An oil, gas, and water holdup and related flow rate sensor

Abstract

An oil, gas and water holdup and related flow sensor, an insulating shell is sealingly arranged on a wire-through pressure-sealing base, two parallel and coaxial capacitor columns are arranged in the insulating shell, a wire-through hole is arranged in the center of the capacitor column, a probe shell is sealingly arranged at the end of the insulating shell, the measuring ends of two optical fibers enter from the center of the wire-through pressure-sealing base, pass through the wire-through holes of the two capacitor columns and the probe shell in sequence and extend out of the probe shell by a certain length, one of the optical fibers extends out by a length greater than that of the other optical fiber, the two optical fibers are fixedly packaged in the probe shell, wires are connected to the two capacitor columns respectively, and the wires pass out of the center of the wire-through pressure-sealing base. The present application realizes the measurement of oil, gas and water three-phase holdup and the flow rate of each phase on the same sensor, and the electrical flow and the optical fiber flow can also be complementary and verified, improving the accuracy and reliability of the measurement, and the correlation of holdup and flow rate is stronger. The present application has the advantages of small size, simple structure, green environmental protection and high precision.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensing technology, specifically relating to an oil, gas and water content and related flow sensor. Background Technology

[0002] In recent decades, to ensure high and stable crude oil production in my country's oilfields and meet the needs of national economic development and improved living standards, various new methods and technologies have been continuously adopted. To maintain stable production pressure, oilfields have employed water-driven oil recovery, achieving high production in the early stages. However, rapid water breakthroughs in later stages, unclear fluid properties across different layers, uneven development and utilization, and a rapid decline in production efficiency have led to overall water cuts exceeding 80%. For example, in the Changqing "three-low" oilfield, the water cut is as high as 90%, with 80% of wells producing less than 5 cubic meters per day. The effective recovery rate is less than 30%, and more than 70% of the crude oil becomes surplus oil.

[0003] To improve the efficiency of remaining oil development, various logging techniques are employed, including small-diameter annular fluid production multi-parameter logging, through-tubing storage multi-parameter logging, horizontal well flow imaging logging, and intelligent stratification monitoring, to accurately obtain constantly changing parameters in development wells. Professional interpreters combine geological, exploration, perforation, fracturing, and water injection information to comprehensively analyze wellbore connectivity and inter-layer inconsistencies, conduct remaining oil assessments, identify main and potential layers, and formulate optimized development systems and measures for increasing and stabilizing production and developing remaining oil. Among these, water holdup, gas holdup, and liquid and gas phase velocities in the wellbore profile are core parameters. Common water holdup sensors include capacitive sensors, electromagnetic wave water holdup meters, microwave water holdup meters, impedance sensors, and sampling sensors; gas holdup is typically measured using radioactive materials; common flow sensors include GR tracer sensors, turbine flow sensors, ultrasonic flow sensors, and electromagnetic flow sensors.

[0004] However, the aforementioned common water holdup and flow rate sensors are all single-parameter independent sensors with low integration, complex structure, and large size, which is not conducive to the miniaturization design of annular fluid production profile instruments and the array design of imaging instrument probes; they are also not suitable for long-term continuous monitoring of stratified oil production monitoring and control instruments, and are not conducive to maintenance; the flow rate measurement scheme is only suitable for special single-phase flow or large flow, and is easily affected by downhole debris particles and heavy oil; the use of radioactive chemical substances to measure gas holdup is not environmentally friendly, oilfield operation approval is difficult, and costs are high; the flow rate measurement has great limitations, electromagnetic ultrasonic flow is suitable for single-phase flow, and turbine flow is easily blocked by sand; 4) the oil, gas and water holdup and flow rate are measured by independent different sensors, the measurement points are not in the same location, and the correlation between holdup and flow rate is not strong.

[0005] In view of the limitations of the common methods and sensors for measuring water holdup, gas holdup, and flow rate, there is an urgent need for an oil, gas, and water holdup and related flow rate sensor to achieve accurate measurement of water holdup, gas holdup, and three-phase flow rate data of oil and gas wells. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide an oil, gas and water holdup and related flow sensor that is small in size, highly integrated, simple in structure, highly accurate, and capable of measuring the three-phase holdup and flow velocity of oil, gas and water and each phase on the same sensor.

[0007] The technical solution adopted to solve the above technical problems is: an oil, gas and water holdup and related flow sensor, wherein an insulating shell is sealed on the pressure-bearing sealed base, and two parallel and coaxial capacitor columns are arranged inside the insulating shell. A wire hole is provided at the center of the capacitor column, and a probe shell is sealed at the end of the insulating shell. The measuring ends of two optical fibers enter from the center of the pressure-bearing sealed base, pass through the wire holes of the two capacitor columns in sequence, and extend out of the probe shell by a certain length. The extension length of one optical fiber is greater than that of the other optical fiber. The two optical fibers are fixedly encapsulated in the probe shell, and wires are connected to the two capacitor columns respectively. The wires pass out from the center of the pressure-bearing sealed base.

[0008] As a preferred technical solution, the length of the two optical fibers extending out of the probe shell is ≤3mm.

[0009] As a preferred technical solution, the measuring ends of both optical fibers are tapered, with a taper angle of 90°.

[0010] As a preferred technical solution, the end of the insulating shell that mounts the probe shell is tapered, the material of the insulating shell is polyetheretherketone or fiberglass, and the wall thickness of the insulating shell is <2mm.

[0011] As a preferred technical solution, the capacitor column is made of beryllium bronze or brass.

[0012] As a preferred technical solution, the outer surface of the insulating shell is coated with an oleophobic and hydrophobic layer.

[0013] As a preferred technical solution, the probe shell is processed with an arc-shaped protective shell at its end. Of the two optical fibers, the measuring end of one optical fiber is located inside the arc-shaped protective shell, and the measuring end of the other optical fiber extends out of the arc-shaped protective shell.

[0014] As a preferred technical solution, the pressure-bearing sealing base for the wire is connected to the insulating housing by threads and is sealed by a surface seal.

[0015] The beneficial effects of this invention are as follows:

[0016] This invention enables the measurement of water holdup and liquid phase velocity using a dual-capacitor column, and the measurement of gas holdup and gas phase velocity using a dual-fiber probe. It achieves the measurement of the three-phase holdup and velocity of oil, gas, and water on a single sensor. Furthermore, the electrical flowmeter and fiber optic flowmeter measurements are complementary and verifiable, improving the accuracy and reliability of the measurements and strengthening the correlation between holdup and velocity. This invention is characterized by its small size, simple structure, environmental friendliness, and high precision. It can be used in ultra-small annular profile logging tools, high-precision multi-parameter logging, flow imaging, and injection-production simultaneous stratified logging control instruments. It meets the needs of annular logging of production profiles in production wells, flow imaging logging in highly deviated wells and horizontal wells, and long-term dynamic production monitoring, providing technical support for the safe and efficient development of oil and gas fields. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention.

[0018] Figure 2 This is a schematic diagram of the structure of the dual-capacitor water holding capacity related flow component and the dual-probe gas holding capacity related flow sensing component of the present invention.

[0019] The components include: 1. Pressure-bearing sealing base for wire crossing; 2. Insulating housing; 3. Probe housing; 4. Optical fiber; 5. Arc-shaped protective housing; 6. Capacitor column; and 7. Conductor wire. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0021] exist Figure 1 In this embodiment, an oil-gas-water holdup ratio and related flow sensor includes a pressure-bearing sealed base 1, a dual-capacitor water holdup ratio related flow component, and a dual-probe gas holdup ratio related flow sensing component. The dual-capacitor water holdup ratio related flow component includes an insulating housing 2 and two capacitor pillars 6. The dual-probe gas holdup ratio related flow sensing component includes a probe housing 3 and two optical fibers 4.

[0022] An insulating shell 2 is threadedly connected to the pressure-bearing sealing base 1. The insulating shell 2 and the pressure-bearing sealing base are sealed by a surface seal. The material of the insulating shell 2 is polyetheretherketone (PEEK), or it can be fiberglass. The wall thickness of the insulating shell 2 is <2mm. In this embodiment, the wall thickness of the insulating shell 2 is 1.5mm. The outer surface of the insulating shell 2 is coated with an oleophobic and hydrophobic layer to prevent oil and water bubbles from sticking to the sensor surface and affecting the accuracy of the measurement results. Two parallel and coaxial capacitor columns 6 are installed inside the insulating shell 2. The two capacitor columns 6 are spaced apart by a distance S2. The distance S2 is adjusted according to the production volume of the application block. When the production volume is larger, the distance S2 is appropriately increased to ensure better resolution. The material of the capacitor column 6 is beryllium bronze, or it can be brass. A wire hole is machined in the center of the capacitor column 6 for the optical fiber 4 to pass through. Wires 7 are connected to the two capacitor columns 6 respectively. The wires 7 pass through the center of the pressure-bearing sealing base 1. The probe shell 3 of the insulating shell 2 is installed... The probe housing 3 is installed in the insulating housing 2 with a tapered structure. The probe housing 3 is connected to the insulating housing 2 by a thread. A sealing ring is installed between the probe housing 3 and the insulating housing 2 to buffer the probe housing 3 from external pressure, ensuring pressure resistance and further protecting the optical fiber 4. The end of the probe housing 3 is processed with an arc-shaped protective shell 5, which is integrated with the probe housing 3. The measuring ends of the two optical fibers 4 enter from the center of the pressure-bearing sealing base 1, pass through the wire holes of the two capacitor pillars 6, the probe housing 3, and extend out of the probe housing 3 by a certain length, which is ≤3mm. The measuring end of one optical fiber 4 is located inside the arc-shaped protective shell 5, and the measuring end of the other optical fiber 4 extends out of the arc-shaped protective shell 5. The distance S1 between the end faces of the measuring ends of the two optical fibers 4 is 2mm. The measuring ends of the two optical fibers 4 are tapered with a taper angle of 90° to ensure the sensitivity of the measuring ends of the two optical fibers 4 to air bubbles. The two optical fibers 4 are encapsulated in the probe housing 3 with high-temperature potting compound.

[0023] In this embodiment, the material of the wire-passing pressure-bearing sealing base 1 is metal. The middle part of the wire-passing pressure-bearing sealing base 1 is machined with an external hexagonal structure to facilitate sensor installation. The left outer side of the wire-passing pressure-bearing sealing base 1 is machined with external threads and a sealing groove. An external sealing ring is installed in the sealing groove for sealing connection with the instrument.

[0024] The working principle of this invention is as follows:

[0025] The principle of the dual-probe gas holdup related flow sensing component is as follows: the refractive index of gas to light is 1, that of water is 1.33, and that of oil is 1.45. Since the refractive index difference between water and oil is not significant, the downhole three-phase flow can be considered as a gas-liquid two-phase flow. When this invention is placed in an oil well, when the liquid flows through the two optical fibers 4 measuring ends, due to the higher refractive index of the liquid phase, some light is refracted at the end faces of the two optical fibers 4 measuring ends, and only a portion of the light is reflected back. At this time, the reflected light received by the host computer is weak. When bubbles flow through the end faces of the two optical fibers 4 measuring ends, since the refractive index of gas is 1, total emission occurs at the end faces of the optical fibers 4 measuring ends, and the reflected light received by the host computer is very strong. The host computer converts the light intensity signal into high and low levels through a photoelectric conversion device. The gas holdup can be obtained by combining the duty cycle of the high and low levels over a fixed period. The more bubbles in the fluid, the more high levels are output; the larger the bubbles, the longer the high level duration at the output end. In this invention, the distance S1 between the end faces of the two optical fibers 4 is less than 3mm. The manifold flowing through the two optical fibers 4 remains unchanged, and the reflection intensity and duration at both ends are equal. After photoelectric conversion by the host computer, the output waveform is identical, only with a certain time lag. The host computer can calculate the waveform lag time ΔT1 using a waveform correlation algorithm, and the flow velocity V1 can be obtained according to V1 = S1 / ΔT1.

[0026] The basic principle of dual-capacitor water-holding capacity related flow sensing: The dielectric constant of oil is 5, and the dielectric constant of water is 80. The difference in dielectric constants between oil and water is significant. Different water-holding capacities result in different equivalent dielectric constants, exhibiting a monotonically increasing relationship: the higher the water-holding capacity, the higher the equivalent dielectric constant. From the relationship between the equivalent dielectric constant and capacitance, it can be seen that the higher the water-holding capacity, the higher the effective capacitance value of the capacitor sensor. In this invention, both capacitor pillars 6 are positive terminals. The invention is installed in the instrument's flow channel, with the instrument casing forming the negative terminal. Each capacitor pillar 6 is a cylindrical capacitor, and its capacitance depends on the medium flowing through at the time of measurement. If water is flowing through at that time, it will have a higher capacitance. The relationship between the frequency output by the RC oscillation circuit of the host computer and the capacitance is: f = 1 / 2πRC. Therefore, the higher the water-holding capacity, the lower f; conversely, if crude oil is flowing through at the time of measurement, the capacitor pillar 6 will have a lower capacitance, and the waveform frequency output by the RC oscillation circuit will be higher. Within a certain time range, the average waveform frequency is positively correlated with the overall water-holding capacity. This invention has two capacitor pillars 6. The manifold flowing through the first capacitor pillar 6 is the same as the manifold flowing through the second capacitor pillar 6. Therefore, the two square wave waveforms output by the RC oscillation circuit of the host computer are the same, except that the time is relatively delayed by ΔT2. The liquid phase fluid velocity in the flow channel of the instrument is V2=S2 / ΔT2, where S2 is the distance between the two capacitor pillars 6.

Claims

1. A sensor for oil, gas, and water holdup and related flow rates, characterized in that: An insulating shell is sealed on the pressure-bearing sealing base for the wire passage. Inside the insulating shell are two parallel and coaxial capacitor columns. A wire passage hole is provided at the center of the capacitor column. A probe shell is sealed at the end of the insulating shell. The measuring ends of two optical fibers enter from the center of the pressure-bearing sealing base for the wire passage, pass through the wire passage holes of the two capacitor columns and the probe shell in sequence, and extend out of the probe shell by a certain length. The extension length of one optical fiber is greater than that of the other optical fiber. The two optical fibers are fixedly encapsulated in the probe shell. Wires are connected to the two capacitor columns respectively, and the wires pass out from the center of the pressure-bearing sealing base for the wire passage. The two parallel and coaxial capacitor columns are used for measuring water holding capacity and liquid phase velocity, and the two optical fibers are used for measuring gas holding capacity and gas phase velocity.

2. The oil, gas, and water holdup and related flow sensor according to claim 1, characterized in that: The length of the two optical fibers extending out of the probe housing is ≤3mm.

3. The oil, gas, and water holdup and related flow sensor according to claim 1 or 2, characterized in that: The measuring ends of both optical fibers are tapered, with a taper angle of 90°.

4. The oil, gas, and water holdup and related flow sensor according to claim 1, characterized in that: The end of the insulating housing that mounts the probe housing is tapered. The insulating housing is made of polyetheretherketone or fiberglass, and the wall thickness of the insulating housing is <2mm.

5. The oil, gas, and water holdup and related flow sensor according to claim 1, characterized in that: The capacitor column is made of beryllium bronze or brass.

6. The oil, gas, and water holdup and related flow sensor according to claim 1 or 4, characterized in that: The outer surface of the insulating shell is coated with an oleophobic and hydrophobic layer.

7. The oil, gas, and water holdup and related flow sensor according to claim 1, characterized in that: The probe housing is provided with an arc-shaped protective shell. Of the two optical fibers, the measuring end of one fiber is located inside the arc-shaped protective shell, while the measuring end of the other fiber extends out of the arc-shaped protective shell.

8. The oil, gas, and water holdup and related flow sensor according to claim 1, characterized in that: The pressure-bearing sealing base is connected to the insulating housing by threads and is sealed by a surface seal.

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