DE1623111B2 - GEOPHYSICAL DEVICE FOR MEASURING UNDERGROUND CAVERNS - Google Patents

Description

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The invention relates to a geophysical device for surveying underground caverns by radiation with a measuring probe that can be lowered into the cavern, the measuring head of which by a Motor rotatable in steps or continuously around its vertical axis and with one or more transmission devices for emitting radiation and one or more receiving devices for the returning radiation is provided and its measuring head against the vertical axis of the measuring probe can be tilted.

In the extraction of salt and other water-soluble minerals using the extraction process a mud circuit is set up via a double-cased borehole or via two boreholes, which creates constantly growing cavities at the bottom of the borehole. The storages of Poorly soluble or water-insoluble geological layers cause the excavated cavities take on a very irregular shape. Often form well up behind the piping reaching chimneys, which can even cause the danger of a collapse of the earth's surface. There too great a horizontal extension of a cavity can cause a break-in Observe mining safety regulations when solubilising. By precisely measuring a Caverns, especially including the cavern sky, could identify a risk of collapse at an early stage will.

After it turned out that caverns extracted in salty rocks are a very economical one Represent storage for gaseous or liquid substances, e.g. light hydrocarbons, is the Knowledge of the exact spatial shape of underground cavities has become even more important.

For the calculation of the storage capacity as well as for the control of losses, the volume of the room be known. Methods are known with which the cavities are echometric by means of ultrasonic pulses be measured. The measuring probes lowered into the cavity for this purpose preferably have Sound transducer for sending and receiving with a horizontal directional characteristic. For recording a The all-round view echogram scans the cavity at certain horizontal angular steps. The probe measuring heads used have a larger number evenly on the circumference of the measuring head distributed transducers that are used one after the other through a remote-controlled switch to be brought; the further development led to a rotatable around the vertical axis of the probe Probe measuring head with only one transmitting and receiving device (USA patent specification 2 825 044).

With these known probe designs, the horizontal echo measurement delivers good results if the reflective surface does not deviate too much from the vertical. On the other hand, if the surface is strong inclined or even parallel to the horizontal, as is the case with the ceiling or the floor, for example a salt cavern can be the case, either echoes of different sizes and shapes arise and running time or long contiguous oscillation trains. The evaluation of such echoes is great difficult, and this often means that it is not possible to give a reliable indication of the delimitation of such cavities will. Another difficulty with measuring horizontally occurs when measuring from the ceiling Larger pieces of rock hanging down or lying on the ground prevent sound from passing through to the im Prevent acoustic shadow lying cavity wall.

In order to avoid the disadvantages mentioned, lowerable ones belonging to the state of the art are already available Probes with a rotatable measuring head have been used, in addition to or instead of a horizontal transducer contains two transducers, each directed at 45 ° upwards and downwards. With this arrangement it is also only partially possible to identify the shortcomings of the horizontal measurement in the area of the ceiling and Level the bottom of the cavity. In particular for a control of whether and to what extent behind the to the The piping leading to the cavern consists of a chimney-like continuation of the cavity, for example Probe construction not suitable (U.S. Patent 2,825,044).

Furthermore, the technique of surveying boreholes is supported by those listed below in printed publications:

(1) German Auslegeschrift 1 085 978;

(2) German Auslegeschrift 1 082 994;

(3) Swiss patent specification 422181;

(4) French patent specification 1189903;

(5) Erdöl-Zeitschrift, Volume 78, October 1962,
P. 587;

(6) VDI-Nachrichten, No. 15, July 20, 1957, p. 4;

(7) The Oil and Gas Journal, Sept. 16, 1968, pp. 76-78 (not prepublished);

(8) U.S. Patent 2,908,863;

(9) German utility model 1 786 877;

(10) German Patent 169 154;

(11) German patent specification 723 764;

(12) Swiss patent specification 183 782;

(13) German Auslegeschrift 1130 089;

(14) U.S. Patent 3,286,163;

(15) U.S. Patent 3,227,804;

(16) U.S. Patent 2,942,111;

(17) U.S. Patent 2,909,661;

(18) U.S. Patent 2,688,095;

(19) U.S. Patent 3,100,259;

(20) Hobby, 3/1961, pp. 152-157;

(21) U.S. Patent 2,825,044;

(22) German interpretation document 1102 306.

The large number of proposals for the implementation of methods or for the use of devices does not reveal any technical teaching, however, underground caverns according to the invention Proposal to measure.

The documents (1), (2), (4) and (5) relate to devices for pressing probes or probe parts on borehole walls in order to eliminate the influence of the borehole fluid on the measurement result or falsifications that result from the penetration of mud into the pending formations to keep low.

In the publication (3) a rigid probe body is described. The only in a narrow range of angles possible change in the direction of radiation or reception in the rigid probe body located transmitting and receiving device serves the sole purpose of the different diffraction angles to balance the materials to be examined.

In the other publications (9) to (12) and (22) are rotatable transmitting and / or receiving devices for electromagnetic waves or radioactive radiation (13). The rotation of these elements (including loop antennas) are preferably used either to decouple these devices from one another or to optimize them Adjusting the same to the direction of the electromagnetic or radioactive to be received Field.

In (14) a device is described which belongs to a group of borehole logging devices that also are equipped with rigid probe bodies. The transmitting and / or receiving devices are only arranged to be pivotable to a limited extent, however, this can in no way be used, for. B. the chimney-like cavity continuation be measured behind a piping above the pipe shoe.

The exact determination of the cavity boundaries excluding the stated disadvantages of the stand the technology can be achieved according to the invention by a device that is characterized is that the measuring head during the measuring process by means of a pulse-controlled stepping mechanism in Control part of the probe continuously or in steps a tilting movement until reaching the horizontal Location.

A measuring head according to the invention preferably contains one horizontally and one vertically directed Sound transducer and performs a rotary movement around the vertical probe axis by means of an additional Drive device through a tilting movement of up to 90 ° against the vertical probe axis. With the vertical converter, the angular range from the vertical to the horizontal and the angular range above the horizontal is detected with the horizontal converter. With a pulse controlled Stepping mechanism in the control section of the probe can either rotate or tilt the the transducer containing the measuring head are effected.

The combination of the rotary movement and the tilting movement of the measuring head results in two Types of implementation for the measurement of caverns by means of the device according to the invention. After lowering the measuring probe into the cavity to be measured, the measuring head is in a certain azimuthal angular position rotated, for example in north direction, and then gradually or continuously tilted from vertical to horizontal. That registered by means of ultrasonic impulses Echogram corresponds to one half of a vertical section through the cavity. After that, will the measuring head is pivoted in the horizontal position into the following azimuthal angular position and then up to tilted back to vertical. When using this type of procedure one obtains one of the number of the azimuthal Angular positions corresponding number of vertical echograms, which are used as the basis for production serve of vertical sections through the cavity.

In another implementation of the method, the measuring head is in a certain angular position tilted between the vertical and the horizontal and then gradually rotated 360 ° around the vertical probe axis rotated. The echograms registered by means of ultrasonic pulses become the individual distance values taken from the same angle of rotation position and in the associated Transfer vertical section. If the measuring head is rotated in 24 angular steps, up to 12 Vertical sections are shown.

A further embodiment of the measuring head according to the invention is the installation of an optical one Transmitter and a photographic camera instead of the acoustic transducer. Will be used with every possible Rotation and tilt angle position of the measuring head made a photographic recording, this results in a complete mapping of the cavity delimitation.

Another embodiment can be advantageous for detecting a chimney-like cavity continuation can be used behind piping above the pipe shoe. In the tiltable according to the invention Instead of an acoustic or optical transmission device, the measuring head is a radioactive radiation source provided in the form of small radioactive floats. Is the measuring head the one in the cavity If the lowered measuring probe emerges from the piping, it is tilted into the horizontal position.

A small number of the radioactive floats are now activated by a suitable remote-controlled device released, which rise in the liquid located in the cavity and are highest Fix the point of the hollow limitation on the outer piping. By additional simultaneous By rotating the measuring head, the floating bodies can be distributed on all sides in the annular space around the pipework will. A detector located in the measuring probe can then be used when driving up the measuring probe with tilted back measuring head determined the depth of the radioactive floating bodies will.

For the real subclaims 2 to 5 patent protection is only given in connection with the main claim desired.

Several embodiments according to the invention are shown in the drawing and are described below described in more detail. It shows

F i g. 1 a complete measuring probe during a measuring process,

F i g. 2 a tipped probe head with two transducers,

F i g. 3 a tilted measuring head with an optical transmitting and receiving device and

F i g. 4 a measuring probe with a tipped measuring head containing a radioactive transmitter.

In Fig. 1 is a measuring probe 1 through a piping 2 into a cavity 3 filled with liquid, which was created by leaching the salt rock 5, shown lowered. The probe 1 consists of the cable head 6, an electronic part 7, and a tilting device 10, which by means of a pulse-controlled Stepping mechanism can be moved gradually or continuously. In the measuring head 8 there is a sound transducer 11 which emits and receives in the axial direction and a sound transducer 11 in a radial direction Direction of radiating and receiving sound transducer 12. The emitted ultrasonic impulses 13 are reflected on the rock 5 delimiting the cavity and from the corresponding Transducers received again. By gradually tilting the measuring head 8 in FIG. 2 keys the sound transducer 11 the cavity delimitation in the angular range from the vertical to the horizontal, the sound transducer 12 delimits the cavity in the angular range above the horizontal away.

F i g. 3 shows a measuring head with an optical transmitting and receiving device. In the measuring head 8 there is a flash lamp 14 and a photographic camera 15. This device can preferably the wall and the ceiling area of the cavity delimitation are mapped.

In Fig. 4, the measuring head 8 according to the invention for sending out radioactive floating bodies for Proof of a cavity continuation 16 behind a piping 2 above the pipe shoe 17 is used. During this measuring process, the probe 1 is lowered through the inner tube 1 into the cavity. If the measuring head 8 is below the tubular shoe 17, the measuring head 8 is in the horizontal position Tilted position. By a remotely operated lock 18 are small floating bodies 19 that a contain suitable radioactive material, released. At the same time, the probe rotates around its vertical axis rotated, and the rising floats collect in the annular cavity continuation 21 behind the piping. The measuring head 8 is now tilted back into the vertical position and then opened the probe. With a detector 22 built into the probe, for example a scintillometer, the depth of the radioactive float can now be determined.

The device according to the invention is thus characterized by a very versatile application the end. Already by probing the shape of the cavity delimitation can largely be determined, in particular in the area of the floor and the ceiling. Also often troublesome Cavity continuations behind a piping leading into the cavity can with high Accuracy can be determined.

1 sheet of drawings

Claims (5)

Patent claims: 1. Geophysical device for measuring underground caverns by radiation with a measuring probe that can be lowered into the cavern, the measuring head of which is driven by a motor in Steps or continuously rotatable around its vertical axis and with one or more Sen- ίο de devices for emitting radiation and one or more receiving devices is provided for the returning radiation and its measuring head against the vertical axis the measuring probe can be inclined, characterized in that the measuring head (8) during the measuring process by means of a pulse-controlled Stepping mechanism in the control part of the probe continuously or in steps of a tilting movement until the horizontal position is reached. 2. Apparatus according to claim 1, characterized in that in which executing the tilting movement Measuring head (8) one or more acoustic transducers (11, 12) are installed as a transmitting and receiving device. 3. Device according to claim 2, characterized in that that in the measuring head (8) executing the tilting movement, there is an acoustic transducer (11) with axially oriented directional characteristic and an acoustic transducer (12) with radially oriented directional characteristics are built in. 4. Apparatus according to claim 1, characterized in that in which executing the tilting movement Measuring head (8) an optical transmitter (14) and a photographic camera as a receiver (15) are installed. 5. Apparatus according to claim 1, characterized in that in which executing the tilting movement Measuring head (8) arranged as a transmitting device ejectable radioactive float and a radiation measuring device (22) is built into the probe as a receiving device. 45