Sample cylinder sub and sampling method

Abstract

The application relates to a sampling cylinder short section and a sampling method, wherein the sampling cylinder short section comprises at least one sampling cylinder structure, a movable piston is arranged in each sampling cylinder structure to divide the inside of the sampling cylinder structure into a sample cavity and a mud cavity, the mud cavity is communicated with the outside of the sampling cylinder structure, each sampling cylinder structure is connected with a fluid main pipeline through a first connecting pipeline and a second connecting pipeline, a sampling valve V1 is arranged on each first connecting pipeline, a connecting structure is arranged in each sampling cylinder structure, the connecting structure is used for connecting the first connecting pipeline and the second connecting pipeline and can connect the first connecting pipeline and the sample cavity, a first on-off unit is arranged on the second connecting pipeline and is used for controlling the connection or disconnection of the second connecting pipeline, and a second on-off unit is arranged on the fluid main pipeline between the first connecting pipeline and the second connecting pipeline. The application can remove residual fluid, sample the required fluid and improve the purity of sampling.

Description

Technical Field

[0001] This invention belongs to the field of fluid sampling technology, specifically relating to a sampling cylinder section and a sampling method. Background Technology

[0002] Performing PVT analysis on formation fluid samples taken from the ground can yield abundant formation fluid data, providing a more comprehensive description of reservoir fluids and their characteristics, which is crucial for oilfield exploration and development.

[0003] Figure 1 A schematic diagram of a formation testing instrument string in positive polarity mode is shown, such as... Figure 1 As shown, the instrument string includes a probe setting section 01, a fluid identification section 02, a pumping section 03, and a sampling tube section 04. After the formation testing instrument string reaches the target sampling layer, the probe setting section 01 sets. Under the reciprocating pumping action of the pumping section 03, the formation fluid enters the instrument through the probe. The fluid flows through the fluid identification section 02 for analysis and identification of its properties. The fluid then flows through the pumping section 03 and the sampling tube section 04. Since the initial fluid does not meet the sampling requirements, the fluid outlet of the sampling tube section 04 needs to be opened to discharge the fluid into the wellbore. After continuous pumping, when the fluid identification section 02 detects that the formation fluid purity meets the sampling requirements, it closes the outlet and opens the sampling valve of the sampling tube section 04 to pour the formation fluid into the sampling tube, completing the sampling operation.

[0004] Figure 2 A schematic diagram of a sampling cylinder section in the prior art is shown, such as... Figure 2 As shown, the sampling tube section is equipped with multiple sampling tube structures. Each sampling tube structure is connected to the instrument's main fluid pipeline via a sampling valve V1. After the instrument is lowered into the well, the well fluid enters the sampling tube structure through the rear channel to compress the sample chamber. After the instrument reaches the predetermined formation in the well, it is continuously pumped. When the fluid identification section 02 detects that the formation fluid purity meets the sampling requirements, it closes the section outlet and opens the sampling valve V1 of the sampling tube structure. The formation fluid is then pumped into the sampling tube structure to complete the sampling operation. However, because the pipeline between the sampling valve V1 and the sample chamber is a "dead volume," fluid from the previous sampling remains in the pipeline and cannot be removed. This causes this part of the fluid to be pumped into the sampling tube during sampling, "contaminating" the fluid sample taken this time.

[0005] Secondly, when the formation testing instrument string is inverted, because the fluid outlet is located at the lower end of the sampling tube section, the inverted state results in... Figure 3As shown, under the reciprocating pumping action of the pumping sub 03, the formation fluid enters the instrument through the instrument probe and flows through the pumping sub 03 and the fluid identification sub 02. Since the initial fluid does not meet the sampling requirements, the fluid outlet needs to be opened to discharge the fluid into the wellbore. Thus, when the fluid outlet is closed and sampling begins, residual fluid will remain in the fluid pipeline between the outlet of the sampling tube sub 04 and the sampling tube sub 04 due to gravity and other reasons. This part of the fluid will also cause contamination of the sampled fluid sample after being added to the sample chamber. Summary of the Invention

[0006] In order to solve all or part of the above problems, the present invention aims to provide a sampling tube section and a sampling method. When the sampling tube section is used to sample formation fluid, it can eliminate residual fluid in the prior art, thereby obtaining a more ideal formation fluid.

[0007] According to one aspect of the present invention, a sampling tube section is provided, comprising at least one sampling tube structure, each of the sampling tube structures having a movable piston that divides the interior of the sampling tube structure into a sample chamber and a mud chamber, the mud chamber being in communication with the exterior of the sampling tube structure.

[0008] The movable piston, in conjunction with the sampling cylinder structure, enables the sample chamber to have a volume of zero. Each sampling cylinder structure is connected to a main fluid pipeline via a first connecting pipe and a second connecting pipe, respectively. The main fluid pipeline is used to connect to the fluid pipeline of the outlet section. Each first connecting pipe is equipped with a sampling valve V1. Each sampling cylinder structure has a connecting structure inside, which connects the first connecting pipe and the second connecting pipe and connects the first connecting pipe and the sample chamber. The second connecting pipe is equipped with a first on / off unit, which controls the connection or disconnection of the second connecting pipe. A second on / off unit is provided on the main fluid pipeline between the first connecting pipe and the second connecting pipe, which controls the connection or disconnection of the main fluid pipeline.

[0009] Furthermore, each of the aforementioned connection structures is connected to the second connection pipe via a connecting pipe, and the first on / off unit is disposed on the connecting pipe, wherein the first on / off unit is a fluid valve V11.

[0010] Furthermore, the second on / off unit is a fluid valve V8.

[0011] Furthermore, each of the sampling cylinder structures includes a sampling cylinder body, with an upper connector and a lower connector connected to both ends of the sampling cylinder body. The upper connector has an upper flow hole, and the lower connector has a lower flow hole. The connecting structure is connected to the second connecting pipe through the lower flow hole, and the connecting structure is connected to the first connecting pipe through the upper flow hole. The connecting structure is used to connect the upper flow hole and the lower flow hole. The movable piston cooperates with the upper connector.

[0012] Furthermore, a first manual valve is connected to the upper connector, which is used to open or close the upper flow hole. A second manual valve is connected to the lower connector, which is used to open or close the lower flow hole. Before the instrument is lowered into the well, both the first manual valve and the second manual valve must be set to the open state.

[0013] Furthermore, the upper connector has a first fluid port, which communicates with the upper flow hole and is connected to the first connecting pipe; the lower connector has a second fluid port, which communicates with the lower flow hole and is connected to the second connecting pipe.

[0014] Furthermore, the connection structure includes a central rod disposed within the sampling cylinder body, with its two ends connected to the upper connector and the lower connector, respectively. The central rod has a residue removal channel extending along its length and penetrating the central rod, which communicates with the upper flow hole and the lower flow hole, respectively. The central rod also has a sample channel communicating with the sample chamber and the residue removal channel. A movable piston is disposed between the central rod and the sampling cylinder body, and the sample channel is disposed at the contact point between the upper connector and the movable piston.

[0015] Furthermore, a stirring block is sleeved on the central rod, the stirring block is disposed between the upper connector and the movable piston, the stirring block cooperates with the upper connector and the movable piston, and the sample channel is disposed at the contact point between the stirring block and the upper connector, or at the contact point between the stirring block and the movable piston.

[0016] Furthermore, a lower connector locking ring and a sampling cylinder locking ring are provided between the lower connector and the sampling cylinder body. The lower connector locking ring is connected to the lower connector, and the sampling cylinder locking ring is connected to the sampling cylinder body. The sampling cylinder locking ring is located between the lower connector locking ring and the lower connector. Both the lower connector locking ring and the sampling cylinder locking ring are provided with mud channels. The two mud channels are interconnected and connect the mud chamber to the outside of the sampling cylinder structure.

[0017] Furthermore, the movable piston includes an upper piston and a lower piston, and a nitrogen chamber is formed between the upper piston and the lower piston. The nitrogen chamber is used to fill with nitrogen, and the lower piston is provided with a nitrogen filling structure for filling the nitrogen chamber with nitrogen.

[0018] Furthermore, the lower piston is provided with a mounting hole, and the nitrogen filling structure is disposed in the mounting hole. The nitrogen filling structure includes a one-way valve and a sealing plug. The one-way valve is configured to allow nitrogen gas to be filled from the mud chamber into the nitrogen chamber, and the sealing plug is used to block the passage of the one-way valve before nitrogen filling.

[0019] Secondly, the present invention also provides a sampling method, wherein the sampling method employs the sampling tube section described in any of the above claims, and the method includes:

[0020] Adjust the second on / off unit to connect the main fluid pipeline, adjust the outlet valve of the outlet short section to open the outlet valve, close the sampling valve V1 of each sampling cylinder structure, and adjust the first on / off unit of each sampling cylinder structure to disconnect the second connecting pipeline.

[0021] Connect the sampling tube section and the outlet section to the sampling instrument string, and lower the sampling instrument string to the target sampling layer;

[0022] After the probe setting sub is set, the pumping sub begins pumping. The pumped fluid is discharged into the wellbore through the fluid main pipeline of the sampling tube sub and the outlet valve of the outlet sub.

[0023] When the fluid identification section detects that the fluid meets the sampling requirements, for any one of the sampling cylinder structures, the sampling valve V1 of that sampling cylinder structure is opened, the first on / off unit is adjusted to connect the second connecting pipe, and the second on / off unit is adjusted to disconnect the main fluid pipeline. The pump continues to pump until the predetermined time. The fluid is discharged into the wellbore after passing through the first connecting pipe, the connecting structure and the second connecting pipe in sequence, or after passing through the second connecting pipe, the connecting structure and the first connecting pipe in sequence.

[0024] Close the sampling valve V1 of the sampling cylinder structure, adjust the first on / off unit to disconnect the second connecting pipe, adjust the second on / off unit to connect the fluid main pipeline, close the outlet valve of the outlet short section, and continue pumping until the pressure of the fluid stored in the fluid main pipeline is equal to the predetermined pressure.

[0025] Open the sampling valve V1 of the sampling cylinder structure, adjust the first on / off unit to connect the second connecting pipe, adjust the second on / off unit to disconnect the main fluid pipeline, keep the outlet valve of the outlet short section closed, continue pumping, the fluid enters the first connecting pipe or the second connecting pipe, and the pressurized fluid pushes the movable piston through the connecting structure to move, thereby pumping the fluid into the sample chamber until the pressure in the main fluid pipeline increases, then stop pumping to complete the sampling operation of the sampling cylinder structure.

[0026] As can be seen from the above technical solution, the sampling tube section and sampling method provided by the present invention have the following beneficial effects:

[0027] The connection structure of the present invention is used to connect the first connecting pipe and the second connecting pipe. Therefore, the liquid remaining in the pipe can be discharged into the fluid main pipeline through the first connecting pipe, the connection structure and the second connecting pipe, and then discharged through the fluid main pipeline and the outlet short section to obtain the required fluid and improve the purity of the sample. Attached Figure Description

[0028] Figure 1 A schematic diagram of a formation testing instrument string is shown;

[0029] Figure 2 A schematic diagram of a sampling tube section in the prior art is shown;

[0030] Figure 3 A schematic diagram of a formation testing instrument string in an inverted position is shown.

[0031] Figure 4 A schematic diagram of a sampling tube section according to an embodiment of the present invention is shown;

[0032] Figure 5 A cross-sectional view of the sampling cylinder structure according to an embodiment of the present invention is shown;

[0033] Figure 6 A schematic diagram of the formation testing instrument string of an embodiment of the present invention is shown in positive connection mode;

[0034] Figure 7 A schematic diagram of the formation testing instrument string of an embodiment of the present invention in inverted mode is shown.

[0035] The attached diagram is labeled as follows: probe setting section 01, fluid identification section 02, pumping section 03, sampling tube section 04, and outlet section 05.

[0036] The sampling cylinder structure includes: 1. Movable piston; 2. Upper piston; 21. Lower piston; 22. One-way valve; 221. Sealing plug; 222. First connecting pipe; 3. Fluid main pipeline; 4. Connecting pipe; 5. Second connecting pipe; 6. First on / off unit; 7. Second on / off unit; 8. Upper connector; 9. First fluid port; 91. First manual valve; 10. Stirring block; 11. Sampling cylinder body; 12. Center rod; 13. Sample channel; 131. Residue removal channel; 132. Lower connector locking ring; 14. Sampling cylinder locking ring; 15. Second manual valve; 16. Lower connector; 17. Second fluid port; 171. Sample chamber; 18. Nitrogen chamber; 19. Mud chamber; 20. Detailed Implementation

[0037] To better understand the purpose, structure, and function of this invention, a sampling cylinder section and sampling method of this invention will be described in further detail below with reference to the accompanying drawings.

[0038] like Figures 4-5 As shown, this invention illustrates a sampling cylinder section according to an embodiment of the present invention, comprising at least one sampling cylinder structure 1. Each sampling cylinder structure 1 is provided with a movable piston 2, which divides the interior of the sampling cylinder structure 1 into a sample chamber 18 and a mud chamber 20. The mud chamber 20 is connected to the outside of the sampling cylinder structure 1. Each sampling cylinder structure 1 is connected to a fluid main pipeline 4 via a first connecting pipe 3. Each first connecting pipe 3 is provided with a sampling valve V1. Each sampling cylinder structure 1 is provided with a connecting structure, and each connecting structure is connected to a second connecting pipe 6. The second connecting pipe 6 is connected to the fluid main pipeline 4. The connecting structure is used to connect the first connecting pipe 3 and the second connecting pipe 6, and can connect the first connecting pipe 3 and the sample chamber 18. The second connecting pipe 6 is provided with a first on / off unit 7, which is used to control the connection or disconnection of the second connecting pipe 6.

[0039] In this embodiment, the sampling tube section includes at least one sampling tube structure 1. A movable piston 2 is disposed inside the sampling tube structure 1, dividing the internal space of the sampling tube structure 1 into a sample chamber 18 and a mud chamber 20. The sample chamber 18 is used to store the sampled material, and the mud chamber 20 is connected to the outside of the sampling tube structure 1. The movable piston 2 and the inner wall of the sampling tube structure 1 are connected in a sealed sliding connection. This sealed connection prevents mud from entering the sample from the mud chamber 20. Inside the sample chamber 18, the movable piston 2 can slide along the inner wall of the sampling cylinder structure 1 under the pressure of the mud. When the sample in the sample chamber 18 is removed and the mud chamber 20 is filled with mud, the movable piston 2 can slide along the inner wall of the sampling cylinder structure 1 under the pressure of the mud to compress the volume of the sample chamber. In this embodiment, the movable piston 2 cooperates with the sampling cylinder structure 1, that is, the movable piston 2 and the sampling cylinder structure 1 can fit together completely, thereby compressing the volume of the sample chamber 18 to 0 under the pressure of the mud in the mud chamber 20.

[0040] A second on / off unit 8 is provided on the fluid main pipeline 4 between the first connecting pipe 3 and the second connecting pipe 6. The second on / off unit 8 is used to control the opening or closing of the fluid main pipeline 4. In this embodiment, the second on / off unit 8 is used to control the opening and closing of the fluid main pipeline 4 connected between the first connecting pipe 3 and the second connecting pipe 6. When the fluid main pipeline 4 is opened by controlling the second on / off unit 8, and both the sampling valve V1 and the first on / off unit 7 are in the conducting state, all the fluid in the fluid main pipeline 4 can only flow back into the fluid main pipeline 4 through the second connecting pipe 6 and the first connecting pipe 3.

[0041] After the sampling device is lowered into the well, the mud in the well enters the mud chamber 20. The sampling valve V1 is installed on the first connecting pipe 3. When the sampling valve V1 is in the open state, the fluid in the main fluid line 4 cannot enter the sample chamber 18 through the sampling valve V1. At this time, the mud chamber 20 is full of mud. Therefore, under the pressure of the mud, the movable piston 2 moves in the direction of compressing the sample chamber 18 until the volume of the sample chamber 18 is compressed to zero. The first on / off unit 7 is used to control the connection or disconnection of the second connecting pipe 6. When the first on / off unit 7 is in the conducting state, the second connecting pipe 6 is connected. When the first on / off unit 7 is in the closed state, the second connecting pipe 6 is disconnected. When both the sampling valve V1 and the first on / off unit 7 are in the conducting state, and the second on / off unit 8 controls the main fluid line 4 to disconnect, the first connecting pipe 3 and the second connecting pipe 6 are in the connected state, so they can be used to remove residual fluid.

[0042] Specifically, after the sampling tube section is lowered into the well, the mud chamber 20 is filled with mud. Therefore, the mud pushes the movable piston 2 to move, minimizing the volume of the sample chamber 18. When the sampling tube section is in the positive connection mode, such as... Figure 6 As shown, when both the sampling valve V1 and the first on / off unit 7 are in the conducting state, the residual fluid flows back into the main fluid pipeline 4 after passing through the first connecting pipe 3, the connecting structure, and the second connecting pipe 6, thereby achieving the purpose of removing residue; when in the inverted mode, as Figure 7 As shown, when both the sampling valve V1 and the first on / off unit 7 are in the conducting state, the residual fluid flows into the main fluid pipeline 4 through the second connecting pipe 6, the connecting structure and the first connecting pipe 3, thereby achieving the purpose of removing residue; thus achieving the purpose of obtaining a relatively pure sample.

[0043] In one specific embodiment, each of the connection structures is connected to the second connection pipe 6 via a connection pipe 5, and the first on / off unit 7 is disposed on the connection pipe 5. The first on / off unit 7 is a fluid valve V11.

[0044] In one specific embodiment, the second on / off unit 8 is a fluid valve V8, which is a normally open valve.

[0045] In one specific embodiment, such as Figure 5 As shown, each sampling cylinder structure 1 includes a sampling cylinder body 12. An upper connector 9 and a lower connector 17 are connected to both ends of the sampling cylinder body 12. An upper flow hole is provided on the upper connector 9, and a lower flow hole is provided on the lower connector 17. A connecting structure is disposed within the sampling cylinder body 12. The connecting structure is connected to the second connecting pipe 6 through the lower flow hole and to the first connecting pipe 3 through the upper flow hole. The connecting structure is used to connect the upper flow hole and the lower flow hole, thereby connecting the first connecting pipe 3 and the second connecting pipe 6. The movable piston cooperates with the upper connector, and the movable piston 2 cooperates with the upper connector 9, thereby making the volume of the sample chamber 18 between the movable piston 2 and the upper connector 9 zero.

[0046] In this embodiment, each sampling cylinder structure 1 includes a sampling cylinder body 12, an upper connector 9, a lower connector 17, and a connecting structure. The connecting structure is disposed within the space formed by the sampling cylinder body 12, the upper connector 9, and the lower connector 17. The upper connector 9 has an upper flow hole for connecting the connecting structure and the first connecting pipe 3, so the fluid in the first connecting pipe 3 can flow into the connecting structure through the upper flow hole. The lower connector 17 has a lower flow hole for connecting the connecting structure and the second connecting pipe 6, so in the upright connection mode, the fluid in the first connecting pipe 3 can flow into the lower flow hole through the connecting structure, and then flow into the second connecting pipe 6 through the lower flow hole. In the inverted mode, the fluid in the first connecting pipe 3 flows into the main fluid pipeline. This achieves the connection between the connecting structure, the first connecting pipe 3, and the second connecting pipe 6, and realizes the purpose of discharging residual fluid.

[0047] In one specific embodiment, a first manual valve 10 is connected to the upper connector 9, which is used to open or close the upper flow orifice. A second manual valve 16 is connected to the lower connector 17, which is used to open or close the lower flow orifice. In this embodiment, the first manual valve 10 and the second manual valve 16 facilitate manual adjustment of the opening or closing of the upper or lower flow orifice. In order to discharge residual fluid through the upper or lower flow orifice, the first manual valve 10 and the second manual valve 16 in this embodiment need to be set to the open state before the instrument is lowered into the well.

[0048] In one embodiment, the upper connector 9 has a first fluid port 91, which communicates with the upper flow hole and is connected to the first connecting pipe 3; the lower connector 17 has a second fluid port 171, which communicates with the lower flow hole and is connected to the second connecting pipe 6 via a connecting pipe. In this embodiment, the first fluid port 91 is used to connect the upper connector 9 to the first connecting pipe 3 and communicates with the upper flow hole; the second fluid port 171 is used to connect the lower connector 17 to the second connecting pipe 6 and communicates with the lower flow hole.

[0049] In one embodiment, the connection structure includes a central rod 13 disposed within the sampling cylinder body 12. The two ends of the central rod 13 are connected to the upper connector 9 and the lower connector 17, respectively. A residue removal channel 132 extending along the length of the central rod 13 and penetrating the central rod 13 is provided on the central rod 13. The residue removal channel 132 communicates with the upper flow hole and the lower flow hole, respectively. A sample channel 131 communicating with the sample chamber 18 and the residue removal channel 132 is opened on the central rod 13. The movable piston 2 is disposed between the central rod 13 and the sampling cylinder body 12. The sample channel 131 is disposed at the contact point between the upper connector 9 and the movable piston 2. Therefore, when the fluid pressure in the residue removal channel 132 is high, the fluid, under its own pressure, can enter the contact point between the upper connector 9 and the movable piston 2 through the sample channel 131, and push the movable piston 2 to move, thereby achieving sampling.

[0050] In this embodiment, the connecting structure specifically includes a central rod 13, on which a residue removal channel 132 is provided. The residue removal channel 132 of the central rod 13 is connected to the sample cavity 18 through a sample channel 131. The sample channel 131 is located on the central rod 13. Specifically, the sample channel 131 can be set to one or more as needed. When there are multiple sample channels 131, the multiple sample channels 131 are distributed on the circumference of the central rod 13. The sample channel 131 is used to connect the sample cavity 18 and the residue removal channel 13. 2. Thus, sample fluid can be pumped into the sample chamber 18 through the residue removal channel 132 and the sample channel 131; the movable piston 2 is sleeved on the central rod 13, and the movable piston 2 and the central rod 13 are sealed and slidably connected, and the movable piston 2 can cooperate with the upper connector 9 to make the volume of the sample chamber 18 zero. When the volume of the sample chamber 18 is zero, the movable piston 2 and the upper connector 9 are in contact. In order to facilitate opening the sample chamber 18, the sample channel 131 is set at the contact point between the upper connector 9 and the movable piston 2.

[0051] Specifically, after the instrument is lowered into the well, the mud chamber 20 is filled with mud. The movable piston 2 compresses the sample chamber 18 under the pressure of the mud. The compression of the sample chamber 18 by the movable piston 2 can squeeze the residual fluid in the sample chamber 18 into the residue removal channel 132. When the movable piston 2 moves under the pressure of the mud to completely cover the sample channel 131, the sample chamber 18 forms a closed space, and the residual fluid in the sample chamber 18 cannot be squeezed out again. Therefore, in this embodiment, the sample channel 131 is located at the contact point between the upper connector 9 and the movable piston 2, so that all the residual fluid in the sample chamber 18 can be squeezed out. The squeezed residual fluid is discharged through the residue removal channel 132 and the second connecting pipe 6 (in the positive connection mode), or through the residue removal channel 132 and the first connecting pipe 3 (in the inverted mode).

[0052] In one specific embodiment, a stirring block 11 is sleeved on the central rod 13. The stirring block 11 is positioned between the upper connector 9 and the movable piston 2. The stirring block 11 cooperates with the upper connector 9 and the movable piston 2, thereby achieving a zero volume in the sample chamber 18. In this embodiment, the stirring block 11 is used to determine whether there is a sample in the sample chamber 18 and to stir the sample in the sample chamber 18, thereby making the sample more uniform. In addition, the stirring block 11, the movable piston 2, and the upper connector 9 need to meet the following conditions: when the movable piston 2 compresses the sample chamber 18, and the stirring block 11 is positioned between the movable piston 2 and the upper connector 9, and the volume of the sample chamber 18 is zero: the sample channel 131 is positioned at the contact point between the stirring block 11 and the upper connector 9, or the sample channel 131 is positioned at the contact point between the stirring block 11 and the movable piston 2.

[0053] In one specific embodiment, a lower connector locking ring 14 and a sampling cylinder locking ring 15 are provided between the lower connector 17 and the sampling cylinder body 12. The lower connector locking ring 14 is connected to the lower connector 17, and the sampling cylinder locking ring 15 is connected to the sampling cylinder body 12. The sampling cylinder locking ring 15 is located between the lower connector locking ring 14 and the lower connector 17. Both the lower connector locking ring 14 and the sampling cylinder locking ring 15 are provided with mud channels. The two mud channels are interconnected and connect the mud chamber 20 to the outside of the sampling cylinder structure 1. In this embodiment, a lower connector locking ring 14 and a sampling cylinder locking ring 15 are provided between the lower connector 17 and the sampling cylinder body 12. The lower connector locking ring 14 and the lower connector 17 are threadedly connected. The sampling cylinder locking ring 15 is located between the lower connector locking ring 14 and the lower connector 17. The sampling cylinder locking ring 15 is threadedly connected to the sampling cylinder body 12. The communication between the mud chamber 20 and the outside of the sampling cylinder structure 1 is achieved through the mud channels on the lower connector locking ring 14 and the sampling cylinder locking ring 15.

[0054] In one specific embodiment, the movable piston 2 includes an upper piston 21 and a lower piston 22, and a nitrogen chamber 19 is formed between the upper piston 21 and the lower piston 22. The nitrogen chamber 19 is used to fill with nitrogen, and the lower piston 22 is provided with a nitrogen filling structure for filling the nitrogen chamber 19 with nitrogen. In this embodiment, the upper piston 21 is located near the upper connector 9, and the lower piston 22 is located near the lower connector 17. The movable piston 2 is configured as two pistons to facilitate the formation of the nitrogen chamber 19, thereby facilitating the filling of nitrogen into the nitrogen chamber 19. In the prior art, as the sample in the sample chamber 18 returns to the surface from downhole, the pressure loss caused by the temperature drop will cause the pressure of the sample in the sample chamber 18 to be lower than the bubble point pressure, thus leading to oil and gas separation. In this embodiment, the movable piston 2 is configured as a double movable piston, and the nitrogen chamber 19 between the double movable pistons is filled with high-pressure nitrogen. This allows the energy storage compensation effect of nitrogen to be utilized to reduce the occurrence of oil and gas separation in the prior art and obtain high-quality fluid samples. The nitrogen-filling structure on the lower piston 22 is used to fill the nitrogen chamber 19 with nitrogen.

[0055] In one specific embodiment, the lower piston 22 has a mounting hole, and the nitrogen filling structure is disposed within the mounting hole. The nitrogen filling structure includes a one-way valve 221 and a sealing plug 222. The one-way valve 221 is configured to allow nitrogen gas to be filled from the mud chamber 20 into the nitrogen chamber 19. The sealing plug 222 is used to block the passage of the one-way valve 221 before nitrogen filling. In this embodiment, the nitrogen filling structure includes a one-way valve 221 and a sealing plug 222. The sealing plug 222 is used to block the passage of the one-way valve 221 to prevent gas from entering the nitrogen chamber 19. When nitrogen filling is required, the sealing plug 222 is opened, and nitrogen gas is introduced into the passage of the one-way valve 221.

[0056] To facilitate a more detailed understanding of a sampling cylinder section according to an embodiment of the present invention, it is described in detail below:

[0057] An embodiment of the present invention provides a sampling cylinder section comprising multiple sampling cylinder structures 1, each sampling cylinder structure 1 including an upper connector 9, a sampling cylinder body 12, a lower connector 17, and a central rod 13; wherein the upper connector 9 is connected to a first connecting pipe 3 via a first fluid port 91, the first connecting pipe 3 is connected to a main fluid pipeline 4, and a sampling valve V1 is provided on the first connecting pipe 3; the upper connector 9 has an upper flow hole communicating with the first fluid port 91, the lower connector 17 has a lower flow hole, the two ends of the central rod 13 are respectively connected to the upper connector 9 and the lower connector 17, and the central rod 13 has a residue removal channel 132, the upper flow hole, the residue removal channel 132, and the lower flow hole are connected; a double movable piston is provided between the central rod 13 and the sampling cylinder body 12, and a sample channel 131 is provided on the central rod 13. The movable piston can slide along the central rod 13, and when the upper piston 21 of the double movable piston slides to cover the sample channel 131, the volume of the sample chamber 18 is 0, thereby avoiding the situation where residual fluid is trapped in the sample chamber and cannot be discharged; the second fluid port 171 on the lower connector 17 is connected to the second connecting pipe 6 through the connecting pipe 5, the second connecting pipe 6 is connected to the fluid main line 4, the connecting pipe 5 is provided with a sampling valve V11, and the fluid main line 4 between the first connecting pipe 3 and the second connecting pipe 6 is provided with a fluid valve V8; in addition, the sampling cylinder short section 04 and the outlet short section 05 in this embodiment of the invention are two modules, so in the inverted mode, the outlet short section 05 can be set above the sampling cylinder short section 04 shown for residual fluid to flow out through the outlet short section 05.

[0058] Secondly, this embodiment of the invention also provides a sampling method, wherein the sampling method employs the sampling tube section described in any of the above embodiments, and the method includes:

[0059] Adjust the second on / off unit 8 to connect the fluid main pipeline 4, adjust the outlet valve of the outlet short section 05 to open the outlet valve, close the sampling valve V1 of each sampling cylinder structure 1, and adjust the first on / off unit 7 of each sampling cylinder structure 1 to disconnect the second connecting pipe 6.

[0060] Connect the sampling tube section 04 and the outlet section 05 to the sampling instrument string, and lower the sampling instrument string to the target sampling layer;

[0061] After the probe setting section 01 is set, the pumping section 03 starts pumping. The pumped fluid is discharged into the wellbore through the fluid main pipeline 4 of the sampling section 01 and the outlet valve of the outlet section 05. This step is used to directly discharge fluid that does not meet the sampling requirements.

[0062] When the fluid identification section 02 detects that the fluid meets the sampling requirements, for any one of the sampling cylinder structures 1, the sampling valve V1 of that sampling cylinder structure 1 is opened, the first on / off unit 7 is adjusted to connect the second connecting pipe 6, and the second on / off unit 8 is adjusted to disconnect the main fluid pipeline 4. Pumping continues until the predetermined time. The fluid is discharged into the well shaft after passing through the first connecting pipe 3, the connecting structure, and the second connecting pipe 6 in sequence, or after passing through the second connecting pipe 6, the connecting structure, and the first connecting pipe 3 in sequence. This step is used to discharge the residual fluid in the pipeline. In specific implementation, the pumping time of this step can be controlled to discharge the residual fluid. For example, when the actual pumping time of this step is equal to the predetermined time, it means that the residual fluid has been completely discharged.

[0063] After the residual fluid is discharged, the sampling valve V1 of the sampling cylinder structure 1 is closed, the first on / off unit 7 is adjusted to disconnect the second connecting pipe 6, the second on / off unit 8 is adjusted to connect the fluid main pipeline 4, the outlet valve of the outlet short section 05 is closed, and the pump continues to pump the fluid to accumulate pressure in the fluid main pipeline 4. This step can be controlled by pressure, for example, by controlling the accumulated pressure to be greater than the predetermined pressure, or it can be controlled by time.

[0064] Open the sampling valve V1 of the sampling cylinder structure 1, adjust the first on / off unit 7 to connect the second connecting pipe 6, adjust the second on / off unit 8 to disconnect the fluid main pipeline 4, keep the outlet valve of the outlet short section 05 closed, continue pumping, the fluid enters the first connecting pipe 3 or the second connecting pipe 6, and the pressurized fluid pushes the movable piston 2 through the connecting structure, thereby pumping the fluid into the sample chamber 18; until the pressure in the fluid main pipeline 4 increases, stop pumping to complete the sampling operation of the sampling cylinder structure 1.

[0065] In a specific implementation, taking an example where there are 6 sampling cylinder structures 1, three of which are connected to the same second connecting pipe 6 via connecting pipe 5, and the other three are connected to another second connecting pipe 6 via connecting pipe 5, the sampling method of this embodiment of the invention will be described in detail.

[0066] In positive connection mode, after the sampling tube section 04 of the present invention is connected to the instrument string, as follows: Figure 6 As shown, from top to bottom, they are: probe setting section 01, fluid identification section 02, pumping section 03, sampling tube section 04, and outlet section 05. The specific sampling method is as follows:

[0067] Before going down into the well, manually open the first manual valve 10 and the second manual valve 16. Control the connection of the main fluid pipeline by adjusting the second on / off unit (open the fluid valve V8). Adjust the outlet valve of the outlet short section to make it open. Connect the sampling tube short section and the outlet short section to the sampling instrument string. Fill the nitrogen chamber 19 with nitrogen. Under the action of high-pressure nitrogen, the upper piston 21 of the double movable piston is pushed to the leftmost end of the sampling tube body 12. The upper piston 21 contacts the stirring block 11 and the upper connector 9. The volume of the sample chamber 18 is 0. The lower piston 22 of the double movable piston is pressed to the rightmost end of the sampling tube body 12 and contacts the lower connector locking ring 14. After the instrument is lowered into the well, the mud in the wellbore enters the mud chamber 20 through the mud channel of the lower connector locking ring 14 and the sampling tube locking ring 15, and acts on the lower piston 22 to compress the high-pressure nitrogen.

[0068] The sampling instrument string is lowered to the target sampling layer. After the formation testing instrument string reaches the target sampling layer, the instrument probe setting section 01 is set. Under the reciprocating pumping action of the pumping section 03, the formation fluid is discharged into the wellbore through the fluid valve V8 and the outlet valve V7.

[0069] When the fluid identification sub 02 detects that the formation fluid purity meets the sampling requirements, it opens the sampling valve V1 and the corresponding sampling valve V11 of the first sampling cylinder body 12, closes the fluid valve V8 (disconnects the main fluid pipeline 4), and continues pumping. In this way, the fluid will enter the first sampling cylinder body 12 through the first fluid port 91. Due to the action of high-pressure nitrogen, the upper piston 214 and the stirring block 11 are pushed to the leftmost end of the sampling cylinder body 12. Therefore, the fluid can only be discharged into the wellbore through the center rod 13, the second manual valve 16, the second fluid port 171, the connecting pipe 5 and the second connecting pipe 6, the main fluid pipeline 4, and the outlet valve V7, thereby discharging the residual fluid.

[0070] After the residual fluid is completely removed, close sampling valve V1 and sampling valve V11, close outlet valve V7, and open fluid valve V8. Continue pumping at this time. Since there is no outlet for the fluid, the pumped fluid will build up high pressure, ready for sample filling.

[0071] Open sampling valve V1 and sampling valve V11, continue pumping and record sampling time and volume. At this time, high-pressure fluid will pass through the sample channel 131 on the central rod 13 of the first sampling cylinder body 12, overcome the nitrogen and mud pressure to push the upper piston 21 to move, and pump the pure sample into the sample chamber 18 of the first sampling cylinder body 12. When the pump pumps up high pressure again, it means that the sample has been filled and the sampling operation of the first sampling cylinder body 12 is completed. Then close sampling valve V1 and sampling valve V11 and store the fluid sample in the first sampling cylinder body 12.

[0072] Following the steps described above, sampling can be completed for the first three sampling tube bodies 12.

[0073] When sampling the last three sampling cylinder bodies 12, open the first fluid valve V8, and operate the corresponding sampling valves V1, sampling valve V11 and fluid valve V8 of the last three sampling cylinder bodies 12 according to the steps described above.

[0074] After the instrument completes its operation downhole and reaches the surface, manually close the first manual valve 10 and the second manual valve 16 to seal the sample in the sampling cylinder body 12. Manually operate the sampling valves V1 and V11 to release the pressure between the sampling valve V1 and the first manual valve 10, and between the sampling valve V11 and the second manual valve 16. Then, remove the sampling cylinder body 12 and transport it to the laboratory for PVT analysis.

[0075] In inverted mode, after the sampling tube section 04 of this invention is connected to the instrument string, as shown... Figure 7 As shown, from top to bottom, they are: outlet subsection 05, sampling cylinder subsection 04, fluid identification subsection 02, pumping subsection 03, and probe setting subsection 01. The specific sampling method is as follows:

[0076] Before going down the well, manually open the first manual valve 10 and the second manual valve 16. Control the connection of the fluid main pipeline by adjusting the second on / off unit. Adjust the outlet valve of the outlet short section to make it open. Connect the sampling tube short section and the outlet short section to the sampling instrument string. Fill the nitrogen chamber 19 with nitrogen. Under the action of high-pressure nitrogen, the upper piston 21 of the double movable piston is pushed to the leftmost end of the sampling tube body 12. The upper piston 21 contacts the stirring block 11 and the upper connector 9, compressing the volume of the sample chamber 18 to 0. The lower piston 22 of the double movable piston is pressed to the rightmost end of the sampling tube body 12 and contacts the lower connector locking ring 14. After the instrument is lowered into the well, the mud in the wellbore enters the mud chamber 20 through the mud channel of the lower connector locking ring 14 and the sampling tube locking ring 15, and acts on the lower piston 22 to compress the high-pressure nitrogen.

[0077] The sampling instrument string is lowered to the target sampling layer. After the formation testing instrument string reaches the target sampling layer, the instrument probe setting section 01 is set. Under the reciprocating pumping action of the pumping section 03, the formation fluid is discharged into the wellbore through the fluid valve V8 and the outlet valve V7. At this time, both the fluid valve V8 and the outlet valve V7 are in the conducting state.

[0078] When the fluid identification sub 02 detects that the formation fluid purity meets the sampling requirements, it opens the sampling valve V1 and the corresponding sampling valve V11 of the first sampling cylinder body 12, closes the corresponding fluid valve V8 (disconnects the main fluid pipeline 4), and continues pumping. In this way, the fluid will enter the first sampling cylinder body 12 through the second fluid port 171. Due to the action of high-pressure nitrogen, the upper piston 214 and the stirring block 11 are pushed to the leftmost end of the sampling cylinder body 12. Therefore, the fluid can only be discharged into the wellbore through the center rod 13, the first manual valve 10, the first fluid port 91, the first connecting pipe 3, and the main fluid pipeline 4 through the outlet valve V7, thereby discharging the residual fluid.

[0079] After the residual fluid in the first sampling cylinder body 12 is completely drained, the sampling valves V1 and V11 are closed, the outlet valve V7 is closed, and the fluid valve V8 is opened. At this time, the pump continues to pump. Since there is no outlet for the fluid to be discharged, the pumped fluid builds up high pressure, ready for sample filling.

[0080] Open sampling valve V1 and sampling valve V11, continue pumping and record sampling time and volume. At this time, high-pressure fluid will pass through the sample channel 131 on the central rod 13 of the first sampling cylinder body 12, overcome the nitrogen and mud pressure to push the upper piston 21 to move, and pump the pure sample into the sample chamber 18 of the first sampling cylinder body 12. When the pump pumps up high pressure again, it means that the sample has been filled and the sampling operation of the first sampling cylinder body 12 is completed. Then close sampling valve V1 and sampling valve V11 to store the fluid sample in the first sampling cylinder body 12.

[0081] Following the steps described above, sampling can be completed for the first three sampling tube bodies 12.

[0082] When sampling the last three sampling cylinder bodies 12, open the first fluid valve V8, and operate the corresponding sampling valves V1, sampling valve V11, and fluid valve V8 of the last three sampling cylinder bodies 12 according to the steps described above.

[0083] After the instrument completes its operation downhole and reaches the surface, manually close the first manual valve 10 and the second manual valve 16 to seal the sample in the sampling cylinder body 12. Manually operate the sampling valves V1 and V11 to release the pressure between the sampling valve V1 and the first manual valve 10, and between the sampling valve V11 and the second manual valve 16. Then, remove the sampling cylinder body 12 and transport it to the laboratory for PVT analysis.

[0084] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by those skilled in the art to which this invention pertains.

[0085] Furthermore, the terms "a," "two," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0086] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A sampling tube section, comprising at least one sampling tube structure, each of the sampling tube structures having a movable piston, the movable piston dividing the interior of the sampling tube structure into a sample chamber and a mud chamber, the mud chamber communicating with the exterior of the sampling tube structure, characterized in that, The movable piston, in conjunction with the sampling cylinder structure, enables the sample chamber to have a volume of zero. Each sampling cylinder structure is connected to a main fluid pipeline via a first connecting pipe and a second connecting pipe. The main fluid pipeline is used to connect to the fluid pipeline of the outlet section. Each first connecting pipe is equipped with a sampling valve V1. Each sampling cylinder structure contains a connecting structure for connecting the first connecting pipe and the second connecting pipe, and for connecting the first connecting pipe and the sample chamber. The second connecting pipe is equipped with a first on / off unit for controlling the connection or disconnection of the second connecting pipe. A second on / off unit is provided on the main fluid pipeline between the first connecting pipe and the second connecting pipe for controlling the connection or disconnection of the main fluid pipeline.

2. The sampling cartridge spool of claim 1, wherein, Each of the aforementioned connection structures is connected to the second connection pipe via a connecting pipe, and the first on / off unit is provided on the connecting pipe, which is a fluid valve V11.

3. The sampling cartridge spool of claim 1 wherein, The second on / off unit is fluid valve V8.

4. The sampling cartridge spool of claim 1 wherein, Each of the sampling cylinder structures includes a sampling cylinder body, with an upper connector and a lower connector connected to both ends of the sampling cylinder body. The upper connector has an upper flow hole, and the lower connector has a lower flow hole. The connecting structure is connected to the first connecting pipe through the upper flow hole, and the connecting structure is connected to the second connecting pipe through the lower flow hole. The connecting structure is used to connect the upper flow hole and the lower flow hole. The movable piston cooperates with the upper connector.

5. The sampling cartridge spool of claim 4 wherein, The upper connector is connected to a first manual valve, which is used to open or close the upper flow hole. The lower connector is connected to a second manual valve, which is used to open or close the lower flow hole. Before the instrument is lowered into the well, both the first manual valve and the second manual valve must be set to the open state.

6. The sampling cartridge spool of claim 4 wherein, The upper connector has a first fluid port, which communicates with the upper flow hole and is connected to the first connecting pipe; the lower connector has a second fluid port, which communicates with the lower flow hole and is connected to the second connecting pipe.

7. The sampling cartridge segment of claim 4 wherein, The connecting structure includes a central rod disposed within the sampling cylinder body. The two ends of the central rod are connected to the upper connector and the lower connector, respectively. The central rod has a residue removal channel extending along the length of the central rod and penetrating the central rod. The residue removal channel communicates with the upper flow hole and the lower flow hole, respectively. The central rod has a sample channel communicating with the sample chamber and the residue removal channel. The movable piston is disposed between the central rod and the sampling cylinder body. The sample channel is disposed at the contact point between the upper connector and the movable piston.

8. The sampling cartridge segment of claim 7, wherein, A stirring block is sleeved on the central rod. The stirring block is positioned between the upper connector and the movable piston. The stirring block cooperates with the upper connector and the movable piston. The sample channel is located at the contact point between the stirring block and the upper connector, or at the contact point between the stirring block and the movable piston.

9. The sampling tube section according to claim 4, characterized in that, A lower connector locking ring and a sampling cylinder locking ring are provided between the lower connector and the sampling cylinder body. The lower connector locking ring is connected to the lower connector, and the sampling cylinder locking ring is connected to the sampling cylinder body. The sampling cylinder locking ring is located between the lower connector locking ring and the lower connector. Both the lower connector locking ring and the sampling cylinder locking ring are provided with mud channels. The two mud channels are interconnected and connect the mud chamber to the outside of the sampling cylinder structure.

10. The sampling tube section according to claim 1, characterized in that, The movable piston includes an upper piston and a lower piston, and a nitrogen chamber is formed between the upper piston and the lower piston. The nitrogen chamber is used to fill with nitrogen, and the lower piston is provided with a nitrogen filling structure for filling the nitrogen chamber with nitrogen.

11. The sampling tube section according to claim 10, characterized in that, The lower piston has an installation hole, and the nitrogen filling structure is disposed in the installation hole. The nitrogen filling structure includes a one-way valve and a sealing plug. The one-way valve is configured to allow nitrogen gas to be filled from the mud chamber into the nitrogen chamber, and the sealing plug is used to block the passage of the one-way valve before nitrogen filling.

12. A sampling method, characterized in that, The sampling method employs the sampling tube section according to any one of claims 1-11, and the method includes: Adjust the second on / off unit to connect the main fluid pipeline, adjust the outlet valve of the outlet short section to open the outlet valve, close the sampling valve V1 of each sampling cylinder structure, and adjust the first on / off unit of each sampling cylinder structure to disconnect the second connecting pipeline. Connect the sampling tube section and the outlet section to the sampling instrument string, and lower the sampling instrument string to the target sampling layer; After the probe setting sub is set, the pumping sub begins pumping. The pumped fluid is discharged into the wellbore through the fluid main pipeline of the sampling tube sub and the outlet valve of the outlet sub. When the fluid identification section detects that the fluid meets the sampling requirements, for any one of the sampling cylinder structures, the sampling valve V1 of that sampling cylinder structure is opened, the first on / off unit is adjusted to connect the second connecting pipe, and the second on / off unit is adjusted to disconnect the main fluid pipeline. The pump continues to pump until the predetermined time. The fluid is discharged into the wellbore after passing through the first connecting pipe, the connecting structure and the second connecting pipe in sequence, or after passing through the second connecting pipe, the connecting structure and the first connecting pipe in sequence. Close the sampling valve V1 of the sampling cylinder structure, adjust the first on / off unit to disconnect the second connecting pipe, adjust the second on / off unit to connect the fluid main pipeline, close the outlet valve of the outlet short section, and continue pumping until the pressure of the fluid stored in the fluid main pipeline is equal to the predetermined pressure. Open the sampling valve V1 of the sampling cylinder structure, adjust the first on / off unit to connect the second connecting pipe, adjust the second on / off unit to disconnect the main fluid pipeline, keep the outlet valve of the outlet short section closed, continue pumping, the fluid enters the first connecting pipe or the second connecting pipe, and the pressurized fluid pushes the movable piston through the connecting structure to move, thereby pumping the fluid into the sample chamber until the pressure in the main fluid pipeline increases, then stop pumping to complete the sampling operation of the sampling cylinder structure.

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