Abstract: The volume of clay within clay-bearing formations is determined throughout the formations. This volume of clay is then functionally related to measurements indicative of the formations. Utilizing measured formation characteristics representative of different clay types, such as potassium content or bound water content, the formation porosity measurements are extrapolated to indicate the porosity log measurements which would be yielded if the logging devices were responsive only to the clay within the formations. In addition the cation exchange capacity and the hydrogen index are used to determine volume, types and distribution of clays. These extrapolated measurements are then related to known or determinable formation characteristics to determine additional formation properties such as porosity, permeability, and fluid saturation characteristics.

Abstract: The volume of clay within clay-bearing formations is determined throughout the formations. This volume of clay is then functionally related to measurements indicative of the formations. Utilizing measured formation characteristics representative of different clay types, such as potassium content or bound water content, the formation porosity measurements are extrapolated to indicate the porosity log measurements which would be yielded if the logging devices were responsive only to the clay within the formations. In addition the cation exchange capacity and the hydrogen index are used to determine volume, types and distribution of clays. These extrapolated measurements are then related to known or determinable formation characteristics to determine additional formation properties such as porosity, permeability, and fluid saturation characteristics.

Abstract: A method for determining the water or residual oil saturation of subsurface earth formations substantially independent of lithology utilizing electromagnetic energy propagation measurements. The subsurface formations are first logged to obtain base log measurements of the dielectric permitivity of the formations as derived from electromagnetic energy propagation time values. The formations are then injected with a sufficient amount of oil miscible solution containing a surface active agent to displace substantially all the residual fluids from the formations for a radial distance at least equal to the radial zone of investigation. The formations are then injected with a sufficient amount of water to render the zone of investigation substantially 100 percent water saturated. The formations are logged a second time to obtain measurements of the dielectric permittivity of the saturated formations.

Abstract: Methods for estimating shear wave travel time in formations of mixed lithology employing the compressional wave travel time in conjunction with other logging derived information. A shear/compressional wave travel time ratio is established for a sand formation as a function of the porosity of the formation. A shear/compressional wave travel time ratio is established for a shale formation as a function of bulk shale density as derived from the bulk density of the formation. A shale factor is used to compensate the two ratios to the mixed lithology of the measured formation providing a shear/compressional wave travel time ratio for the measured formation. Shear wave travel time is determined using the formation travel time ratio and a compressional wave travel time measurement.

Abstract: The volume of clay within clay-bearing formations is determined throughout the formations. This volume of clay is then functionally related to measurements indicative of the formations. Utilizing measured formation characteristics representative of different clay types, such as potassium content or bound water content, the formation porosity measurements are extrapolated to indicate the porosity log measurements which would be yielded if the logging devices were responsive only to the clay within the formations. In addition the cation exchange capacity and the percent of expandable clay layers for the shale zones are determined. These extrapolated measurements are then related to known or determinable formation characteristics to determine additional formation properties such as porosity, permeability, and fluid saturation characteristics.

Abstract: A method for determining the water saturation of subsurface earth formations substantially independent of lithology utilizing electromagnetic energy propagation measurements. The subsurface formations are first logged to obtain base log measurements of the dielectric permittivity of the formations as derived from electromagnetic energy propagation time values. The formations are then injected with a sufficient amount of oil miscible solution containing a surface active agent to displace substantially all the residual fluids from the formations for a radial distance at least equal to the radial zone of investigation. The formations are then injected with a sufficient amount of water to render the zone of investigation substantially 100 percent water saturated. The formations are logged a second time to obtain measurements of the dielectric permittivity of the saturated formations.

Abstract: The volume of clay within clay-bearing formations is determined throughout the formations. This volume of clay is then functionally related to measurements indicative of formation porosity, such as density and neutron well logs of the formations. Utilizing measured formation characteristics representative of different clay types, such as potassium content or bound water content, the formation porosity measurements are extrapolated to indicate the porosity log measurements which would be yielded if the logging devices were responsive only to the clay within the formations. These extrapolated measurements are then related to known or determinable formation characteristics to determine additional formation properties such as porosity, permeability, and fluid saturation characteristics.

Abstract: An activation well logging method and apparatus for identifying and measuring the presence of vanadium in earth formations surrounding a borehole. A well logging instrument including a source of neutrons is used to irradiate formations for a period of time sufficient to activate vanadium. The gamma radiation emanating from the irradiated formations are detected by a scintillation detector having output pulses directly proportional to the energies of the incident gamma rays. The output pulses having energies characteristic of the element vanadium are separated and counted to provide indication of any vanadium present in the irradiated formations.

Abstract: A method for determining the water saturation of subsurface earth formations substantially independent of lithology utilizing electromagnetic energy propagation measurements. The subsurface formations are first logged to obtain base log measurements of the dielectric permittivity of the formations as derived from electromagnetic energy propagation time values. The formations are then injected with a sufficient amount of oil miscible solution containing a surface active agent to displace substantially all the residual fluids from the formations for a radial distance at least equal to the radial zone of investigation. The formations are then injected with a sufficient amount of water to render the zone of investigation substantially 100 percent water saturated. The formations are logged a second time to obtain measurements of the dielectric permittivity of the saturated formations.

Abstract: The volume of clay within earth formations is determined throughout the vertical extent of a borehole using measurements of the natural gamma rays emitted from these formations comprised substantially entirely of clay. The clay volume determination is used for evaluating the volume of potassium oxide present in the formations. The percent of expandable layers present within the formations is determined, as a direct indicator of potential clay swelling difficulties and thus sensitivity to formation damage sensitivity, based on an extropolated and normalized potassium oxide volume. The percent expandable layers determination is used for determining the cation exchange capacity of the formations.

Abstract: A multiple stage formation fracturing operation is conducted with separate radioactive tracer elements injected into the well during each stage of the fracturing operation. After completion of the fracturing operation the well is logged using natural gamma ray logging. The resulting signals are sorted into individual channels or energy bands characteristic of each separate radioactive tracer element. The results of the multiple stage fracturing operation are evaluated based on dispersement of the individual tracer elements.

Abstract: A method is disclosed for monitoring the flood front movement during enhanced recovery operations wherein flooding fluids are pumped into a number of injection wells forcing residual oil movement toward a production well. A plurality of monitoring wells located between the injection wells and the producing well are logged to establish base logs functionally related to oil saturation and water salinity. Periodically during the water flood operation, the monitoring wells are relogged to detect changes in oil saturation and water salinity. By comparison of the base logs with the series of later derived logs it is possible to accurately monitor the flood front movement including detecting high-permeability zones and monitoring of the flood front profile.

Abstract: A clay content curve, for the borehole under investigation is developed through logging procedures such as a gamma ray log or a spectral gamma ray log. Additionally, compaction trend curves based upon historic logging data are obtained for the geologic area of interest. Information provided by the total porosity trend curve is corrected using a function of the shaliness indicator curve. This correction allows the deviation of an effective porosity log for the reservoir which can be recorded or can be used to edit porosity logs.

Abstract: A method is disclosed for the in situ examination of each subsurface formation penetrated by a borehole to ascertain the cation exchange capacity of such formations within a geological region. Natural gamma ray logging is used to develop signals functionally related to the total gamma radiation and to the potassium -40, uranium and thorium energy-band radiations. A first borehole is traversed by a potential gamma ray spectrometer to provide selected measurements of natural gamma radiation. Core samples are taken from the logged formation and laboratory tests performed to determine the cation exchange capacity thereof. The cation exchange capacities thus are developed then correlated with selected parameters provided by the gamma ray spectrometer to establish functional relationships. Cation exchange capacities of formations in subsequent boreholes within the region are then determined in situ by use of the natural gamma ray spectrometer and these established relationships.

Abstract: A method is disclosed for the in situ examination of earth formations penetrated by a borehole to ascertain the optimum location along the length thereof for instituting well stimulation operations or, where the well is cased, the optimum location for perforating the casing. The method utilizes natural gamma ray logging to determine the optimum locations with the natural gamma ray radiation of the earth formation surrounding the borehole measured and the total measurement then separated into potassium-40, uranium, and thorium energy-band signals. A differential value is derived by subtracting the energy-band signal for either potassium or thorium from the energy-band signal for uranium, with the differential thereafter compared to a energy-level standard having a preselected magnitude. The optimum locations for perforating and/or instituting well stimulation operations will be those zones in which the differential exceeds the preselected energy level standard.

Abstract: Well is first logged with gamma ray detection system to provide a base log. Fluid containing salt of potassium, uranium or thorium is then injected into the well opposite the interval of interest. When the well head pressure is increased, some of the injected fluid will move into the fracture or other highly permeable localized zones. The gamma ray detection system is then run again one or more times through the well to provide a log which is compared with the base log. The fracture is detected by localized drastically higher readings observed on the repeat run of the gamma ray detection logging system.

Abstract: Well is first logged with gamma ray detection system to provide a base log. Fluid containing salt of potassium, uranium or thorium is then injected into the well opposite the interval of interest. When the well head pressure is increased, some of the injected fluid will move into the channel which is allowing fluid to move between different zones in the formations around the well. The gamma ray detection system is then again run through the well to provide a log which is compared with the base log. The channel between zones is detected by localized drastically higher readings observed on the repeat run of the gamma ray detection logging system.

Abstract: A method is provided for determining the shale content of mined coal by monitoring the thorium content of the coal. Thorium content and ash content are shown to be related whereby a direct reading of the thorium will be indicative of the shale content of the coal and the ash content of the coal. The method utilizes the natural radiation of thorium to provide the continuous or selective control of mined coals.

Abstract: A method for determining the distance from a given point in a coal seam to shale by sensing the thorium radiation from shale layers positioned about the coal seam. The invention is useful for maintaining a drill in a desired position in a coal seam and guiding the drill in response to the sensed radiation.

Abstract: A method is disclosed for the in situ examination of earth formations penetrated by a borehole to ascertain the optimum location along the length thereof for instituting well stimulation operations or, where the well is cased, the optimum location for perforating the casing. The method utilizes natural gamma ray logging to determine the optimum locations with the natural gamma ray radiation of the earth formation surrounding the borehole measured and the total measurement then separated into potassium-40, uranium, and thorium energy-band signals. A differential value is derived by subtracting the energy-band signal for either potassium or thorium from the energy-band signal for uranium, with the differential thereafter compared to a energy-level standard having a preselected magnitude. The optimum locations for perforating and/or instituting well stimulation operations will be those zones in which the differential exceeds the preselected energy level standard.