Fracturing flowback carbon dioxide production quantity monitoring system

Abstract

The utility model relates to a fracturing flowback carbon dioxide production quantity monitoring system which comprises a multiphase flow meter, a gas-liquid separation tank and a gas concentration monitoring unit which are integrated in a prying frame, an inlet of the multiphase flow meter is used for introducing flowback liquid, and an outlet of the multiphase flow meter is connected with an inlet of a tee joint; a first outlet of the tee joint is connected with the liquid storage tank, and a second outlet is connected with an inlet of the gas-liquid separation tank; a gas outlet of the gas-liquid separation tank is connected with a gas concentration monitoring unit, and a liquid outlet of the gas-liquid separation tank is connected with the liquid storage tank. The system disclosed by the utility model can be used for accurately metering the CO2 extracted after the flowback of the CO2 fracturing well, so that the problem that the intermittent sampling test error is relatively large is avoided, and the real-time online and continuous monitoring of the fracturing flowback carbon dioxide extraction quantity is realized.

Description

Technical Field

[0001] This utility model belongs to the field of carbon capture, utilization and storage technology, and specifically relates to a monitoring system for carbon dioxide production during fracturing flowback. Background Technology

[0002] CO2 pre-fracturing involves injecting a certain amount of CO2 before conventional hydraulic fracturing. This induces more microfractures in the rock and simultaneously seals the CO2. Furthermore, pure liquid CO2 fracturing technology is gradually being adopted, and the application of CO2 in fracturing is increasing. However, during the flowback process of fractured wells, some CO2 will return to the wellhead. To accurately calculate the CO2 storage situation, the amount of returned CO2 needs to be precisely measured.

[0003] The commonly used method for monitoring CO2 content at the wellhead is to take samples using sampling bags at the wellhead and analyze the gas component concentration in a laboratory. Alternatively, a mobile CO2 monitor can be used at the sampling point to monitor the gas concentration. While these methods are convenient, the measurement results have significant errors, and they can only test the CO2 concentration. To accurately calculate the CO2 production rate, the total gas flow rate also needs to be measured. CO2 is readily soluble in water, and its content fluctuates during fracturing and flowback due to continuous pressure changes. Mobile CO2 monitors cannot provide real-time or continuous monitoring.

[0004] Therefore, existing CO2 wellhead content monitoring methods suffer from large measurement errors and cannot achieve real-time online and continuous monitoring of CO2 production. Utility Model Content

[0005] To address the aforementioned problems in the existing technology, this utility model provides a monitoring system for carbon dioxide production during fracturing flowback. The technical problem to be solved by this utility model is achieved through the following technical solution:

[0006] This utility model embodiment provides a fracturing flowback carbon dioxide production monitoring system, comprising: a multiphase flow meter, a gas-liquid separator, and a gas concentration monitoring unit integrated within a skid, wherein...

[0007] The inlet of the multiphase flow meter is used to introduce backflow liquid, and the outlet is connected to the inlet of the tee.

[0008] The first outlet of the three-way valve is connected to the liquid storage tank, and the second outlet is connected to the inlet of the gas-liquid separator.

[0009] The gas outlet of the gas-liquid separator is connected to a gas concentration monitoring unit, and the liquid outlet is connected to the liquid storage tank.

[0010] In one embodiment of this utility model, the gas-liquid separator includes a tank body, a liquid level detector, and a pressure gauge, wherein,

[0011] The liquid level detector and pressure gauge are externally connected to the tank and communicate with the interior of the tank. The pressure gauge is installed on the top of the tank.

[0012] In one embodiment of this utility model, the gas concentration monitoring unit includes at least one dryer and a CO2 / CH4 concentration monitor, wherein,

[0013] The at least one dryer is connected in sequence, with the inlet of the first dryer connected to the gas outlet of the gas-liquid separator and the outlet of the last dryer connected to the CO2 / CH4 concentration monitor.

[0014] In one embodiment of the present invention, a wireless transmission unit is further included. The wireless transmission unit is electrically connected to the multiphase flow meter and the CO2 / CH4 concentration monitor, respectively, and the wireless transmission unit, the at least one dryer, and the CO2 / CH4 concentration monitor are installed in the same housing.

[0015] In one embodiment of this utility model, a data acquisition system is also included, which is communicatively connected to the wireless transmission unit.

[0016] In one embodiment of this utility model, a power supply unit is further included, which is electrically connected to the multiphase flow meter, the gas-liquid separator, the gas concentration monitoring unit, and the wireless transmission unit, respectively.

[0017] In one embodiment of this utility model, the power supply unit includes a solar photovoltaic panel and / or an external power supply.

[0018] In one embodiment of the present invention, a first valve and a second valve are further included, wherein the first valve is connected between the first outlet of the tee and the liquid storage tank, and the second valve is connected between the second outlet of the tee and the inlet of the gas-liquid separator.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0020] This system incorporates a multiphase flow meter, a gas-liquid separator, and a gas concentration monitoring unit. The multiphase flow meter monitors the total oil, gas, and liquid volumes of the flowback fluid and measures the dissolved CO2 in the liquid phase. The gas-liquid separator separates a portion of the flowback fluid, solving the gas-liquid separation problem in fracturing wells. The gas concentration monitoring unit measures the concentrations of CO2 and CH4 in the separated gas, enabling precise measurement of CO2 produced after CO2 flowback from fracturing wells. This avoids the problem of large errors in intermittent sampling and testing, achieving real-time online and continuous monitoring of CO2 production from fracturing flowback. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of a fracturing flowback carbon dioxide production monitoring system provided in an embodiment of the present invention. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0023] Example 1

[0024] Please see Figure 1 , Figure 1 This is a schematic diagram of a fracturing flowback carbon dioxide production monitoring system provided in an embodiment of the present invention.

[0025] This embodiment of the fracturing flowback carbon dioxide production monitoring system includes a multiphase flowmeter 1, a gas-liquid separator 2, and a gas concentration monitoring unit 3 integrated within a skid. The inlet of the multiphase flowmeter 1 is used to introduce flowback fluid, and its outlet is connected to the inlet of a tee. The first outlet of the tee is connected to a storage tank, and the second outlet is connected to the inlet of the gas-liquid separator 2. The gas outlet of the gas-liquid separator 2 is connected to the gas concentration monitoring unit 3, and the liquid outlet is connected to the storage tank.

[0026] Specifically, after the CO2 fracturing well begins flowback, the flowback fluid exits the wellhead and first passes through a choke manifold. The choke manifold controls the flow rate and pressure at the wellhead. After exiting the choke manifold, the flowback fluid enters the carbon dioxide production monitoring system.

[0027] The multiphase flow meter 1 in the carbon dioxide production monitoring system can monitor the total oil, gas, and liquid volumes of the return fluid, and measure the dissolved CO2 in the liquid phase. A tee is connected to the multiphase flow meter 1. The first outlet of the tee is connected to the venting pipeline directly to the storage tank, while the second outlet serves as a bypass pipeline connected to the gas-liquid separator 2, allowing some of the return fluid to enter the separator. The gas-liquid separator 2 is a small-scale separator that separates the incoming return fluid into gas and liquid. The separated liquid flows directly into the storage tank through the drain pipeline at the bottom of the separator, while the separated gas flows into the gas concentration monitoring unit 3 through the top gas outlet. The gas concentration monitoring unit 3 measures the concentrations of CO2 and CH4 in the separated gas.

[0028] Furthermore, a first valve 7 is connected between the first outlet of the tee and the liquid storage tank, and the flow rate of the return liquid entering the liquid storage tank is adjusted by the first valve 7. A second valve 8 is connected between the second outlet of the tee and the inlet of the gas-liquid separator 2, and the flow rate of the return liquid entering the gas-liquid separator is adjusted by the second valve 8.

[0029] Specifically, in this embodiment, all equipment is integrated according to the process flow and integrated into a single skid to form a carbon dioxide intelligent monitoring system. During monitoring construction, it is only necessary to connect the monitoring skid in the middle of the return pipeline.

[0030] The system in this embodiment is equipped with a multiphase flow meter, a gas-liquid separator, and a gas concentration monitoring unit. The multiphase flow meter can monitor the total oil, gas, and liquid volumes of the flowback fluid and measure the amount of CO2 dissolved in the liquid phase. The gas-liquid separator separates a portion of the flowback fluid into gas and liquid, solving the gas-liquid separation problem in the flowback fluid of the fracturing well site. The gas concentration monitoring unit can measure the concentrations of CO2 and CH4 in the separated gas, thereby enabling accurate measurement of CO2 produced after CO2 flowback from the fracturing well. This avoids the problem of large errors in intermittent sampling and testing, and realizes real-time online and continuous monitoring of the amount of carbon dioxide produced during fracturing flowback.

[0031] The phase flow meter 1 includes a flow meter tube body, a venturi tube, a phase fraction probe, and a PVT analysis module. The venturi tube and phase fraction probe are both located inside the flow meter tube body. The PVT analysis module is mounted on the side wall of the flow meter tube body and extends into its interior. Further, the PVT analysis module includes a temperature sensor, a pressure sensor, and a display unit. The temperature and pressure sensors pass through the side wall of the flow meter tube body to its interior to measure the fluid temperature and pressure. The display unit is located on the outside of the flow meter tube body and performs calibration calculations on the data using software.

[0032] Specifically, the venturi tube 12 in the multiphase flow meter 1 can measure the total flow rate, and the phase fraction probe 13 can measure the phase fraction of oil, gas, and water. When combined, they can measure the instantaneous flow rates of oil, gas, and water in the return fluid and the total oil volume Q in real time. o Total gas volume Q g Total liquid volume Q W By collecting data on oil, gas, and water in the backflow fluid, the time of oil (gas) exposure and production during the backflow period can be monitored, providing a basis for formulating backflow regulations. The PVT analysis module 14 in the multiphase flowmeter 1 can automatically calculate and calibrate the CO2 content and directly read the standard CO2 content Q dissolved in the liquid phase. 溶CO2 Since CH4 is a substance that is sparingly soluble in water, its solubility is not considered.

[0033] In one specific embodiment, the gas-liquid separator 2 includes a tank body, a level sensor, and a pressure gauge. The level sensor and pressure gauge are externally connected to the tank body and communicate with the interior of the tank body, with the pressure gauge installed at the top of the tank body. The level sensor and pressure gauge are used to monitor the liquid level and pressure inside the gas-liquid separator 2.

[0034] In one specific embodiment, the gas concentration monitoring unit 3 includes at least one dryer 31 and a CO2 / CH4 concentration monitor 32, wherein at least one dryer 31 is connected in sequence, and the inlet of the first dryer 31 is connected to the gas outlet of the gas-liquid separator 2, and the outlet of the last dryer 31 is connected to the CO2 / CH4 concentration monitor 32.

[0035] Specifically, after the gas enters the gas concentration monitoring unit 3, it first undergoes drying filtration to remove moisture, and then enters the CO2 / CH4 concentration monitor 32 to measure the CO2 and CH4 gas concentrations. CO2 and C CH4 express.

[0036] Specifically, the drying and filtration can be performed using a single drying chamber 31 or multiple drying chambers 31 connected in sequence, such as using two connected drying chambers for double drying and filtration.

[0037] In one specific embodiment, the fracturing flowback carbon dioxide production monitoring system further includes a wireless transmission unit 4 and a data acquisition system 5. The wireless transmission unit 4 is electrically connected to the multiphase flow meter 1 and the CO2 / CH4 concentration monitor 32, respectively, and is installed in the same housing as at least one dryer 31 and the CO2 / CH4 concentration monitor 32. The data acquisition system 5 is communicatively connected to the wireless transmission unit 4.

[0038] Specifically, both the multiphase flow meter 1 and the CO2 / CH4 concentration monitor 32 can transmit data to the cloud-based data acquisition system 5 via a wireless transmission unit. The data acquisition system 5 is used to combine the total gas volume Q measured by the multiphase flow meter 1. g The total extraction rate of CH4 and CO2 is automatically calculated based on the CO2 and CH4 gas concentrations measured by the CO2 / CH4 concentration monitor 32.

[0039] The total output of CH4 is: Q CO2 =Qg*C CH4 ;

[0040] The total CO2 output is: Q CO2 =Q 溶CO2 +Qg*C CO2 .

[0041] Furthermore, the amount of CO2 buried underground during this fracturing can be obtained by subtracting the amount of CO2 produced from the amount of CO2 injected during fracturing.

[0042] The flowback cycle for fracturing generally varies depending on the reservoir conditions and fracturing process of the fracturing well, typically ranging from 1 to 3 months. However, in the later stages of monitoring, as the flowback fluid production gradually decreases to a low value and the fracturing well gradually returns to normal production, the CO2 production also decreases. A monitoring lower limit can be established based on the field application, for example, a total CO2 production of less than 0.2 m³ per day. 3 Monitoring can be stopped when the CO2 concentration of the monitoring well is the same as that of the surrounding wells under normal production conditions.

[0043] In one specific embodiment, the fracturing flowback carbon dioxide production monitoring system also includes a power supply unit 6, which is electrically connected to the multiphase flow meter 1, the gas-liquid separator 2, the gas concentration monitoring unit 3, and the wireless transmission unit 4, respectively.

[0044] Specifically, power supply unit 6 includes solar photovoltaic panels and / or an external power source. It can be understood that power supply unit 6 can use solar photovoltaic panels, or it can be directly powered by an external power source, or both solar photovoltaic panels and an external power source can be used as power supply units. The solar photovoltaic panels provide power to the entire monitoring system, are installed on the top of the monitoring system skid, and are equipped with batteries capable of powering the entire system for five consecutive days of cloudy or rainy weather. The external power source can be a 220V power supply.

[0045] In this embodiment, the monitoring data from the multiphase flow meter and CO2 / CH4 concentration monitor can be wirelessly transmitted to the cloud-based data acquisition system, achieving real-time online and continuous monitoring of CO2 production from fracturing flowback, avoiding the problem of large errors in intermittent sampling and testing. Furthermore, it solves the gas-liquid separation problem of the flowback fluid in the fracturing well site, and the addition of solar photovoltaic panels can power the entire monitoring system, ensuring normal power supply even when power is unavailable or difficult to obtain. Therefore, the CO2 production monitoring system in this embodiment can accurately measure the CO2 produced after CO2 flowback from fracturing wells, solving the problems of gas-liquid separation and drying of the flowback fluid, as well as the power supply and data transmission issues of the equipment, achieving real-time online monitoring of CO2 production.

[0046] The intelligent monitoring system for carbon dioxide production in this embodiment can calculate the CO2 reserves of the CCUS (Carbon Fusion and Reinforcement) technology and generate economic value through carbon trading taxes.

[0047] In the description of this utility model, it should be understood that the terms "upper", "lower", "front", "rear", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model.

[0048] Furthermore, the terms "first" and "second" 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0049] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," 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 utility model according to the specific circumstances.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0051] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0052] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the protection scope of the present invention.

Claims

1. A monitoring system for carbon dioxide production during fracturing flowback, characterized in that, include: A multiphase flow meter (1), a gas-liquid separator (2), and a gas concentration monitoring unit (3) are integrated into a single skid. The inlet of the multiphase flow meter (1) is used to introduce backflow liquid, and the outlet is connected to the inlet of the tee. The first outlet of the three-way valve is connected to the liquid storage tank, and the second outlet is connected to the inlet of the gas-liquid separator (2). The gas outlet of the gas-liquid separator (2) is connected to the gas concentration monitoring unit (3), and the liquid outlet is connected to the liquid storage tank.

2. The fracturing flowback carbon dioxide production monitoring system according to claim 1, characterized in that, The gas-liquid separator (2) includes a tank body, a liquid level detector, and a pressure gauge, wherein, The liquid level detector and pressure gauge are externally connected to the tank and communicate with the interior of the tank. The pressure gauge is installed on the top of the tank.

3. The fracturing flowback carbon dioxide production monitoring system according to claim 1, characterized in that, The gas concentration monitoring unit (3) includes at least one dryer (31) and a CO2 / CH4 concentration monitor (32), wherein, The at least one dryer (31) is connected in sequence, with the inlet of the first dryer (31) connected to the gas outlet of the gas-liquid separator (2) and the outlet of the last dryer (31) connected to the CO2 / CH4 concentration monitor (32).

4. The fracturing flowback carbon dioxide production monitoring system according to claim 3, characterized in that, It also includes a wireless transmission unit (4), which is electrically connected to the multiphase flow meter (1) and the CO2 / CH4 concentration monitor (32) respectively, and the wireless transmission unit (4) is installed in the same housing as the at least one dryer (31) and the CO2 / CH4 concentration monitor (32).

5. The fracturing flowback carbon dioxide production monitoring system according to claim 4, characterized in that, It also includes a data acquisition system (5), which is communicatively connected to the wireless transmission unit (4).

6. The fracturing flowback carbon dioxide production monitoring system according to claim 5, characterized in that, It also includes a power supply unit (6), which is electrically connected to the multiphase flow meter (1), the gas-liquid separator (2), the gas concentration monitoring unit (3), and the wireless transmission unit (4), respectively.

7. The fracturing flowback carbon dioxide production monitoring system according to claim 6, characterized in that, The power supply unit (6) includes a solar photovoltaic panel and / or an external power source.

8. The fracturing flowback carbon dioxide production monitoring system according to claim 1, characterized in that, It also includes a first valve (7) and a second valve (8), wherein the first valve (7) is connected between the first outlet of the tee and the liquid storage tank, and the second valve (8) is connected between the second outlet of the tee and the inlet of the gas-liquid separator (2).

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