Underground fluid multi-stage sampler applied to injection well and sampling method

Abstract

The invention discloses an underground fluid multi-stage sampler applied to an injection well and a sampling method. The problems that an existing injection well sampler needs to be matched with a downhole tool, the sampling number is limited, and instruments need to be pulled out and put in multiple times are mainly solved. The device is characterized in that the sampling barrel comprises an inner barrel (6) and an outer barrel (7), wherein the inner barrel (6) is connected with the driving motor (4); a plurality of outer cylinder sampling ports which are distributed at equal intervals in the axial direction are formed in the side wall of the outer cylinder (7), a plurality of inner cylinder sampling ports which are distributed at equal intervals in the axial direction are formed in the side wall of the inner cylinder (6), and the distance between the inner cylinder sampling port groups is smaller than that between the outer cylinder sampling port groups. The underground fluid multi-stage sampler applied to the injection well does not need to be matched with an underground tool, a test instrument does not need to be put in repeatedly, and sampling of a plurality of injection allocation sections can be completed by putting in the well once.

Description

Technical Field

[0001] The invention relates to the technical field of oil field production engineering, in particular to a downhole fluid multi-stage sampler and a sampling method used in an injection well. Background Art

[0002] In the later stage of water polymer flooding and ternary flooding in oil fields, the downhole conditions become increasingly complicated, and the ternary composite flooding causes the fluid in the well to have high viscosity and severe emulsification, which leads to increased pressure in the injection well and reduced injection volume. In order to understand the downhole conditions more directly, it is necessary to develop downhole fluid samplers for injection wells, sample downhole fluids, and then obtain the polymer concentration and viscosity of the sampled fluids at each sampling point through ground testing, and then conduct a comprehensive analysis to effectively determine the swept volume, effectiveness, and advance direction of the ternary fluid injection, and provide technical assistance for oilfield production. At present, in the sampling of injection wells, some use matching downhole tools for sampling, but the structure of the downhole tools is complex, the construction cost is high, and the number of samples is limited; some use a suction method similar to the principle of a syringe to achieve fluid sampling. Due to the travel limit of the drive motor screw, only single-layer or two-layer sampling can be achieved. For multi-level injection wells, the instrument needs to be lifted and lowered many times, which has a high construction risk and high labor cost. Summary of the invention

[0003] In order to overcome the problems that the existing injection well samplers need to be equipped with downhole tools, the sampling quantity is limited, and the instrument needs to be raised and lowered multiple times, the present invention provides a downhole fluid multi-stage sampler and a sampling method for injection wells. The downhole fluid multi-stage sampler for injection wells does not need to be matched with downhole tools, does not need to repeatedly lower test instruments, and can complete the sampling of multiple injection sections in a single trip.

[0004] The technical solution of the present invention is: a downhole fluid multi-stage sampler used in injection wells, including a driving motor and a sampling cylinder, the sampling cylinder including an inner cylinder and an outer cylinder, wherein the inner cylinder is connected to the driving motor; a plurality of outer cylinder sampling ports equidistantly distributed along the axial direction are opened on the side wall of the outer cylinder, a plurality of inner cylinder sampling ports equidistantly distributed along the axial direction are opened on the side wall of the inner cylinder, and the spacing between the inner cylinder sampling ports is smaller than the spacing between the outer cylinder sampling ports.

[0005] Each outer cylinder sampling port includes a plurality of monomer outer cylinder sampling ports evenly distributed along the circumferential direction, and each inner cylinder sampling port includes a plurality of monomer inner cylinder sampling ports evenly distributed along the circumferential direction.

[0006] Sealing rings are arranged between the inner cylinder and the outer cylinder at both ends of the inner cylinder sampling port.

[0007] The inner cylinder sampling port includes a first inner cylinder sampling port, a second inner cylinder sampling port, and a third inner cylinder sampling port, and the outer cylinder sampling port includes a first outer cylinder sampling port, a second outer cylinder sampling port, and a third outer cylinder sampling port, and the difference between the spacing between the outer cylinder sampling ports and the spacing between the inner cylinder sampling ports is N; Before the sampler is lowered into the well, the first outer cylinder sampling port is located below the first inner cylinder sampling port, and the axial distance between the two is N; the axial spacing between the second inner cylinder sampling port and the outer cylinder sampling port is 2N, and the axial spacing between the third inner cylinder sampling port and the third outer cylinder sampling port is 3N. At this time, all sampling ports are in a closed state.

[0008] Furthermore, it also includes a circuit cylinder and a multi-way travel switch. The circuit cylinder is connected to a power source to supply power to the driving motor, and the multi-way travel switch is used to stop and reverse the driving motor.

[0009] Furthermore, it also includes a magnetic locator, which is used for downhole depth correction of the instrument.

[0010] A downhole fluid sampling method applied to an injection well, comprising: S1. Before the sampler is lowered into the well, the first outer cylinder sampling port is located below the first inner cylinder sampling port, and the axial distance between the two is N; the axial distance between the second inner cylinder sampling port and the first outer cylinder sampling port is 2N, and the axial distance between the third inner cylinder sampling port and the third outer cylinder sampling port is 3N. At this time, all sampling ports are in a closed state; S2, the instrument is lowered into the well to calibrate the depth, the power supply is positive, the driving motor drives the inner tube to move downward, when the inner tube moves a distance of N, the driving motor stops moving forward, and the first-stage sampling tube starts sampling; S3, after the first-stage sampling tube has finished sampling, the power supply supplies negative electricity, the driving motor drives the inner tube to continue to move forward, and after moving a distance N, the driving motor stops moving, and the second-stage sampling tube starts sampling; S4, after the second-stage sampling tube has finished sampling, the power supply is positive, the driving motor drives the inner tube to continue to move forward, and the motor stops moving after moving a distance N, and the third-stage sampling tube starts sampling; S5. The power supply alternately supplies positive and negative electricity, and the driving motor drives the inner tube to continue to move forward to complete the sampling of the remaining layers in turn. After the sampling is completed, the instrument is lifted to the ground, and the instrument is equipped with a vent valve to lay out the samples of different layers.

[0011] Furthermore, in step S2, the first inner cylinder sampling port is aligned with the first outer cylinder sampling port, the axial spacing between the second inner cylinder sampling port and the third outer cylinder sampling port is N, the axial spacing between the third inner cylinder sampling port and the third outer cylinder sampling port is 2N, the first-stage sampling cylinder samples, and the second and third-stage sampling cylinders are closed.

[0012] Further, in step S3, the first inner cylinder sampling port is located above the first outer cylinder sampling port, the distance is N, the second inner cylinder sampling port is aligned with the second outer cylinder sampling port, the axial spacing between the third inner cylinder sampling port and the third outer cylinder sampling port is N, the first and third sampling cylinders are in a closed state, and the second sampling cylinder is sampling.

[0013] Further, in step S4, the distance between the first inner cylinder sampling port and the first outer cylinder sampling port is 2N, the distance between the second inner cylinder sampling port and the second outer cylinder sampling port is N, and the third inner cylinder sampling port is aligned with the third outer cylinder sampling port. At this time, the first and second sampling cylinders are in a closed state, and the third sampling cylinder is sampling.

[0014] The present invention has the following beneficial effects: due to the adoption of the above scheme, the present invention is not limited by the length of the driving device, and through the multi-stage travel switch and the stepping offset method, multiple points can be directly sampled in a single downhole without changing the length of the driving device, which can streamline the construction process, save labor costs, and reduce construction risks. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the inner cylinder and the outer cylinder; Figure 3 It is the positional relationship between the inner tube sampling port and the outer tube sampling port before the sampler is lowered into the well; Figure 4 It is a circuit schematic diagram of the present invention.

[0016] In the figure, 1-circuit cylinder, 2-magnetic positioner, 3-multi-way travel switch, 4-driving motor, 5-push rod, 6-inner cylinder, 61-first inner cylinder sampling port, 62-second inner cylinder sampling port, 63-third inner cylinder sampling port, 7-outer cylinder, 71-first outer cylinder sampling port, 72-second outer cylinder sampling port, 73-third outer cylinder sampling port. Implementation

[0017] The present invention will be further described below in conjunction with the accompanying drawings: Depend on Figure 1 , Figure 2As shown, a downhole fluid multi-stage sampler for injection wells includes a driving motor 4 and a sampling tube. The sampling tube includes an inner tube 6 and an outer tube 7. The output shaft of the driving motor 4 is connected to the inner tube 6 through a push rod 5, and can push the inner tube 6 to move in the outer tube 7. The side wall of the outer tube 7 is provided with a plurality of outer tube sampling ports equidistantly distributed along the axial direction, and the side wall of the inner tube 6 is provided with a plurality of inner tube sampling ports equidistantly distributed along the axial direction; each outer tube sampling port includes a plurality of outer tube sampling ports uniformly distributed along the circumferential direction, and each inner tube sampling port includes a plurality of inner tube sampling ports uniformly distributed along the circumferential direction, so that when the inner and outer tube sampling ports are aligned axially, the inside and outside of the sampling tube are connected. The spacing between the inner tube sampling ports is smaller than the spacing between the outer tube sampling ports. Sealing rings are provided between the inner tube 6 and the outer tube 7 at both ends of the inner tube sampling ports to ensure that both ends of the inner tube sampling ports are sealed. The outer cylinder 7 is usually an integral cylinder, and the inner cylinder 6 is formed by multiple independent single-section cylinders connected by threads. The number of inner cylinders can be increased or decreased in real time according to the number of sampling layers. The sampling volume of a single inner cylinder is 400ml and 200ml, which can be replaced as needed.

[0018] The multi-stage sampler also includes a circuit tube 1, a magnetic locator 2 and a multi-way travel switch 3. The circuit tube 1 supplies power to the system through a power supply, and the depth of the instrument in the well is corrected through the magnetic locator 2, so as to determine the depth of the measuring point; the multi-way travel switch 3 stops the drive motor 4 at a suitable position and ensures that the motor always keeps rotating in the positive direction under positive and negative power conditions, so that the motor keeps moving forward.

[0019] The following takes the example of three inner and outer tube sampling ports to explain the detailed structure and working process of the sampler. Figure 3 As shown, the outer cylinder sampling ports are, from top to bottom, the first outer cylinder sampling port 71, the second outer cylinder sampling port 72, and the third outer cylinder sampling port 73, and the distance between two adjacent outer cylinder sampling ports is X; the inner cylinder sampling ports are, from top to bottom, the first inner cylinder sampling port 61, the second inner cylinder sampling port 62, and the third inner cylinder sampling port 63, and the distance between two adjacent inner cylinder sampling ports is XN.

[0020] Before the sampler is lowered into the well, the first outer cylinder sampling port 71 is located below the first inner cylinder sampling port 61, and the axial distance between the two is N; the axial spacing between the second inner cylinder sampling port 62 and the outer cylinder sampling port 72 is 2N, and the axial spacing between the third inner cylinder sampling port 63 and the third outer cylinder sampling port 73 is 3N. Under the action of the sealing ring, each sampling port is in a closed state at this time.

[0021] The control principle of the sampler is to keep the motor rotating in the positive direction by cross-powering the positive and negative electricity, so that the motor always moves forward and multiple sampling is achieved. Figure 4As shown, M is the drive motor, S1 and S2 are the sample taking and sample placing reversing switches, D1, D2, D3, and D4 are diodes respectively, and the diodes have the functions of unidirectional conduction and reverse cutoff. Before the instrument is lowered into the well, S1 and S2 are connected as shown in the figure, the travel switches A and B are grounded, and the instrument is supplied with positive power. At this time, the power supply end is at a high potential, the diodes D1 and D4 are turned on, and D2 and D3 are cut off. The current flows through the power supply, D1, and the 3 and 2 paths of S2, the drive motor M, and the 2 and 3 paths of S1, and finally flows into the travel switch B to form a loop; the drive motor rotates forward to push the pull rod forward until it encounters the internal preset contact, and the contact presses down the travel switch, disconnecting the travel switch B, and the drive motor stops, completing the first-level sampling. At this time, the travel switch A is still grounded and turned on. The instrument supplies negative electricity, at this time the power supply end is at low potential, diodes D3 and D2 are turned on, D1 and D4 are turned off, and the current flows through the 3 and 2 paths of the travel switch A, D2, S2, the 2 and 3 paths of the drive motor M and S1, and finally flows into the power supply to form a loop; the drive motor rotates forward to push the pull rod forward until it encounters the preset contact inside the pull plate, which acts to disconnect the travel switch A, and the travel switch B is grounded and turned on, and the drive motor stops, completing the second-level sampling. In this way, the remaining sampling tubes are sampled respectively. After the instrument test is completed, it is lifted out of the ground and S1 and S2 are reversed. At this time, regardless of the positive and negative power supply, the drive motor is reversed to achieve the setting out.

[0022] A downhole fluid sampling method applied to an injection well, comprising: S1. Before the sampler is lowered into the well, the first outer cylinder sampling port 71 is located at the lower part of the first inner cylinder sampling port 61, and the axial distance between the two is N; the axial spacing between the second inner cylinder sampling port 62 and the outer cylinder sampling port 72 is 2N, and the axial spacing between the third inner cylinder sampling port 63 and the third outer cylinder sampling port 73 is 3N. Under the action of the sealing ring, each sampling port is in a closed state at this time.

[0023] S2. After the instrument is lowered into the well, the depth is calibrated by the magnetic positioner 2, and then lowered to the top of the first-stage water distributor. The power supply is positive, and the drive motor 4 drives the push rod 5 to drive the inner cylinder 6 to move downward. When the inner cylinder 6 moves a distance of N, it touches the first-stage travel switch, the current returns to zero, the motor stops moving, the first inner cylinder sampling port 61 is aligned with the first outer cylinder sampling port 71, the axial spacing between the second inner cylinder sampling port 62 and the outer cylinder sampling port 72 is N, and the axial spacing between the third inner cylinder sampling port 63 and the third outer cylinder sampling port 73 is 2N. At this time, the first-stage sampling cylinder starts sampling, and the second and third-stage sampling cylinders are closed.

[0024] S3, after being stationary for a period of time, due to the pressure difference, the first-stage sampling tube completes sampling. After the first-stage sampling tube completes sampling, the power supply supplies negative electricity, and the driving motor drives the push rod to continue to move forward. After moving a distance N, it encounters the second-stage travel limit switch, the current returns to zero, and the motor stops moving. At this time, the first inner tube sampling port 61 is located above the first outer tube sampling port 71, the distance is N, the second inner tube sampling port 62 is aligned with the second outer tube sampling port 72, and the axial spacing between the third inner tube sampling port 63 and the third outer tube sampling port 73 is N. Under the sealing of the sealing ring, the first and third-stage sampling tubes are in a closed state, and the second-stage sampling tube is sampling.

[0025] S4, after being stationary for a period of time, due to the pressure difference, the second-stage sampling tube completes sampling. After the second-stage sampling tube completes sampling, the power supply is positive, and the driving motor drives the push rod to continue to move forward. After moving a distance N, it encounters the third-stage travel limit switch, the current returns to zero, and the motor stops moving. At this time, the first inner tube sampling port 61 is located above the first outer tube sampling port 71, the distance is 2N, the distance between the second inner tube sampling port 62 and the second outer tube sampling port 72 is N, the third inner tube sampling port 63 is aligned with the third outer tube sampling port 73, and under the sealing of the sealing ring, the first and second-stage sampling tubes are in a closed state, and the third-stage sampling tube is sampling.

[0026] S5. Similarly, samples are taken from the third, fourth and even more sampling tubes. After sampling, the instrument is lifted to the ground to complete stratified sampling. After the instrument is lifted out of the ground, a special vent valve is used to lay out samples from different layers, and then the sampled liquid is tested.

Claims

1. A downhole fluid multi-stage sampler for an injection well, comprising a drive motor (4) and a sampling tube, characterized in that: The sampling cylinder comprises an inner cylinder (6) and an outer cylinder (7), wherein the inner cylinder (6) is connected to a drive motor (4); a plurality of outer cylinder sampling ports equidistantly distributed along the axial direction are formed on a side wall of the outer cylinder (7); a plurality of inner cylinder sampling ports equidistantly distributed along the axial direction are formed on a side wall of the inner cylinder (6), and a spacing between the inner cylinder sampling ports is smaller than a spacing between the outer cylinder sampling ports.

2. The multi-stage downhole fluid sampler for injection wells according to claim 1, characterized in that: Each outer cylinder sampling port includes a plurality of monomer outer cylinder sampling ports evenly distributed along the circumferential direction, and each inner cylinder sampling port includes a plurality of monomer inner cylinder sampling ports evenly distributed along the circumferential direction.

3. The multi-stage downhole fluid sampler for injection wells according to claim 2, characterized in that: Sealing rings are provided between the inner cylinder (6) and the outer cylinder (7) at both ends of the inner cylinder sampling port.

4. The multi-stage downhole fluid sampler for injection wells according to claim 3, characterized in that: The inner cylinder sampling ports include an inner cylinder first sampling port (61), an inner cylinder second sampling port (62), and an inner cylinder third sampling port (63); the outer cylinder sampling ports include an outer cylinder first sampling port (71), an outer cylinder second sampling port (72), and an outer cylinder third sampling port (73); and the difference between the spacing between the outer cylinder sampling ports and the spacing between the inner cylinder sampling ports is N; Before the sampler is lowered into the well, the first outer cylinder sampling port (71) is located below the first inner cylinder sampling port (61), and the axial distance between the two is N; the axial distance between the second inner cylinder sampling port (62) and the outer cylinder sampling port (72) is 2N, and the axial distance between the third inner cylinder sampling port (63) and the third outer cylinder sampling port (73) is 3N. At this time, all the sampling ports are in a closed state.

5. The multi-stage downhole fluid sampler for injection wells according to any one of claims 1 to 4, characterized in that: It also includes a circuit cylinder (1) and a multi-way travel switch (3). The circuit cylinder (1) is connected to a power source to supply power to a drive motor (4). The multi-way travel switch (3) is used to stop and reverse the drive motor (4).

6. The multi-stage downhole fluid sampler for injection wells according to claim 5, characterized in that: It also includes a magnetic locator (2), which is used for downhole depth calibration of the instrument.

7. A method for sampling downhole fluid applied to an injection well, characterized in that include: S1. Before the sampler is lowered into the well, the first outer cylinder sampling port (71) is located below the first inner cylinder sampling port (61), and the axial distance between the two is N; The axial distance between the second inner cylinder sampling port (62) and the outer cylinder sampling port (72) is 2N, and the axial distance between the third inner cylinder sampling port (63) and the third outer cylinder sampling port (73) is 3N. At this time, all the sampling ports are in a closed state; S2, the instrument is lowered into the well to calibrate the depth, the power supply is positive, the drive motor (4) drives the inner tube (6) to move downward, when the inner tube (6) moves a distance N, the drive motor (4) stops moving forward, and the first-stage sampling tube starts sampling; S3, after the first-stage sampling tube has finished sampling, the power supply supplies negative electricity, the driving motor (4) drives the inner tube (6) to continue to move forward, and after moving a distance N, the driving motor stops moving, and the second-stage sampling tube starts sampling; S4, after the second-stage sampling tube has finished sampling, the power supply is positive, the driving motor (4) drives the inner tube (6) to continue to move forward, and after moving a distance N, the motor stops moving, and the third-stage sampling tube starts sampling; S5. The power supply alternately supplies positive and negative electricity, and the driving motor (4) drives the inner cylinder (6) to continue to move forward, and completes the sampling of the remaining layers in sequence. After the sampling is completed, the instrument is lifted to the ground, and the instrument is equipped with a vent valve to sample the samples of different layers.

8. The downhole fluid sampling method for injection wells according to claim 7, characterized in that: In step S2, the first inner cylinder sampling port (61) is aligned with the first outer cylinder sampling port (71), the axial spacing between the second inner cylinder sampling port (62) and the third outer cylinder sampling port (72) is N, the axial spacing between the third inner cylinder sampling port (63) and the third outer cylinder sampling port (73) is 2N, the first-stage sampling cylinder is sampling, and the second and third-stage sampling cylinders are closed.

9. The downhole fluid sampling method for injection well according to claim 7, characterized in that: In step S3, the first inner cylinder sampling port (61) is located above the first outer cylinder sampling port (71) at a distance of N, the second inner cylinder sampling port (62) is aligned with the second outer cylinder sampling port (72), the axial spacing between the third inner cylinder sampling port (63) and the third outer cylinder sampling port (73) is N, the first and third sampling cylinders are in a closed state, and the second sampling cylinder is sampling.

10. The downhole fluid sampling method for injection well according to claim 7, characterized in that: In step S4, the distance between the first inner cylinder sampling port (61) and the first outer cylinder sampling port (71) is 2N, the distance between the second inner cylinder sampling port (62) and the second outer cylinder sampling port (72) is N, and the third inner cylinder sampling port (63) is aligned with the third outer cylinder sampling port (73). At this time, the first and second stage sampling cylinders are in a closed state, and the third stage sampling cylinder is sampling.

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