SU1395819A1 - Method of measuring rock temperature in blast holes - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to increase productivity by reducing the sensor exposure in the hole. For this purpose, a sensor with two identical sensing elements is used. Estimate the value of the measured t-ry. A sensor t is inserted into the borehole. Contact its sensitive element with the surface of rocks in the metering section. Hold the sensor in the hole and register the sensor's t-ru. Then, one of the sensing elements is heated, and the other is cooled, respectively, above and below the value of t-ry of rocks in the measurement section by equal values relative to the previously estimated value of t-ry. The difference between the pre-contact values of the t-ras of sensitive elements is determined. The time of their contact with the rocks in the hole is determined by the f-le obtained as a result of the solution of the model problem of changing the temperature of a two-layer plate brought into contact with a semi-boundary array. The averaged value of the t-ry of sensitive elements is recorded, by which the t-d of rocks in the bore-holes is judged. 7 il. o (l

Description

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The invention relates to a measurement technique and can be used to measure the temperature of rocks in boreholes drilled from underground structures.

The purpose of the invention is to increase productivity by reducing the sensor exposure in the hole.

FIG. 1 shows a graph of measurements of the temperature of rocks; in fig. 2 is a schematic of the location of the sensing elements in the metering section of the hole; in fig. 3 shows the layout of the sensitive element in the sensor design; in fig. 4 is a block diagram of a device for measuring the temperature of rocks in boreholes; in fig. 5 - b; 1ok diagram of the auxiliary heating device; in fig. 6 and 7 are graphs for determining the coefficients taking into account the radius of the hole and the diameter of the heat receptacle. sensitive plate.

The method is implemented using a borehole sensor, built according to the type known, equipped with clamping devices for two identical sensitive elements 1 and 2 (Fig. 3), mounted between the heat-receiving plates 3 and the heat insulating substrates 4. Sensitive elements 1 and 2 are included ( Fig. 4) to the circuit of the current stabilizer 5 and the measuring amplifier 6, the output of which is fed to the input of the indicator 7. The auxiliary device (Fig. 5) for heating or cooling the sensitive element contains thermoelectric thermal us OS 8, mounted on a heat-generating body (not shown) and through a block of 9 keys connected to the power source 10 (for example, an NCGK-PD battery).

The method is implemented as follows.

After drilling and drilling, the estimated temperature of rocks in the measuring area of the drill pin is estimated in advance. To do this, use the calculated dependencies or the results of previous measurements. In geothermal studies, the formula

t o t3 ,, - f GN, where H is the depth of the measurement

element 2 to a temperature t ' j leads to a voltage drop at the input of the measuring amplifier b, corresponding to the voltage drop, if the temperature values of the sensing elements 1 and 2 were the same and equal to only when

,

The output signal of the amplifier b corresponding to this value is indicated in the indicator 7. The device shown in FIG. 2 is used for heating (or cooling) the sensitive element 2. 5. For this, using the key block 9, the heat pump 8 is supplied with a current of the appropriate polarity from the power source 10. The heat pump 8 removes heat from the sensing element 2 through their contact to the heat body (not shown).

The sensor is inserted into the hole. As the sensing elements 1 and 2 are sent to the metering section of the hole between elements 1 and 2 and the rocks, heat exchange takes place in the hole (to intensify the heat exchange, the surfaces of the heat-receiving plates 3 must be blackened). As a result of heat exchange during T | (Fig. 1) the difference between the temperatures of the sensitive elements 1, 2 and the temperature of the rocks to is reduced due to the heat of the rocks removed

from the large surface of the bore-hole, the temperature of the sensing element 1 rises to tni, and the temperature of the sensing element 2 decreases to tn2, practically without distorting the temperature field of the rocks in the borehole. Moreover, the difference in equality of deviations 1i | and tH2 from to, which occur as a result of t a to, is somewhat smoothed over the TI time due to more intensive heat exchange with the sensitive element 1, which has a greater temperature deviation from to than the sensitive element 2. During n

Sensing elements 1 and 2 are sent to the metering section of the bore-hole, where through heat-receiving plates 3 by means of clamping devices (not shown) they are brought into contact with rocks with

the site of the hole from the surface; 45 Diametrically opposed surfaces - geothermal stage; tan is the average temperature of the earth's surface of the geothermal area within which it is necessary to measure. The tan and G values are determined from the tables.

Sensing elements 1 and 2 have a temperature, for example, im below the previously estimated t o. Then, for example, the sensitive element 2 is heated (FIG. 1) to tH2. The heating is stopped when the indicator 7 (Fig. -4) is set to readings corresponding to the value of to. This corresponds to a deviation of tin, and tii2 from to. The current stabilizer 5 supplies the sensing elements 1 and 2 with the same current. Heat

article mi shpura (Fig. 2). Prior to this, the difference between the pre-contact temperature values (tna-tni) of the sensing elements 1 and 2 is recorded, for which differential thermocouple 50 can be used with the junction arrangement of the sensing elements 1 and 2. The sensing elements are kept in contact with rocks for a period of time from the expression

tg Ksh

55 (tn2-t.,); J:; p 0

where (tn2-tn |) is the difference between the pre-contact temperature values of the sensitive elements 2 and 1;

 45 Diametrically opposite surfaces of the pinhead (Fig. 2). Prior to this, the difference between the pre-contact temperature values (tna-tni) of the sensing elements 1 and 2 is recorded, for which differential thermocouple 50 can be used with the junction arrangement of the sensing elements 1 and 2. The sensing elements are kept in contact with rocks for a period of time from the expression

tg Ksh

55 (tn2-t.,); J:; p 0

where (tn2-tn |) is the difference between the pre-contact temperature values of the sensitive elements 2 and 1;

Cip | hi-f-.C2p2h2

2DD / l is the constant coefficient of the sensor;

D - tolerance of measurement;

w, cd are coefficients taking into account the radius R of the hole (Fig. 6) and the diameter D of the heat-receiving plate (Fig. 7); - volumetric heat capacity of the material of sensitive elements 1 and 2; - the same heat sensing plate 3;

- thickness of the sensitive elements 1, 2 and the heat-receiving plate 3; X, -c-p is the minimum value of heat assimilability (the product of thermal conductivity and the volumetric heat capacity) of rocks encountered in the region of the measurements taken.

Clpl 2p2

i, h2

The use of two sensitive elements in the implementation of the method while ensuring the same sensitivity of the measuring apparatus and interchangeability of the sensor and the secondary device reduces the thickness (hi) of the sensitive element by at least 2 times, since the nominal electrical resistance is provided by the sum of the electrical resistances of the two sensitive elements (Fig. four),

During time (Fig. 1), 25 is significantly reduced by the time of heat exchange acquired by thermal conductivity between rocks and sensing elements 1 and 2 through the heat-receiving plates 3 and the thermal contact with the sensing element of those rocks 1 (see calculation formula for the duration t contact). It should be noted that this also leads to a decrease in measurement error, caused by the resistance between the heat-absorbing

the shadows are a sensitive element of the themes of the rock formation (see calculation formula for the duration of contact t). It should be noted that this also leads to a decrease in measurement error caused by the plates 3 and rocks. Due to overheating of the thermistor resistance element during the passage of the measuring current. This is due to a twofold increase (the condition of the identity of the sensitive elements) of the area of the sensitive element dissipating these

The element 2 is cooled by 35 heat generation to the rocks, and reducing heat exchange with the rocks, which, by halving the halves, intensifies the heat exchange, accelerates the acquisition of temperature values by sensitive elements 1 and 2, the temperature of the sensing elements 1, 2 and to is reduced. Moreover, the overall thermal balance of the rocks is practically maintained, since the sensitive element 1 is heated, and the sensory resistance is through the thickness of the sensitive element. On the contrary, while maintaining the same error from the passageways to to. For the contact time t of the measuring current sensing current, the posed elements 1 and 2 take the values --- - ...., ..., - ,,.,. .. „, .., g. O„. „G ,,, ;;

temperatures ti and t2 respectively. Due to more intensive heat exchange between rocks and sensing element 1 as compared with sensing element, it is possible to reduce the diameter of the thermal resistance wire, and to manufacture the sensitive elements, which leads to a further decrease in the thickness (h |) of the sensing element and, consequently, to a decrease

ment of 2 due to (to-tn,) (tn2-to) of the 45-speed sensor in the hole, to the reduction

the clone ti and t2 from to almost unambiguously. For the desired temperature (measured temperature ton) of rocks in the hole, the average of these values is taken as ton

duration of measurement of the temperature of rocks in the hole.

Claims (1)

Invention Formula liii2. Q indicator readings 7 50 Method of measuring mountain temperature rocks in the bore-holes, consisting in the fact that (Fig. 4) after contact of the sensing elements 1 and 2 with rocks in the bore-hole for t (Fig. 1) and more. The formula for determining the contact time t is obtained as a result of solving a model problem of changing the temperature of a two-layer plate brought into contact with a semi-finite massif (mountain a temperature sensor is inserted into the hole, its sensor is in contact with the surface of rocks in the metering section, the sensor is held in the hole, and the temperature of the sensor is recorded, which, in order to improve performance by reducing the sensor's exposure time dy), and the coefficients Ksh and Kd (Fig. 6 and 7) were found experimentally. The implementation of the proposed method makes it possible to shorten the sensor's exposure to a chip by eliminating the need for the sensitive element to come into contact with the rocks until the sensitive element acquires the desired temperature of the rocks. This is ensured by the use of the average temperatures of two sensitive elements, one of which always has a temperature higher and the other one lower than the temperature of rocks in the hole. The use of two sensitive elements in the implementation of the method while ensuring the same sensitivity of the measuring apparatus and interchangeability of the sensor and the secondary device reduces the thickness (hi) of the sensitive element by at least 2 times, since the nominal electrical resistance is provided by the sum of the electrical resistances of the two sensitive elements (Fig. four),  significantly reduces the time to purchase  significantly reduces the time to purchase the shadows are a sensitive element of the themes of the rock formation (see calculation formula for the duration of contact t). It should be noted that this also leads to a decrease in the measurement error, caused by heat generation in rocks, and a decrease (by a halve) in thermal resistance across the thickness of the sensing element. On the contrary, while maintaining the same error due to the passage of the measuring current, the marked pos- ...., ..., - ,,.,. .. „, .., g. O„. „G ,,, ;; It will reduce the diameter of the thermal resistance wire, ideally for the manufacture of sensitive elements, which leads to a further decrease in the thickness (h |) of the sensitive element and, consequently, to a decrease in duration of measurement of the temperature of rocks in the hole. Invention Formula rocks in the bore-holes, consisting in the fact that five a temperature sensor is inserted into the hole, its sensor is in contact with the surface of rocks in the metering section, the sensor is held in the hole, and the temperature of the sensor is recorded, which, in order to improve performance by reducing the sensor's exposure time A sensor with two identical sensing elements is used, the measured temperature is tentatively estimated, then one of the sensing elements is heated, and the other is cooled, respectively, higher and lower than the temperature of the rocks in the measurement area, equal values relative to the previously estimated temperature value the difference between the pre-contact temperature values of sensitive elements, and the time of their contact with rocks in the hole is determined by the formula where (tna-tni) is the difference between the pre-contact temperature values of the sensitive elements; K is a constant for the sensor; Ksh, Kd are the coefficients of the influence of the radius of the hole and the diameter of the heat-receiving plate of the sensitive element; X с р is the minimum value of the heat digestibility of the rocks encountered in the region, and the average temperature of the sensitive elements is recorded, which is used to judge the temperature of the rocks in the bore-holes. Fig. 2 //////// 777. 1 3 h 7)