초록 ▼

A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inela

A generalized computer-based system and method for acquisition of nuclear well logging data. A feature of the present invention is the ability to provide time distribution spectra over the entire interval between source firings, such spectra including the gamma radiation produced from both the inelastic scattering and capture of neutrons from said neutron source. The spectra so generated may be analyzed and processed to derive parameters indicative of formation and borehole conditions, for example, a parameter sensitive to borehole geometry and a parameter sensitive to porosity. Certain parameters may be compared as an indication of the presence of gas in a fluid filled formation. Still further, a quantitative measure of the repeatability of the macroscopic thermal neutron absorption capture cross-section may be derived and used to control the weight of the capture cross-section filter.

대표청구항 ▼

In a well logging method utilizing a counting measurement from a counting log, a method for quantitatively measuring the repeatability of a parameter, wherein said parameter is a function of the counts from said counting measurement, comprising the steps of: gathering counting data for each of a plu

In a well logging method utilizing a counting measurement from a counting log, a method for quantitatively measuring the repeatability of a parameter, wherein said parameter is a function of the counts from said counting measurement, comprising the steps of: gathering counting data for each of a plurality of vertical depth increments, said increments being less than the vertical depth resolution of said counting log; deriving from said counting data a value of said parameter for each of said plurality of increments; deriving from a first and second parameter value a value indicative of the statistical deviation between said first and second values, said first and second values being from consecutive increments; filtering a plurality of statistical values to generate said quantitative measure of the repeatability of said parameters; and filtering by use of a variable weighted filter a preselected number of said parameter values, said number being dependent upon said quantitative measure of the repeatability of said parameters, wherein said quantitative measure controls the weight of said filter and said number is preselected as a function of said weight of said filter.