JPS61186694A - Measurement of depth of bore hole - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is useful for geological surveys in which borehole logging devices, borehole wall observation televisions, water sampling samplers, etc. are suspended by cables into boreholes. The present invention relates to a borehole depth measurement method for measuring the depth of a layer device.

[Conventional technology]

When conducting a geological survey by suspending a borehole logging device, borehole wall observation TV, water sampling sampler, etc. into a borehole (poling hole) using a cable, the depth position of the logging device is as follows:
Conventionally, it has been common to measure depth using the rotational speed of a pulley.

FIG. 2 is a diagram for explaining the conventional borehole depth measurement method, in which 1 is a borehole, 2 is a logging device, 3 is a pulley, 4 is a cable drum, and 5 is a logging data logger.
are shown respectively. In FIG. 2, when the depth of the logging device 3 is measured based on the rotational speed of the pulley 3, a depth measurement error occurs due to slippage of the pulley 3 and the like. Therefore,
Hanging is a method of correcting errors caused by slippage of the pulley 3. The method used is to mark the cable at regular intervals. In the case of investigating civil engineering structures, the depth is up to about 300 m, so this method can also determine the depth with a measurement accuracy of about ±1 m, which is sufficient for practical use. It was obtained.

[Problem that the invention seeks to solve]

However, recently, survey polling for civil engineering at a depth of 1,000 to 1,500 m has become necessary. However, depth 10
00m class, the conventional method described above stretches the cable itself due to its own weight, etc.
There is a problem that it becomes impossible to grasp the exact depth.

SUMMARY OF THE INVENTION An object of the present invention is to provide a borehole depth measurement method that eliminates the above-mentioned drawbacks and can accurately measure the depth even in deep poling holes.

[Means for solving problems]

To this end, the borehole depth measurement method of the present invention is a borehole depth measurement method that calculates the depth by measuring the propagation time of a signal in the borehole. Let me reply with
This method is characterized by measuring the propagation time of the signal from the time of transmission to the time of reply, and calculating the depth from the borehole entrance to the measurement point based on the propagation time.

[Effect]

In the borehole depth measurement method of the present invention, the depth is calculated by measuring the propagation time of the signal, so even if a cable for suspending a logging device etc. is stretched into the borehole, the actual depth will be calculated regardless of the length of the cable. A measurement signal corresponding to the
Depth values can be obtained with high accuracy. In addition, the configuration for this purpose can be made compact because it only requires electrical means such as signal transmitting means, detecting means, and calculating means.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining an embodiment of the borehole depth measuring method of the present invention. In Figure 1, 1 is a borehole, 2 is a well logging device, 3 is a pulley, 4 is a cable drum, 5 is a logging data logger, 16 is a signal transmission time measuring device, 7 is a time difference measuring device, 8 is a guided electromagnetic wave Detector, 9 is a signal transmitter, 10 is a sound wave transmitter, 1) is a sound wave detector, 12
Reference numeral 13 indicates a sound wave transmitting device, and 13 indicates a sound wave transmission time measuring device.

In the example shown in Fig. 1 (a1), a conductive wire (or optical fiber, ultrasonic wire) is provided in the cable for depth measurement, and a signal transmission time measuring device 6 is provided for calculating the elongation length of the cable in the borehole 1. Furthermore, by attaching a mark for cable length measurement to the cable, the extension length of the cable within the borehole 1 is calculated, the cable length is corrected 1, and the accurate depth is measured.

In FIG. 1(a), the signal transmission time measuring device 6 transmits an electric pulse signal (or optical signal, or ultrasonic signal) and detects a signal reflected (U-turn) near the well logging device 22. By doing so, the reciprocating transmission time is measured and the length of extension of the cable within the borehole 1 is calculated. That is, the transmission time measured when the cable is fully wrapped around the cable drum 4 is compared with the transmission time measured when the logging device 2 is actually suspended in the borehole 1, and the difference is calculated. Based on this, calculate the length of cable extension inside borehole 1.

Therefore, the length of the cable inside the borehole 1 is measured by equally spaced marks attached to the cable in advance, and the length is corrected by the elongation length calculated by the signal transmission time measuring device 6. Accurate depth is required.

The example shown in Fig. 1 (b1) uses a time difference measuring device 7, a guided electromagnetic wave detector 8, and a signal transmitter 9 to calculate the round trip transmission time of the signal in the cable in the borehole, similar to the example shown in Fig. 1 (a1). This is to measure the depth of the well logging device 2.

In FIG. 1(b), the signal transmitting device 9 transmits an electric pulse signal to the well logging device 2 through a cable, and the induced electromagnetic wave detector 8 detects electromagnetic waves generated by the electric pulse signal passing through the cable. The time difference measuring device 7 measures the time difference between the electromagnetic waves detected by the induced electromagnetic wave detector 8, and calculates the distance from this measured value. That is, when an electric pulse signal is transmitted from the signal transmitting device 9 to the well logging device 2, electromagnetic waves are detected by the induced electromagnetic wave detector 8 at the time of transmission and when the electric pulse signal is reflected near the well logging device 2. be done. Then, the time difference measuring device 7 measures the round trip transmission time of the electric pulse signal from the guided electromagnetic wave detector 8 to the vicinity of the well logging device 2, and based on this round trip transmission time, the guided electromagnetic wave detector 8
The depth from the depth to the vicinity of the well logging device 2 is calculated.

The propagation time in this case is theoretically independent of cable elongation and depends on the length including elongation, so the cable length including cable elongation can be measured, and as a result, accurate depth measurement as described above is possible. It becomes possible. That is, in the cross section of a coaxial cable, if the radius of the core is a, the radius of the dielectric is ε, and the dielectric constant is ε, then when the length l becomes l+Δl, the following equation holds true.

2tta"1m2tca" DJ+Δl) Similarly, a' is the radius of the core when the cable is stretched, and b' is the radius of the dielectric when the cable is stretched.

Here, the electric constant C of the coaxial cable is L = 0.
4593 log+o(b/a)C=24.13t/
Since log+o(b/a), these are determined by b8. Therefore, when a cable of length l is stretched by Δl (
The radius of the dielectric body/(radius of the core) is as follows, and the electric constant C does not change. Therefore, the propagation velocity V does not change even if the cable is stretched.

In other words, for example, a 990 m long cable can be extended to 1000 m.
m, a propagation delay time of 1000 m will be observed.

1st) 1fflfC) [ffl The example shown is the sound wave transmitter 1
0, the sound wave propagation time in the water filling the borehole 1 is measured using the sound wave detector 1), the sound wave transmission device 12, and the sound wave propagation time measuring device 13, and the depth to the vicinity of the logging device 2 is determined. It is calculated.

In FIG. 1 (C1, the sound wave transmitter 10 is connected to the well logging device 2
It is installed directly above the sound wave generator 12 and is activated by an electric signal sent from the sound wave generator 12 to emit a sound wave. The sound wave detector 1) is installed at the entrance of the borehole 1 and is a sensor that detects the sound waves emitted by the sound wave transmitter 10. The sound wave propagation time is measured from when the electrical signal is transmitted, that is, from when the sound wave transmitter 10 is activated and the sound wave is transmitted until the sound wave is detected by the sound wave detector 1), and based on the measured value, the well logging device 2 This is to calculate the depth to the vicinity.

It should be noted that the present invention is not limited to the example explained in FIG. Needless to say.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the transmission time is measured using electrical signals, optical signals, sound wave signals, etc., and the depth to the well logging device is measured.
It is possible to accurately measure the depth of a well logging device suspended to a depth of m class, regardless of the length of the cable.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining an embodiment of the borehole depth measurement method of the present invention, and FIG. 2 is a diagram for explaining a conventional borehole depth measurement method. DESCRIPTION OF SYMBOLS 1... Borehole, 2... Well logging device, 3... Pulley, 4... Cable drum, 5... Well logging data logger 16... Signal transmission time measuring device, 7... - Time difference measuring device, 8... Guided electromagnetic wave detector, 9... Signal transmitting device, 10... Sound wave transmitter, 1)... Sound wave detector, 12... Sound wave transmitting device, 13. ...Sound wave propagation time measuring device. Patent applicant: Shimizu Corporation Representative Patent Attorney Ryukichi Abe Figure 1 (phantom 1st cause fl))

Claims (4)

[Claims] (1) A borehole depth measurement method that calculates the depth by measuring the signal propagation time in the borehole, in which a signal is transmitted from the borehole entrance to the measurement point and sent back at the measurement point, and from the time of transmission to the time of reply. A borehole depth measurement method characterized by measuring the propagation time of a signal from the borehole entrance to the measurement point and calculating the depth from the borehole entrance to the measurement point based on the propagation time. (2) Measure the round-trip propagation time of the signal over the entire length of the cable when the cable is suspended in the borehole and when the cable is fully wound, and calculate the elongated length of the cable inside the borehole from the difference between the two round-trip propagation times. The method for measuring the depth of a borehole according to claim 1, wherein the measured depth is corrected based on the cable extension length. (3) By detecting the electromagnetic waves generated by the electric pulse signal passing through the cable at the borehole entrance, the round trip propagation time of the electric pulse signal from the borehole entrance to the measurement point is measured, and the depth is calculated. A borehole depth measuring method according to claim (1). (4) A sound wave transmitting means that is activated by a signal sent from outside the borehole to transmit a sound wave is provided at the measurement point, and the depth is calculated based on the time it takes for the sound wave to reach the entrance of the borehole. The borehole depth measurement method described in paragraph (1).