A device and method for online measuring water content of oil wells

Abstract

The present invention provides an apparatus and method for measuring the water content of an oil well online. The apparatus and method are as follows: an oil inlet pipeline (3) and an oil outlet pipeline (6) are led out from an oil main pipeline (1), a specific heat capacity water content measuring instrument (9) is arranged between the oil inlet pipeline (3) and the oil outlet pipeline (6), the water content of the oil, gas and water fluid extracted from the oil well is measured by the specific heat capacity method, and the crude oil is then transported back to the oil main pipeline. In addition, a flow thermal conductivity flowmeter (8) is also arranged between the oil inlet pipeline (3) and the oil outlet pipeline (6) for measuring the flow of the oil, gas and water fluid, which can timely detect the water content in the oil, gas and water fluid while improving the detection precision and accuracy, and the measurable range of the water content is also larger. Moreover, the thermal conductivity flowmeter and the specific heat capacity water content measuring instrument are arranged in parallel, and the flow and water content of the oil, gas and water fluid can be measured successively, and there is no need to connect the pipelines at other positions of the oil main pipeline, which is simple and easy to operate, occupies little space, and saves time and space. It is also conducive to data statistics and maintenance of instruments and pipelines.

Description

Technical Field

[0001] The invention relates to the field of crude oil detection, and in particular to a device and method for online measuring the water content of an oil well. Background Art

[0002] There are tens of thousands of oil and gas wells in oil fields. The water content parameter of oil and gas wells is one of the important parameters for observing and evaluating whether the oil well production is normal. At present, the measurement methods of oil well water content mainly include offline measurement and online measurement, with offline measurement being the main method.

[0003] Offline measurement is to manually obtain a small amount of oil, gas and water fluid produced from the oil well at the wellhead, and then measure the water content of the sample indoors through instruments. Although the offline measurement method is simple to operate, it has large human errors, poor sample representativeness, cumbersome sampling process, high labor intensity, and samplers need to overcome various difficulties in extreme weather (cold, windy, high temperature, etc.). It is difficult to accurately and timely reflect the changes in water content in the produced oil, gas and water fluids, and therefore cannot meet the requirements of oilfield automation management, which is not conducive to the construction of digital oilfields.

[0004] Online measurement is to install instruments and equipment on the produced fluid pipeline for online real-time measurement. The advantages of this method are: automatic measurement, avoiding the manual wellhead sampling process; disadvantages: low measurement accuracy, which is generally less than 75%. The principles of online measurement of oil well water content mainly include: density meter method, microwave method, γ-ray method, radio frequency method, conductivity method, capacitance method, etc. The measurement methods currently in practical use include: γ-ray method, radio frequency method and capacitance method.

[0005] (1) Gamma ray method The gamma ray method measures the water content of oil, gas and water fluids based on the principle that gamma rays will attenuate to different degrees when passing through different types of media. Due to the different properties of oil, gas and water fluids, their absorption capacity for gamma rays is also different. When gamma rays pass through oil, gas and water fluids, the water content of the oil, gas and water fluids can be obtained based on their different absorption coefficients. This method does not directly contact the fluid and can achieve continuous measurement. The disadvantage is that for 60MeV gamma rays, although the absorption coefficients of oil, gas and water fluids for this ray are still different, they are only about 20%, which will result in low sensitivity and accuracy of the water analyzer. Typical representatives of this type of instrument are the CM-3 and FDH-1 water content detectors developed in the United States.

[0006] (2) Radio frequency method: The dielectric constant of the produced oil, gas and water fluid is several times different from that of water, which are 2.3 and 80 respectively. When the water content in the oil, gas and water fluid changes, its mixed dielectric constant also changes. After the signal is converted, the receiver receives the current signal, and finally calculates the volume of water in the oil and water according to the change in the current. This method has a simple circuit, reliable operation, and easy installation and maintenance. If the conductivity measurement circuit is combined, the test range can be further expanded. Analyzers represented by the radio frequency method include the CA-71-718 intelligent type developed and produced in the United States and the SH intelligent water content analyzer developed in China. Due to the limitations of design conditions, this type of product is generally only suitable for oil wells with a water content of less than 50%.

[0007] (3) Capacitance method: The principle of capacitance method for measuring the water content of produced oil, gas and water fluids is relatively simple. The dielectric constants of oil and water are quite different. When oil, gas and water fluids with different water contents flow through the two poles of a specially made capacitance probe, their mixed dielectric constants are also different, which will produce different capacitance values. The capacitance values ​​are converted into electrical signals through professional electronic circuits and components, thereby realizing real-time monitoring of the water content. However, it is greatly affected by mineralization and temperature, and the measurement accuracy is low. Summary of the invention

[0008] Based on the problems existing in the prior art, the present invention provides an online device and method for measuring the water content of oil wells, which aims to accurately and timely detect the water content of oil, gas and water fluids extracted from oil wells, while improving the detection precision and accuracy, and is applicable to oil wells with a water content in the range of 0%-100%. The present invention is achieved through the following technical solutions.

[0009] A device for online measuring water content of an oil well, comprising:

[0010] An oil inlet pipeline, one end of which is connected to the main oil pipeline, and is used to introduce the oil, gas and water fluid produced by the single well to be measured and transmitted by the main oil pipeline;

[0011] The first inlet valve is arranged on the oil inlet pipeline and close to the front end of the specific heat capacity water content measuring instrument, and is used to introduce the oil, gas and water fluid into the specific heat capacity water content measuring instrument to measure the water content;

[0012] The front end of the specific heat capacity water content measuring instrument is connected to the other end of the oil inlet pipeline, and is used to measure the specific heat capacity of the oil, gas and water fluid, and calculate the water content of the oil, gas and water fluid according to the specific heat capacity; the oil outlet pipeline, one end of the oil outlet pipeline is connected to the rear end of the specific heat capacity water content measuring instrument, and the other end of the oil outlet pipeline is connected to the oil main pipeline, and is used to transport the oil, gas and water fluid back to the oil main pipeline;

[0013] A first outlet valve is disposed on the oil outlet pipeline and close to the rear end of the specific heat capacity water content measuring instrument, and is used to lead the oil, gas and water fluid from the specific heat capacity water content measuring instrument to the oil outlet pipeline after measurement;

[0014] The main pipeline is provided with a main pipeline valve, which is located between the connection between the main pipeline and the oil inlet pipeline and between the connection between the main pipeline and the oil outlet pipeline, and is used to control the connection and disconnection of the main pipeline;

[0015] The control device is electrically connected to the first inlet valve, the specific heat capacity water content measuring instrument and the first outlet valve, respectively, and is used to: before measurement, control the opening of the first inlet valve, closing the specific heat capacity water content measuring instrument and the first outlet valve, closing the first inlet valve and the first outlet valve and opening the specific heat capacity water content measuring instrument during measurement, and closing the specific heat capacity water content measuring instrument after measurement, and opening the first inlet valve and the first outlet valve at the same time.

[0016] Furthermore, it also includes: a second inlet valve, which is arranged at one end of the oil inlet pipeline connected to the oil main pipeline, and is used to control the opening and closing of the oil inlet pipeline;

[0017] The second outlet valve is arranged at one end of the oil outlet pipeline connected to the oil main pipeline, and is used to control the opening and closing of the oil outlet pipeline.

[0018] Furthermore, it also includes: an oil-water mixer, which is arranged on the oil inlet pipeline and located between the first inlet valve and the second inlet valve, and is used to mix the oil, gas and water fluids evenly.

[0019] Furthermore, it also includes:

[0020] A thermal conductivity flowmeter is used to measure the flow of oil, gas and water fluids, the oil inlet end of the thermal conductivity flowmeter is connected to the end of the first inner bypass pipeline, and the oil outlet end of the thermal conductivity flowmeter is connected to the starting end of the second inner bypass pipeline;

[0021] The starting end of the first inner bypass pipeline is connected to the oil inlet pipeline and is located between the oil-water mixer and the first inlet valve;

[0022] The end of the second inner bypass pipeline is connected to the oil outlet pipeline and is located between the first outlet valve and the second outlet valve;

[0023] The control device is also connected to the thermal conductivity flowmeter and is used for controlling the start of the thermal conductivity flowmeter before the water content test.

[0024] Furthermore, the first inlet valve and the first outlet valve are both solenoid valves.

[0025] Furthermore, the control device is a programmable logic control device.

[0026] A method for online measuring the water content of an oil well, using the above-mentioned device for online measuring the water content of an oil well, comprises the following steps:

[0027] Step A1, close the main pipeline valve, and introduce the oil, gas and water fluid produced by the single well to be measured from the oil main pipeline into the oil inlet pipeline;

[0028] Step A2, the control device controls the first inlet valve to open, controls and keeps the first outlet valve closed, and introduces the oil, gas and water fluid into the specific heat capacity water content measuring instrument;

[0029] Step A3, the control device controls the first inlet valve to close, controls to keep the first outlet valve closed, controls to open the specific heat capacity water content measuring instrument, the specific heat capacity water content measuring instrument measures the specific heat capacity of the oil-gas-water fluid, and calculates the water content of the oil-gas-water fluid according to the specific heat capacity;

[0030] Step A4, the control device controls closing the specific heat capacity water content measuring instrument, controls opening the first inlet valve and the first outlet valve, and transports the oil, gas and water fluid back to the oil main pipeline.

[0031] Furthermore, before step A2, the method further includes step B1: mixing the oil, gas and water fluids using an oil-water mixer.

[0032] Furthermore, before step A2, step B2 is also included: introducing the oil, gas and water fluid into the thermal conductivity flowmeter, and the control device controls the thermal conductivity flowmeter to start measuring the flow of the oil, gas and water fluid;

[0033] Wherein, the oil inlet end of the thermal conductivity flowmeter is connected to the end of the first inner bypass pipeline, and the oil outlet end of the thermal conductivity flowmeter is connected to the starting end of the second inner bypass pipeline;

[0034] The starting end of the first inner bypass pipeline is connected to the oil inlet pipeline and is located between the oil-water mixer and the first inlet valve;

[0035] The end of the second inner bypass pipeline is connected to the oil outlet pipeline and is located between the first outlet valve and the second outlet valve;

[0036] The second outlet valve is arranged at one end of the oil outlet pipeline connected to the oil main pipeline, and is used to control the opening and closing of the oil outlet pipeline.

[0037] The beneficial technical effects of the present invention are:

[0038] The device and method for online measuring the water content of oil wells provided by the present invention can improve the detection precision and accuracy while accurately and timely detecting the water content of the oil, gas and water fluid extracted from the oil well, and expand the measurable range of the water content. In addition, the thermal conductivity flowmeter and the specific heat capacity water content measuring instrument are set in parallel, and the flow rate and water content of the oil, gas and water fluid can be measured successively, without having to connect the pipeline at other locations of the oil pipeline, which is simple and easy, takes up little space, and saves time and space. It is also conducive to data statistics and maintenance of instruments and pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the device structure of the present invention.

[0040] Figure 2-4 The figure is a flow chart of the method steps of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0042] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0043] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0044] See also Figure 1The present invention provides an online device for measuring the water content of an oil well, characterized in that it comprises: an oil inlet pipeline (3), one end of which is connected to an oil main pipeline (1) and is used to introduce the oil, gas and water fluid produced from a single well to be measured and transmitted by the oil main pipeline (1); a first inlet valve (7), which is arranged on the oil inlet pipeline (3) and close to the front end of a specific heat capacity water content measuring instrument (9), and is used to introduce the oil, gas and water fluid into the specific heat capacity water content measuring instrument (9) for measuring the water content; a specific heat capacity water content measuring instrument (9) which is used to measure the water content of the oil, gas and water fluid; The front end of the water content measuring instrument (9) is connected to the other end of the oil inlet pipeline (3) and is used to measure the specific heat capacity of the oil, gas and water fluid and calculate the water content of the oil, gas and water fluid according to the specific heat capacity; an oil outlet pipeline (6), one end of the oil outlet pipeline (6) is connected to the rear end of the water content measuring instrument (9), and the other end of the oil outlet pipeline (6) is connected to the oil main pipeline (1) and is used to transport the oil, gas and water fluid back to the oil main pipeline (1); a first outlet valve (11) is arranged on the oil outlet pipeline (6) and close to the rear end of the specific heat capacity water content measuring instrument (9), and used to lead the oil, gas and water fluid from the specific heat capacity water content measuring instrument (9) to the oil outlet pipeline (6) after measurement; a main pipeline valve (2) is provided on the oil main pipeline (1), and the main pipeline valve (2) is located between the connection of the oil main pipeline (1) and the oil inlet pipeline (3) and the connection of the oil main pipeline (1) and the oil outlet pipeline (6), and is used to control the connection and disconnection of the oil main pipeline (1); the control device (10) is respectively The device is electrically connected to the first inlet valve (7), the specific heat capacity water content measuring instrument (9) and the first outlet valve (11) and is used to: before measurement, control the opening of the first inlet valve (7) and the closing of the specific heat capacity water content measuring instrument (9) and the first outlet valve (11); during measurement, the first inlet valve (7) and the first outlet valve (11) are closed and the specific heat capacity water content measuring instrument (9) is opened; after measurement, the specific heat capacity water content measuring instrument (9) is closed and the first inlet valve (7) and the first outlet valve (11) are opened at the same time.

[0045] Specifically, the oil delivery main pipe (1) is a main pipe for transmitting oil, gas and water fluids, and the oil inlet pipe (3) is a bypass pipe connected to the side of the oil delivery main pipe (1). When measuring, the main pipe valve (2) is closed, and the oil, gas and water fluids flow into the oil inlet pipe (3); when not measuring, the main pipe valve (2) is opened, and the oil, gas and water fluids are still transmitted on the oil delivery main pipe (1).

[0046] The first inlet valve (7) and the first outlet valve (11) are arranged at the two ends of the specific heat capacity water content measuring instrument (9). When the first inlet valve (7) is controlled to be opened and the first outlet valve (11) is closed, the oil, gas and water fluid enter the specific heat capacity water content measuring instrument (9). After that, the first inlet valve (7) is controlled to be closed. At this time, the first inlet valve (7) and the first outlet valve (11) are both in a closed state, and the oil, gas and water fluid are maintained in the specific heat capacity water content measuring instrument (9). The specific heat capacity water content measuring instrument (9) is controlled to be opened, and the water content of the oil, gas and water fluid is measured. Since the specific heat capacity of oil and water is greatly different, different water contents have different temperature rise ranges, thereby determining the water content of the measured fluid. The specific heat capacity water content measuring instrument (9) can use existing test instruments and calculation methods, which need not be described in detail here.

[0047] After the measurement is completed, the control device (10) controls the first inlet valve (7) and the first outlet valve (11) to open, and the oil, gas and water fluids are sent back to the oil main pipeline (1). The opening of the first inlet valve (7) is mainly to ensure that the remaining oil, gas and water fluids in the oil inlet pipeline (3) are sent back to the oil main pipeline (1).

[0048] Furthermore, the device also includes: a second inlet valve (4), arranged at one end of the oil inlet pipeline (3) connected to the oil main pipeline (1), and used to control the opening and closing of the oil inlet pipeline (3); a second outlet valve (13), arranged at one end of the oil outlet pipeline (6) connected to the oil main pipeline (1), and used to control the opening and closing of the oil outlet pipeline (6).

[0049] The second inlet valve (4) is a manually opened manual valve. When opened, the oil, gas and water fluid in the oil main pipeline (1) are introduced into the oil inlet pipeline (3). The second outlet valve (13) is a manually opened manual valve. When opened, the oil, gas and water fluid in the oil outlet pipeline (6) are sent back to the oil main pipeline (1).

[0050] Furthermore, the device also includes: an oil-water mixer (5), which is arranged on the oil inlet pipeline (3) and located between the first inlet valve (7) and the second inlet valve (4), and is used to mix the oil, gas and water fluids uniformly. After the oil, gas and water fluids enter the oil inlet pipeline (3), they are mixed in the oil-water mixer (5) to ensure the uniformity of subsequent sampling and measurement.

[0051] Furthermore, the device also includes a thermal conductivity flowmeter (8) for measuring the flow of oil, gas and water fluids, the oil inlet end of the thermal conductivity flowmeter (8) being connected to the end of the first inner bypass pipe (14), and the oil outlet end of the thermal conductivity flowmeter (8) being connected to the starting end of the second inner bypass pipe (12);

[0052] The starting end of the first internal bypass pipeline (14) is connected to the oil inlet pipeline (3) and is located between the oil-water mixer (5) and the first inlet valve (7);

[0053] The end of the second inner bypass pipeline (12) is connected to the oil outlet pipeline (6) and is located between the first outlet valve (11) and the second outlet valve (13);

[0054] The control device (10) is also connected to the thermal conductivity flowmeter (8) and is used to control the thermal conductivity flowmeter (8) to start working before the water content test.

[0055] Of course, as another embodiment of the present invention, the connection point between the first internal bypass pipe (14) and the oil inlet pipe (3) can also be arranged before the oil-water mixer (5), that is, between the second inlet valve (4) and the oil-water mixer (5), that is, when the thermal conductivity flowmeter (8) is working, it is not necessary to mix oil and water.

[0056] At present, the gathering and transportation network of the oil field oil well production fluid generally adopts a plurality of oil wells to transport the oil, gas and water fluids through pipelines to the oil main pipeline (1), and the oil, gas and water fluid flow of each well is measured in turn in the oil main pipeline (1), and then transported to the downstream pipeline by the oil main pipeline (1). The present invention introduces a specific heat capacity water content measuring instrument (9) at the flow metering device, i.e., the thermal conductivity flowmeter (8), introduces the oil, gas and water fluid of the single well to be measured into the device for water content measurement, and then sends the oil, gas and water fluid back to the oil main pipeline (1). The flow of the oil, gas and water fluid is measured first and then the water content of the oil, gas and water fluid is measured. It is not necessary to set up a thermal conductivity flowmeter (8) to measure the flow or to set up a specific heat capacity water content measuring instrument (9) to measure the water content in another place of the oil main pipeline (1), which saves time and space. It is also conducive to data statistics and maintenance of instruments and pipelines.

[0057] Furthermore, the first inlet valve (7) and the first outlet valve (11) are both solenoid valves.

[0058] Furthermore, the control device (10) is a programmable logic control device.

[0059] See also Figure 2-4 The present invention also provides a method for online measuring the water content of an oil well, which is performed using the aforementioned device for online measuring the water content of an oil well, and comprises the following steps:

[0060] Step A1, closing the main pipeline valve (2), and introducing the oil, gas and water fluid produced by the single well to be measured from the oil main pipeline (1) into the oil inlet pipeline (3);

[0061] Step A2, the control device (10) controls the first inlet valve (7) to open, controls the first outlet valve (11) to be closed, and introduces the oil-gas-water fluid into the specific heat capacity and water content measuring instrument (9); Step A3, the control device (10) controls the first inlet valve (7) to be closed, controls the first outlet valve (11) to be closed, controls the specific heat capacity and water content measuring instrument (9) to be opened, and the specific heat capacity and water content measuring instrument (9) measures the specific heat capacity of the oil-gas-water fluid, and calculates the water content of the oil-gas-water fluid based on the specific heat capacity;

[0062] Step A4, the control device (10) controls the closing of the specific heat capacity water content measuring instrument (9), controls the opening of the first inlet valve (7) and the first outlet valve (11), and transports the oil, gas and water fluid back to the oil main pipeline (1).

[0063] Furthermore, step B1 is included before step A2: using an oil-water mixer (5) to mix the oil, gas and water fluids.

[0064] Furthermore, before step A2, step B2 is also included: introducing the oil, gas and water fluid into the thermal conductivity flowmeter (8), and the control device (10) controls the thermal conductivity flowmeter (8) to start measuring the flow rate of the oil, gas and water fluid. The oil inlet end of the thermal conductivity flowmeter (8) is connected to the end of the first internal bypass pipe (14), and the oil outlet end of the thermal conductivity flowmeter (8) is connected to the starting end of the second internal bypass pipe (12);

[0065] The starting end of the first internal bypass pipeline (14) is connected to the oil inlet pipeline (3) and is located between the oil-water mixer (5) and the first inlet valve (7);

[0066] The end of the second inner bypass pipeline (12) is connected to the oil outlet pipeline (6) and is located between the first outlet valve (11) and the second outlet valve (13);

[0067] The second outlet valve (13) is arranged at one end of the oil outlet pipeline (6) connected to the oil main pipeline (1) and is used to control the opening and closing of the oil outlet pipeline (6).

[0068] As an embodiment of the present invention, the connection between the first internal bypass pipeline (14) and the oil inlet pipeline (3) can also be arranged before the oil-water mixer (5), that is, between the second inlet valve (4) and the oil-water mixer (5), that is, when the thermal conductivity flowmeter (8) is working, it is not necessary to mix oil and water. Of course, the connection between the first internal bypass pipeline (14) and the oil inlet pipeline (3) can also be arranged after the oil-water mixer (5), that is, between the first inlet valve (7) and the oil-water mixer (5), that is, after the oil and water are mixed, they enter the thermal conductivity flowmeter (8) for flow measurement.

[0069] The device and method for online measuring the water content of oil wells provided by the present invention can accurately and timely detect the water content in oil, gas and water fluids, improve the detection precision and accuracy, and expand the measurable range of water content. In addition, the flow rate of oil, gas and water fluids can also be detected without the need to set up additional flow metering equipment.

[0070] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for online measurement of water content in oil wells, characterized in that: include: An oil inlet pipeline (3), one end of which is connected to the oil main pipeline (1) and is used to introduce the oil, gas and water fluid produced from the single well to be measured and transmitted by the oil main pipeline (1); A first inlet valve (7) is arranged on the oil inlet pipeline (3) and close to the front end of the specific heat capacity water content measuring instrument (9), and is used to introduce the oil, gas and water fluid into the specific heat capacity water content measuring instrument (9) to measure the water content; The front end of the specific heat capacity water content measuring instrument (9) is connected to the other end of the oil inlet pipeline (3) and is used to measure the specific heat capacity of the oil, gas and water fluid and calculate the water content of the oil, gas and water fluid based on the specific heat capacity; an oil outlet pipeline (6), one end of which is connected to the rear end of the specific heat capacity water content measuring instrument (9), and the other end of which is connected to the oil main pipeline (1) for transporting the oil, gas and water fluid back to the oil main pipeline (1); a first outlet valve (11), arranged on the oil outlet pipeline (6) and close to the rear end of the specific heat capacity water content measuring instrument (9), and used for leading the oil, gas and water fluid from the specific heat capacity water content measuring instrument (9) to the oil outlet pipeline (6) after measurement; The main oil pipeline (1) is provided with a main pipeline valve (2), and the main pipeline valve (2) is located between the connection between the main oil pipeline (1) and the oil inlet pipeline (3) and the connection between the main oil pipeline (1) and the oil outlet pipeline (6), and is used to control the connection and disconnection of the main oil pipeline (1); A control device (10) is electrically connected to the first inlet valve (7), the specific heat capacity water content measuring instrument (9) and the first outlet valve (11) respectively, and is used to: control the first inlet valve (7) to be opened, the specific heat capacity water content measuring instrument (9) and the first outlet valve (11) to be closed before measurement; during measurement, the first inlet valve (7) and the first outlet valve (11) are closed, the specific heat capacity water content measuring instrument (9) is opened, and after measurement, the specific heat capacity water content measuring instrument (9) is closed, and the first inlet valve (7) and the first outlet valve (11) are opened at the same time; and further comprises: A second inlet valve (4), arranged at one end of the oil inlet pipeline (3) connected to the oil main pipeline (1), and used to control the opening and closing of the oil inlet pipeline (3); A second outlet valve (13), arranged at one end of the oil outlet pipeline (6) connected to the oil main pipeline (1), and used to control the opening and closing of the oil outlet pipeline (6); The oil-water mixer (5) is arranged on the oil inlet pipeline (3) and located between the first inlet valve (7) and the second inlet valve (4), and is used to mix the oil, gas and water fluids evenly.

2. The device for online measuring water content of oil wells according to claim 1, characterized in that: Also includes: A thermal conductivity flowmeter (8) for measuring the flow of the oil, gas and water fluids, wherein the oil inlet end of the thermal conductivity flowmeter (8) is connected to the end of the first inner bypass pipe (14), and the oil outlet end of the thermal conductivity flowmeter (8) is connected to the starting end of the second inner bypass pipe (12); The starting end of the first internal bypass pipeline (14) is connected to the oil inlet pipeline (3) and is located between the oil-water mixer (5) and the first inlet valve (7); The end of the second inner bypass pipeline (12) is connected to the oil outlet pipeline (6) and is located between the first outlet valve (11) and the second outlet valve (13); The control device (10) is also connected to the thermal conductivity flowmeter (8) and is used to control the thermal conductivity flowmeter (8) to start working before the water content test.

3. The device for online measuring water content of oil wells according to claim 1, characterized in that: The first inlet valve (7) and the first outlet valve (11) are both solenoid valves.

4. The device for online measuring water content of oil wells according to claim 1, characterized in that: The control device (10) is a programmable logic control device.

5. A method for online measurement of water content in oil wells, characterized in that: The device for online measuring the water content of an oil well as claimed in claim 1 comprises the following steps: Step A1, closing the main pipeline valve (2), and introducing the oil, gas and water fluid with the measured single well from the oil main pipeline (1) into the oil inlet pipeline (3); Step A2, the control device (10) controls the first inlet valve (7) to open, controls and keeps the first outlet valve (11) closed, and introduces the oil, gas and water fluid into the specific heat capacity water content measuring instrument (9); Step A3, the control device (10) controls the first inlet valve (7) to be closed, controls the first outlet valve (11) to be kept closed, controls the opening of the specific heat capacity water content measuring instrument (9), the specific heat capacity water content measuring instrument (9) measures the specific heat capacity of the oil-gas-water fluid, and calculates the water content of the oil-gas-water fluid according to the specific heat capacity; Step A4, the control device (10) controls the closing of the specific heat capacity water content measuring instrument (9), controls the opening of the first inlet valve (7) and the first outlet valve (11), and transports the oil, gas and water fluid back to the oil main pipeline (1); Before step A2, the method further includes step B1: using an oil-water mixer (5) to mix the oil, gas and water fluids.

6. The method for online measuring water content of an oil well as claimed in claim 5, characterized in that: Before step A2, the method further includes step B2: introducing the oil, gas and water fluid into a thermal conductivity flowmeter (8), and the control device (10) controls the thermal conductivity flowmeter (8) to start measuring the flow of the oil, gas and water fluid; The oil inlet end of the thermal conductivity flowmeter (8) is connected to the end of the first internal bypass pipe (14), and the oil outlet end of the thermal conductivity flowmeter (8) is connected to the starting end of the second internal bypass pipe (12); The starting end of the first internal bypass pipeline (14) is connected to the oil inlet pipeline (3) and is located between the oil-water mixer (5) and the first inlet valve (7); The end of the second inner bypass pipeline (12) is connected to the oil outlet pipeline (6) and is located between the first outlet valve (11) and the second outlet valve (13); The second outlet valve (13) is arranged at one end of the oil outlet pipeline (6) connected to the oil main pipeline (1), and is used to control the opening and closing of the oil outlet pipeline (6).

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