Digital mineral logging system

• US 4,227,405 A
• Filed: 04/06/1979
• Issued: 10/14/1980
• Est. Priority Date: 04/06/1979
• Status: Expired due to Term

• Current Assignee: Century Geophysical Corporation
• Original Assignee: Century Geophysical Corporation
• Inventors: West, Jerry B.
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US06/027,676
• Time in Patent Office: 557 Days
• Field of Search: 73/151, 73/152, 33/312, 33/313, 324/10, 250/256, 364/422, 367/81
• US Class Current: 73/152.14
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: E21B 47/12 Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling

Abstract

A digital mineral logging system acquires data from a mineral logging tool passing through a borehole and transmits the data uphole to an electronic digital signal processor. A predetermined combination of sensors, including a deviometer, is located in a logging tool for the acquistion of the desired data as the logging tool is raised from the borehole. Sensor data in analog format is converted in the logging tool to a digital format and periodically batch transmitted to the surface at a predetermined sampling rate. An identification code is provided for each mineral logging tool, and the code is transmitted to the surface along with the sensor data. The self-identifying tool code is transmitted to the digital signal processor to identify the code against a stored list of the range of numbers assigned to that type of tool. The data is transmitted up the d-c power lines of the tool by a frequency shift key transmission technique. At the surface, a frequency shift key demodulation unit transmits the decoupled data to an asynchronous receiver interfaced to the electronic digital signal processor. During a recording phase, the signals from the logging tool are read by the electronic digital signal processor and stored for later processing. During a calculating phase, the stored data is processed by the digital signal processor and the results are outputted to a printer or plotter, or both.

Claims

1. A mineral logging tool connected by a cable to an electronic digital signal processing means located at the site of the borehole for acquiring mineral logging data of the logging tool in a borehole, comprising:

a deviometer data sensor having magnetic sensors for generating the five analog signals representing the sensor data to compute the location and orientation of a borehole, including the three magnetic sensors to determine the three mutually orthogonal components of the earth'"'"'s magnetic field and the two gravitational sensors for generating analog signals representing mutually orthogonal components of the earth'"'"'s gravitational field;

means in the tool for digitizing said analog deviometer data signals;

means for storing said digitized signals representing each of said analog signals of said deviometer data; and

means for periodically batch transmitting said stored digital deviometer data signals up to the cable at a predetermined rate to the electronic digital signal processing means to perform computations to determine the location and orientation of the borehole.

2. The mineral logging tool of claim 1 wherein said magnetic sensors comprise three independent flux gates for measuring the three mutually orthogonal components of the earth'"'"'s magnetic field.

3. The mineral logging tool of claim 1 wherein said gravity sensors comprise two accelerometers mechanically aligned with said magnetic sensors for measuring the two orthogonal gravitational components of the earth'"'"'s gravitational field.

4. The mineral logging tool of claim 1 wherein said means for periodically batch transmitting said stored digital signals from said storage means comprises a frequency shift key transmission system.

5. The mineral logging tool of claim 4 wherein DC power to said deviometer sensor and said stored digital signals are transmitted on the same cable.

6. The mineral logging tool of claim 1 and further comprising:

at least one additional logging data sensor for acquiring digital logging data other than deviometer data during the same logging run when said deviometer sensor is operating;

means for storing the digital logging data from said additional logging data sensor together with said stored digital signals representing the deviometer data; and

means for periodically batch transmitting said stored digital data representing said deviometer data and said additional logging sensor data up the cable at a predetermined rate to the electronic digital signal processing means.

7. The mineral logging tool of claim 6 wherein said additional sensor comprises:

a sensor generating a digital signal measuring the natural gamma radiation from the borehole including means for counting said natural gamma radiation;

means for storing said count of the natural gamma radiation; and

means for periodically transmitting said stored natural gamma count up the cable to the electronic digital signal processing means for preparing a natural gamma log.

8. The mineral logging tool of claim 6, wherein said additional sensor generates a digital signal representing the neutron count returned to the mineral logging tool by the formation, said additional sensor comprising:

an isotopic neutron source for bombarding the formation with neutrons;

means for counting the neutrons returned to the tool by the formation;

means for storing said neutron count; and

means for periodically transmitting said stored neutron count up the cable to the electronic digital signal processing means for preparing a continuous curve of said neutron count.

9. The mineral logging tool of claim 6 for use in a mineral logging system including an electrode at the surface and further comprising:

an electrode positioned within the mineral logging tool;

a sensor for generating signals measuring the formation resistance between the mineral logging tool electrode and the surface electrode;

means for storing said resistance measurement; and

means for periodically transmitting said stored resistance measurement up the cable to the electronic digital signal processing means.

10. The mineral logging tool of claim 6 wherein said means for periodically transmitting said stored digital data representing said deviometer data and said additional logging sensor data is transmitted at a predetermined rate to enable said electronic digital signal processing means to perform real time calculations to generate a mineral log by said deviometer data and said additional sensor data while the mineral log is being withdrawn from the borehole.

11. The mineral logging tool of claim 1 wherein a reference electrode is located at the surface and connected to the tool through the cable and further comprising:

a second electrode located in the mineral logging tool;

means for measuring the natural electromagnetic potential between the reference electrode and said second electrode and for generating an analog signal in response thereto; and

an analog to digital converter for digitizing analog data signals;

means comprising an analog multiplexer for sequentially applying said potential signal to said analog to digital converter for transmitting said digitized spontaneous potential signal up the cable to the electronic digital signal processor.

12. The mineral logging tool of claim 11, wherein said multiplexer selects said potential analog signal on every other periodic transmission, such that a continuous plot of the spontaneous potential may be made by the electronic digital signal processor.

13. The mineral logging tool of claim 1 and further comprising:

means for generating an analog signal representing the temperature in the borehole; and

an analog to digital converter for digitizing analog data signals;

means comprising an analog multiplexer to selectively apply said analog temperature signal to said analog to digital converter, such that said temperature signal is periodically transmitted from said storage means up the cable to the electronic digital signal processing means of the mineral logging system.

14. The mineral logging tool of claim 1 for use in a mineral logging system including an electrode at the surface and further comprising:

an electrode positioned within the mineral logging tool;

a sensor for generating signals measuring the formation resistance between the mineral logging tool electrode and the surface electrode;

means for storing said resistance measurement; and

means for periodically transmitting said stored resistance measurement up the cable to the electronic digital signal processing means.

15. The mineral logging tool of claim 1 wherein said storage means comprises a plurality of shift registers.

16. The mineral logging tool of claim 1, wherein said means for periodically batch transmitting said stored digital deviometer data signals transmits said data at a predetermined rate to enable the electronic digital signal processing means to perform real time computations to generate a mineral log of the deviometer data as the tool is withdrawn from the borehole.

17. A mineral logging tool connected by a cable to an electronic digital signal processor means located at the site of the borehole for acquiring mineral logging tool in a borehole, comprising:

a deviometer data sensor having magnetic sensors for generating analog signals representing mutually orthogonal components of the earth'"'"'s magnetic field and further having gravitational sensors for generating analog signals representing mutually orthogonal components of the earth'"'"'s gravitational field;

means in the tool for digitizing said analog signals and for storing the digitized signals;

means for periodically transmitting said stored digital signals up the cable to the electronic digital signal processor which performs computations to determine the location and orientation of the borehole;

read only memory means for storing an identification code for the mineral logging tool; and

means for periodically transmitting said mineral logging tool self-identification code periodically from said read only memory means up the cable to the digital signal processor for identification of the logging tool and verification of the accuracy of said means for transmitting.

18. The mineral logging tool of claim 17, wherein said tool identification code is subdivided into groups of numbers corresponding to types of logging tools for identifying both the particular tool and the type of logging tool.

19. The mineral logging tool of claim 17, wherein said read only memory means comprises a shift register having its terminals wired to generate a binary coded tool identification code.

20. A mineral logging tool connected by a cable to an electronic digital signal processor means located at the site of the borehole for acquiring mineral logging data of the logging tool in a borehole, comprising:

a deviometer data sensor having magnetic sensors for generating analog signals representing mutually orthogonal components of the earth'"'"'s magnetic field and further having gravitational sensors for generating analog signals representing mutually orthogonal components of the earth'"'"'s gravitational field;

means in the tool for digitizing said analog signals and for storing the digitized signals;

means for periodically transmitting said stored digital signals up the cable to the electronic digital signal processor which performs computations to determine the location and orientation of the borehole;

at least one additional logging data sensor for acquiring digital logging data other than deviometer data during the same logging run when said deviometer sensor is operating;

means for storing the digital logging data from said additional logging data sensor;

means for periodically transmitting data from said storage means up the cable to the electronic digital signal processing means;

read only memory means for storing an identification code for the mineral logging; and

means for periodically transmitting said mineral logging tool self-identification code periodically from said read only memory means up the cable to the digital signal processor for identification of the logging tool and verification of the accuracy of said means for transmitting.

21. The method of obtaining the true path of a borehole through an ore formation and other mineral logging data from a mineral logging tool connected by a cable to a mineral logging system in a single pass of the mineral logging tool through the borehole, comprising:

generating the analog signals containing the information for the mineral log from a deviometer sensor and at least one other mineral logging sensor located in the logging tool;

converting the analog signals generated by said sensors to digital signals;

sequencing the order in which said analog signals are converted to digital signals;

storing the converted digital signal of each of the sensors; and

periodically batch transmitting said converted digital signals from said storing means up the cable to the digital mineral logging system.

22. The method of obtaining a mineral log of claim 21, and further comprising:

developing a mineral log from the converted digital signals of the plurality of sensors of the mineral logging tool.

23. The method of obtaining a mineral log of claim 22, and further comprising:

recording the converted digital signals from the mineral logging tool during a mineral logging run, such that a mineral log may be developed from said recording.

24. The method of obtaining a mineral log of claim 21, wherein the DC power is transmitted down to the mineral logging tool in the borehole through the cable and

said periodic batch transmission of said converted digital data is a frequency shift key transmission.

25. The method of obtaining the true path of the borehole through an ore formation and other mineral logging data of claim 21 and further comprising:

generating a mineral log of the true path of the borehole and other mineral logging data in real time, whereby mineral logging information on the borehole is available on site during the mineral logging operation.

26. A mineral logging tool connected by a cable to an electronic digital signal processing means for determining the true path of a borehole through an ore formation and for acquiring additional mineral logging data for a digital logging system during a single pass of the logging tool in the borehole, comprising:

a deviometer data sensor and at least one other mineral logging data sensor housed within the mineral logging tool for providing the mineral logging data on a single pass of the mineral logging tool through the borehole;

means for converting the deviometer sensor data and other analog sensor data from analog signals to digital signals;

means for storing said digital signals from said sensors; and

means for periodically batch transmitting said stored digital signals up the cable at a predetermined rate to the electronic digital signal processing means to perform computations to determine the location and orientation of the borehole and additional logging information from said other sensor.