Protector for capillary probe

Abstract

The application provides a protector of a capillary probe, which can be used in the technical field of test protection devices and comprises a needle, a filter screen, a first protective sleeve sleeved on a sleeve and a second protective sleeve sleeved on the first protective sleeve; the second protective sleeve is provided with a through hole, the filter screen is accommodated in the through hole, the two ends of the second protective sleeve and the first protective sleeve are in sealing connection with the sleeve, and a chamber is formed between the first protective sleeve and the sleeve; the capillary probe is inserted into the chamber, one end of the capillary probe is connected with a capillary, the other end of the capillary probe is provided with the needle, and the needle faces the filter screen; when the protector is lowered to the outside of the filter screen for a designated coal seam, gas is injected into the capillary probe, the needle is pushed out and pierces the first protective sleeve, and the gas of the designated coal seam flows into the chamber through the filter screen. The protector of the capillary probe provided by the application has the advantages of simple structure and reliability, can avoid damage of the capillary probe caused by collision with a well wall during lowering, and can avoid mud pollution of the capillary probe during well cementation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of testing protection devices, in particular to a protector of a capillary probe. BACKGROUND

[0002] The underground coal gasification technology is a coal clean and efficient utilization technology integrating well construction, coal mining and gasification, and is one of the key research directions in the new energy and new business field.

[0003] The pressure of the coal seam in the underground coal gasification production process is one of the main parameters for maintaining the normal production of the underground coal gasification and the quality control of the synthesis gas. Since the bottom hole temperature of the underground coal gasification is between 600 and 800 DEG C, all electronic, quartz and other pressure sensors and related test equipment cannot operate under this working condition. The capillary pressure sensor, since there is no any electronic device in the downhole, is a cost-effective test tool for pressure testing in the underground high temperature environment.

[0004] In order to ensure the safe and normal operation of the capillary pressure sensor, the sensor needs to be lowered with the production casing. However, the capillary probe is easy to be damaged by collision with the well wall during the lowering process, and the capillary probe is easy to be contaminated by the mud during the cementing process. SUMMARY

[0005] In view of at least one problem in the prior art, the present application provides a protector of a capillary probe, which is simple and reliable in structure, can avoid the damage of the capillary probe caused by collision with the well wall during the lowering process, and can avoid the contamination of the capillary probe by the mud during the cementing process, thereby improving the safety of the capillary probe.

[0006] In order to solve the above technical problems, the present application provides the following technical solutions:

[0007] The present application provides a protector of a capillary probe, comprising:

[0008] a needle, a filter screen, a first protective sleeve sleeved on the casing, and a second protective sleeve sleeved on the first protective sleeve;

[0009] The second protective sleeve is provided with a first through hole, the filter screen is accommodated in the first through hole, the two ends of the second protective sleeve and the first protective sleeve are sealingly connected with the casing, and a cavity is formed between the first protective sleeve and the casing;

[0010] The capillary probe extends into the cavity, one end of the capillary probe is connected with a capillary, the connection between the capillary and the cavity is sealingly connected, the other end of the capillary probe is provided with the needle, and the needle faces the inner side of the filter screen;

[0011] When the protector is lowered to the designated coal seam outside the filter screen, the capillary tube injects gas into the capillary tube probe, the gas pushes the needle head out and pierces the first protective sleeve, and the gas in the designated coal seam flows into the chamber through the filter screen.

[0012] In one embodiment, the first protective sleeve is a hollow rubber protective sleeve, and the hollow rubber protective sleeve is filled with water.

[0013] In one embodiment, the first protective sleeve is in close contact with the second protective sleeve.

[0014] In one embodiment, the needle head is a hollow needle head.

[0015] The hollow needle head comprises a needle plug, a needle stem and a needle tip connected in sequence, the needle plug is provided with a channel, and the needle tip faces the inside of the filter screen.

[0016] In one embodiment, the hollow needle head further comprises an aluminum metal film that completely covers the channel.

[0017] When the protector is lowered to the designated coal seam outside the filter screen, the capillary tube injects gas into the capillary tube probe, the gas pushes the needle head out, pierces the first protective sleeve and breaks the aluminum metal film.

[0018] In one embodiment, the capillary tube probe is L-shaped, and the bend is arc-shaped.

[0019] In one embodiment, one end of the second protective sleeve is provided with a second through hole, one end of the first protective sleeve is provided with a third through hole, the capillary tube probe extends into the chamber through the second through hole and the third through hole in sequence, and the capillary tube is sealingly connected with the second through hole and the third through hole through a one-way valve joint.

[0020] In one embodiment, one end of the second protective sleeve and the first protective sleeve is sealingly connected with the sleeve through a first sealing plug, and the other end of the second protective sleeve and the first protective sleeve is sealingly connected with the sleeve through a second sealing plug.

[0021] In one embodiment, the needle stem side wall is provided with a plurality of fourth through holes.

[0022] In one embodiment, the second protective sleeve is a metal protective sleeve.

[0023] As can be seen from the above technical solution, this application provides a protector for a capillary probe. The protector includes: a needle, a filter, a first protective sleeve fitted onto a casing, and a second protective sleeve fitted onto the first protective sleeve. The second protective sleeve has a first through hole, and the filter is housed in the first through hole. Both ends of the second and first protective sleeves are sealed to the casing, forming a chamber between the first protective sleeve and the casing. The capillary probe extends into the chamber, with one end connected to a capillary tube. The connection between the capillary tube and the chamber is sealed, and the other end of the capillary probe has the needle facing inwards towards the filter. When the protector is lowered to the outer side of the filter to a designated coal seam, gas is injected into the capillary probe through the capillary tube. This gas pushes the needle out and pierces the first protective sleeve. The gas in the designated coal seam flows into the chamber through the filter. This protector for the capillary probe has a simple and reliable structure and can prevent capillary... The capillary probe is easily damaged by collisions with the well wall during installation. Preventing mud contamination during cementing improves its safety. A second protective sleeve protects the probe from collisions with the well wall. The first protective sleeve provides further cushioning. When the needle punctures the first protective sleeve, it breaks, allowing gas to enter the capillary probe through the filter, preventing mud contamination during cementing. Specifically, the capillary probe protector ensures safe installation during drilling and completion, preventing mud and other debris from clogging it and damaging it. When the probe is in place, the hollow needle punctures the first protective sleeve, creating a large pressure-conducting space for rapid pressure transmission. In other words, the hollow structure of the capillary needle ensures rapid gas transfer from the coal seam to the capillary. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a first structural schematic diagram of the protector of the capillary probe in the embodiments of this application;

[0026] Figure 2 This is a schematic diagram showing the relationship between the needle, capillary probe, first protective sleeve, and filter screen before the needle is pressed out in the embodiment of this application.

[0027] Figure 3 This is a schematic diagram showing the relationship between the needle, capillary probe, first protective sleeve, and filter screen after the needle is pressed out in the embodiment of this application.

[0028] Figure 4 This is a cross-sectional schematic diagram of the hollow needle in the embodiments of this application;

[0029] Figure 5 This is a side view of the hollow needle in the embodiment of this application;

[0030] Figure 6 This is a second structural schematic diagram of the protector for the capillary probe in the embodiments of this application.

[0031] Symbol Explanation

[0032] 1. Needle;

[0033] 01. Needle plug;

[0034] 02. Needle stem;

[0035] 03. Needle tip;

[0036] 04. Passage;

[0037] 05. Fourth through hole;

[0038] 06. Aluminum metal film;

[0039] 2. Filter screen;

[0040] 3. Sleeve;

[0041] 4. First protective cover;

[0042] 5. Second protective cover;

[0043] 6. Capillary probe;

[0044] 7. Capillary tube;

[0045] 8. One-way valve connector;

[0046] 9. First sealing plug;

[0047] 10. Second sealing plug;

[0048] 11. Shaft. Detailed Implementation

[0049] To enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0050] In the coalbed methane underground gasification operation control process, to improve gasification operation stability, resource conversion rate, and gasification efficiency, it is necessary to study gasification operation control methods and formulate gasification operation procedures in advance. The pressure at the bottom of the production well at the end of the gasification chamber in the coal seam is one of the key operating parameters. For specific coal seam conditions, obtaining the pressure at the bottom of the underground coalbed methane production well is one of the important bases for determining the production well's operating procedures. Therefore, during the implementation of the on-site process plan, it is essential to obtain the pressure data at the bottom of the production well in real time to determine the production status of the target coal seam and the corresponding implementation conditions, serving as an important basis for adjusting the plan during the pilot demonstration and commercial development stages. Since the temperature around the bottom of the coalbed methane production well is generally high, typically 600–800 degrees Celsius, conventional pressure gauges cannot be used in this environment due to the temperature limitation of their electronic components within the 200°C range. Therefore, capillary pressure sensors are currently the most cost-effective testing tool for pressure testing in high-temperature underground environments.

[0051] This application proposes a method for the hollow needle to pierce the capsule, and proposes a pressure balancing method using a first protective sleeve to ensure tight contact between the first and second protective sleeves, preventing mud contamination and probe blockage. The second protective sleeve is fixed to the casing to prevent damage caused by collision between the probe and the well wall during lowering. The second protective sleeve provides space for communication between the capillary probe and the coal seam. The main technical specifications of the capillary probe protector provided in this application include: applicable pressure range of 0–50 MPa, temperature range of 0–1000 °C, and depth range of 0–4000 m.

[0052] The capillary probe protector provided in this application effectively protects the capillary probe from contamination or blockage by mud and other debris during its insertion. It also effectively prevents mechanical damage caused by collisions with the wellbore during insertion, creating an effective space to maintain good communication between the capillary probe and the coal seam outside the casing. Furthermore, it provides protection during the insertion of the capillary pressure sensor into the well. Further, it can be used to obtain bottom-hole pressure data for underground coal gasification production wells during production process adjustments, providing data for gasification operation parameters (gasifying agent ratio, injection rate). It is applicable to basic research on gasification processes in shallow, medium-deep, and deep underground coal gasification, as well as research on gasification operation control methods and process technologies. It can effectively support normal coal seam pressure testing in underground coal gasification, providing more reliable pressure conditions at the bottom of syngas production wells, and providing technical assurance for controlling the quality and yield of underground coal gasification synthesizers. This is of great significance for improving the level of basic research on underground coal gasification, enhancing experimental capabilities, and promoting the research and development and business development of underground coal gasification technology.

[0053] The following examples illustrate this in detail.

[0054] To prevent damage to the capillary probe from collisions with the wellbore during installation and to avoid mud contamination during cementing, thereby improving the safety of the capillary probe, this application provides an embodiment of a capillary probe protector, such as... Figure 1 As shown, in this embodiment, the protector specifically includes the following components:

[0055] The device comprises a needle 1, a filter screen 2, a first protective sleeve 4 fitted onto a sleeve 3, and a second protective sleeve 5 fitted onto the first protective sleeve 4. The second protective sleeve 5 has a first through hole, into which the filter screen 2 is housed. Both ends of the second protective sleeve 5 and the first protective sleeve 4 are sealed to the sleeve 3, forming a chamber between the first protective sleeve 4 and the sleeve 3. A capillary probe 6 extends into the chamber, with one end connected to a capillary tube 7. The connection between the capillary tube and the chamber is sealed, and the other end of the capillary probe 6 is equipped with the needle 1, which faces inward towards the filter screen 2. When the device is lowered to the outer side of the filter screen 2, where a designated coal seam is located, gas is injected into the capillary probe 6 through the capillary tube. This gas pushes the needle 1 outward and pierces the first protective sleeve 4, allowing the gas in the designated coal seam to flow into the chamber via the filter screen 2. The second protective sleeve can be made of a rigid material, such as steel. The first protective cover can be a protective cover made of elastic material, such as a rubber protective cover.

[0056] Specifically, the filter screen can be fixedly connected to the first through hole and completely block the first through hole; before the gas pushes the needle 1 out and pierces the first protective sleeve, the cavity formed between the first protective sleeve and the casing is a sealed cavity; after the protector is installed and fixed to the capillary probe and the casing respectively, the protector and the capillary probe can be lowered into the wellbore 11 along with the casing to the outside of the filter screen, which is the designated coal seam; the designated coal seam can be designated according to actual needs, and this application does not limit this. Gas can be injected from the ground to the capillary probe 6 through the capillary. The injected gas can be nitrogen. After the first protective sleeve 4 is broken, the injection of gas into the capillary probe 6 can be stopped. The gas in the designated coal seam can represent the air in the designated coal seam. The gas in the designated coal seam flows into the cavity through the filter screen 2, which can realize the transmission of the coal seam pressure to the capillary probe 6, and then transmit the pressure to the ground pressure measuring device through the capillary. The well casing can be the casing of an underground coal gasification production well, or a vertical well casing, etc. To improve the efficiency of pushing the needle, the capillary probe can be L-shaped with an arc-shaped bend. For example... Figure 2 As shown, the needle is inside the capillary probe before it is pressed out, such as... Figure 3 As shown, the needle pierces the first protective sleeve after being pressed out.

[0057] To further enhance the cushioning effect of the first protective sleeve when the second protective sleeve collides with the well wall, preferably, the first protective sleeve is a hollow rubber protective sleeve filled with water. The first and second protective sleeves can be in close contact. When a needle punctures the hollow rubber protective sleeve, it ruptures, and the water inside the hollow rubber protective sleeve flows out.

[0058] To ensure rapid gas transfer from the coal seam to the chamber, such as Figure 4 and Figure 5 As shown, preferably, the needle 1 is a hollow needle; the hollow needle includes: a needle plug 01, a needle shaft 02 and a needle tip 03 connected in sequence; the needle plug 01 is provided with a channel 04, and the needle tip faces the inside of the filter screen.

[0059] Specifically, the needle plug, slightly smaller than the capillary diameter, is placed inside the capillary probe. When the pressure is high enough, the pressure on the side of the needle plug is greater than the frictional force, causing it to be propelled forward by the air pressure, without the needle needing to retract. When the protector is lowered to the designated coal seam outside the filter screen 2, gas is injected from the ground through the capillary into the capillary probe 6. This gas pushes the hollow needle out and pierces the first protective sleeve 4. The gas in the coal seam can enter the chamber through the rupture in the first protective sleeve 4, or it can enter the capillary probe 6 through the needle tip 03, needle shaft 02, and needle plug 01. Pressurization and inflation from the top of the capillary at the ground cause the gas to pass through a one-way valve, pushing the hollow needle in the curved section inside the capillary to pierce the wall of the first protective sleeve 4, connecting the capillary with the annular space within the protector. This allows communication with the external coal seam through the filter screen 2, enabling the measurement of the pressure in the coal seam outside the casing. It can effectively prevent external mud and other substances from entering the capillary protector, and at the same time protect the capillary protector from mechanical damage caused by collision with the well wall during the lowering process; through the hollow structure inside the hollow needle, the gas is transmitted to the capillary probe, which can further improve the timeliness and efficiency of gas transmission from the coal seam to the capillary probe.

[0060] To improve the efficiency of the needle, preferably, the hollow needle further includes an aluminum metal film 06, which completely blocks the channel 04. When the protector is lowered to the designated coal seam outside the filter 2, gas is injected into the capillary probe 6 through the capillary tube. This gas pushes the needle 1 outward, piercing the first protective sleeve 4 and breaking through the aluminum metal film 06. When the first protective sleeve 4 breaks through the aluminum metal film, the capillary probe 6, the channel 04, the needle shaft 02, and the needle tip 03 can be sequentially connected.

[0061] To further create a larger pressure-conducting space for the capillary probe and ensure rapid pressure transmission, preferably, the sidewall of the needle shank 02 is provided with multiple fourth through holes 05. When the hollow needle pierces the first protective sleeve 4, at least a portion of the multiple fourth through holes 05 remain within the cavity, which can accelerate the transmission of gas from the coal seam to the cavity through the through holes.

[0062] To prevent backflow of water within the capillary tube, preferably, one end of the second protective sleeve 5 has a second through hole, and one end of the first protective sleeve 4 has a third through hole. The capillary probe 6 extends into the chamber sequentially through the second and third through holes. The capillary tube is sealed to the second and third through holes via a one-way valve connector 8. When the needle pierces the rubber protective sleeve, the one-way flow valve opens, connecting the space between the capillary tube and the second protective sleeve, increasing the pressure transmission space and facilitating pressure conduction to the capillary tube.

[0063] To further improve the stability of the connection between the protector and the sleeve 3, preferably, one end of the second protective sleeve 5 and the first protective sleeve 4 are sealed to the sleeve 3 via a first sealing plug 9, and the other end of the second protective sleeve 5 and the first protective sleeve 4 are sealed to the sleeve 3 via a second sealing plug 10. Both the first sealing plug 9 and the second sealing plug 10 can be metal threaded sealing plugs.

[0064] To further illustrate this solution, this application provides an application example of a protector for a capillary probe. In this application example, the protector includes: a pressure-measuring capillary; a one-way valve; a metal protective sleeve; a metal threaded sealing plug; a filter screen; a rubber protective sleeve; and a hollow needle.

[0065] The metal protective sleeve is placed outside the vertical well casing and sealed with a metal threaded plug. A filter structure is installed at the bottom of the metal protective sleeve, allowing airflow between the inside and outside while preventing large particles of mud and other debris from entering. A rubber protective sleeve is placed inside the metal protective sleeve, filled with water to support it and ensure a tight seal with the metal sleeve, occupying space and preventing external mud and other debris from entering. A one-way valve connector passes through the metal and rubber protective sleeves to connect to the pressure-sensing capillary tube, preventing backflow of water within the capillary. The pressure-sensing capillary tube passes through the one-way valve, through the metal protective sleeve, and into the space within the rubber protective sleeve. Its bottom is bent horizontally, and a hollow needle is placed inside the horizontal section. The end of the pressure-sensing capillary tube must be positioned at the same horizontal level as the filter screen, facing the filter screen. By applying sufficient pressure, the pressure-testing capillary can force out a hollow needle to puncture the rubber protective sleeve. Once punctured, water flows out, allowing air to enter the protector and then the pressure-testing capillary, transmitting pressure to the ground-based pressure testing device. The lower end of the capillary passes through a one-way valve into both the metal and rubber protective sleeves. After the rubber protective sleeve is filled with water, it is tightly connected to the metal sleeve. The lower end of the capillary is positioned at the same level as the filter screen, ensuring sufficient space outside the rubber sleeve for easy puncturing. The outlet faces the rubber protective sleeve, where the hollow needle punctures it upon pressure application. Water flowing out of the rubber protective sleeve exits the protector and connects to the outside environment through the filter screen. The tight connection between the rubber and metal protective sleeves effectively prevents the entry of external mud and other debris. The capillary, protected by both the metal and rubber sleeves, is safer and less susceptible to contamination.

[0066] To avoid damage to the capillary probe from collisions with the wellbore during installation and to prevent mud contamination during cementing, thereby improving the safety of the capillary probe, such as... Figure 6 As shown, this application provides another embodiment of a protector for a capillary probe. In this embodiment, the protector specifically includes the following components:

[0067] A first protective sleeve 4 and a second protective sleeve 5 are fitted onto the sleeve 3; the second protective sleeve has a first through hole, the filter screen 2 is housed in the first through hole, both ends of the second and first protective sleeves are sealed to the sleeve, and a cavity is formed between the first and second protective sleeves; the capillary probe 6 extends into the cavity, one end of the capillary probe is connected to the capillary 7, and the connection between the capillary and the cavity is sealed; gas in the coal seam outside the filter screen flows into the cavity through the filter screen.

[0068] Preferably, one end of the second protective sleeve and the first protective sleeve is sealed to the sleeve via a first sealing plug 9, and the other end of the second protective sleeve and the first protective sleeve is sealed to the sleeve via a second sealing plug 10. Both the first sealing plug and the second sealing plug can be metal threaded sealing plugs.

[0069] Preferably, the first protective sleeve is a hollow rubber protective sleeve, and the hollow rubber protective sleeve body is filled with water.

[0070] Preferably, one end of the second protective sleeve is provided with a second through hole, and the capillary probe extends into the chamber through the second through hole. One end of the capillary probe is connected to the capillary, and the capillary is sealed to the through hole through a one-way valve connector 8.

[0071] Specifically, the second protective sleeve can be a metal protective sleeve. The pressure-measuring capillary probe is inserted into the metal protective sleeve through a one-way valve, outside the rubber protective sleeve. After the rubber protective sleeve is filled with water, it is tightly connected to the metal protective sleeve. There are no requirements for the placement of the capillary probe. The outlet of the capillary probe faces the side of the rubber protective sleeve and is connected to the outside through a filter screen. The capillary is located inside the metal protective sleeve and outside the rubber protective sleeve, which does not have strict requirements for the placement of the capillary end and results in higher efficiency.

[0072] This application uses specific embodiments to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A protector for a capillary probe, characterized in that The protection device comprises: a needle, a filter screen, a first protective sleeve sleeved on a sleeve, and a second protective sleeve sleeved on the first protective sleeve; the second protective sleeve is provided with a first through hole, the filter screen is accommodated in the first through hole, both ends of the second protective sleeve and the first protective sleeve are in sealed connection with the sleeve, and a cavity is formed between the first protective sleeve and the sleeve; the capillary probe extends into the cavity, one end of the capillary probe is connected with a capillary, the connection between the capillary and the cavity is in sealed connection, and the other end of the capillary probe is provided with the needle, and the needle faces the inside of the filter screen; when the protector is lowered to a designated coal seam outside the filter screen, gas is injected into the capillary probe through the capillary, the gas pushes the needle to extrude and pierce the first protective sleeve, and the gas in the designated coal seam flows into the cavity through the filter screen; the needle is a hollow needle, which comprises a needle plug, a needle stem and a needle tip connected in sequence, the needle plug is provided with a channel, and the needle tip faces the inside of the filter screen; the hollow needle further comprises an aluminum metal film which completely blocks the channel; when the protector is lowered to a designated coal seam outside the filter screen, the capillary injects gas into the capillary probe, the gas pushes the needle to extrude, pierce the first protective sleeve and break the aluminum metal film.

2. The protector for a capillary probe according to claim 1, characterized in that the first protective sleeve is a hollow rubber protective sleeve, and the hollow rubber protective sleeve is internally provided with water.

3. The protector for a capillary probe according to claim 1, wherein the first protective sleeve is in close contact with the second protective sleeve.

4. The protector for a capillary probe according to claim 1, wherein the capillary probe is L-shaped, and the bend is arc-shaped.

5. The protection device for the capillary probe according to claim 2, wherein one end of the second protective sleeve is provided with a second through hole, one end of the first protective sleeve is provided with a third through hole, the capillary probe extends into the cavity through the second through hole and the third through hole in sequence, and the capillary is in sealed connection with the second through hole and the third through hole through a one-way valve joint.

6. The protector for a capillary probe according to claim 1, wherein both ends of the second protective sleeve and the first protective sleeve are in sealed connection with the sleeve through first sealing plugs, and the other ends of the second protective sleeve and the first protective sleeve are in sealed connection with the sleeve through second sealing plugs.

7. The protector for a capillary probe according to claim 1, wherein the side wall of the needle stem is provided with a plurality of fourth through holes.

8. The protector for a capillary probe according to claim 1, wherein the second protective sleeve is a metal protective sleeve.

Images