Method and system for quality control in gamma-gamma data during mineral exploration

Patent metadata

Field	Value
Publication number	US-10401530-B2
Application number	US-201514701180-A
Country	US
Kind code	B2
Filing date	Apr 30, 2015
Priority date	May 5, 2014
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A method for quality control of gamma-gamma well logging data within a borehole for mineral exploration, including receiving, at a computing device, raw well logging data; identifying and formatting data sets from the raw well logging data; applying at least one quality control process to the formatted data sets, the at least one quality control process being selected from: a linear verification process comparing linearity of density data readings between a long and a short spaced sensor in a probe; a density range verification process comparing density readings at the probe with density ranges for the borehole lithology; a diameter comparison process comparing actual diameter of the borehole at a depth with density readings at the depth; and a residual verification process for verifying a proportionality between densities measured by the long spaced sensor and short spaced sensor; compiling the results and providing an output of the compiled results.

First claim

The invention claimed is:

1. A method of mineral exploration, comprising:
receiving, at a computing device, raw well logging data from a gamma-gamma well logging probe within a borehole;
identifying and formatting data sets from the raw well logging data;
applying at least one quality control process to the formatted data sets, the at least one quality control process comprising one or more of:
a linear verification process comparing linearity of density data readings between a long spaced sensor and a short spaced sensor of the gamma-gamma well logging probe;
a density range verification process comparing density readings at the gamma-gamma well logging probe with density ranges for borehole lithology;
a diameter comparison process comparing actual diameter of the borehole at a depth with density readings at the depth; and/or
a residual verification process for verifying a proportionality between densities measured by the long spaced sensor and the short spaced sensor;

adjusting at least a portion of the well logging data based on the at least one quality control process;
compiling results of the at least one quality control process including the adjusted portion of the well logging data; and
providing an output of the compiled results.

2. The method of claim 1 , wherein the linear verification process comprises comparing the linearity of the density readings of the long spaced sensor and the short spaced sensor for the entire length of the borehole.

3. The method of claim 2 , wherein the providing the output provides a chart comparing a combined density reading for the long spaced sensor and short spaced sensor with a density reading for one of the long spaced sensor and the short spaced sensor.

4. The method of claim 1 , wherein the density range verification process comprises excluding data that falls outside of the borehole lithology density ranges.

5. The method of claim 4 , wherein the at least one quality control process includes both the linear verification process and the density range verification process, wherein the excluding data is done prior to the linear verification process.

6. The method of claim 1 , wherein the diameter comparison process comprises establishing a maximum diameter variation for the borehole.

7. The method of claim 1 , wherein the diameter comparison process comprises establishing validity of density measurements at a depth based on whether an actual diameter of the borehole compared to a nominal diameter of the borehole at the depth is within a defined range.

8. The method of claim 7 , wherein the output of the compiled results includes a graph of borehole diameter compared to nominal diameter for a depth of the borehole.

9. The method of claim 1 , wherein the residual verification process comprises determining relative differences between density readings at the long spaced sensor and short spaced sensors.

10. The method of claim 9 , wherein the relative differences are computed in accordance with
ε=√{square root over ( DENB 2 +DENL 2 )}

where ε is the relative difference, DENB is the density reading at the short sensor and DENL is the density reading at the long sensor.

11. The method of claim 10 , wherein the residual verification process further comprises establishing a threshold tolerance for residuals to provide a set of valid density ranges.

12. The method of claim 11 , wherein the output comprises a chart of relative differences in residuals over a depth of the borehole.

13. The method of claim 1 , wherein the at least one quality control process comprises all four of the linear verification process, the density range verification process; the diameter comparison process; and the residual verification process.

14. The method of claim 13 , wherein the compiling the results comprises superimposing results of the four quality control processes to establish an indication of valid depth ranges and non-valid depth ranges.

15. The method of claim 1 , wherein the receiving comprises obtaining a file in a standard logging format.

16. The method of claim 15 , wherein the method further comprises confirming validity of the file.

17. The method of claim 15 , wherein the identifying comprises parsing header information in the file.

18. The method of claim 1 , wherein the output is in a numerical format.

19. The method of claim 1 , wherein the output is provided to other computer processes for further processing.

20. A non-transitory computer readable medium for storing instructions which, when executed by a processor of a computing device, are configured to perform the method of claim 1 .

21. The method of claim 1 , further comprising generating a geological model based on the compiled results.

22. The method of claim 1 , further comprising exploring for minerals based on the geological model.

Assignees

• Vale Sa

Inventors

• Pereira Wanderson Roberto
• Carlos Dionisio Uendro

Classifications

• G01V5/12 Primary

  using gamma or X-ray sources {(gamma sources using isotopes G21G4/00; X-ray tubes H01J35/00)} · CPC title

• G01V5/045

  Transmitting data to recording or processing apparatus; Recording data · CPC title

• G01V5/125

  and detecting the secondary gamma- or X-rays in different places along the bore hole · CPC title