be avoided if possible. Hydrocarbon shows may also be indicative of producible formation fluids.