JPS6367156B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the position of a pig that is run within a pipeline for purposes such as inspection.

For example, in the pipeline of an oil production system, in order to inspect the pipeline, a pig equipped with an inspection device is run along with the fluid flowing inside the pipeline, but this pig is completely separated from the outside. Therefore, it is necessary to store the information detected by the inspection device internally, and also store position information along with the information, and therefore the pig itself needs to detect its position.

As a device that can be used to detect the position of such a pig, there has been a known distance/position measuring device mounted on the pig that uses sound waves or ultrasonic waves. The transmitter and receiver are integrated, and increasing the power to widen the measurement range would make the entire device large and heavy, making it impossible to mount it on a pig. It is also possible to measure the pig's position from the outside, but in this case it is necessary to constantly convey position information to the pig, which poses a difficult problem.

Furthermore, in order to detect the position of a pig in such a pipeline, when pressure waves are transmitted through the pipeline, the reflected waves are generated not only from the pig but also from bends in the pipe, making it difficult to make accurate measurements. There is also the problem of not being able to do so.

The present invention solves these problems and allows the position of an inspection pig in a pipeline to be determined with high precision using a device with a simple configuration, and also within the pig itself, without installing a large measuring device on the pig. The aim is to provide a detectable method.

In order to achieve the above object, the position detection method of the present invention includes an oscillating means for generating and propagating a positive or negative pressure impulse to the fluid in the pipeline, in which the inspection pig runs.
A pressure pickup is installed to detect the reflected wave of the pressure impulse reflected back from an inspection pig or a curved part of the pipe in the pipeline, and the detection signal of the reflected wave detected by the pressure pickup is By subtracting the reflected wave detected when there is no pig in the pipeline with the reference signal, the reflected wave from the pig which has canceled the reflected wave in the pipeline is detected, and when the reflected wave is detected, the oscillation means oscillates again. to generate pressure impulses, and while repeating this, the pressure impulses are received by a pressure sensor provided on the inspection pig and the time interval is measured, thereby detecting the position of the inspection pig. This is a characteristic feature.

The method of the present invention will be explained in more detail below with reference to the drawings.

FIG. 1 shows the configuration of an apparatus used to carry out the present invention, in which 1 is a pipeline, 2 is a pig launcher, 3 is an inspection pig that runs through the pipeline and performs appropriate inspections, and 4 is a fluid Solenoid valve for creating a negative pressure impulse with a small outflow,
Reference numeral 5 indicates a fluid receiver for containing the fluid that has flowed out, and reference numeral 6 indicates a pressure pickup for detecting pressure changes.

A control section that processes the detection signal obtained by the pressure pickup 6 and outputs a control signal for opening and closing the solenoid valve 4 for a short time is connected to the pressure pickup 6.
an amplifier that amplifies the detection signal from the pressure pickup 6, and a wave that generates the impulse in advance in the absence of the pig 3 in the pipeline and stores the reflected wave obtained by the pressure pickup 6 at that time as a reference signal. a memory; a wave memory for temporarily storing the output signal of the amplifier;
A subtraction circuit extracts only the reflected wave from the inspection pig 3, which eliminates the reflected wave in the pipeline by subtracting between the signals stored in both wave memories, and a solenoid valve 4 based on the reflected wave. It is equipped with a solenoid valve drive circuit that outputs a control signal to open the valve for a short period of time.

In addition to means for performing appropriate inspection, the inspection pig 3 also includes a pressure sensor 11 for detecting the pressure impulse as a pulse signal, and a low-pass filter 12 for passing only the pulse signal.
and a time interval coefficient unit 13 that detects the time interval of the passing pulse signal as the position of the pig 3.

In order to detect the position of the pig 3 with the device having the above configuration, it is necessary to open and close the solenoid valve 4 once by any means to generate a negative pressure impulse. The pig 3 operates at time intervals corresponding to the distance up to 3, and the time intervals of the pressure impulses generated accordingly are detected by the pig 3, and the position of the pig 3 is determined from the time intervals.

To explain more specifically, first, when the first pressure impulse is generated, in addition to the pressure impulse 21, as shown in FIG. A detection signal having pulses 22, 23 is detected by the pressure pickup 6, amplified by an amplifier and then stored in a wave memory. Prior to this, the wave memory contains the second
As shown in Figure A, the reference signal includes a reflected wave detected by the pressure pickup in the absence of the pig 3 in the pipeline, that is, a pressure impulse 21 and reflected pulses 23 and 24 resulting from the pressure impulse 21 being reflected at a bend in the pipe, etc. is memorized. Therefore, after subtracting these detection signals and the reference signal in the subtraction circuit in the next stage, waveform shaping is performed by appropriate means, and as shown in FIG. By erasing , an output signal consisting only of the reflected pulse 22 from the pig 3 is obtained. Therefore, when a control signal for driving the solenoid valve 4 is output from the solenoid valve drive circuit using this output signal, the solenoid valve 4 is operated again and a new negative pressure impulse is generated, thereby causing the above-mentioned The above operations are repeated continuously in sequence, so that the pressure impulses occur continuously at time intervals corresponding to the distance from the pressure pickup 6 to the pig 3.

In addition, when the pig 3 travels through the pipeline, among the reflected pulses 23 and 24 generated at curved parts of the pipeline as shown in FIG. does not occur, and therefore it is not necessarily possible to obtain only the reflected wave from Pig 3 as the output of the subtraction circuit, but since the first pulse signal that appears always corresponds to the reflected wave from Pig 3, subsequent pulse signals You can configure it to ignore it.

Each time the pressure impulse generated in this way reaches the pig 3, it is sent to the time interval counter 13 via the pressure sensor 11 and the low-pass filter 12 in the pig 3;
3, the distance between the pig 3 and the pressure pickup 6 is calculated from the time interval between impulses.

The above position detection can be performed even while the pig 3 is moving, and therefore the position is continuously detected.

As the oscillation means for generating pressure impulses for detecting the position of the pig, oscillation means for generating positive pressure impulses can also be used, and in that case, the position is detected in the same manner as described above. FIG. 3 shows a device for generating the positive pressure impulse, in which a high-pressure pump unit 35 is connected to the pig launcher 32 via a solenoid valve 33, and an electromagnetic pump unit 35 is connected to the pig launcher 32 via a solenoid valve 33. The valve 33 is opened only for a short period of time to allow a small amount of fluid to be forced into the pig launcher 32 from the high pressure pump unit 35. In the figure, 36 is a pump, 37 is a motor for driving it, 38 is a pressure setting valve, and 39 and 40 are fluid receivers, respectively.

As is clear from the above detailed description, according to the method of the present invention, the position of the inspection pig in the pipeline can be continuously detected by the pig itself, and furthermore, Since the reflected waves caused by the noise are eliminated and the pressure impulses are oscillated at time intervals corresponding to the position of the pig, the position of the pig can be detected accurately.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the apparatus used to carry out the present invention, FIGS. 2A to 2C are diagrams showing waveforms of signals at each part thereof, and FIG. 3 is another block diagram of the oscillation means. DESCRIPTION OF SYMBOLS 1...Pipeline, 3...Pig, 6...Pressure pick-up, 11...Pressure sensor, 13...Time interval counter, 21...Pressure impulse, 22, 23, 24...
reflected pulse.

Claims (1)

[Claims] In the pipeline with an inspection pig running inside,
An oscillation means for generating and propagating positive or negative pressure impulses in the fluid in the pipeline, and detecting reflected waves of the pressure impulses reflected back from inspection pigs, pipe bends, etc. in the pipeline. A pressure pickup is provided, and the detection signal of the reflected wave detected by the pressure pickup is subtracted from the reference signal of the reflected wave detected beforehand in the absence of a pig in the pipeline.
Detecting a reflected wave from the pig that has eliminated the reflected wave from the pipeline, and when the reflected wave is detected, generating a pressure impulse again by the oscillation means,
Inspection in a pipeline characterized in that while repeating this, the pressure impulses are received by a pressure sensor provided on the inspection pig and the time interval is measured, thereby detecting the position of the inspection pig. How to detect the position of a commercial pig.