Abstract: Systems and method presented herein enable the estimation of porosity using neutron-induced gamma ray spectroscopy. For example, the systems and methods presented herein include receiving, via a control and data acquisition system, data relating to energy spectra of gamma rays captured by one or more gamma ray detectors of a neutron-induced gamma ray spectroscopy logging tool. The method also includes deriving, via the control and data acquisition system, one or more spectral yields relating to one or more elemental components from the data relating to the energy spectra of the gamma rays. The method further includes estimating, via the control and data acquisition system, a measurement of porosity based on the one or more spectral yields relating to the one or more elemental components.

Abstract: Embodiments of the present disclosure are directed towards a method for improving neutron interpretations in a subsurface formation. Embodiments may include estimating mineral concentrations and kerogen concentrations at one or more depths in the subsurface formation and determining kerogen properties at one or more depths in the subsurface formation. Embodiments may further include calculating mineral properties at one or more depths in the subsurface formation and calculating a neutron-based log response to a rock matrix based upon, at least in part, the kerogen properties and the mineral properties at one or more depths in the subsurface formation by subtracting.

Abstract: Embodiments of the present disclosure are directed towards a method for improving neutron interpretations in a subsurface formation. Embodiments may include estimating mineral concentrations and kerogen concentrations at one or more depths in the subsurface formation and determining kerogen properties at one or more depths in the subsurface formation. Embodiments may further include calculating mineral properties at one or more depths in the subsurface formation and calculating a neutron-based log response to a rock matrix based upon, at least in part, the kerogen properties and the mineral properties at one or more depths in the subsurface formation by subtracting.

Abstract: An earth formation traversed by a borehole is investigated. A borehole tool having a neutron source and a photon detector is located in the borehole and used to obtain photon scatter information in or about the borehole. A chemical element located in a region in or about the borehole is quantified by using the photon scatter information and at least two different spectral standards for that element.

Abstract: The systems and methods provided herein relate to extracting maturity-based properties from input log data obtained by a downhole well logging tool. A maturity inversion is performed using the input log data, a log response model, and at least one maturity model to extract maturity-based properties from the input log data. The maturity-based properties are provided in an output log, such that subsequent down hole operation of the formation may account for the maturity-based properties.

Abstract: A method can include receiving data for a geologic environment where the data include data acquired via different types of borehole tool sensors; based at least in part on the data, determining rock composition of the geologic environment where the rock composition includes depositional components and diagenetic components; and, based at least in part on the rock composition, outputting a stratigraphic model of at least a portion of the geologic environment.

Abstract: A method can include receiving data for a geologic environment where the data include data acquired via different types of borehole tool sensors; based at least in part on the data, determining rock composition of the geologic environment where the rock composition includes depositional components and diagenetic components; and, based at least in part on the rock composition, outputting a stratigraphic model of at least a portion of the geologic environment.

Abstract: A logging method and a logging tool for approximating a logging tool response in a layered formation are provided. The method includes obtaining a first layered profile of at least one first measurement log provided by a logging tool using a squaring process, obtaining a filtered measurement log from the first layered profile using a forward physical model for the logging tool, and estimating an approximation of the forward physical model using a parameterized function so as to provide a first logging tool response.

Abstract: The systems and methods provided herein relate to extracting maturity-based properties from input log data obtained by a downhole well logging tool. A maturity inversion is performed using the input log data, a log response model, and at least one maturity model to extract maturity-based properties from the input log data. The maturity-based properties are provided in an output log, such that subsequent down hole operation of the formation may account for the maturity-based properties.

Abstract: The invention relates to techniques, such as a system for generating a density of a cased wellbore. The system includes at least one downhole tool deployable into the cased wellbore, a radiation source supportable by the downhole tool for passing radiation through the subterranean formation, at least one detector supportable by the downhole tool for measuring the radiation, and a measurement tool for generating at least one apparent density log from the measured radiation. The measurement tool has at least one quality indicator tool for generating at least one quality indicator and for generating at least one compensated density log based on the apparent density log and the quality indicator whereby error is removed therefrom.

Abstract: The disclosure provides methods and systems for improving the interpretation of formation evaluation measurements. The methods involve using a downhole tool to measure a property of a formation at multiple depths of investigation and calculating a spatial integrated J function, a spatial integrated K function, or both from the measurements. The J function and K function are used in different applications to improve interpretation. The system includes a tool for measuring a formation property and a processor for calculating a spatial integrated J function, a spatial integrated K function from the measurements taken at different depths of investigation. The processor may also perform interpretations such as classifications, probability distributions and initialization steps for radial inversion using the J and K functions.

Abstract: A logging method and a logging tool for approximating a logging tool response in a layered formation are provided. The method includes obtaining a first layered profile of at least one first measurement log provided by a logging tool using a squaring process, obtaining a filtered measurement log from the first layered profile using a forward physical model for the logging tool, and estimating an approximation of the forward physical model using a parameterized function so as to provide a first logging tool response.

Abstract: A probe for measuring electromagnetic properties of a subsurface formation includes a pad having a face adapted for engagement with a borehole wall, a pair of transmitting antennas, and two pairs of receiving antennas. The transmitting antennas and receiving antennas are mounted in the face of the pad, and each of the two pairs of receiving antennas include a first and second antenna distributed on opposite sides of the pair of transmitting antennas. The probe further includes an electronic arrangement having a transmitter module and a receiver module. The transmitter module is arranged to operate the pair of transmitting antennas in either a broadside mode or an endfire mode by applying an excitation signal modulated by two or more frequencies, and the receiver module is arranged to determine an attenuation and a phase shift of each reception signal provided by each receiving antenna relatively to the excitation signal.

Abstract: An apparatus for determining a property of a downhole formation, the apparatus comprising: an array having a plurality of transmitters and receivers capable of propagating electromagnetic waves through the formation; measuring circuitry for measuring an effect of the formation on the propagating waves; control circuitry arranged to vary the propagating waves as a function of at least one of frequency, spacing and polarization; and processing circuitry arranged to combine the effects of the propagating waves that are varied according to frequency, spacing and polarization for determining the property of the downhole formation.

Abstract: A probe for measuring electromagnetic properties of a subsurface formation includes a pad having a face adapted for engagement with a borehole wall, a pair of transmitting antennas, and two pairs of receiving antennas. The transmitting antennas and receiving antennas are mounted in the face of the pad, and each of the two pairs of receiving antennas include a first and second antenna distributed on opposite sides of the pair of transmitting antennas. The probe further includes an electronic arrangement having a transmitter module and a receiver module. The transmitter module is arranged to operate the pair of transmitting antennas in either a broadside mode or an endfire mode by applying an excitation signal modulated by two or more frequencies, and the receiver module is arranged to determine an attenuation and a phase shift of each reception signal provided by each receiving antenna relatively to the excitation signal.

Abstract: The invention relates to techniques, such as a system for generating a density of a cased wellbore. The system includes at least one downhole tool deployable into the cased wellbore, a radiation source supportable by the downhole tool for passing radiation through the subterranean formation, at least one detector supportable by the downhole tool for measuring the radiation, and a measurement tool for generating at least one apparent density log from the measured radiation. The measurement tool has at least one quality indicator tool for generating at least one quality indicator and for generating at least one compensated density log based on the apparent density log and the quality indicator whereby error is removed therefrom.

Abstract: An apparatus for determining a property of a downhole formation, the apparatus comprising: an array having a plurality of transmitters and receivers capable of propagating electromagnetic waves through the formation; measuring circuitry for measuring an effect of the formation on the propagating waves; control circuitry arranged to vary the propagating waves as a function of at least one of frequency, spacing and polarization; and processing circuitry arranged to combine the effects of the propagating waves that are varied according to frequency, spacing and polarization for determining the property of the downhole formation.

Abstract: An electromagnetic probe 1 measures the electromagnetic properties of a sub surface formation GF in a limited zone surrounding a well-bore hole WBH. The well-bore hole is filled with a well-bore fluid DM. The probe comprises a pad 2 having a first face defining a first area arranged to be positioned in contact with a well-bore wall WBW. The probe 1 further comprises: at least two transmitting antennas 4A, 4B defining a central point CP between them, each antenna being spaced from a distance do from the central point, and at least a first 5A, 5B and a second set 5C, 5D of receiving antennas, each set comprising a first receiving antenna 5A; 5C and a second receiving antenna 5B; 5D, the first receiving antenna being positioned on one side of the transmitting antennas and the second receiving antenna being positioned on other side of the transmitting antennas so that each set encompass the transmitting antennas 4A, 4B.