Method for measuring the detonation velocity of an explosive in a borehole

Abstract

The invention relates to measuring methods and to devices for automatically monitoring the parameters of drilling and blasting operations, inter alia, at quarries, mine faces and other mining industry sites. The essence of the invention lies in a method for measuring the detonation velocity of an explosive in a borehole which is implemented using a coaxial cable connected to an electronic measuring device, and in which the data obtained are processed by an electronic computing device using polynomial approximation to obtain coefficients of a polynomial that represents an approximating function for measuring the magnitude of detonation velocity. The technical result toward which the invention is directed is that of increasing the accuracy of a method for measuring the detonation velocity of an explosive using an electronic computing device by reducing the effect of fluctuation errors and discrete errors on the measuring results.

Description

[0001] Method for measuring the detonation velocity of an explosive in a borehole

[0002] The invention relates to methods of measuring and devices for automated control of parameters of drilling and blasting operations, including in quarries, faces and other mining industry facilities.

[0003] A method for measuring the detonation velocity of an explosive in a well is known, which involves placing piezoelectric sensors connected to each other by a cable in the well, connecting them to an electronic measuring device, and pouring water into the well. Measuring the detonation velocity consists in the fact that during the explosion, the value of the water pressure read by the piezoelectric sensors changes, and the obtained data on the change in pressure is converted into the detonation velocity in the sections of the well where the sensors are installed, after which the obtained velocity values ​​are averaged. [CN107703323A, date of publication: 16.02.2018]

[0004] The disadvantage of the known technical solution is the low accuracy of measuring the detonation velocity of the explosive in the well, as well as the high complexity of implementing the method. The complexity of the implementation lies in the fact that in the proposed technical solution it is necessary to pre-position a system of sensors in the well, connect them to each other and then fill with water. In the process of implementing the proposed method, there is a risk of a short circuit due to incorrect or inaccurate connection, which will lead to the failure of the entire sensor system, as well as the electronic measuring device. At the same time, it is also necessary to correctly and accurately calculate the expected locations of the sensors before installing them, which requires sufficient practical experience and knowledge in this field of technology. Thus, the complexity of implementing the method increases. At the same time, the step of determining the speed is also limited by the use of sensors as a measuring device, sinceto reduce the step between measurements, it is necessary to increase the number of sensors, which significantly increases the material intensity of the method and also negatively affects the increase in the complexity of its implementation. In addition, determining the detonation velocity by averaging the velocity values ​​increases the influence of discrete errors and significantly reduces the accuracy of the measurement result obtained. A method for measuring the detonation velocity of an explosive was chosen as a prototype, during which a coaxial cable connected to an electronic device is placed in a well, and then the explosive is detonated, while simultaneously with the detonation of the explosive, the device generates electrical pulses passing through the cable and reflecting from its end, and are received back.As the cable length decreases during detonation, the delay between the transmitted and reflected pulses decreases, and the resulting delays in velocity values ​​are averaged, which is used to determine the detonation velocity of the explosive. [AU2016265975A1, published date: 15.06.2017].

[0005] The advantage of the prototype over the known technical solution is the reduced material consumption of the method, as well as the comparative simplicity of its implementation due to the use of a coaxial cable, due to which the need for preliminary calculations of the locations of the sensors is eliminated, and the complexity of processing the obtained data is reduced.

[0006] However, the disadvantage of the prototype is the low accuracy of the method for measuring the detonation velocity of explosives in a well, due to the fact that in order to obtain the velocity value, it is necessary to obtain the delay value between pulses, and it strongly depends on the noise component of the reflected signal, and non-stationary conditions of reflection of the electric pulse from the end of the cable, in addition, the measurements are carried out discretely, by digital methods. This leads to the fact that when assessing the detonation velocity, the obtained data contain significant fluctuation and discrete errors. In this case, as a result of the entire measurement cycle, several hundred time delay readings are obtained, as a rule. In this area of ​​technology, there is a need to measure the detonation velocity with a relatively large step, so that several dozen data readings fall into the required range of time intervals for measuring the detonation velocity.The obtained data, as in the previous technical solution, are processed by means of arithmetic averaging of the obtained speed values, thereby significantly increasing the influence of fluctuation and discrete errors on the obtained result and thus reducing the accuracy of the method for measuring the detonation speed of an explosive and, as a consequence, the efficiency of the method. The technical problem, to which the invention is directed, is the need to increase the efficiency of the method for measuring the detonation speed of an explosive in a well.

[0007] The technical result that the invention is aimed at achieving consists in increasing the accuracy of the method for measuring the detonation velocity of an explosive substance by reducing the influence of fluctuation and discrete errors on the measurement results.

[0008] An additional technical result, which the invention is aimed at achieving, consists in reducing the material intensity of the method for measuring the detonation velocity of an explosive substance in a well.

[0009] An additional technical result, which the invention is aimed at achieving, consists in simplifying the method for measuring the detonation velocity of an explosive substance in a well.

[0010] The essence of the invention is as follows.

[0011] The method for measuring the detonation velocity of an explosive in a borehole involves the use of a coaxial cable connected to an electronic measuring device, by means of which: during the detonation of the explosive, a sequence of time delays of signal propagation in the cable is obtained, and by means of an electronic computing device:

[0012] — measure, by calculation, the detonation velocity of an explosive substance, for which:

[0013] — the obtained sequence of time delays of signal propagation in the cable is recalculated into a sequence of cable lengths;

[0014] — perform a polynomial approximation of the obtained sequence of cable lengths, on the basis of which the coefficients of the approximating polynomial are obtained;

[0015] — an approximating function is constructed based on the obtained polynomial coefficients;

[0016] — the obtained approximating function is divided into the required number of measurement segments;

[0017] — the average value of the detonation velocity is obtained for each segment of the approximating function; — based on the obtained values ​​of detonation velocities, the detonation velocity function of the explosive is constructed.

[0018] The coaxial cable reduces the material intensity of the method due to the absence of the need to use unique and expensive cable systems, sensors or other devices created specifically for this task. At the same time, the use of this cable eliminates the need for complex and multi-stage well preparation due to the fact that it is sufficient to connect it to an electronic measuring device and place it in the well. This also optimizes and simplifies the method of measuring the detonation velocity of the explosive.

[0019] The electronic measuring device provides the ability to obtain a sequence of time delays of signal propagation in the cable during the detonation of the explosive, and the electronic computing device provides subsequent data processing. The electronic computing device can be implemented as a personal computer (PC) or another device, such as a remote server. In this case, the measuring device can be presented as a device that includes a control device to which a transmitter is connected and a time-to-digital converter, to which in turn a receiver is connected. In this case, the electronic measuring and computing devices can be implemented as a single device or represented by a set of devices.

[0020] The sequence of time delays of signal propagation in the cable can be obtained directly during the detonation process, and subsequent data processing can be performed after the detonation is complete. In this case, subsequent processing can be performed using a PC.

[0021] The time delay is the interval between the sent and received electrical impulses. To determine the time delays, the microcontroller has the ability to transmit electrical impulses to the cable during the detonation process.

[0022] Polynomial approximation is one of the methods of mathematical processing of data array. In this case, polynomial approximation can be mainly implemented by the least squares method. Based on polynomial approximation, polynomial approximation coefficients are obtained, which are used to construct the approximating function. Polynomial approximation coefficients can be obtained by any known mathematical solution methods. In this case, polynomial approximation coefficients can be mainly obtained by the Gauss method.

[0023] The invention can be made from known materials using known means, which indicates its compliance with the patentability criterion of “industrial applicability”.

[0024] The invention is characterized by a previously unknown set of essential features from the state of the art, which makes it possible to implement the proposed method for measuring the detonation velocity of an explosive.

[0025] The set of essential features of the invention allows to compensate for the influence of noise during the propagation of electrical impulses along the cable, and also simplifies the analysis and processing of the array of data obtained during the measurement process. At the same time, it is possible to increase the step between measurements, due to which it is possible to average the obtained data, thereby reducing the statistical, discrete and fluctuation errors in measuring the detonation velocity of the explosive in the well.

[0026] This ensures the achievement of a technical result consisting in increasing the accuracy of the method for measuring the detonation velocity of an explosive by reducing the influence of fluctuation and discrete errors on the measurement results, thereby increasing the efficiency of the method for measuring the detonation velocity of an explosive in a well.

[0027] The invention has a set of essential features previously unknown in the state of the art, which indicates its compliance with the patentability criterion of “novelty”.

[0028] The prior art includes methods for measuring the detonation velocity of an explosive in a well, including the use of an electronic computing device and a coaxial cable.

[0029] However, the prior art does not know a method for measuring the detonation velocity of an explosive in a well, during which an averaging filter is used in an electronic computing device based on a polynomial approximation of the obtained time delays, which makes it possible to eliminate the discrete error and reduce the impact of the fluctuation error on the results of measuring the detonation velocity of an explosive in a well.

[0030] In view of this, the invention meets the patentability criterion of “inventive step”.

[0031] The invention is illustrated by the following figures.

[0032] Fig. 1 - Schematic representation of a charging well with a coaxial cable placed in it, connected to an electronic measuring device.

[0033] Fig. 2 - Structural diagram of an electronic measuring device for measuring the detonation velocity of an explosive.

[0034] Fig. 3 a-c - Schematic representations of the change in the length of the coaxial cable during the detonation of the explosive in the well.

[0035] Fig. 4 — Algorithm for measuring the detonation velocity of an explosive.

[0036] To illustrate the possibility of implementation and a more complete understanding of the essence of the invention, an embodiment of it is presented below, which can be changed or supplemented in any way, while the present invention is in no way limited to the presented embodiment.

[0037] A measuring device 100 is presented as a device for measuring the detonation velocity of an explosive substance, including a transmitter 102, a receiver 104, a control device 106 and a time-to-digital converter 108, wherein a personal computer (PC) 110 is connected to the control device 106, on which data on the value of the detonation velocity of the explosive substance are processed and output. In this case, a coaxial cable 200 is connected to the measuring device 100.

[0038] The method for measuring the detonation velocity of an explosive in a well is as follows.

[0039] Before drilling and blasting operations, one end of the coaxial cable 200 is placed in the charging well.

[0040] Then the explosive substance (ES) is detonated, during the explosion of which the detonation area moves from bottom to top along the length of the cable 200 located in the vertical charging well, thereby gradually destroying and reducing its length as shown in Fig. 3a, 36, 3b. At step 300, the time delays of signal propagation in the cable 200 during the detonation of the ES are determined. This process is carried out due to the physical phenomenon and the algorithm of operation of the measuring device 100 described below.

[0041] Simultaneously with the process of detonation of explosives, the measuring device 100 generates pulses of the required duration with a certain periodicity, controlling the transmitter 102. The transmitter 102 forms and transmits probing pulses to the cable 200. These pulses also arrive at the receiver 104, which, under the influence of the probing pulses, forms a logical signal at the output, which starts the time-to-digital converter 108. The electrical pulse in the cable 200 is reflected from the heterogeneity at the end of the cable 200, thereby returning the signal to the input of the receiver 104 with a certain delay. The reflected pulse is received by the receiver 104, which, under its influence, forms a logical signal at the output, stopping the time-to-digital converter 108. Then the time-to-digital converter 108 transmits data on the measured delay time to the control device 106.

[0042] Since the speed of propagation of the electric pulse in the cable 200 is known, the propagation delay can be unambiguously recalculated into its length, which provides the possibility for the control device 106 to accumulate the necessary amount of data and store it on the internal digital medium. After this, the data is processed using the PC software.

[0043] At step 400, the measured time delays are converted into the corresponding lengths C of cable 200 depending on the elapsed time by means of the following expression:

[0044] Li(t) = v • Дт;, where: v is the speed of propagation of an electrical impulse in a cable 200;

[0045] At, - is the measured time delay of signal propagation in cable 200.

[0046] At step 500, a polynomial approximation of the sequence of cable lengths 200 obtained at step 400 is performed using the least squares method, for which the following system of linear equations is solved:

[0047] The Gauss method is used to calculate the coefficients of the equation of the polynomial a, approximating the length function dimension [1...ш]. Moreover, the order of the polynomial n of the approximation is chosen as N / 2, where N is the number of cable lengths 200 for which it is necessary to estimate the detonation velocity.

[0048] At step 600, using the coefficients of the polynomial a obtained at step 500, the following approximating function Ai(t) is constructed:

[0049] Then, this approximating function is divided into N sections, in accordance with the cable lengths 200, on which it is necessary to estimate the detonation velocity.

[0050] At step 700, the function D(N) is constructed, characterizing the detonation velocity of the explosive, for which, for each section of the obtained approximating function, the detonation velocity is calculated using the following expression: k - the number of readings of measured cable lengths 200 in the speed estimation interval;

[0051] T is the period of repetition of probing pulses.

[0052] At step 800, based on the constructed function, the detonation velocity of the explosive is measured at the well depth ranges of interest. The proposed method for measuring the detonation velocity of the explosive, thanks to the averaging filter based on the polynomial approximation applied in the computing device, allows for reducing the effect of fluctuation and discrete errors and thereby reducing the risk of possible deviations in the results of measuring the detonation velocity of the explosive. This ensures the achievement of a technical result consisting in increasing the accuracy of the method for measuring the detonation velocity of the explosive by reducing the effect of fluctuation and discrete errors on the measurement results, thereby increasing the efficiency of the method for measuring the detonation velocity of the explosive in the well.

Claims

Invention formula 1. A method for measuring the detonation velocity of an explosive in a borehole, which includes the use of a coaxial cable connected to an electronic measuring device, by means of which, during the detonation of the explosive, a sequence of time delays in the propagation of a signal in the cable is obtained, and by means of an electronic computing device: — measure, by calculation, the detonation velocity of an explosive substance, for which: — the obtained sequence of time delays of signal propagation in the cable is recalculated into a sequence of cable lengths; — perform a polynomial approximation of the obtained sequence of cable lengths, on the basis of which the coefficients of the approximating polynomial are obtained; — an approximating function is constructed based on the obtained polynomial coefficients; — the obtained approximating function is divided into the required number of measurement segments; — obtain the average value of the detonation velocity for each segment of the approximating function; — based on the obtained values of detonation velocities, a function of the detonation velocity of the explosive is constructed.

2. The method according to item 1, characterized in that the used electronic measuring device is presented in the form of a device that includes a control device to which a transmitter is connected and a time-to-digital converter to which a receiver is connected.

3. The method according to item 1, characterized in that the polynomial approximation of the obtained sequence of cable lengths is carried out using the least squares method. SUBSTITUTE SHEET (RULE 26) 4. The method according to paragraph 3, characterized in that the coefficients of the polynomial approximation of the obtained sequence of cable lengths are calculated using the Gauss method. SUBSTITUTE SHEET (RULE 26)

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