WO2015161326A9

WO2015161326A9 - A method of obtaining seismic information

Info

Publication number: WO2015161326A9
Application number: PCT/ZA2015/000020
Authority: WO
Inventors: Michiel Jacobus KRUGER
Original assignee: Detnet South Africa (Pty) Limited
Priority date: 2014-04-16
Filing date: 2015-04-08
Publication date: 2016-07-14
Also published as: WO2015161326A2; AR100092A1; WO2015161326A3

Abstract

A method of generating seismic information wherein time stamped information on the tiring of an electronic: detonator is related to time stamped seismic information produced by tiring the electronic detonator.

Description

A METHOD OF OBTAINING SEISMIC INFORMATION

BACKGROUND OF THE INVENTION

[0001] This invention relates generally to the use of one or more detonators, in a geophysical exploration process, to generate seismic information. [0002] In a geophysical exploration platform use can be made of one or more electronic detonators to initiate an explosive which acts as a seismic source i.e. the explosion, when ignited, creates seismic waves. Reflections of the seismic waves by geophysical formations and discontinuities in the earth are measured and are processed to obtain an indication of properties below the earth's surface. [0003] In a seismic application boreholes are normally primed well in advance before firing the respective detonators in the boreholes. An unattended primed borehole with a seismic blasting detonator may be prematurely initiated by stray currents or by tampering. Different approaches have been used to address this situation. In US8166879 a transient suppressor is connected in series with an electric detonator to raise a minimum voltage required to initiate the detonator. In US201 1/0247517 a switch in a detonator enables the detonator to be fired only after a unique ID code, associated with the detonator, has been supplied.

[0004] In another technique a conventional electric seismic firing system is interfaced to an electronic detonator firing platform. A trigger signal from the electric seismic firing system is used to cause initiation of an electronic detonator. A benefit is that an electronic detonator is largely immune to extraneous signals and only responds to specifically encoded firing signals. Consequently, inadvertent initiation of the electronic detonator by an external energy source is prevented. A disadvantage of this system however lies in the fact that an electric seismic firing system and an electronic detonator firing platform are required. [0005] US6079333 describes a GPS controlled blaster wherein a master GPS receiver can communicate with each of a number of charge control transceivers. The master GPS receiver computes detonation times using GPS-based time information. Location information is determined by the charge control GPS transreceivers. Other disclosures based on the use of GPS techniques include US6941870 and US7650841 . [0006] An object of the present invention is to provide a method of obtaining seismic information wherein an electric seismic firing system is not required and wherein use of a GPS, although possible, is not mandatory.

SUMMARY OF INVENTION

[0007] The invention provides a method of obtaining seismic information which includes the steps of:

1. generating time data;

2. providing an electronic detonator;

3. placing the electronic detonator in a blast hole;

4. providing an electronic detonator firing platform;

5. connecting the electronic detonator to the electronic detonator firing platform;

6. programming the electronic detonator as may be required;

7. providing a seismic recording platform; 8. activating the seismic recording platform to record seismic information;

9. generating a first user input signal;

10. arming the electronic detonator firing platform in response to the first user input signal;

1 1. generating a second user input signal;

12. in response to the second user input signal, using the electronic detonator firing platform to fire the electronic detonator ("the firing event");

13. using the seismic recording platform to record seismic information generated by the firing of the electronic detonator;

14. utilising the time data (step 1 ) to time stamp the recorded seismic information;

15. utilising the time data (step 1 ) to time stamp the firing event (step 12) or a related event which is a known time offset from the firing event; and

16. using the time stamped seismic information (step 14) and the time stamped firing event or related event (step 15), to relate the recorded seismic information (step 13), with respect to time, to the firing event.

[0008] In step 1 the time data may be generated using an appropriate positioning system. The positioning system may be a local positioning system or a global positioning system (GPS). Time data could also be generated by means of a master clock which transmits time information to an operating location. BRIEF DESCRIPTION OF THE DRAWING

[0009] The invention is further described by way of example with reference to the accompanying drawing which is a block diagram representation of a system used to implement the method of the invention. DESCRIPTION OF PREFERRED EMBODIMENT

[0010] The accompanying drawing illustrates in block diagram form apparatus 10 used to implement the method of the invention.

[0011] The apparatus includes a processor 12 in the form of a microcontroller or the like, and a keyboard 14 and an optional display 16 which are connected to the processor. [0012] A module 18 which generates time data in response to a GPS 18A is connected to the processor 12. The use of the GPS 18A is exemplary and non-limiting. Time data can be generated using different techniques. For example, use can be made of a local positioning system established for the purpose. An alternative technique is to employ a signal transmitted from a master clock which delivers precise timing information. [0013] A line driver/receiver circuit 20, connected to the processor, enables two-way communication to be established between the processor 12 and one or more electronic detonators 22 which are positioned in boreholes, loaded with explosives (not shown).

[0014] It is possible to use multiple processors, which interact with one another, to enable blasting to take place. Use may also be made of electronic keys and other authentication methods to enhance the safety of operation. Generally these aspects are known in the art and for this reason are not further described herein. [0015] The module 18 produces, with a high degree of accuracy, synchronisation pulses 24 which are applied to the processor 12 together with a data string 26 which details the time at which a previous pulse 24 was generated. The timing information is obtained from the module 16. The data string 26 can be sent to the processor using any appropriate protocol e.g. the data string can be sent to the processor in serial fashion.

[0016] The processor 12 is configured to run a local clock 12A that is synchronised to the synchronisation pulses 24. The clock 12A provides time information which is not necessarily as accurate as that available from the module 18 e.g. information which is delivered by the GPS 18A. It is then necessary to calibrate the processor clock 12A in terms of one second interrupts 28 from the module 18. In one example the processor clock 12A runs at one megahertz to achieve a one microsecond resolution and, during each second, counts 1000010 cycles. These are exemplary and non-limiting figures. In this case any time measurements made in terms of the local microcontroller clock must be adjusted appropriately. [0017] The synchronisation pulses 24 are used to time stamp information to the electronic detonators 22 and, in particular, to time stamp a firing signal (from the processor 12) to the detonators. Alternatively, an event which is related to the firing signal, such as a user input, which is offset by a known time from the firing signal, can be time stamped.

[0018] Upon firing, the detonators generate seismic information 30 which is recorded by a seismic recording platform 32. The module 18 is used to time stamp the operation of the recorder 32. [0019] Subsequently, the time at which the detonators were initiated is correlated on a time basis with the information recorded by the recorder 32. This enables the seismic data in the recorder to be accurately linked to the time at which the detonators were fired.

[0020] Any suitable technique can be used for the time stamping of the firing signal to the detonators and for the time stamping of the operation of the recorder 32. An important aspect in this regard is that the time stamping should be accurate and applied with equal effect in each application. The time stamping need not be correct in an absolute sense. However, there should be no deviation in the time information which is used to control the time stamping between the time stamping of the firing signal and the time stamping of the recorded information. Any error which may occur would be common to the first and second time stamping processes and inherently is eliminated.

[0021] The implementation of the method of the invention eliminates the need for an electric seismic firing system.

Claims

CLAIMS 1. A method of obtaining seismic information which includes the steps of:

1. generating time data;

2. providing an electronic detonator;

3. placing the electronic detonator in a blast hole;

4. providing an electronic detonator firing platform;

6. programming the electronic detonator;

7. providing a seismic recording platform;

8. activating the seismic recording platform to record seismic information;

9. generating a first user input signal;

1 1. generating a second user input signal;

16. using the time stamped seismic information (step 14) and the time stamped firing event or related event (step 15), to relate the recorded seismic information (step 3), with respect to time, to the firing event.

A method according to claim 1 wherein, in step 1 , the time data is generated using at least one of the following: a local positioning system, a global positioning system, and a master clock which transmits time information to an operating location.