Underground supercritical carbon dioxide mass flow testing device and testing method

Abstract

The invention discloses an underground supercritical carbon dioxide mass flow testing device and a testing method. The device comprises a measuring short section and a flow collecting short section, the measuring short section comprises a volume flow meter, a temperature sensor, a pressure sensor, a flow plate and a magnetic positioning module, and a density prediction model is preset on the flow plate; and the flow plate is used for predicting a density value by using a density prediction model based on the obtained temperature value and pressure value, and converting the mass flow rate of the overflowing carbon dioxide according to the density value and the obtained volume flow rate. The device can monitor a plurality of injection parameters such as mass and flow of carbon dioxide injection in different underground intervals in real time, and provides an on-line testing means for the mass and flow regulation and control of the carbon dioxide flooding injection well intervals in an oil field.

Description

Technical Field

[0001] This invention relates to the field of downhole production testing technology in oil extraction, and particularly to a downhole supercritical carbon dioxide mass flow rate testing device and testing method. Background Technology

[0002] Carbon dioxide flooding and storage have become important technologies for oilfields to achieve peak carbon levels and carbon neutrality. The use of CO2 to enhance oil recovery has seen rapid development in oilfields. Chinese oil reservoirs exhibit significant vertical heterogeneity. When CO2 is injected indiscriminately, the injected gas tends to surge along high-permeability layers, causing gas channeling and reducing oil recovery efficiency and storage rate. Practice has proven that stratified CO2 injection is an effective technology for achieving balanced reservoir utilization.

[0003] Accurate monitoring of mass flow rate in layered CO2 injection is a fundamental requirement. Currently, the main method used is neutron oxygen activation logging, which is costly, leads to untimely testing, and results in a low success rate for injection. Furthermore, due to the highly diffusive and compressible properties of supercritical carbon dioxide, variations in temperature and pressure across different layers can cause changes in carbon dioxide density. Therefore, there is an urgent need to develop low-cost, accurate downhole supercritical CO2 mass flow rate testing technology. Summary of the Invention

[0004] This invention was developed to achieve rapid and accurate measurement of supercritical carbon dioxide mass flow rate in wells.

[0005] As one aspect of the present invention, an embodiment of the present invention provides a downhole supercritical carbon dioxide mass flow rate testing device, including a measuring section and a collecting section. The measuring section includes a volumetric flow meter, a temperature sensor, a pressure sensor, a flow plate, and a magnetic positioning module. The flow plate is preset with a density prediction model.

[0006] The flow meter is used to predict the density value based on the obtained temperature and pressure values ​​using the density prediction model, and to calculate the mass flow rate of carbon dioxide flowing through the flow based on the density value and the obtained volumetric flow rate.

[0007] Optionally, the density prediction model is obtained by training an XGBoost machine learning model using a sample set, wherein a sample in the sample set includes the temperature and pressure values ​​of the environment in which carbon dioxide is located, as well as the density value of carbon dioxide.

[0008] Optionally, the current collector subsection includes a main control board, a motor, a support mechanism, and a sealing cup;

[0009] The motor is used to rotate in response to the measurement command of the main control board, so as to sequentially open the support mechanism through the transmission component, so that the device is supported on the inner wall of the oil pipe, and the continued rotation opens the sealing cup, thus completing the sealing of the annular space between the device and the oil pipe;

[0010] The motor is also used to rotate in the opposite direction in response to the retraction command of the main control board, so as to realize the retraction of the sealing cup and the support mechanism in sequence through the transmission assembly.

[0011] Optionally, the volumetric flow meter is an eccentric vortex volumetric flow meter.

[0012] As another aspect of the present invention, embodiments of the present invention provide a method for testing the mass flow rate of supercritical carbon dioxide in wells, comprising:

[0013] A cable is used to lower any of the above-mentioned downhole supercritical carbon dioxide mass flow rate testing devices into the target location of the carbon dioxide stratified injection system in the injection well, and the carbon dioxide mass flow rate at the target location is obtained through the flow plate of the device.

[0014] The device is sequentially raised to a position between two adjacent downhole devices above the current position, and the carbon dioxide mass flow rate at the corresponding position is obtained through the main control board of the device, until there is only one downhole device above the current position. The downhole device is a water distributor or a packer.

[0015] Optionally, the target location is the position between the fixed ball seat and the adjacent upper downhole device. After obtaining the carbon dioxide mass flow rate at the target location, the method further includes:

[0016] Determine whether the carbon dioxide mass flow rate at the target location is 0;

[0017] If not, generate and send a notification that the fixed ball seat has leaked.

[0018] Optional, also includes:

[0019] For each carbon dioxide mass flow rate measurement location other than the bottommost one, the difference between the carbon dioxide mass flow rate at that measurement location and the carbon dioxide mass flow rate at the adjacent measurement location below it is determined as the carbon dioxide mass flow rate injected into the injection layer between the two measurement locations.

[0020] Optionally, if the oil layers in the reservoir where the carbon dioxide stratified injection system is located are all thick oil layers;

[0021] The water distributor in the carbon dioxide stratified injection system is a single-control valve water distributor, and the packer is a single-rubber tube cable packer.

[0022] Optionally, if a thin oil layer exists in the reservoir where the carbon dioxide stratified injection system is located, the carbon dioxide stratified injection system is equipped with a double-sleeve packer at the corresponding position of the thin oil layer, so that the thin oil layer is located between the upper and lower sleeves of the double-sleeve packer.

[0023] The dual-tube packer includes an upper connector, a central tube, a tube assembly, a setting / unsetting assembly, a backwashing assembly, and a lower connector. The tube assembly includes an upper tube and a lower tube that are airtightly connected. The dual-tube packer also includes a thrust-guided fluid ring disposed between the upper and lower tubes. The central tube has an axially drilled fluid flow channel and a backwashing channel in its wall. The outlet position of the fluid flow channel matches the corresponding first through hole of the guide ring, so that after the dual-tube packer is set, the injected fluid can flow out of the dual-tube packer through the corresponding through hole of the guide ring. The outlet of the backwashing channel is located below the lower tube, and after the dual-tube packer is set, the backwashing channel is connected through the guide ring.

[0024] Optionally, the central tube of the double-tube packer has multiple axial fluid flow channels and multiple backwash channels drilled circumferentially along its wall, with the fluid flow channels and backwash channels arranged alternately.

[0025] Optionally, the wall of the central tube is also drilled with an axial cable channel, which communicates with the corresponding through hole of the upper connector and the corresponding through hole of the lower connector.

[0026] The upper connector is provided with a through hole that matches the position of the fluid flow channel.

[0027] Optionally, the liquid guiding ring is provided with a number of first through holes that are the same as the number of liquid flow channels and whose positions match the positions of the liquid flow channels. The first through holes are provided on a circumference.

[0028] The backwash channel is divided into upper and lower sections. The liquid guide ring is provided with a number of second through holes that are twice the number of the backwash channel. The second through holes are evenly distributed on the two circumferences. After the packer is set, the upper section of the backwash channel, the second through hole that is matched on one circumference, the second through hole that is matched on the other circumference, and the lower section of the backwash channel are connected in sequence. The two second through holes are connected by a connecting bridge.

[0029] Optionally, depending on the combination of thin and thick oil layers, at least one of the following can be provided at other corresponding locations of the carbon dioxide stratified injection system: a single-control valve cable water distributor, a dual-control valve cable water distributor, and a single-rubber tube cable packer.

[0030] Optionally, if the reservoir consists of alternating thin and thick single layers, and the uppermost oil layer is a thin layer, then, depending on the combination of thin and thick oil layers, at least one of the following is provided at other corresponding positions of the carbon dioxide stratified injection system: a single-control valve cable-connected water distributor, a dual-control valve cable-connected water distributor, and a single-rubber sleeve cable-connected packer, including:

[0031] The carbon dioxide stratified injection system is equipped with a single-control valve cable water distributor above the position corresponding to the uppermost thin oil layer, which is used to supply water to the double rubber sleeve packer of the thin oil layer.

[0032] If the lowest oil layer of the reservoir is a thick oil layer, a single-control valve through-cable water distributor is installed at the corresponding position of the thick oil layer to inject water into the thick oil layer; a double-control valve through-cable water distributor is installed at the corresponding position of other thick oil layers to inject water into the thick oil layer and to distribute water to the adjacent lower double rubber sleeve packer.

[0033] Optionally, if the reservoir consists of alternating thin and thick single layers, and the uppermost oil layer is a thick oil layer, then, depending on the combination of thin and thick oil layers, at least one of the following is provided at other corresponding positions of the carbon dioxide stratified injection system: a single-control valve cable-connected water distributor, a dual-control valve cable-connected water distributor, and a single-rubber sleeve cable-connected packer, including:

[0034] The carbon dioxide stratified injection system has a single rubber tube cable packer installed above the position corresponding to the uppermost thick oil layer;

[0035] If the lowest oil layer of the reservoir is a thick oil layer, a single-control valve through-cable water distributor is installed at the corresponding position of the thick oil layer to inject water into the thick oil layer; a double-control valve through-cable water distributor is installed at the corresponding position of other thick oil layers to inject water into the thick oil layer and to distribute water to the adjacent lower double rubber sleeve packer.

[0036] Optionally, depending on the combination of thin and thick oil layers, at least one of the following is provided at other corresponding locations in the carbon dioxide stratified injection system: a single-control valve cable-through water distributor, a dual-control valve cable-through water distributor, and a single-rubber-tube cable-through packer:

[0037] If the uppermost oil layer is a thick oil layer, a single rubber tube cable packer is installed above the corresponding position of the thick oil layer;

[0038] If two thick oil layers are adjacent, a single rubber tube cable packer is installed at the corresponding position between the two adjacent thick oil layers;

[0039] If the water distributor at the location corresponding to the thick oil layer needs to supply water to the adjacent double-sleeve packer, a double-control valve cable-connected water distributor is installed at that location to inject water into the thick oil layer and supply water to the double-sleeve packer; if the water distributor at the location corresponding to the thick oil layer does not need to supply water to the adjacent double-sleeve packer, a single-control valve cable-connected water distributor is installed at that location to inject water into the thick oil layer.

[0040] Optionally, the thickness boundary between the thick and thin oil layers is determined based on the sum of the thicknesses of the water distributor and the single-tube cable packer.

[0041] The beneficial effects of the above-mentioned technical solutions provided in the embodiments of the present invention include at least the following:

[0042] (1) In this embodiment of the invention, a downhole supercritical carbon dioxide mass flow rate testing device is provided, which can monitor multiple parameters such as pressure, temperature, carbon dioxide volume flow rate and mass flow rate in the downhole section of the CO2 injection well in real time.

[0043] (2) In this embodiment of the invention, a downhole supercritical carbon dioxide mass flow rate testing device is provided. The density prediction model is pre-installed, and the density can be directly calculated based on the measured temperature and pressure of the carbon dioxide environment. Thus, the mass flow rate of the flowing carbon dioxide can be calculated based on the measured volume flow rate, thereby realizing the direct measurement of downhole carbon dioxide mass flow rate.

[0044] (3) In this embodiment of the invention, a downhole supercritical carbon dioxide mass flow test device is provided, which uses a sealing cup to collect carbon dioxide. Compared with setting a sealing ring on the outside of the device, this greatly reduces the probability of the sealing structure being damaged during the device’s lowering and raising.

[0045] (4) In this embodiment of the invention, a method for testing the mass flow rate of supercritical carbon dioxide in a well is provided. The mass flow rate of carbon dioxide at each measuring point is measured in order from bottom to top. First, since the fluid injection direction is from top to bottom, selecting the measurement order from bottom to top can make the device flushed under the action of the reverse fluid, avoiding the decrease in measurement accuracy caused by fluid contamination. Second, the measurement can be started from below the bottom of the bottom well device of the carbon dioxide stratified injection system to determine whether the fixed ball seat below has leaked.

[0046] (5) In this embodiment of the invention, a method for testing the mass flow rate of supercritical carbon dioxide in a well is provided, which realizes the injection development of thin oil layers through a double rubber packer.

[0047] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0048] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0049] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0050] Figure 1 This is an overall structural and axial cross-sectional view of the measuring section of the downhole supercritical carbon dioxide mass flow testing device provided in Embodiment 1 of the present invention;

[0051] Figure 2 This is an overall structural and axial cross-sectional view of the flow collection section of the downhole supercritical carbon dioxide mass flow rate testing device provided in Embodiment 1 of the present invention;

[0052] Figure 3 This is a diagram showing the distribution of the carbon dioxide stratified injection system and various carbon dioxide measurement points provided in Embodiment 3 of the present invention.

[0053] Figure 4 Here is an axial cross-sectional view of the existing Y341 packer;

[0054] Figure 5 This is an axial cross-sectional view of the double-tube packer in Embodiment 4 of the present invention;

[0055] Figure 6 This is a cross-sectional view of a double-tube packer in the "AA" and "BB" directions according to Embodiment 4 of the present invention;

[0056] Figure 7 This is a structural diagram of the double-tube packer in Embodiment 4 of the present invention;

[0057] Figure 8 This is a diagram showing the distribution of the carbon dioxide stratified injection system and various carbon dioxide measurement points provided in Embodiment 5 of the present invention.

[0058] Figure 9 This is a diagram showing another carbon dioxide stratified injection system and the distribution of each carbon dioxide measurement point provided in Embodiment 5 of the present invention. Detailed Implementation

[0059] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0060] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "far," "near," "front," and "rear," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0061] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0062] Example 1

[0063] Embodiment 1 of the present invention provides a downhole supercritical carbon dioxide mass flow rate testing device, comprising a measuring sub and a collecting sub connected sequentially from top to bottom. In this embodiment, "top" and "bottom" refer to their relative positions downhole. See also Figure 1 The diagram shown is the overall structural diagram and axial cross-sectional view of the measuring section. (See attached image.) Figure 2 The diagram shown is the overall structural diagram and axial cross-sectional view of the collector section.

[0064] The measuring section includes a volumetric flow meter 11, a temperature sensor, a pressure sensor (the temperature sensor and pressure sensor are not shown in the figure), a flow plate 12, and a magnetic positioning module 13. The flow plate 12 is preset with a density prediction model.

[0065] Specifically, the magnetic positioning module 13 is equipped with magnets 131 for detecting the downhole location of the device. The magnetic positioning device 13 can monitor the tubing coupling in real time to determine the location of the device when it is lowered into the well.

[0066] To meet the requirement of a maximum outer diameter of 42 mm for the device, the volumetric flow meter 11 can be an eccentric vortex flow meter.

[0067] The density prediction model is obtained by training an XGBoost machine learning model using a sample set. Each sample in the sample set includes the temperature and pressure values ​​of the environment containing carbon dioxide, as well as the density value of carbon dioxide.

[0068] The flow plate 12 is used to predict the density value based on the temperature value obtained by the temperature sensor and the pressure value obtained by the pressure sensor, and to calculate the mass flow rate of carbon dioxide passing through based on the density value and the volumetric flow rate obtained by the volumetric flow meter.

[0069] In some embodiments, the front end of the measuring sub is further provided with an upper stabilizer 14 for aligning the device. The upper stabilizer 14 is provided with an upper pin assembly 141.

[0070] The downhole supercritical carbon dioxide mass flow rate testing device provided in Embodiment 1 of the present invention can monitor multiple parameters such as pressure, temperature, carbon dioxide volumetric flow rate, and mass flow rate in the downhole section of a CO2 injection well in real time.

[0071] The pre-installation of the density prediction model allows for the direct calculation of the density of carbon dioxide based on the measured temperature and pressure of the surrounding environment. This enables the calculation of the mass flow rate of carbon dioxide flowing through the well based on the measured volumetric flow rate, thus achieving direct measurement of the mass flow rate of carbon dioxide downhole.

[0072] In some embodiments, the current collector stub includes a main control board 21, a motor 22, a support mechanism 23, and a sealing cup 24.

[0073] The motor 22 is used to rotate in response to the measurement command of the main control board 21, so as to drive the support mechanism 23 with rollers at the end to open through the transmission component, so that the device is supported on the inner wall of the oil pipe; the motor 22 continues to rotate to open the sealing cup 24, and complete the sealing of the annulus between the device and the oil pipe.

[0074] The motor 22 is also used to rotate in the opposite direction in response to the retraction command of the main control board 21 (here, "reverse" means rotating in the opposite direction to the direction of the received measurement command) so as to realize the retraction of the sealing cup 24 and the support mechanism 23 in sequence through the transmission assembly.

[0075] Furthermore, the transmission assembly includes a coupling 251, a thrust bearing 252, and a push rod 253.

[0076] A middle pin assembly 26 is provided at the front end of the collector stub.

[0077] The use of a sealing cup to collect carbon dioxide significantly reduces the likelihood of damage to the sealing structure during the lowering and raising of the device compared to setting a sealing ring on the outside of the device.

[0078] Example 2

[0079] Embodiment 2 of the present invention provides a method for testing the mass flow rate of supercritical carbon dioxide in wells, comprising:

[0080] The downhole supercritical carbon dioxide mass flow rate testing device described in Embodiment 1 is lowered into the target location of the carbon dioxide stratified injection system in the injection well using a cable, and the carbon dioxide mass flow rate at the target location is obtained through the flow plate of the device.

[0081] The device is sequentially moved up to a position between two adjacent downhole devices above the current position, and the carbon dioxide mass flow rate at the corresponding position is obtained through the main control board of the device, until there is only one downhole device above the current position.

[0082] Specifically, the aforementioned downhole device is a water distributor or a packer.

[0083] The target location can be set as the position between the fixed ball seat and the adjacent upper downhole device. In this case, after obtaining the carbon dioxide mass flow rate at the target location, the following is also included:

[0084] Determine if the carbon dioxide mass flow rate at the target location is 0; if not, generate and send a notification that a leak has occurred at the fixed ball seat.

[0085] After measuring the carbon dioxide mass flow rate at each measurement location, the injection flow rate of each injection layer can be calculated. Specifically, for each carbon dioxide mass flow rate measurement location other than the bottommost one, the difference between the carbon dioxide mass flow rate at that measurement location and the carbon dioxide mass flow rate at the adjacent measurement location below it can be determined as the carbon dioxide mass flow rate injected into the injection layer between the two measurement locations.

[0086] The downhole supercritical carbon dioxide mass flow rate testing method provided in Embodiment 2 of the present invention measures the carbon dioxide mass flow rate at each measurement point in a bottom-up order. First, since the fluid injection direction is from top to bottom, choosing a bottom-up measurement sequence allows the device to be flushed by the reverse fluid, avoiding fluid contamination that could lead to a decrease in measurement accuracy. Second, measurements can be started from below the bottommost downhole device in the carbon dioxide stratified injection system to determine whether the fixed ball seat below is leaking.

[0087] Example 3

[0088] Embodiment 3 of the present invention provides a downhole supercritical carbon dioxide mass flow rate testing method, which is applicable to situations where the oil layers in the reservoir where the carbon dioxide stratified injection system is located are all thick oil layers.

[0089] The carbon dioxide stratified injection system and the distribution of each carbon dioxide measurement point in this embodiment are shown in [reference]. Figure 3 As shown. The water distributors in the carbon dioxide stratified injection system are all single-control valve water distributors, located at positions matching the corresponding injection layers; the packers are all single-rubber sleeve cable packers.

[0090] A carbon dioxide mass flow rate testing device (hereinafter referred to as the device) is lowered into the center channel of the downhole tubing using a cable. The tubing coupling is monitored in real time by a magnetic positioning device to determine the device's lowering position. After reaching the position between the fixed ball seat of the carbon dioxide stratified injection system and the adjacent upper configurator, the support mechanism and the cup open, and the flow rate value Q0 is tested. After the test, the device is lifted to the second test point (the position between the adjacent configurator and packer above the Q0 test point), and the flow rate value Q1 is tested. This process is repeated until the last flow rate point Qi is tested, after which the device is lifted to the surface.

[0091] Q0 can determine whether the bottom fixed ball seat of the injection tubing is leaking. If it is 0m 3 / d indicates no leakage. The CO2 injection flow rate of the lowest level is Q1-Q0, and the injection flow rates of the upper levels are Q1-Q0 respectively. i -Q i-1 .

[0092] Example 4

[0093] Embodiment 4 of the present invention provides a dual-tube packer for layered injection of thin oil layers.

[0094] Figure 4 A schematic diagram of an existing Y341 fluid flow through a packer. Figure 4 In this design, 1 is the upper connector, which connects the packer to the upper tool and introduces the fluid flow; 2 is the central tube, through which the fluid flows and merges with the backwash fluid flow via an internal channel in the tube wall; 9 is the backwash component containing the backwash channel 7, which controls the pressure opening and closing of the backwash channel; 3 is the rubber sleeve component, which holds the rubber sleeve assembly; 10 is the setting and unsetting component, which compresses and recycles the rubber sleeve; and 4 is the lower connector, which connects the packer to the lower tool. The backwash component 9, the setting and unsetting component 10, and the lower connector 4 are relatively mature and will not be described in detail. The key design areas in this embodiment are the upper connector 1, the central tube 2, and the rubber sleeve component 3.

[0095] The double-tube packer provided in Embodiment 4 of the present invention refers to... Figure 5-7 As shown, it includes an upper connector, a central tube, a rubber sleeve assembly, a setting and unsealing assembly, a backwashing assembly, and a lower connector. The rubber sleeve assembly includes an upper rubber sleeve 31 and a lower rubber sleeve 32 that are airtightly connected. The packer also includes a thrust liquid guiding ring 5 disposed between the upper rubber sleeve 31 and the lower rubber sleeve 32.

[0096] The central tube has an axially drilled liquid flow channel 6 and a backwash channel 7.

[0097] The outlet position of the fluid flow channel 6 matches the corresponding first through hole of the thrust guide ring 5, so that after the packer is set, the injected fluid can flow out of the packer through the corresponding through hole of the thrust guide ring 5.

[0098] The outlet of the backwash channel 7 is located below the lower rubber cylinder 32. After the packer is set, the backwash channel 7 is connected through the thrust guide ring 5.

[0099] The setting and unsealing components can be the existing setting and unsealing components of the Y341 packer. The upper glue cylinder 31 and the lower glue cylinder 32 of this application are airtightly connected, so the setting and unsealing of the two glue cylinders can be controlled simultaneously by an existing set of setting and unsealing components. During setting, the expansion of the upper glue cylinder 31 and the lower glue cylinder 32 pushes the thrust guide ring 5 to move, so that the liquid flow channel 6 is connected to the corresponding first through hole of the thrust guide ring 5, and the backwash channel 7 is connected through the thrust guide ring 5. After unsealing, the thrust guide ring 5 is reset, so that the liquid flow channel 6 is no longer connected to the corresponding first through hole of the thrust guide ring 5, and the entire backwash channel 7 is no longer connected.

[0100] The dual-tube packer provided in Embodiment 4 of this invention can use a set of setting and unsetting components to drive two tubes, thereby achieving the sealing of thin oil layers. From the perspective of tubing process, this packer only needs to bear the risk of one packer being installed and only needs to provide the unsetting force of one packer, but can achieve the function of two complete packers, greatly improving the cost-effectiveness. The water injection function is achieved through the middle position of the two tubes, enabling water injection development of thin oil layers.

[0101] The upper connector 1 is provided with a through hole that matches the position of the fluid flow channel 6, used to connect the packer to the upper tool and introduce fluid flow. The lower connector is used to connect the packer to the lower tool. The lower connector can be set in the same way as the lower connector of the existing Y341 packer. Unlike the pipe-clip connection method of the upper connector of the Y341 packer, the double-tube packer provided in this application embodiment has a plug-in upper connector, and at least one sealing ring is fitted on the upper end of the upper connector. Compared with the conventional pipe-clip connection method, the plug-in method shortens the connection distance and makes it easier to set the fluid flow channel 6 and backwash channel 7 on the tube wall of the central tube.

[0102] The inlet of backwash channel 7 is consistent with that of the Y341 packer, and the outlet of backwash channel 7 needs to be located below the lower rubber sleeve 32 so that the backwash fluid flows out of the packer housing from below the lower rubber sleeve 32. At the same time, it is necessary to ensure that the backwash channel is isolated from other fluid flow channels and does not interfere with each other.

[0103] To achieve the maximum flow channel cross-sectional area, the central tube has multiple axial liquid flow channels and multiple backwash channels drilled circumferentially along its wall. The liquid flow channels 6 and backwash channels 7 can be arranged in a way that is evenly distributed circumferentially and interspersed circumferentially.

[0104] Furthermore, the double-tube packer provided in this application embodiment is a double-tube cable-controlled packer, in which an axial cable channel 8 is drilled in the wall of the central tube, and the cable channel 8 communicates with the corresponding through hole of the upper connector and the corresponding through hole of the lower connector.

[0105] The cable enters through the annulus of the upper water distributor, passes through cable channel 8 of the double-sleeve packer, and exits through the annulus at the lower end of the double-sleeve packer. The liquid flow is introduced through the annulus of the upper water distributor to the position between the two sets of rubber sleeves and flows out of the packer shell, achieving thin-layer injection.

[0106] Optionally, the cable channel 8 can be shared with a fluid channel 6 until the fluid channel 6 ends, after which the cable channel 8 continues to extend to the lower connector and protrudes from the annulus.

[0107] Since the liquid flow channel 6 and the backwash channel 7 intersect between the two rubber tubes, it is necessary to circumferentially stagger the radial outflow channel of the liquid flow channel 6 and the axial flow channel of the backwash channel 7. This embodiment achieves this through the thrust guide ring 5.

[0108] The thrust guide ring 5 is provided with a number of first through holes that are the same as the number of liquid flow channels 6 and the positions of the liquid flow channels 6 are matched. The first through holes are provided on a circumference.

[0109] The backwash channel 7 is divided into upper and lower sections. The thrust guide ring 5 is provided with a number of second through holes that are twice the number of backwash channels 7. The second through holes are evenly distributed on the two circumferences. After the packer is set, the upper section of the backwash channel, the second through hole that is matched on one circumference, the second through hole that is matched on the other circumference, and the lower section of the backwash channel are connected in sequence. The two second through holes are connected by a connecting bridge.

[0110] Reference Figure 6 The image shown is a cross-sectional view of a double-tube packer provided in this embodiment. The channel at the 12 o'clock position on the circumference of the main view is the cable channel 8 (right side of AA). The cable enters through the through hole of the upper connector, passes through the through hole at the corresponding position on the upper end of the thick-walled central tube, and exits from the lower end of the central tube. Finally, it exits through the corresponding through hole of the lower connector and enters the lower oil sleeve annulus of the packer. The outlet is sealed with a ferrule.

[0111] Of the eight circumferentially distributed locations in the main view, only the passageway at the aforementioned 12 points penetrates both the upper and lower ends of the central tube; the remaining channels are all fluid flow channels 6, such as... Figure 3 As shown on the right side of BB. The fluid enters through the through hole of the upper connector, and then enters the through hole located at the corresponding position on the upper end of the thick-walled central tube. After passing through the upper rubber sleeve 31, the fluid flows radially out of the rubber sleeve seat and the thrust guide ring 5, and flows out of the tool housing. The fluid channel 6 is sealed with an O-ring.

[0112] With the main view Figure 8 The other eight circumferential directions, which are evenly distributed at the same locations, form the backwash channels 7. Figure 6 As shown on the left side of AA. After the backwash piston opens, the backwash fluid flows from the annulus into the backwash channel 7 outside the central tube. Flowing downwards, it enters the thrust guide ring 5 at the corresponding circumferential position, where it intersects with the fluid flow channel 6. After bypassing the fluid outlet of the fluid flow channel 6, it re-enters the outside of the central tube, finally flowing out of the tool housing after passing through the lower rubber sleeve 32. The backwash channel 7 is sealed with an O-ring.

[0113] Figure 7This is a structural diagram of the central tube in this embodiment, partially cut out for clarity. The cable channel 8 and its seven circumferentially distributed channels constitute the fluid flow channels 6 (the upper part of the cable channel 8 shares one fluid flow channel 6). The fluid flows radially out of the tool housing from position A. The cable passage hole of the cable channel 8 continues downward within the protrusion at position B and exits at the lower end. Figure 7 The backwash channel 7 shown in the figure and the seven backwash channels 7 evenly distributed around it flow into the thrust guide ring from position A, flow into the annular space around the protrusion at position B after passing the outlet of the liquid flow channel 6, and flow out from the normal position after passing the lower rubber tube.

[0114] Example 5

[0115] Embodiment 5 of this invention provides a downhole supercritical carbon dioxide mass flow rate testing method, applicable to reservoirs where the carbon dioxide stratified injection system is located and the oil layers contain thin layers, i.e., thin interbedded oil reservoirs. The carbon dioxide mass flow rate testing device used in Embodiment 5 is the same as that in Embodiment 1, and the double-sleeve packer used is the same as that in Embodiment 4.

[0116] In this embodiment, the carbon dioxide stratified injection system has a double-tube packer at the corresponding position of the thin oil layer, so that the thin oil layer is located between the upper and lower tubes of the double-tube packer.

[0117] Depending on the combination of thin and thick oil layers, at least one of the following is provided at other corresponding locations in the carbon dioxide stratified injection system: a single-control valve cable-through water distributor, a dual-control valve cable-through water distributor, and a single-rubber tube cable-through packer.

[0118] Specifically, if the uppermost oil layer is a thick oil layer, a single rubber tube cable packer is installed above the corresponding position of the thick oil layer; if two thick oil layers are adjacent, a single rubber tube cable packer is installed at the corresponding position between the two adjacent thick oil layers; it is determined whether the water distributor at the corresponding position of the thick oil layer needs to supply water to the adjacent double rubber tube packer. If so, a double control valve cable water distributor is installed at the corresponding position to supply water to the thick oil layer and the double rubber tube packer; if not, a single control valve cable water distributor is installed at the corresponding position to supply water to the thick oil layer.

[0119] In this case, if the thin-interbedded reservoir consists of alternating thin and thick single layers, and the uppermost oil layer is a thin oil layer:

[0120] A single-control valve water distributor via cable is installed above the position corresponding to the uppermost thin oil layer to supply water to the double-sleeve packer of the thin oil layer; if the lowermost oil layer of the thin interlayer reservoir is a thick oil layer, a single-control valve water distributor via cable is installed at the position corresponding to the thick oil layer to inject water into the thick oil layer; a double-control valve water distributor via cable is installed at the positions corresponding to other thick oil layers to inject water into the thick oil layer and supply water to the adjacent lower double-sleeve packer.

[0121] If a thin-layered interbedded reservoir consists of alternating thin and thick single layers, with the uppermost oil layer being a thick oil layer:

[0122] A single rubber tube cable packer is installed above the position corresponding to the uppermost thick oil layer; if the lowermost oil layer of the thin interlayer reservoir is a thick oil layer, a single control valve cable water distributor is installed at the position corresponding to the thick oil layer to inject water into the thick oil layer; a double control valve cable water distributor is installed at the position corresponding to other thick oil layers to inject water into the thick oil layer and to distribute water to the adjacent lower double rubber tube packer.

[0123] In this embodiment, the thickness boundary between the thick oil layer and the thin oil layer is determined based on the sum of the thicknesses of the water distributor and the single rubber tube cable packer.

[0124] In terms of existing technology for water distributors and single-tube cable packers, the thickness limit between thick and thin oil layers is 1.5 meters.

[0125] See Figure 8 As shown, the thin interbedded oil reservoir develops, from top to bottom, a thick oil layer (upper thick oil layer), a thin oil layer (upper thin oil layer), a thick oil layer (lower thick oil layer), and a thin oil layer (lower thin oil layer). A conventional cable-passing packer (i.e., a single-tube cable-passing packer) is installed above the position corresponding to the upper thick oil layer; a dual-channel, dual-tube cable-passing packer (i.e., the dual-tube packer provided in this embodiment) is installed at the position corresponding to the upper thin oil layer; a dual-control valve cable-controlled water distributor (i.e., a dual-control valve cable-passing water distributor) is installed at the position corresponding to the upper thick oil layer for water injection into the upper thick and upper thin oil layers; a dual-channel, dual-tube cable-passing packer is installed at the position corresponding to the lower thin oil layer; and a dual-control valve cable-controlled water distributor is installed at the position corresponding to the lower thick and lower thin oil layers for water injection into the lower thick and lower thin oil layers. Through the above configuration, stratified water injection development of this thin interbedded oil reservoir can be achieved.

[0126] See Figure 9 As shown, the thin interbedded reservoir consists of a thin oil layer (upper thin oil layer), a thick oil layer, and a thin oil layer (lower thin oil layer) from top to bottom. Dual-channel, dual-sleeve cable-operated packers are installed at the corresponding positions of the upper and lower thin oil layers. A single-control valve cable-controlled water distributor (i.e., a single-control valve cable-operated water distributor) is installed above the position corresponding to the upper thin oil layer to inject water into it. A dual-control valve cable-controlled water distributor is installed at the position corresponding to the thick oil layer to inject water into both the thick and lower thin oil layers.

[0127] Figure 8 and Figure 9 The red ellipse in the image represents the test point for carbon dioxide mass flow rate.

[0128] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. This disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A downhole supercritical carbon dioxide mass flow rate testing device, comprising a measuring sub and a collecting sub, characterized in that, The measurement section includes a volumetric flow meter, a temperature sensor, a pressure sensor, a flow plate, and a magnetic positioning module. The flow plate is pre-loaded with a density prediction model. The flow meter is used to predict the density value based on the obtained temperature and pressure values ​​using the density prediction model, and to calculate the mass flow rate of carbon dioxide flowing through the flow based on the density value and the obtained volumetric flow rate.

2. The apparatus as claimed in claim 1, characterized in that, The density prediction model is obtained by training the XGBoost machine learning model using a sample set. Each sample in the sample set includes the temperature and pressure values ​​of the environment containing carbon dioxide, as well as the density value of carbon dioxide.

3. The apparatus as described in claim 1, characterized in that, The current collection section includes a main control board, a motor, a support mechanism, and a sealing cup; The motor is used to rotate in response to the measurement command of the main control board, so as to sequentially open the support mechanism through the transmission component, so that the device is supported on the inner wall of the oil pipe, and the continued rotation opens the sealing cup, thus completing the sealing of the annular space between the device and the oil pipe; The motor is also used to rotate in the opposite direction in response to the retraction command of the main control board, so as to realize the retraction of the sealing cup and the support mechanism in sequence through the transmission assembly.

4. The apparatus as claimed in claim 1, characterized in that, The volumetric flow meter is an eccentric vortex volumetric flow meter.

5. A method for testing the mass flow rate of supercritical carbon dioxide in downhole wells, characterized in that, include: The downhole supercritical carbon dioxide mass flow rate testing device according to any one of claims 1 to 4 is lowered into the target position of the carbon dioxide stratified injection system of the injection well using a cable, and the carbon dioxide mass flow rate at the target position is obtained through the flow plate of the device. The device is sequentially raised to a position between two adjacent downhole devices above the current position, and the carbon dioxide mass flow rate at the corresponding position is obtained through the main control board of the device, until there is only one downhole device above the current position. The downhole device is a water distributor or a packer.

6. The method as described in claim 5, characterized in that, The target location is the position between the fixed ball seat and the adjacent upper downhole device. After obtaining the carbon dioxide mass flow rate at the target location, the method further includes: Determine whether the carbon dioxide mass flow rate at the target location is 0; If not, generate and send a notification that the fixed ball seat has leaked.

7. The method as described in claim 5, characterized in that, Also includes: For each carbon dioxide mass flow rate measurement location other than the bottommost one, the difference between the carbon dioxide mass flow rate at that measurement location and the carbon dioxide mass flow rate at the adjacent measurement location below it is determined as the carbon dioxide mass flow rate injected into the injection layer between the two measurement locations.

8. The method as described in claim 5, characterized in that, If the oil layers in the reservoir where the carbon dioxide stratified injection system is located are all thick oil layers; The water distributor in the carbon dioxide stratified injection system is a single-control valve water distributor, and the packer is a single-rubber tube cable packer.

9. The method as described in claim 5, characterized in that, If a thin oil layer exists in the reservoir where the carbon dioxide stratified injection system is located, the carbon dioxide stratified injection system shall install a double-sleeve packer at the corresponding position of the thin oil layer, so that the thin oil layer is located between the upper and lower sleeves of the double-sleeve packer. The dual-tube packer includes an upper connector, a central tube, a tube assembly, a setting / unsetting assembly, a backwashing assembly, and a lower connector. The tube assembly includes an upper tube and a lower tube that are airtightly connected. The dual-tube packer also includes a thrust-guided fluid ring disposed between the upper and lower tubes. The central tube has an axially drilled fluid flow channel and a backwashing channel in its wall. The outlet position of the fluid flow channel matches the corresponding first through hole of the guide ring, so that after the dual-tube packer is set, the injected fluid can flow out of the dual-tube packer through the corresponding through hole of the guide ring. The outlet of the backwashing channel is located below the lower tube, and after the dual-tube packer is set, the backwashing channel is connected through the guide ring.

10. The method as described in claim 9, characterized in that, The central tube of the double rubber sleeve packer has multiple axial liquid flow channels and multiple backwash channels drilled circumferentially along its wall, with the liquid flow channels and backwash channels arranged alternately.

11. The method as described in claim 10, characterized in that, The wall of the central tube is also drilled with an axial cable channel, which communicates with the corresponding through hole of the upper connector and the corresponding through hole of the lower connector. The upper connector is provided with a through hole that matches the position of the fluid flow channel.

12. The method as described in claim 10, characterized in that, The liquid guiding ring is provided with a number of first through holes that are the same as the number of liquid flow channels and whose positions match the positions of the liquid flow channels. The first through holes are provided on a circumference. The backwash channel is divided into upper and lower sections. The liquid guide ring is provided with a number of second through holes that are twice the number of the backwash channel. The second through holes are evenly distributed on the two circumferences. After the packer is set, the upper section of the backwash channel, the second through hole that is matched on one circumference, the second through hole that is matched on the other circumference, and the lower section of the backwash channel are connected in sequence. The two second through holes are connected by a connecting bridge.

13. The method as described in claim 9, characterized in that, Depending on the combination of thin and thick oil layers, at least one of the following is provided at other corresponding positions of the carbon dioxide stratified injection system: a single-control valve cable water distributor, a dual-control valve cable water distributor, and a single rubber tube cable packer.

14. The method as described in claim 13, characterized in that, If the reservoir consists of alternating thin and thick single layers, and the uppermost oil layer is a thin layer, then, based on the combination of thin and thick oil layers, at least one of the following is provided at other corresponding positions in the carbon dioxide stratified injection system: a single-control valve cable-through water distributor, a dual-control valve cable-through water distributor, and a single-rubber sleeve cable-through packer: The carbon dioxide stratified injection system is equipped with a single-control valve cable water distributor above the position corresponding to the uppermost thin oil layer, which is used to supply water to the double rubber sleeve packer of the thin oil layer. If the lowest oil layer of the reservoir is a thick oil layer, a single-control valve through-cable water distributor is installed at the corresponding position of the thick oil layer to inject water into the thick oil layer; a double-control valve through-cable water distributor is installed at the corresponding position of other thick oil layers to inject water into the thick oil layer and to distribute water to the adjacent lower double rubber sleeve packer.

15. The method as described in claim 13, characterized in that, If the reservoir consists of alternating thin and thick single layers, and the uppermost oil layer is a thick oil layer, then, based on the combination of thin and thick oil layers, at least one of the following is provided at other corresponding positions in the carbon dioxide stratified injection system: a single-control valve cable-through water distributor, a dual-control valve cable-through water distributor, and a single-rubber sleeve cable-through packer: The carbon dioxide stratified injection system has a single rubber tube cable packer installed above the position corresponding to the uppermost thick oil layer; If the lowest oil layer of the reservoir is a thick oil layer, a single-control valve through-cable water distributor is installed at the corresponding position of the thick oil layer to inject water into the thick oil layer; a double-control valve through-cable water distributor is installed at the corresponding position of other thick oil layers to inject water into the thick oil layer and to distribute water to the adjacent lower double rubber sleeve packer.

16. The method as described in claim 13, characterized in that, According to the combination of thin and thick oil layers, at least one of the following is provided at other corresponding positions of the carbon dioxide stratified injection system: a single-control valve cable-through water distributor, a dual-control valve cable-through water distributor, and a single-rubber sleeve cable-through packer: If the uppermost oil layer is a thick oil layer, a single rubber tube cable packer is installed above the corresponding position of the thick oil layer; If two thick oil layers are adjacent, a single rubber tube cable packer is installed at the corresponding position between the two adjacent thick oil layers; If the water distributor at the location corresponding to the thick oil layer needs to supply water to the adjacent double-sleeve packer, a double-control valve cable-connected water distributor is installed at that location to inject water into the thick oil layer and supply water to the double-sleeve packer; if the water distributor at the location corresponding to the thick oil layer does not need to supply water to the adjacent double-sleeve packer, a single-control valve cable-connected water distributor is installed at that location to inject water into the thick oil layer.

17. The method according to any one of claims 8 to 16, characterized in that, The thickness boundary between thick and thin oil layers is determined by the sum of the thicknesses of the water distributor and the single-tube cable packer.

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