Method and apparatus for calibrating readings of a downhole tool
AssigneeSchlumberger Technology Corporation
InventorRonald E. Plasek
Life of this patent
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Abstract
A method and apparatus for calibrating readings of a downhole tool are provided. The method including collecting data representative of gamma ray photon energies detected by a downhole tool during the well-logging, a spectrum of the gamma ray photon energies detected by the downhole tool having a derivative with respect to the gamma ray photon energies. The method and program comprise calibrating the readings of the downhole tool using at least one predetermined correction factor based on the derivative of the spectrum of the gamma ray photon energies detected by the downhole tool. A computer-readable program storage device and a computer programmed to perform a set of instructions are also provided.
Claims21
A method of calibrating readings of a downhole tool, the method comprising:
- collecting data representative of gamma ray photon energies detected by the downhole tool during well-logging, a spectrum of the gamma ray photon energies detected by the downhole tool having a derivative with respect to the gamma ray photon energies;
- and
- calibrating the readings of the downhole tool using at least one predetermined correction factor based on the derivative of the spectrum of the gamma ray photon energies detected by the downhole tool.
A method of calibrating readings of a downhole tool, the method comprising:
- generating fast neutrons using the downhole tool during well-logging, the downhole tool having first and second gamma ray photon detectors;
- collecting data representative of inelastic gamma ray photon energies detected by the first and second gamma ray photon detectors of the downhole tool during the well-logging, a spectrum of the inelastic gamma ray photon energies detected by the first and second gamma ray photon detectors of the downhole tool having a derivative with respect to the gamma ray photon energies;
- and
- calibrating the readings using at least one predetermined first correction factor for the first gamma ray photon detector and at least one predetermined second correction factor for the second gamma ray photon detector based on the derivative of the spectrum of the gamma ray photon energies detected by the downhole tool.
A computer-readable, program storage device, encoded with instructions that, when executed by a computer, perform a method comprising:
- collecting data representative of gamma ray photon energies detected by a downhole tool during well-logging, a spectrum of the gamma ray photon energies detected by the downhole tool having a derivative with respect to the gamma ray photon energies;
- and
- calibrating readings of the downhole tool using at least one predetermined correction factor based on the derivative of the spectrum of the gamma ray photon energies detected by the downhole tool.
A computer programmed to perform a method comprising:
- collecting data representative of gamma ray photon energies detected by a downhole tool during well-logging, a spectrum of the gamma ray photon energies detected by the downhole tool having a derivative with respect to the gamma ray photon energies;
- and
- calibrating readings of the downhole tool using at least one predetermined correction factor based on the derivative of the spectrum of the gamma ray photon energies detected by the downhole tool.
Dependencies are inferred from the claim text.