Nuclear well logging with neutron source and separate spaced radiation detectors to determine silicon/oxygen ratio
AssigneeTexaco Inc.
InventorsHarry D. Smith, Jr., Ward E. Schultz
Life of this patent
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Abstract
Earth formations surrounding a well borehole are bombarded with high energy neutrons which react with chemical elements in the formation components, giving rise to gamma radiation. The gamma radiation is detected by two separate, spaced detectors from which well logs are obtained indicating a ratio of the relative presence of silicon to oxygen in the formations.
Claims20
A well logging apparatus for simultaneously obtaining a measuring of the relative presence of the elements silicon and oxygen in earth formations in the vicinity of a fluid-filled well borehole, comprising:
- (a) sonde means for moving through the well borehole past formations of interest;
- (b) source means mounted in said sonde means for bombarding the formation with high energy neutrons;
- (c) first detector means mounted in said sonde spaced a first distance from said source means for detecting gamma radiation from neutron activation of oxygen;
- (d) second detector means mounted in said sonde spaced a second distance from said source means for detecting gamma radiation from neutron activation of silicon;
- (e) said second distance being such that when said second detector is moved to a formation of interest substantially all oxygen activation gamma radiation has dissipated;
- and
- (f) sonde circuit means for forming electrical signals representing gamma radiation detected by said first and second detectors.
A well logging apparatus for simultaneously obtaining a measure of the relative presence of the elements silicon and oxygen in earth formations in the vicinity of a fluid-filled well borehole, comprising:
- (a) sonde means for moving through the well borehole past formations of interest;
- (b) source means mounted in said sonde means for bombarding the formation with high energy neutrons;
- (c) first detector means mounted in said sonde spaced a first distance from said source means for detecting gamma radiation produced by oxygen activation;
- (d) second detector means mounted in said sonde spaced a first distance from said source means for detecting gamma radiation produced by silicon activation;
- (e) said second distance exceeding said first distance by a factor of two or more;
- and
- (f) sonde circuit means for forming electrical signals representing gamma radiation detected by said first and second detectors.
Dependencies are inferred from the claim text.