Abstract: Component weight and/or volume fractions of subterranean rock are determined. A formation model generates mineral and fluid concentration data from which elemental concentrations are calculated. Forward modeling produces a simulated energy spectrum, and simulation produces a simulated constraining log. Spectra is generated by detecting gamma radiation with a neutron logging tool, and a constraining log is generated. The spectrum and the simulated energy spectrum are compared with resultant error determined. The constraining log and simulated constraining log are compared with resultant error determined. The formation model generates further mineral and fluid concentration to calculate further elemental concentrations. Forward modeling produces further simulated energy spectrum signal and further constraining logs. The spectrum signals and further simulated spectrum signal are compared with resultant error determined.

Abstract: In acoustic well logging, for each inversion depths of a well at which logging of data occurs, acoustic log signals representative of waveforms received at acoustic receivers are processed in a frequency domain to derive field dispersion curve(s). A neural net is operated to generate formation shear slowness value(s) from the curve(s), and resulting signal(s) indicative of shear slowness values are saved, transmitted, plotted, printed or processed. An apparatus for carrying out the method includes a logging tool having at least one activatable acoustic wave source; spaced and acoustically isolated therefrom in the logging tool an array of acoustic detectors that on the detection of acoustic wave energy generate electrical or electronic log signal(s) characteristic of acoustic energy waves detected by the acoustic detector(s); and at least one processing device associated with or forming part of the logging tool for processing the log signal(s).

Abstract: Component weight and/or volume fractions of subterranean rock are determined. A formation model generates mineral and fluid concentration data from which elemental concentrations are calculated. Forward modeling produces a simulated energy spectrum, and simulation produces a simulated constraining log. Spectra is generated by detecting gamma radiation with a neutron logging tool, and a constraining log is generated. The spectrum and the simulated energy spectrum are compared with resultant error determined. The constraining log and simulated constraining log are compared with resultant error determined. The formation model generates further mineral and fluid concentration to calculate further elemental concentrations. Forward modeling produces further simulated energy spectrum signal and further constraining logs. The spectrum signals and further simulated spectrum signal are compared with resultant error determined.

Abstract: In acoustic well logging, for each inversion depths of a well at which logging of data occurs, acoustic log signals representative of waveforms received at acoustic receivers are processed in a frequency domain to derive field dispersion curve(s). A neural net is operated to generate formation shear slowness value(s) from the curve(s), and resulting signal(s) indicative of shear slowness values are saved, transmitted, plotted, printed or processed. An apparatus for carrying out the method includes a logging tool having at least one activatable acoustic wave source; spaced and acoustically isolated therefrom in the logging tool an array of acoustic detectors that on the detection of acoustic wave energy generate electrical or electronic log signal(s) characteristic of acoustic energy waves detected by the acoustic detector(s); and at least one processing device associated with or forming part of the logging tool for processing the log signal(s).

Abstract: Inverting nuclear log data for a geological formation surrounding a borehole involves acquiring nuclear log data for a borehole portion using a moveable nuclear logging tool and acquiring additional log data for the borehole portion using another logging device with superior resolution. Boundaries between adjacent zones are identified that exhibit an attribute of the geological formation to a detectably contrasting degree. From pre-acquired data describing one or more characteristics of the nuclear logging tool, a modeled log of the attributes is generated over the borehole portion, and a zone response is calculated from the pre-acquired data for each zone by using the boundaries to define an initial measure of the depth of each zone and ascribing a value of the attribute in dependence on the depth of each zone.

Abstract: Inverting nuclear log data for a geological formation surrounding a borehole involves acquiring nuclear log data for a borehole portion using a moveable nuclear logging tool and acquiring additional log data for the borehole portion using another logging device with superior resolution. Boundaries between adjacent zones are identified that exhibit an attribute of the geological formation to a detectably contrasting degree. From pre-acquired data describing one or more characteristics of the nuclear logging tool, a modelled log of the attributes is generated over the borehole portion, and a zone response is calculated from the pre-acquired data for each zone by using the boundaries to define an initial measure of the depth of each zone and ascribing a value of the attribute in dependence on the depth of each zone.