Texaco Inc.

Halliburton Company

Halliburton Logging Services, Inc.

Michael P Smith

Harry D Smith, Jr

Ward E Schultz

Dan M Arnold

Hans J Paap

Dennis F Wyatt, Jr

The method employs standard processing techniques in order to derive and maintain raw data as well as background corrected and shop calibrated data. Specific data from standard processing is used for the Enhanced Vertical Resolution (EVR) processing. The method uses corrected and calibrated data from standard processing. This data is filtered using improved standard processing material matching filters. Density correction factors .DELTA..rho..sub.LONG (or equivalently .DELTA..rho..sub.SHORT) is calculated for the long and short detectors and used in further processing. .DELTA..rho..sub.LONG and .DELTA..rho..sub.SHORT are used to calculate the standard calibrated compensated density .rho.. Enhanced processing begins with the iterative deconvolution and filtering (or smoothing) of .DELTA..rho..sub.SHORT. The background corrected and shop calibrated short density data, calculated during standard processing, is materially matched using an improved EVR filter. Finally, an enhanced calibrated borehole compensated density .rho..sub.B is calculated. The use of the same processing methods and a strict enforcement of material matching, both for the standard and enhanced processing, insures that neither short nor long detector count rates are overemphasized and that shop calibrations and borehole compensation are accurately maintained.

Enhanced vertical resolution processing of dual-spaced density tools

A method of deconvolving the far-spaced detector response of a dual-spaced neutron logging tool, coupled with dynamic matching of the near-spaced detector response, improves the vertical resolution of the tool's formation porosity measurements. Near/far ratio processing and the standard shop calibration procedure are retained to continue to provide accurate, borehole compensated formation porosity measurements.

Enhanced vertical resolution processing of dual-spaced neutron and

A textile machine is lubricated with oil characterized as non-staining to nylon textile. The lubricating oil comprises a paraffinic base lubricating oil and 1 to 3 wt % of a surfactant of the formula:

Method of lubricating a textile machine

Improved vertical resolution from pulse neutron logs is obtained by the disclosed process; a pulse of fast neutrons is emitted from a source and counts are taken at near and far dectors. This is done repetitively so that the interval between neutron bursts is conveniently divided into a number of gates, the preferred form being six contiguous gates. The count rate especially in gates 3-6 is obtained and is processed in a modified form to thereby enhance vertical resolution. While before vertical resolution was dependent in part in spacing of the detectors and source, improved vertical resolution is obtained to thereby locate thin beds which would otherwise be obscured.

Technique for obtaining high vertical resolution formation capture cross

By taking the ratio of silicon to calcium pulsed neutron capture gamma radiations together with a formation capture cross section measurement, in formations (20) having low hydrogen index, a measurement indicator is provided for differentiating low porosity limestones from high porosity gas sands.

Method and apparatus for differentiating low porosity limestones from

A simultaneous pulsed neutron porosity and thermal neutron capture cross section logging system is provided in the present invention. A logging tool provided with a 14 MeV pulsed neutron source, an epithermal neutron detector, and a combination gamma ray and fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron and epithermal neutron populations are sampled. During the interval between bursts the thermal neutron capture gamma ray population is sampled in two or more time intervals. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity .phi.. The capture gamma ray measurements are combined to provide a simultaneous determination of the thermal neutron capture cross section .SIGMA..

Simultaneous thermal neutron decay time and porosity logging system

An improved measurement of earth formation porosity is provided by the present invention using measurements of the energy spectrum of fast neutrons. A continuous source of fast neutrons is used to irradiate earth formations penetrated by a well borehole. Two neutron detectors, a fast neutron detector sensitive in the high energy range of the fast neutron energy spectrum, and an epithermal neutron detector, sensitive in the lower energy range of fast neutrons, are spaced at the same effective distance from the neutron source. Measurements of the neutron population at each detector are combined according to predetermined relationships to derive a measurement of earth formation porosity.

Earth formation porosity log using measurement of fast neutron energy

An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MEV pulsed neutron source, an epithermal neutron detector and an inelastic scattering gamma ray detector is moved through a borehole. The detection of inelastic gamma rays provides a measure of the fast neutron population in the vicinity of the detector. Repetitive bursts of neutrons irradiate the earth formation and, during the bursts, inelastic gamma rays representative of the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity.

Earth formation pulsed neutron porosity logging system utilizing

An improved pulsed neutron porosity logging system is provided in the present invention. A logging tool provided with a 14 MEV pulsed neutron source, an epithermal neutron detector, and a fast neutron detector is moved through a borehole. Repetitive bursts of neutrons irradiate the earth formations and, during the bursts, the fast neutron population is sampled. During the interval between bursts the epithermal neutron population is sampled along with background gamma radiation due to lingering thermal neutrons. The fast and epithermal neutron population measurements are combined to provide a measurement of formation porosity.

Pulsed neutron porosity logging system

A fast neutron source is used to irradiate earth formations in the vicinity of a well borehole. Dual spaced epithermal neutron detectors are used to sample the epithermal neutron population at two different spaced distances from the source. A compensated formation porosity is obtained from the ratio of counting rates at the dual spaced detectors. An uncompensated porosity value is obtained from the count rate at the short spaced detector. Borehole washout or cement void regions are located by comparing the compensated and uncompensated values of formation porosity obtained in this manner.

Method for detecting cement voids or borehole washouts

Methods are disclosed for measuring simultaneously the thermal neutron lifetime of the borehole fluid and earth formations in the vicinity of a well borehole, together with the formation porosity. A harmonically intensity modulated source of fast neutrons is used to irradiate the earth formations with fast neutrons at three different intensity modulation frequencies. Intensity modulated clouds of thermal neutrons at each of the three modulation frequencies are detected by dual spaced detectors and the relative phase shift of the thermal neutrons with respect to the fast neutrons is determined at each of the three modulation frequencies at each detector. These measurements are then combined to determine simultaneously the thermal neutron decay time of the borehole fluid, the thermal neutron decay time of surrounding earth formation media and the porosity of the formation media.

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Bellaire, TX, United States of America

Michael P Smith