JPS5852191B2 - P-wave/S-wave logging source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a source for PS logging used in a well containing borehole water, and more specifically, the present invention relates to a source for PS logging used in a well containing borehole water. This relates to the source for P-wave/S-wave logging, which is made to move rapidly, generate compressive force in the hole along with a strong backward force, and radiate P-waves at the same time as S-waves.

PS logging is a method of directly measuring underground elastic wave velocities, that is, P-wave (longitudinal wave) velocity and S-wave (transverse wave) velocity, in a hole bowl, and investigating the elastic properties of the underground from these values.

In recent years, highly accurate elastic wave data deep underground has been required from fields such as earthquake engineering and resource engineering.

On the other hand, the P-wave logging device is the only device that has become widespread as a practical device for measuring elastic waves deep underground.

This is because P waves propagate at the fastest speed among elastic waves, so it is relatively easy to confirm, whereas S waves have a waveform that is easily distorted by waves that propagate faster (mainly P waves). This is because it is difficult.

In response to this, a method has been proposed that can suppress the radiation of P waves and effectively radiate only S waves (Japanese Patent Laid-Open No. 54
(Refer to Publication No.-107401).

This applies a source force in one direction perpendicular to the hole axis to the hole wall surface as positive and negative indirect pressure through the water in the hole by operating a motion mechanism within the source body, thereby applying a source force in a direction perpendicular to the source force. It radiates S-waves with excellent directivity.

This method is certainly an excellent method for suppressing the generation of P waves and radiating pure S waves.

However, in order to actually accurately investigate the elastic properties of the underground, it is necessary to observe P waves and S waves simultaneously.

That is, this is the case where physical quantities based on P waves and S waves are measured and then combined to obtain another factor, such as Poisson's ratio.

If a source that radiates only S waves is used, a separate source for P waves should be installed at a different position in the series of sondes, or a sonde for P waves should be lowered and observed separately from the S wave observation. It will have to be done.

However, with such a configuration, there is no guarantee that P waves and S waves can be excited at the same location, and the deeper the depth, the more difficult it becomes to excite at the same location. Because this is done at the source of the data, there remain problems with reliability and error evaluation as data of separate physical quantities obtained by combining both observed quantities.

Therefore, P waves and S waves can be radiated at the same time, and the generated P waves and S waves do not have an extreme difference in amplitude.
In other words, it is desired to develop a source that prevents the S waves from being hidden due to the amplitude of the P waves being too large.

The present invention has been made in view of the actual state of the prior art and various demands therefor, and its purpose is to be able to simultaneously generate P waves and S waves in a hole, and to generate P waves during observation. The objective is to provide a source that allows good separation of the and S waves and allows easy confirmation of both waves.

Hereinafter, the present invention will be explained in detail based on the drawings.

First, the basic configuration and operating principle of the present invention will be explained.

As shown in FIG. 1, the source 1 is used in a borehole 3 with borehole water 2. As shown in FIG.

Inside the source 1 is a rigid body 4 that is movable in one direction, and a collision plate 5 that faces the end face of the rigid body 4 at a distance is provided so as to be able to protrude outward.

Note that the inside of the source 1 is surrounded by a rubber seal 6 and is liquid-tight.

Now, in such a structure, the rigid body 4 is moved in the X direction and is caused to collide with the collided plate 5.

Then, due to this collision, the impacted plate 5 moves impulsively in the X direction, exerting force only on the hole wall in the X direction via the hole water 2, and at the same time, within the hole, a force is generated by the amount of movement of the impacted plate 5. Pressure increases.

Therefore, at observation points in the hole axis direction that are located at a large distance compared to the hole diameter, it is possible to observe not only S waves caused by forces in the X direction, but also P waves caused by impulsive pressure changes. It is.

With this configuration, firstly, since the collision is used, the generated force becomes a simple pulse-like force, which improves the separation of the P wave and S wave on the recording paper, and secondly, the collision If the direction is reversed, only the S waves will be reversed, which is expected to have the effect of making it easier to confirm the S waves.

The rigid body 4 within the source 1 is typically driven by electromagnetic forces, as shown in FIG.

That is, a magnetic yoke 11 containing coils 10a and 10b is attached to the housing side, and the rigid body 4 consists of a cylindrical magnetic plunger 12 and collision bodies 13a and 13b attached to both ends thereof.

Coil 10a. 10b forms a so-called bidirectional solenoid, and by selecting the coil through which current flows with the switch 14, the rigid body 4 can be driven in either the X direction or the opposite -X direction.

Details of source 1 are shown in FIGS. 3 and 4.

The cylindrical housing 20 is provided with a through hole in a direction perpendicular to its central axis, and the rigid body 4 and the like are housed inside the through hole.

A pure iron yoke 11 is attached to the inner peripheral wall of the through hole. a, 1
lb and the coils 10a and 10b incorporated therein are located.

A rigid body 4 consisting of a pure iron plunger 12 and collision bodies 13a and 13b is supported by spiral leaf springs 21a and 21b so as to be movable in a non-contact manner along the central axis of the through hole.

A spiral leaf spring 21a. 21b is fixed by CIJ songs 2 and 23.

In addition, collision plates 5a and 5b are positioned so as to face both ends of the rigid body 4 with a space therebetween, and their outsides are covered with rubber waterproof sealing materials 6a and 6b.
, the presser fitting 25 and the screw 26 fix the housing 20.
Fixed.

Note that the reference numeral 27 is an O-ring seal.

Collision plate 5a. Since the inner end portion of 5b is in contact with the fixed metal 24, it can only protrude outward and will not be displaced inward.

In addition, since it is covered with rubber waterproof sealing materials 6a and 5b, even if the collided plates 5a and sb protrude outward due to a collision with the rigid body 4, water in the hole will not infiltrate into the inside of the housing 20. .

Such sources are inserted into the borehole as a series of sondes along with receivers and the like.

Figure 5 shows an example of actual application to P-wave and S-wave logging.

From below, a weight 30 for facilitating the insertion of the sonde 29
, two stray type geophones 31 and 32 each incorporating a vertical motion receiving element for P waves and a horizontal motion receiving element for S wave phase.
, a filter tube 33 for blocking in-hole sound waves that prevent the reception of S waves, a preamplifier 34, a damper 35 for preventing damage waves propagating through the sonde body, a source 36 according to the present invention, and driving the source 36. The source drivers 37 are successive in this order, and the winch 40 is connected via the sheave 39.
It is raised and lowered to a predetermined position within the well 3.

On the ground surface, there is a gas cylinder 41. for supplying gas to the filter tube 33. A control device 42 and a recording device (for example, an electromagnetic oscilloscope) 43 are arranged.

A block diagram of the measurement system is shown in Figure 6.

A measurement system control circuit 50 controls the vibration direction N or R and input switches 51, 52, and 53.

Power is supplied from the DC high voltage source 54 to the source driver 3T.

A trigger pulse is applied to the root driver 37 by the trigger pulse source 55 to drive the rigid body 4 in a predetermined N or R direction to collide with the colliding plate 5 and radiate S waves and P waves. Start the six channel waveform storage device 56 with a pulse.

The radiated S waves and P waves are detected by stray geophones 31 and 32, amplified by a preamplifier, and sent to a 6-channel waveform storage device 56 on the ground surface.The radiated S-waves and P-waves are recorded on recording paper by an 8-channel electromagnetic oscilloscope 43. A record is taken along with the mark.

An example is shown in FIG. P waves and S waves are recorded with approximately the same amplitude.

The S wave can be reliably confirmed by changing the direction of vibration (N and R) since the waveform is reversed.

Analyzing the velocity distribution of P waves and S waves from these data is performed using the same conventional method.

In order to further enhance the effect of the device of the present invention, as described above, the collision plate 5 is arranged so as to come into contact with a member that serves as a stopper so as not to be displaced inwardly, and
The colliding plate 5 is made of a rigid material such as metal, and the sealing member that makes the colliding plate 5 and the housing liquid-tight is:
It is preferable to use a member having a spring constant that is weak enough not to affect the collision between the rigid body 4 and the colliding plate 5.

Since the present invention is configured as described above, P waves and S waves can be radiated at the same position, and the observed values of both can be combined to provide highly reliable and directional data of another physical quantity. Both the S wave generated by the force and the P wave generated by the compressive force as a whole have their amplitude directivity peaks on the hole axis, and therefore a full-scale sonde incorporating the source and the geophone into a single sonde. It is very advantageous as a well-logging device, and if the direction of the collision is reversed, the waveform of the S wave will be reversed, but the waveform of the P wave will not be reversed, making it easy to confirm the S wave. Therefore, the generated force has a pulse-like waveform in terms of time, and the pulse width is simple and narrow, so the P wave and S wave can be separated well on recording paper, and it generates a strong force despite its small size. It is possible to achieve superior effects that are not available in the prior art.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the operating principle of the present invention, Fig. 2 is an explanatory diagram showing one driving principle of the rigid body inside the root, Fig. 3 is a sectional view of one embodiment of the root, and Fig. 4 is the second example. Partially broken perspective view, No. 5
The figure is an explanatory diagram of the usage state, Figure 6 is a block diagram of the measurement system,
FIG. 7 is a diagram showing an example of the obtained waveform recording. 1... Root, 3... Koi, 4...
... Rigid body, 5 ... Collided plate.

Claims (1)

[Claims] 1. A movable rigid body provided at the center of the root blade axis perpendicular to the central axis direction of the logging sonde so as to be movable along the root blade axis, and a space between the end faces of the rigid body at both ends of the vibration force axis. A source for P-wave/S-wave logging, characterized in that it is provided with a plate to be collided and provided so as to be able to protrude outward, facing each other at a distance, and to be able to collide with the plate to be collided by driving the rigid body.