EP1166037B1 - Method for triggering detonators via a line of a large length - Google Patents

Abstract

When triggering detonators via lines of a large length, which is often the case in exploration wells in oil or natural gas fields, signal distortions occur due to the capacitive and inductive behavior of the long line (3) as well as of the consumers connected in incoming circuit to the detonators (4a, 4b, 4c). For this reason, a sure triggering of the detonators is no longer guaranteed. The invention thus provides that, before the detonators are triggered, the existing capacitors (8) are charged by applying a direct current to the line. Said capacitors (8) are charged to a level such that, at least up to the time at which the last detonator is triggered, the capacitors are not subjected to an additional charging that is induced by charge losses.

Description

The invention relates to a method for triggering detonators via a line great length.

Drilling for the exploration and digestion of oil and gas fields, extend over lengths, especially horizontally already well over 10000 m transcend. The hole is usually at several predetermined locations perforated to allow access, for example, of oil to the wellbore. Other blasts loosen the rock around the hole to the To facilitate inflow of oil to the wellbore. For these purposes, the provided appropriate explosive charges positioned with detonators be ignited in a predetermined order. There are also several, one behind the other ignition ignited on a common line. Such a Ignition circuit is known for example from EP 0 588 685 B1. The detonators will be each individually controlled and then triggered. The ignition signal consists of a Information component for addressing and unlocking the individual detonators and an energy component that triggers the ignition.

From the patent US-A 3,417,259 it is known to use a control system Variety of explosive charges successively over a line to ignite, at the no other consumers are connected. To the required energy to be able to provide, via a first power source, a capacitor charged. The charging voltage is just below the voltage, the Triggering the detonator to detonate the explosive charges is required, so no Igniter is triggered. Only the connection of a second energy source provides a so high voltage that the resistor is one of the first explosive charge overcome threshold switch and the first explosive charge can be ignited. The second energy source may be small because of the energy already provided by the first energy source only the Reaching the ignition voltage required difference must be provided.

From the patent US-A 3,564,278 is a comparable circuit for triggering Known fuses.

In DE-OS 23 56 875 a circuit arrangement for generating time successive surges, which, inter alia, for each other the following ignition of explosive devices can be used, with several each generating a surge of a series of power surges Surge units are connected in series. There are two signals different delay time generated, of which with the shorter time to Recharging Energiespeichem and with the longer time exclusively for Connecting the serving as an energy source for the surge energy storage with the detonator serves.

Known electronic detonators require a Entsicherungssequenz, the Polarity changes the rated voltage, which at the output of Igniter triggering device is applied. In addition to the number of bills is the time Evaluated between the changes of the arming sequence Only if correct Number of polarity changes in a defined time and a defined time Slope of the polarity change is this code from the electronic detonator accepted.

With large cable lengths, the information transfer reaches its limits. Of the Voltage level can be so low and the signals of the transmitted data can be so be distorted so that the detonator does not recognize the signals and does not fire the ignition becomes. The distortion of the signals is primarily due to the lack of edge steepness caused between the polarity changes of the rated voltage. The cause of these disturbances lie in the capacitive and inductive behavior of the long line as well as the detonators upstream consumers such as the Feed drive of the drill head in the horizontal direction, its protective relay, the Auxiliary tools and positioning. These consumers are over the same line is supplied with energy over which the detonators are triggered. at Disconnection of the supply voltage and connection of the signal and Ignition voltage for data transmission or triggering of the detonators The discharging capacities of consumers are affected by this voltage charged. The result is a voltage drop and therefore requires a Signal attenuation.

It is therefore the object of the present invention, a trouble-free release of detonators, in particular explosive detonators, over a long line sure.

The solution of the task is done using the features of the first Claim. Advantageous embodiments of the invention are in the Claimed subclaims.

According to the invention, the effects of capacitive resistances on the Signals of the detonator device thereby reduced that before the release of the Igniter on the line to the detonators a DC voltage is switched on, with the capacity of consumers are charged to such a level that in the subsequent generation of the signals for triggering the detonator the Consumer capacity is no longer effective. The capacities of Consumers will recharge themselves after being charged, but the one before Charging to a high level ensures that at least until the time of Triggering of the last igniter no charging losses due to the charge Capacities done. This reduces the time required to generate the signals Rated voltage not below its required level.

To charge the capacity to a correspondingly high level To ensure it is advantageous if the switched DC voltage is higher as the rated voltage for generating the signals. For example, is the Rated voltage 24 volts, it can charge a capacity of 28 for charging the capacity Voltage DC be provided. To charge the capacities on the to ensure the desired level, a corresponding time may be provided for in which the increased voltage is switched. In the proposed example would be a switch-on of about 5 seconds advantageous.

It should be noted that the increased voltage is below a critical voltage which can cause the triggering of an igniter. The detonators are usually like that they are designed to be of a certain magnitude above the rated voltage required for Generating the signals intended to trigger a detonator, are resistant, without it triggering. According to the invention, however, the intended Tolerance range not exhausted to avoid any risk, on the other hand the amount of voltage is chosen so that within a very short time intended to boost the capacity of consumers.

As the capacitive resistances vary depending on the length of the pipe and the hole different and additional consumers connected to it, it is advantageous if, prior to charging the capacity of the consumer of Capacitive resistance is determined and depending on its size for charging the capacity is determined at least required DC voltage. This is ensures that no the critical value of the voltage for triggering a Igniter is exceeded. The aufzusaltende DC voltage can thus be tailored to the particular application.

The line to the detonators with their additionally connected consumers provides due to the inductances and capacities a resonant circuit with a Low-pass filter effect. The low-pass filter effect is in particular by the Capacities affected. By determining the capacitive resistance can be determine the critical frequency at which the low-pass filter effect occurs. Thereupon becomes a suitable signal frequency is chosen to make the low pass filter effect effective excluded. It is inventively such a reduced frequency chosen that in each period, the voltage rises again up to the final voltage. Furthermore, this voltage must over a predetermined time until the next Polarity change at their nominal level, so that the characteristic Signaling is retained and the polarity change of the signal receivers the detonator can also be detected.

The invention will be explained in more detail with reference to the following description.

Figur 1

ein Ersatzschaltbild einer Bohrlochbestückung mit Sprengzündern und zusätzlichen Verbrauchern,

Figur 2

den herkömmlichen Verlauf der Signal- und Zündspannung bei der Ankunft an einem Zünder und

Figur 3

den Verlauf der Signal- und Zündspannung entsprechend der Erfindung.

Show it:

FIG. 1

an equivalent circuit diagram of a borehole assembly with detonators and additional consumers,

FIG. 2

the conventional course of the signal and ignition voltage on arrival at a detonator and

FIG. 3

the course of the signal and ignition voltage according to the invention.

1 shows the equivalent circuit diagram of a borehole assembly with detonators and additional consumers. From the detonator device 2 leads a conduit 3 with two strands 3a and 3b to the detonators 4a, 4b and 4c. Assigned to them are each to be ignited charges 5a, 5b and 5c. The additional consumers are as ohmic resistors 6, inductive resistors. 7 and capacitive resistors 8 symbolizes. It is for example the Feed drive of the drill head, its protective relay, the auxiliary tools and the Positioning. To supply in particular the feed drive of Drill head is a higher voltage required than to generate the Trigger the detonator necessary signals. The voltage source for supply this additional consumer is designated 9. Denoted by 10 is a Circuit breaker with which the igniter 4a to 4c during the supply of the rest Consumer via the voltage source 9 of the strands 3a and 3b be separated. With a steering means 11 is designated, with, as by a Line 12 indicated, the circuit breaker 10 can be operated. To the Disconnect voltage source 9 from the consumer is another switch 13th provided, which, as indicated by the line 14, from the control device 11th can be operated.

When the power source 9 is disconnected from the line 3, the circuit breaker becomes 10 closed and the voltage source 15 to the line strands 3a, 3b switched on, without first signals for triggering the igniter for 4a to 4c to be generated. Then, according to the present embodiment via a designated 16 tester, via the lines 17 and 18 to the Line strands 3a and 3b is connected, the capacitive resistance and the Voltage drop in line 3 determined. These values are sent via the line 19 the Zündauslöseeinrichtung 2 transmitted. To charge the capacity 8 of the Consumer is then for a predetermined time from the voltage source 15 a higher voltage applied than to generate the signals to trigger the Detonator is provided.

With the test device 16 can also be provided, the capacitive conditional Low pass filter effect of line 3 and the additional connected To determine consumers due to the capacitive resistance and to the Zünderauslöseeinrichtung 2 to report, so from this one on the capacitive Resistance of the line and the consumer tuned frequency of Potential change of the voltage to generate the signals to trigger the Igniter is set.

FIG. 2 shows the conventional course of a signal on arrival at a detonator in a voltage-time diagram (U, t). In order to generate the ignition signals, a DC voltage of the voltage source 15 in the amount U _{n +} is applied by the fuze triggering device 2 to the line 3. It is the nominal voltage required to generate the signals. At time t ₀ , the signal sequence begins, characterized by a polarity change of the nominal voltage between the polarities U _{n +} and U _n- with the frequency f. The duration of half a period is designated t ₁ .

Ideally, a square wave of the nominal voltage between the two polarities U _{n +} and U _{n - would} occur. In particular, due to the capacitive and inductive resistors, however, a distortion of the signal waveform occurs. Within the polarity changes, the edges of the signal voltage fall and rise greatly delayed and no longer reach the respective rated voltage. Due to the drop to a lower voltage U _o or U _u and the distortion of the signal edges, the electronics of the igniter is no longer able to detect the signal.

According to the invention, before the generation of the signals, a charging of the capacitors of the consumers takes place. As a result, the signal voltage no longer has to additionally charge the capacitors. As can be seen from FIG. 3, the respective nominal voltage U _{n +} or U _{n- is} reached at each polarity change.

Furthermore, the frequency f _{e is} lowered with respect to the low-pass filter effect with respect to the original frequency f of FIG. The interval t ₁ according to FIG. 2 is extended by a time t ₂ . Within this time, the voltage increases in each case to the nominal voltage and is held for a predetermined time t ₃ at this level before the next polarity change begins.

Characterized in that at each polarity change, the nominal voltage is actually reached in its full height and t _{3 held} at this level over a certain predetermined time, it is the electronics of the detonator possible to receive the signals properly and identify. The invention thus enables a secure and trouble-free signal transmission between the fuze triggering device and the detonators and thus ensures that each detonator is triggered at the intended time.

Claims (6)

1. Method for triggering detonators, in particular blasting detonators, wherein the detonators communicate with the detonator-triggering device by way of a line of a large length and in addition loads are supplied with electrical energy by way of the line and on account of the additional loads and the line length a high capacitive reactance occurs during the transmission of signals that are generated by means of potential change, wherein before the detonators are triggered, the capacitances that are present are charged by applying a direct voltage to the line to such a level that at least up to the time of triggering the last detonator during the transmission of signals that are generated by means of potential changes the capacitances are not charged in a way caused by charge losses.
2. Method according to claim 1, characterised in that in order to charge the capacitances a higher voltage is applied over a predeterminable time than that provided to generate the signals.
3. Method according to claim 1 or 2, characterised in that the increased voltage lies below a critical voltage for triggering a detonator.
4. Method according to one of claims 1 to 3, characterised in that the capacitive reactance is ascertained and as a function of its magnitude the direct voltage that is at least required to charge the capacitances is determined.
5. Method according to one of claims 1 to 4, characterised in that the capacitively caused low-pass filter effect of the line and of the additional loads that are connected on the signals that are generated by the detonator-triggering device is compensated for by a frequency of the potential changes that is matched to the capacitive reactance.
6. Method according to claim 5, characterised in that the frequency of the potential changes is selected so that the level of the required signal voltage is reached and maintained over a predeterminable time within a period.

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