Measurement probe, device and method for dissolved oxygen content of shaft

Abstract

The invention relates to a probe, a device and a method for measuring the dissolved oxygen content of a shaft, and belongs to the technical field of shaft dissolved oxygen detection. The measuring probe comprises a shell, a cavity is formed in the shell, and a probe body is arranged in the cavity of the shell; a cooling coil is annularly arranged in the shell wall of the shell; a connecting port is formed in the shell wall of the shell and extends into a cavity of the shell, and a filter screen is arranged at the position, away from the connecting port, of the shell. According to the measuring probe for the content of the dissolved oxygen in the shaft, through the arrangement of the shell, the difficulty that components for measuring the dissolved oxygen are generally light and are difficult to descend to the preset depth under the action of shaft fluid buoyancy is overcome, and measurement of the preset depth under the shaft page is achieved; through the arrangement of the structure of the detection body, the measurement principle of the detection body is readjusted, and the measurement of the dissolved oxygen is realized through the measurement time.

Description

Technical Field

[0001] The invention belongs to the technical field of wellbore dissolved oxygen detection, and in particular relates to a measuring probe, device and method for wellbore dissolved oxygen content. Background Art

[0002] Dissolved oxygen can cause corrosion of carbon steel production and water injection pipes. Under normal circumstances, there is no dissolved oxygen in the formation. Most of the dissolved oxygen in the wellbore is caused by dissolved oxygen in the atmosphere entering the injected water and not being fully treated. However, when analyzing the water sample of a water source well in the H oil field in the Middle East, 0.3-1ppm of dissolved oxygen was measured. The test methods used included (1) sampling under pressure downhole and then sending it to the laboratory for analysis, and (2) installing a dissolved oxygen meter at the wellhead for online testing. Since the H oil field is a large oil field, it has entered the water injection development stage and has a large demand for water sources. Whether the water layer contains dissolved oxygen and its content have an important impact on the selection of anti-corrosion materials for the water source well: if there is no dissolved oxygen, carbon steel can be selected, with a unit price of about 6,000 yuan / ton. If there is this level of dissolved oxygen, stainless steel should be considered, with a unit price of about 50,000 yuan / ton. In addition, the oil field has deployed dozens of water source wells. If the dissolved oxygen content cannot be accurately measured, it will seriously affect the safe and efficient development of the oil field.

[0003] When testing the water source well, the pressure-maintaining sampling method was used. Since there is a long time interval between sampling and transferring to the laboratory, the dissolved oxygen in the atmosphere may have dissolved into the water sample. If the online test is carried out on the ground, the water flowing out of the wellbore will also be exposed to the atmosphere and will be affected by the dissolved oxygen in the atmosphere. Both of the above water sample collection methods affect the accurate measurement of the dissolved oxygen content of the wellbore produced fluid. In addition, the accuracy of dissolved oxygen analysis using colorimetric cards and other methods is not high.

[0004] Reducing the impact of environmental changes on the dissolved oxygen test results of water samples and improving the accuracy of dissolved oxygen content analysis and calculation methods are of great significance to improving the accuracy of detecting dissolved oxygen content in wellbore fluids. Summary of the invention

[0005] In view of the above problems, the present invention provides a measuring probe, device and method for the dissolved oxygen content in a wellbore, and provides an underground dissolved oxygen measuring probe, device and method based on the dissolved oxygen (DO) measurement principle. The provided probe and measuring device can place the probe 200m below the liquid level in the wellbore, and measure the dissolved oxygen content at the location in real time and store the measurement results or transmit them to the ground in real time via cables, thereby overcoming the influence of high temperature in the wellbore on the performance of electronic components and solving the problem of inaccurate measurement of traditional methods for measuring dissolved oxygen in wellbore.

[0006] The first object of the present invention is to provide a measuring probe for the dissolved oxygen content in a wellbore, the measuring probe comprising a shell, a cavity inside the shell, and a probe body disposed in the cavity of the shell;

[0007] A cooling coil is provided in the inner ring of the shell wall of the shell;

[0008] A connection port is provided on the shell wall of the shell, and the connection port extends into the cavity of the shell;

[0009] A filter screen is provided on the shell body away from the connecting port.

[0010] Furthermore, a photodiode and a plurality of LED lights are provided inside the probe body;

[0011] A sensor cap is sleeved on one end of the probe body away from the connection port, and a surface of the sensor is covered with a fluorescent material layer;

[0012] The photodiode is signal-connected to the sensor cap;

[0013] A plurality of the LED lights are signal-connected to the sensor cap.

[0014] A second object of the present invention is to provide a device for measuring dissolved oxygen content in a wellbore, comprising the above-mentioned measuring probe;

[0015] Also includes a cooling circuit in communication with the cooling coil, the cooling circuit being used to cool the measuring probe;

[0016] The cooling circuit is provided with a cooling compression pump and a water pump, the cooling compression pump and the water pump are connected through a pipeline, and the cooling compression pump and the water pump are both arranged outside the shell.

[0017] Furthermore, the cooling circuit includes an inflow pipeline and an outflow pipeline, the inflow pipeline is connected to the water pump and the cooling coil, and the outflow pipeline is connected to the cooling coil and the cooling compression pump.

[0018] Furthermore, the inflow pipeline and the outflow pipeline both enter the cavity of the shell from the connecting port and then communicate with the cooling coil.

[0019] Furthermore, the measuring device also includes a computer connected to the probe body signal.

[0020] The third object of the present invention is a method for measuring dissolved oxygen content in a wellbore, which is implemented by the above-mentioned device for measuring dissolved oxygen content in a wellbore, comprising:

[0021] Add coolant into the cooling circuit, and turn on the cooling compression pump and water pump, so that the coolant circulates in the cooling coil;

[0022] After the coolant circulates in the cooling coil for a fixed time, the measuring probe is lowered into the wellbore. After it reaches the liquid surface, it is tested several times at certain distances until a fixed distance below the liquid surface is detected.

[0023] Furthermore, the fixed time is 1-2h.

[0024] Furthermore, the interval is 2-6m, and the number of detections is 2-5 times.

[0025] Furthermore, the fixed distance is less than or equal to 200m.

[0026] Furthermore, the measurement method also includes processing the detection data.

[0027] Beneficial effects of the present invention:

[0028] The measuring probe for dissolved oxygen content in a wellbore provided by the present invention overcomes the difficulty that the components for measuring dissolved oxygen are generally light and difficult to reach a predetermined depth under the action of the buoyancy of the wellbore fluid, and realizes the measurement of the predetermined depth below the wellbore page;

[0029] By setting up the structure of the detection body and re-adjusting the measurement principle of the detection body, the dissolved oxygen is determined by measuring time, which overcomes the problem that when measuring in the wellbore, the sensor will be subjected to a certain pressure. At this time, the measurement value transmitted by the sensor (i.e., the fluorescence intensity tested by the traditional fluorescence method) may be distorted due to the wellbore pressure, thereby improving the measurement accuracy;

[0030] The device for measuring dissolved oxygen content in a wellbore provided by the present invention overcomes the limitation that the components involved in the traditional fluorescence method test can withstand a maximum temperature of 50°C by coordinating the cooling coil and the cooling circuit of the measuring probe, and realizes the measurement of dissolved oxygen in the wellbore of a water source well (target oil field) (the water source layer of the water source well of the target oil field, i.e., the H oil field, is about 2200m, and the wellbore fluid may be as high as 65°C);

[0031] The method for measuring dissolved oxygen content in a wellbore provided by the present invention has the following effects:

[0032] No calibration required - the fluorescence method is designed so that no calibration is required; stable measurement results - no substances are consumed during the measurement process, nor is the dissolved oxygen in the water consumed; reduced cleaning frequency - the traditional membrane method requires frequent cleaning, otherwise it will seriously affect the permeation of oxygen and thus affect the measurement. The fluorescence method does not require high cleaning of the probe, and only requires the sensor cap to be wiped off regularly; low maintenance - only one sensor cap needs to be replaced every two years; no interference - pH changes, chemicals contained in sewage, H2S, heavy metals, etc. will not interfere with the measurement; fast response time - the fluorescence method dissolved oxygen can respond as soon as it comes into contact with water, and the time is very short; no polarization time is required - because no electrodes are used, there is no polarization problem; the dissolved oxygen content at a predetermined depth below the wellbore and below the liquid surface can be measured, with a maximum depth of 200m.

[0033] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0035] Figure 1 A schematic diagram of the structure of a measuring probe for wellbore dissolved oxygen content according to an embodiment of the present invention is shown;

[0036] Figure 2 A schematic diagram of the structure of a probe body according to an embodiment of the present invention is shown;

[0037] Figure 3 A schematic diagram of the detection principle of the probe body according to an embodiment of the present invention is shown;

[0038] Figure 4 A schematic diagram of the structure of a device for measuring dissolved oxygen content in a wellbore is shown;

[0039] In the figure: 10, probe body; 101, photodiode; 102, sensor cap; 103, LED lamp; 104, fluorescent material layer; 11, connection port; 12, filter; 13, cooling coil; 14, shell; 15, data cable; 20, computer; 30, water pump; 31, inflow pipeline; 40, cooling compression pump; 41, outflow pipeline. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] like Figure 1 As shown, a measuring probe for dissolved oxygen content in a wellbore according to an embodiment of the present invention comprises a shell 14, wherein the shell 14 has a cavity, and a probe body 10 is arranged in the cavity of the shell 14. The shell 14 can increase the weight of the probe body 10, so that the probe body 10 can enter the well to be measured more easily, and on the other hand, it can provide good protection for the probe body 10, so as to prevent the probe body 10 from being damaged by collision with the well wall during the process of lowering the measuring probe into the well.

[0042] A cooling coil 13 is provided in the inner ring of the shell wall of the shell 14, and the cooling coil 13 is used for circulating the cooling liquid;

[0043] The shell wall of the shell 14 is provided with a connection port 11, and the connection port 11 extends into the cavity of the shell 14;

[0044] A filter screen 12 is provided on the shell 14 away from the connection port 11 . The filter screen 12 is used to prevent water in the well to be tested from entering the cavity of the shell 14 and contacting the probe body 10 so that the measuring probe can complete the detection.

[0045] In the embodiment of the present invention, Figure 2 As shown, a photodiode 101 and a plurality of LED lights 103 are provided inside the probe body 10;

[0046] The top end of the probe body 10 is covered with a sensor cap 102 , and the surface of the sensor cap 102 is covered with a fluorescent material layer 104 ;

[0047] The photodiode 101 is signal-connected to the sensor cap 102;

[0048] A number of the LED lights 103 are connected to the sensor cap 102 by signal, some of the LED lights 103 are used to excite the fluorescent material in the fluorescent material layer 104 to emit light, which is detected by the photodiode 101, and another part of the LED lights 103 is used as a reference light for the light detected by the photodiode 101, and the colors of the two parts of the LED lights 103 are different;

[0049] In the embodiment of the present invention, the number of the LED lights 103 is 2, the color of one LED light 103 is blue, and the color of the other LED light 103 is red;

[0050] In the embodiment of the present invention, the oxygen content detection by the probe body 10 involves the DO measurement principle of the fluorescence method, and the DO measurement principle of the fluorescence method is specifically as follows:

[0051] 1) Luminescence mechanism of fluorescent molecules

[0052] When a substance is irradiated by light, the molecules of the substance transition from a lower energy level to a higher energy level due to the energy of the photon, becoming excited state molecules. Excited state molecules are unstable and need to lose excess energy through the deactivation process to return to a stable ground state. There are two ways of deactivation. One of the processes is non-radiative transition, and the excess energy is eventually converted into heat and released; the other process is that the excited state molecules return to the ground state through radiative transition, and the excess energy is released in the form of emitted photons, which is manifested as fluorescence or phosphorescence. Stokes shift, fluorescence lifetime and quantum yield are three important luminescence parameters of fluorescent substances. Stokes shift is affected by factors such as the structure of fluorescent molecules and solvent effects. Generally speaking, a large Stokes shift is conducive to emitting strong fluorescence signals. Fluorescence lifetime refers to the time it takes for the fluorescence intensity of a molecule to decay to 1 / e of the original intensity after the excitation light source is cut off. Fluorescence lifetime is a property of the fluorescent molecule itself and is not easily disturbed by external factors. Fluorescence quantum yield is the ratio of the number of fluorescence photons emitted by the fluorescent molecule to the number of excitation light photons absorbed. Generally, the quantum yield of fluorescent molecules is related to the structure of the fluorescent substance or the environment in which it is located.

[0053] 2) Fluorescence quenching effect

[0054] Fluorescence quenching effect refers to the phenomenon that the fluorescence intensity of fluorescent molecules decreases due to the interaction between quenchers and fluorescent substances. The quenchers discovered so far mainly include halogen compounds, nitro compounds, heavy metal ions and oxygen molecules. Among them, oxygen is a very important type of quencher, and the quenching process of fluorescent substances by oxygen has been proven to be a dynamic quenching process. The principle is that during the diffusion process, oxygen collides with fluorescent substances in an excited state, and the excited fluorescent substances transfer energy to oxygen and return to the ground state, thereby causing the fluorescence intensity to decrease. However, the two separate immediately after the collision, and the fluorescent molecules do not undergo chemical changes, so the quenching of fluorescent molecules by oxygen is reversible. This dynamic quenching process can be described by the Stern-Volmer equation, as shown in formula (1):

[0055] I0 / I=τ0 / τ=1+KSV [O2] (1)

[0056] In formula (1), I0 and I are the fluorescence intensities in the absence of oxygen and in the presence of oxygen, respectively; τ0 and τ are the fluorescence lifetimes in the absence of oxygen and in the presence of oxygen, respectively; KSV is the quenching constant of the quencher; and [O2] is the dissolved oxygen concentration. As can be seen from formula (1), the concentration of dissolved oxygen can be calculated by measuring the fluorescence intensity or fluorescence lifetime. Fluorescence lifetime is an inherent property of fluorescent substances and is not easily affected by external interference, but its measurement is relatively complicated. Therefore, the content of dissolved oxygen is often detected by measuring fluorescence intensity.

[0057] In the embodiment of the present invention, the measurement process of the probe body 10 is as follows:

[0058] When the blue LED lamp 103 emits a beam of blue light to illuminate the fluorescent material in the fluorescent material layer 104, the fluorescent material is randomly excited by the blue light. When the excited material returns to its original state, it emits red light. This red light is detected by the photodiode 101, and the sensor cap 102 simultaneously measures the time it takes for the fluorescent material to return to its original state after being excited by the blue light and emitting red light. The red LED lamp 103, between two emissions of the blue LED lamp 103, will emit a beam of red light to the sensor cap 102. This red LED light is used as an internal standard (or reference light) to be compared with the red fluorescence generated by the fluorescent material in the fluorescent material layer 104.

[0059] It can be seen that the photodiode 101 in the probe body 10 does not measure the intensity of the red light, but measures the time from the excitation to the generation of red light until the red light disappears, that is, the release time of the fluorescence. In the presence of oxygen, when oxygen comes into contact with the fluorescent substance, the intensity of the red light generated will decrease, and the time for generating red light will also be shortened. The higher the concentration of oxygen, the lower the intensity of the red light generated, and the shorter the time for generating red fluorescence. Figure 3 express, Figure 3 In the figure, the horizontal axis is time, the vertical axis is light intensity, τ1 and τ2 are the release time of fluorescence, and thus, the dissolved oxygen content in the wellbore is detected based on the release time of fluorescence.

[0060] like Figure 4 As shown, in an embodiment of the present invention, a device for measuring dissolved oxygen content in a wellbore is also provided, comprising the measuring probe in the above embodiment;

[0061] It also includes a cooling circuit in communication with the cooling coil 13, wherein the cooling circuit is used to cool the measuring probe;

[0062] The cooling circuit is provided with a cooling compression pump 40 and a water pump 30 . The cooling compression pump 40 and the water pump 30 are connected through a pipeline. The cooling compression pump 40 and the water pump 30 are both arranged outside the housing 14 .

[0063] In the embodiment of the present invention, the cooling circuit includes an inflow pipeline 31 and an outflow pipeline 41 . The inflow pipeline 31 connects the water pump 30 and the cooling coil 13 , and the outflow pipeline 41 connects the cooling coil 13 and the cooling compression pump 40 .

[0064] In the embodiment of the present invention, both the inflow pipeline 31 and the outflow pipeline 41 enter the cavity of the shell 14 from the connecting port 11 and then communicate with the cooling coil 13 .

[0065] In certain embodiments of the present invention, in order to save the manufacturing cost of the measuring device and take into account the gravity of the measuring probe, the inflow pipeline 31 is composed of an oil pipe, and the outflow pipeline 41 is also composed of an oil pipe.

[0066] In the embodiment of the present invention, a computer 20 connected to the probe body 10 by signal is further included, and the computer 20 is connected to the probe body 10 via a data line 15;

[0067] The data line 15 and the power line of the probe body 10 are both sheathed in an oil pipe, and this oil pipe is again combined and sheathed in the same oil pipe with the constituent oil pipes of the inflow pipeline 31 and the outflow pipeline 41, and finally combined into a composite oil pipe, so as to improve the safety and accuracy of detection. For the sake of stability, the oil pipes sheathed with the data line 15 and the power line of the probe body 10, the constituent oil pipes of the inflow pipeline 31, and the constituent oil pipes of the outflow pipeline 41 can be filled with fillers, and the fillers are polypropylene filler ropes or sand materials, etc.

[0068] The working process of the measuring device provided by the embodiment of the present invention is as follows:

[0069] Inject the coolant into the inflow pipeline 31, turn on the water pump 30 and the cooling compression pump 40, and the coolant flows into the cooling coil 13 under the action of the dormitory water pump 30 to cool the cavity of the shell 14 and the probe body 10, and then flows into the cooling compression pump 40 through the cooling coil 13, and is cooled again by the cooling compression pump 40 to obtain the coolant again, forming a cooling circuit;

[0070] After the cooling circuit is stabilized, a measuring probe is placed down the wellbore and lowered to the liquid surface to measure the dissolved oxygen content.

[0071] The embodiment of the present invention further provides a method for measuring dissolved oxygen content in a wellbore, which is implemented by the measuring device described in the above embodiment, and includes:

[0072] Add coolant into the cooling circuit, and start the cooling compression pump 40 and the water pump 30, so that the coolant circulates in the cooling coil 13;

[0073] After the coolant circulates in the cooling coil 13 for a fixed time, the measuring probe is lowered into the wellbore. After it reaches the liquid surface, it is tested several times at intervals until it reaches a fixed distance below the liquid surface.

[0074] In the embodiment of the present invention, the fixed time is 1-2 hours.

[0075] In the embodiment of the present invention, the interval is 2-6m, and the number of detections is 2-5 times.

[0076] In the embodiment of the present invention, the fixed distance is less than or equal to 200m.

[0077] In an embodiment of the present invention, the detection data is also processed, that is, the data detected by the detection body several times at intervals are averaged to obtain the dissolved oxygen content at intervals under the wellbore page.

[0078] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A probe for measuring dissolved oxygen content in a wellbore, characterized in that: It comprises a shell (14), wherein the shell (14) has a cavity inside, and a probe body (10) is arranged inside the cavity of the shell (14); A cooling coil (13) is provided in an inner ring of the shell wall of the shell (14); A connection port (11) is provided on the shell wall of the shell (14), and the connection port (11) extends into the cavity of the shell (14). A filter screen (12) is provided on the housing (14) away from the connection port (11).

2. A probe for measuring dissolved oxygen content in a wellbore according to claim 1, characterized in that: A photodiode (101) and a plurality of LED lights (103) are provided inside the probe body (10); A sensor cap (102) is sleeved on one end of the probe body (10) away from the connection port (11), and a surface of the sensor is covered with a fluorescent material layer (104); A plurality of LED lights (103) are signal-connected to the sensor cap (102).

3. A device for measuring dissolved oxygen content in a wellbore, characterized in that: A measuring probe comprising any one of claims 1 to 2; It also includes a cooling circuit connected to the cooling coil (13), wherein the cooling circuit is used to cool the measuring probe; The cooling circuit is provided with a cooling compression pump (40) and a water pump (30); the cooling compression pump (40) and the water pump (30) are connected via a pipeline; and the cooling compression pump (40) and the water pump (30) are both arranged outside the housing (14).

4. A device for measuring dissolved oxygen content in a wellbore according to claim 3, characterized in that: The cooling circuit comprises an inflow pipeline (31) and an outflow pipeline (41), wherein the inflow pipeline (31) is connected to the water pump (30) and the cooling coil (13), and the outflow pipeline (41) is connected to the cooling coil (13) and the cooling compression pump (40).

5. A device for measuring dissolved oxygen content in a wellbore according to claim 4, characterized in that: The inflow pipeline (31) and the outflow pipeline (41) both enter the cavity of the shell (14) from the connection port (11) and then communicate with the cooling coil (13).

6. A device for measuring dissolved oxygen content in a wellbore according to any one of claims 4-5, characterized in that: It also includes a computer (20) connected to the probe body (10) by signal.

7. A method for measuring dissolved oxygen content in a wellbore, characterized in that: The method is implemented by a device for measuring dissolved oxygen content in a wellbore according to any one of claims 3 to 6, comprising: Adding coolant into the cooling circuit, and starting the cooling compression pump (40) and the water pump (30), the coolant circulates in the cooling coil (13); After the coolant circulates in the cooling coil (13) for a fixed time, the measuring probe is lowered into the wellbore. After it reaches the liquid surface, it is tested several times at intervals until a fixed distance below the liquid surface is detected.

8. A method for measuring dissolved oxygen content in a wellbore according to claim 7, characterized in that: The fixed time is 1-2h.

9. A method for measuring dissolved oxygen content in a wellbore according to claim 7, characterized in that: The distance between each section is 2-6m, and the number of detections is 2-5 times.

10. A method for measuring dissolved oxygen content in a wellbore according to claim 7, characterized in that: The fixed distance is less than or equal to 200m.

11. A method for measuring dissolved oxygen content in a wellbore according to any one of claims 9-10, characterized in that: The method also includes processing the detection data.

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