CN111380589A - Liquid level measuring device and liquid level measuring method for pressure difference type gas storage - Google Patents

Abstract

The invention discloses a pressure difference type gas storage liquid level measuring device and a liquid level measuring method. The device comprises a sleeve and a pressure difference sensor; two capillary tubes are opened in the cylinder wall of the sleeve from top to bottom. The capillary tube includes two pressure guiding tubes and a large bubble chamber, one end of one pressure guiding tube communicates with the outside of the sleeve, and communicates with another pressure guiding tube through the large air bubble chamber ; The other end of the other pressure guiding pipe is communicated with the inside of the sleeve; the pressure is transmitted through the capillary pipe, and the pressure points of the two liquid levels to be measured are led upward to the same position, and then the pressure difference is measured by the differential pressure sensor. The difference is converted into the liquid level difference, so as to realize the measurement of the liquid level of the gas storage. The pressure difference type gas storage liquid level measuring device provided by the invention has a simple structure, and the large bubble chamber is provided to not only improve the accuracy of the liquid level measurement, but also avoid the contact between the pressure difference sensor probe and the liquid, thereby prolonging the service life of the device .

Description

A pressure difference type gas storage liquid level measuring device and liquid level measuring method

technical field

The invention belongs to the technical field of gas storage liquid level measurement, and more particularly, relates to a pressure difference type gas storage liquid level measurement device and a liquid level measurement method.

Background technique

The salt cavern gas storage is constructed by injecting fresh water into the salt mine as a solution cavity for gas storage. Dissolving, the brine is discharged from the drain pipe, and the spacer between the water injection pipe and the casing is injected into the spacer to avoid dissolution at the top; Finally, a gas storage that meets the design requirements is obtained. In this process, the liquid level measurement of the gas-liquid interface in the cavity is of great significance. At the same time, after the gas storage is completed and put into use, strict sealing is required, and a permanent packer will be used on the central pipe, which makes the wired measurement method that can be used in the construction process unusable, and the environmental conditions in the well are more severe. The above conditions make it difficult for some existing measurement methods and devices to meet the accuracy requirements.

With the advancement of gas storage technology, more accurate liquid level measurement devices are needed to assist the construction of gas storages. However, the liquid level measurement equipment currently used is mostly based on echo ranging, laser ranging and other logging equipment. At this level, echo ranging and laser ranging have strict requirements for downhole logging environment: changes in the medium outside the hole and the vibration of objects in the downhole will lead to a decrease in the accuracy of echo ranging; It will cause the failure of the laser logging device. However, since the pressure measurement does not involve the influence of the above external medium, the accuracy of the pressure measurement can be improved when the downhole liquid level is measured. When using pressure logging, two pressure values must be measured: the pressure value above the liquid surface and the pressure value below the liquid surface. The difference is then converted into a liquid level difference, and finally the actual liquid level height is obtained.

However, it will also face huge difficulties when using the differential pressure sensor for liquid level measurement: although the absolute pressure value downhole is very large (the maximum may reach 35Mpa), the pressure difference between the two measurement points is very small. Under the existing technology, this makes Using only two pressure sensors to measure two absolute pressures will produce huge errors, which is also the main challenge for differential pressure-based measurement methods.

A liquid level measuring device based on a double differential pressure transmitter is disclosed in the Chinese invention patent document with the authorized publication number CN 106352942A. The main advantage of this device is that it uses two pressure guiding tubes to reduce the error caused by the uncertainty of liquid density. However, the biggest defect of this device is that when the differential pressure transmitter is used to measure the pressure difference in the pressure guiding pipe, the horizontal measurement method is used. This method is effective when measuring the liquid level in the sewage plant, but it is applied to the gas storage. It is not feasible to measure the liquid level, because the space in the central pipe of the gas storage is limited, and it is impossible to add a device outside the pipeline to assist in the measurement; at the same time, when the liquid level exceeds the estimated liquid level, the device will directly contact the external liquid , which will not only interfere with the measurement accuracy of the device, but also shorten the life of the measurement device.

SUMMARY OF THE INVENTION

Aiming at the defects and improvement needs of the prior art, the present invention provides a differential pressure type gas storage liquid level measuring device and a liquid level measuring method. It is difficult to measure the liquid level in the reservoir and the measurement accuracy is not high, and at the same time, the service life of the downhole liquid level measurement device is improved.

In order to achieve the above object, according to one aspect of the present invention, the present invention provides a differential pressure type gas storage liquid level measuring device, comprising: a sleeve and a differential pressure sensor; A first capillary channel and a second capillary channel are opened at the bottom;

The first capillary tube includes a first pressure guiding tube, a first large bubble chamber, and a second pressure guiding tube; one end of the first pressure guiding tube is communicated with the outside of the sleeve, and passes through the first large bubble chamber. The air bubble chamber is communicated with the second pressure guiding tube; the other end of the second pressure guiding tube is communicated with the inside of the sleeve;

The second capillary tube includes a third pressure guiding tube, a second large bubble chamber, and a fourth pressure guiding tube; one end of the third pressure guiding tube is communicated with the outside of the sleeve, and passes through the second large The air bubble chamber is communicated with the fourth pressure guiding tube; the other end of the fourth pressure guiding tube is communicated with the inside of the sleeve;

The elevation difference between the first pressure guiding pipe and the third pressure guiding pipe is greater than or equal to the difference between the highest liquid level and the lowest liquid level of the gas storage;

The two probes of the differential pressure sensor probe into the second pressure guiding tube and the fourth pressure guiding tube respectively.

Further, the volume of the first large air bubble chamber is more than 3 orders of magnitude larger than the volumes of the first pressure guiding tube and the second pressure guiding tube; the volume of the second large air bubble chamber is larger than the volume of the The volumes of the third pressure guiding tube and the fourth pressure guiding tube are more than 3 orders of magnitude larger.

Further, the cross-sectional areas of the first large bubble chamber and the second large bubble chamber gradually decrease from bottom to top.

Further, the bottom of the first large air bubble chamber and the bottom of the first pressure guiding tube are on the same level; the bottom of the second large air bubble chamber and the bottom of the third pressure guiding tube are on the same level. on the horizontal plane.

Further, the sleeve is formed by connecting multiple sections of sleeves, and the differential pressure sensor is installed at the threaded connection of the two sleeves.

Further, the gap formed by the two probes of the differential pressure sensor and the second pressure guiding tube and the fourth pressure guiding tube is sealed by a high pressure resistant material.

Another aspect of the present invention provides a method for measuring the liquid level of a gas storage, which is measured by the above-mentioned device, comprising the following steps:

Place the liquid level measuring device in the gas storage so that the third pressure guiding pipe is at the lowest liquid level of the gas storage, and obtain the height h ₁ of the third pressure guiding pipe from the ground ;

The pressure difference is measured by the differential pressure sensor, and the height Δh between the actual liquid level of the gas storage and the third pressure guiding pipe is calculated based on the formula ΔP=ρgΔh;

The actual liquid level of the gas storage is calculated to be the height h=h ₁ -Δh from the ground.

In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

(1) The pressure is transmitted by establishing a capillary tube with a large bubble chamber in the cylinder wall of the sleeve, and the pressure points of the two liquid levels to be measured are directed upward to the same position, and then the pressure difference is measured by the differential pressure sensor and Converted into liquid level difference, so as to realize the measurement of the liquid level of the gas storage, and at the same time improve the accuracy of the liquid level measurement.

(2) Due to the existence of the large bubble chamber, when the liquid level of the gas storage exceeds the highest liquid level that can be measured by the device, the liquid immersed in the third pressure guiding tube cannot be pressed into the fourth pressure guiding tube, so that it will not interfere with the measurement The contact of the device prolongs the service life of the device; and after the liquid level of the gas storage tank drops, the device can continue to work normally.

(3) The measuring device provided by the present invention has a simple structure and is easy to implement.

Description of drawings

1 is a schematic structural diagram of a differential pressure type gas storage liquid level measuring device provided by the present invention;

Fig. 2 is the partial enlarged schematic diagram of the pressure difference type gas storage liquid level measuring device provided by the present invention;

Figure 3-1 and Figure 3-2 are schematic diagrams of the liquid level change before and after the liquid enters the second capillary pipe during the downhole process of the device;

Throughout the drawings, the same reference numbers are used to refer to the same elements or structures, wherein:

1 is the sleeve; 2 is the differential pressure sensor; 3 is the probe; 4-1 is the first pressure guiding tube; 4-2 is the second pressure guiding tube; 4-3 is the third pressure guiding tube; 4-4 is the first pressure guiding tube Four pressure guiding tubes; 5-1 is the first large bubble chamber; 5-2 is the second large bubble chamber; 6 is the sleeve wall.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

As shown in FIG. 1 , the present invention provides a differential pressure type gas storage liquid level measuring device, comprising a sleeve 1 and a differential pressure sensor 2;

A first capillary conduit and a second capillary conduit are opened in the cylindrical wall of the sleeve 1 from top to bottom;

The first capillary tube includes a first pressure guiding tube 4-1, a first large bubble chamber 5-1, and a second pressure guiding tube 4-2; one end of the first pressure guiding tube 4-1 and the sleeve The outside of the cylinder 1 communicates with the second pressure guiding tube 4-2 via the first large air bubble chamber 5-1; the other end of the second pressure guiding tube 4-2 and the sleeve 1 internal connectivity;

Preferably, the volume of the first large bubble chamber 5-1 is more than 3 orders of magnitude larger than the volumes of the first pressure guiding tube 4-1 and the second pressure guiding tube 4-2; The liquid in the capillary will not cause rapid changes in the height of the liquid column, thereby increasing the accuracy of the measurement.

Preferably, the cross-sectional area of the first large bubble chamber 5-1 gradually decreases from bottom to top.

Preferably, the bottom of the first large bubble chamber 5-1 and the bottom of the first pressure guiding tube 4-1 are on the same level.

The second capillary tube includes a third pressure guiding tube 4-3, a second large bubble chamber 5-2, and a fourth pressure guiding tube 4-4; one end of the third pressure guiding tube 4-3 and the sleeve The outside of the cylinder 1 communicates with the fourth pressure guiding tube 4-4 via the second large air bubble chamber 5-2; the other end of the fourth pressure guiding tube 4-4 and the sleeve 1 internal connectivity;

Preferably, the volume of the second large bubble chamber 5-2 is more than 3 orders of magnitude larger than the volumes of the third pressure guiding tube 4-3 and the fourth pressure guiding tube 4-4; The liquid in the capillary will not cause rapid changes in the height of the liquid column, thereby increasing the accuracy of the measurement.

Preferably, the cross-sectional area of the second large bubble chamber 5-2 gradually decreases from bottom to top.

Preferably, the bottom of the second large bubble chamber 5-2 and the bottom of the third pressure guiding tube 4-3 are on the same level.

The elevation difference between the first pressure guiding pipe 4-1 and the third pressure guiding pipe 4-3 is greater than or equal to the difference between the highest liquid level and the lowest liquid level of the gas storage;

The two probes 3 of the differential pressure sensor 2 respectively probe into the second pressure guiding tube 4-2 and the fourth pressure guiding tube 4-4.

Preferably, the sleeve 1 is formed by connecting multiple sections of sleeves, and the differential pressure sensor 2 is installed at the threaded connection of the two sleeves.

Preferably, the gaps formed by the two probes 3 of the differential pressure sensor 2 and the second pressure guiding tube 4-2 and the fourth pressure guiding tube 4-4 are sealed by a high pressure resistant material.

The measurement principle of the differential pressure type gas storage liquid level measurement device provided by the present invention is further described in detail below in conjunction with the downhole process of the measurement device.

The sleeve with the differential pressure sensor installed is lowered into the well, and the two capillary pipes are filled with high-pressure gas in the gas storage, with a maximum pressure of nearly 35Mpa. When the third pressure guiding pipe is in contact with the actual liquid level of the gas storage, the liquid enters the second capillary pipe to achieve liquid sealing, and the high-pressure gas is sealed into the second capillary pipe, as shown in Figure 3, for the liquid to enter the second capillary pipe during the downhole process of the device. Schematic diagram of the liquid level change before and after the capillary. With the continuous increase of the downhole depth, the external air pressure continues to increase, so the volume of the liquid entering the second capillary pipeline continues to increase; however, due to the existence of the large bubble chamber, when the height of the liquid column increases extremely slowly, the internal gas pressure It will also increase sharply, and this negative feedback mechanism is constantly slowing the rate at which the external liquid enters the large bubble chamber, eventually balancing the internal and external air pressure. Since the liquid entering the third pressure guiding tube is reduced, the height of the liquid column in the large bubble chamber is extremely small, thereby reducing the error in estimating the height of the liquid column and increasing the measurement accuracy.

When the liquid level of the gas storage is higher than the preset maximum liquid level, the liquid is pressed into the first pressure guiding tube. At this time, due to the existence of the large conical bubble chamber, the volume of the liquid-sealed gas enters the first capillary tube along with the volume of the liquid-sealed gas. The height of the liquid column decreases sharply as the height of the liquid column increases, and the gas pressure of the liquid seal in the first capillary channel increases sharply. This negative feedback adjustment adjusts the liquid column entering the first capillary channel to a very small height, so as to prevent the liquid from directly contacting the probe. achieve the purpose of protecting the device. When the liquid level of the gas storage tank falls within the measurement range, the device can resume the measurement.

Since the liquid level of the reservoir has the highest liquid level and the lowest liquid level, the liquid level measuring device is placed in the gas reservoir, so that the third pressure guiding pipe is at the lowest liquid level of the gas reservoir, In practical applications, a negligible error is allowed, that is, the third pressure guiding pipe can be close to the lowest liquid level of the gas storage, and the height h ₁ of the third pressure guiding pipe from the ground is obtained, that is, The height of the lowest liquid level from the ground; the pressure difference is measured by the differential pressure sensor, and the height Δh between the actual liquid level of the gas storage and the third pressure guiding pipe is calculated based on the formula ΔP=ρgΔh; The height of the actual liquid level of the gas storage from the ground is h=h ₁ -Δh.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (7)

1. A differential pressure type gas storage liquid level measuring device is characterized by comprising a sleeve (1) and a differential pressure sensor (2);

a first capillary pipeline and a second capillary pipeline are arranged in the wall of the sleeve (1) from top to bottom;

the first capillary pipeline comprises a first pressure guide pipe (4-1), a first large bubble chamber (5-1) and a second pressure guide pipe (4-2); one end of the first pressure guide pipe (4-1) is communicated with the outside of the sleeve (1), and is communicated with the second pressure guide pipe (4-2) through the first large bubble chamber (5-1); the other end of the second pressure guide pipe (4-2) is communicated with the interior of the sleeve (1);

the second capillary pipeline comprises a third pressure guide pipe (4-3), a second large bubble chamber (5-2) and a fourth pressure guide pipe (4-4); one end of the third pressure guide pipe (4-3) is communicated with the outside of the sleeve (1), and is communicated with the fourth pressure guide pipe (4-4) through the second large bubble chamber (5-2); the other end of the fourth pressure guide pipe (4-4) is communicated with the interior of the sleeve (1);

the elevation difference between the first pressure guide pipe (4-1) and the third pressure guide pipe (4-3) is greater than or equal to the difference between the highest liquid level and the lowest liquid level of the gas storage;

two probes (3) of the differential pressure sensor (2) respectively probe into the second pressure guide pipe (4-2) and the fourth pressure guide pipe (4-4).

2. The pressure-differential gas storage tank liquid level measuring device according to claim 1,

the volume of the first large bubble chamber (5-1) is more than 3 orders of magnitude larger than the volume of the first pressure guide pipe (4-1) and the second pressure guide pipe (4-2);

the volume of the second large bubble chamber (5-2) is more than 3 orders of magnitude larger than the volume of the third pressure guide pipe (4-3) and the fourth pressure guide pipe (4-4).

3. The pressure-differential gas storage tank liquid level measuring apparatus according to claim 2,

the cross-sectional areas of the first large bubble chamber (5-1) and the second large bubble chamber (5-2) are gradually reduced from bottom to top.

4. The pressure-differential gas storage tank liquid level measuring apparatus according to claim 3,

the bottom of the first large bubble chamber (5-1) and the bottom of the first pressure guide pipe (4-1) are on the same horizontal plane;

the bottom of the second large bubble chamber (5-2) and the bottom of the third pressure guide pipe (4-3) are on the same horizontal plane.

5. The pressure-differential gas storage tank liquid level measuring device according to claim 1,

the sleeve (1) is formed by connecting a plurality of sections of sleeves, and the differential pressure sensor (2) is arranged at the connection position of the screw threads of the two sleeves.

6. The pressure-differential gas storage tank liquid level measuring device according to claim 1,

gaps formed by the two probes (3) of the differential pressure sensor (2) and the second pressure guide pipe (4-2) and the fourth pressure guide pipe (4-4) are sealed by high-pressure-resistant materials.

7. A gas storage tank liquid level measuring method using the pressure-difference type gas storage tank liquid level measuring device according to any one of claims 1 to 6, characterized by comprising the steps of:

placing the liquid level measuring device in the gas storage, enabling the third pressure guide pipe (4-3) to be at the lowest liquid level of the gas storage, and obtaining the height h of the third pressure guide pipe (4-3) from the ground₁；

Measuring the pressure difference through the differential pressure sensor (2), and calculating the height delta h between the actual liquid level of the gas storage and the third pressure guide pipe (4-3) based on a formula delta P ═ rho g delta h;

calculating to obtain the height h of the actual liquid level of the gas storage from the ground₁-Δh。

Images