Armored heating composite optical cable and oil and gas layer simulation testing device and method using same

Abstract

The application discloses armored heating composite optical cable and oil and gas layer simulation testing device and method using the same. From inside to outside, the armored heating composite optical cable comprises a first optical transmission unit, an inner metal tube, a second optical transmission unit and an outer metal tube. The first optical transmission unit is inserted into the inner metal tube and extends along the length direction of the inner metal tube. The first optical transmission unit comprises a first optical fiber and an electric wire cable for heating. The second optical transmission unit is wrapped on the outer wall of the inner metal tube and extends along the length direction of the inner metal tube. The second optical transmission unit comprises a second optical fiber and a metal wire. The armored heating composite optical cable can realize rapid detection and analysis of multiple interface positions such as gas-oil-water interface position, and has high precision, high speed and high stability.

Description

Technical Field

[0001] The present invention relates to the technical field of salt cavern gas storage cavity making, and in particular to an armored heating composite optical cable and an oil and gas layer simulation test device and method using the same. Background Art

[0002] The construction of salt-cavern gas storage in my country has entered a period of rapid development. As one of the key factors in ensuring the safe and stable operation of the cavern, monitoring the gas-oil-water interface is receiving increasing attention. During the cavern construction process, the dissolution operation exploits the insolubility of salt rock in diesel fuel, using diesel fuel as a dissolving agent to control the contact surface between water and salt rock, protecting the upper salt rock layer and achieving the desired cavern construction. If the interface is not effectively controlled, the cavern volume will be lost, affecting its shape and, consequently, its stability in subsequent operations. Furthermore, if the cavern roof dissolves at the end of the construction phase, this will affect the sealing of the entire cavern. Therefore, accurate measurement of the gas-oil-water interface is particularly important.

[0003] The Jintan salt-cavern gas storage facility features a single-well, three-tube solution cavity structure, utilizing a solvent-blocking convection solution process. This involves running two solution cavity strings (an inner tube and an outer tube) through the production casing, suspended at the wellhead. A circulating brine solution cavity is established between the inner and outer annuli for brine extraction. Diesel fuel is injected into the annulus between the outer tube and the production casing to control the upward dissolution of the cavity. During the construction of the salt-cavern gas storage cavity, the gas-oil-water interface was tested between the outer 7-inch (177.8 mm) casing and the 9.6-inch (244.5 mm) casing. Brine was discharged through the 4.5-inch (114.3 mm) center casing, while diesel fuel was injected through the outer 7-inch casing. Therefore, the salt-cavern gas storage wellbore structure and testing methods significantly impacted the distribution of the gas-oil-water interface.

[0004] Because controlling the position of the gas-oil-water interface is key to controlling the morphology of the solution cavity and restricting the storage capacity and stability of the gas storage reservoir, real-time monitoring and control of the gas-oil-water interface is an essential technology in the salt cavern construction process. Common methods for controlling the gas-oil-water interface include surface observation, pressure gauge monitoring, downhole resistance sensor measurement, and neutron logging. The surface observation method is simple, direct, and low-cost, but is only applicable to positive circulation cavern construction. The pressure gauge monitoring method produces inaccurate measurement results. Neutron logging is accurate but expensive. Downhole resistance sensor measurements have poor stability and a limited measurement range. None of these methods can achieve gas-oil-water interface testing during large-scale reverse circulation cavern construction.

[0005] Therefore, it is necessary to provide a technical solution to the actual engineering application situations such as low accuracy and slow speed of gas-oil-water interface testing in salt cavern gas storage wells and the technical difficulties existing in general oil and gas formation interface detection. Summary of the Invention

[0006] In view of this, the present application provides an armored heating composite optical cable and an oil and gas layer simulation test device and method using the same, which can realize rapid detection and analysis of multiple interface positions such as "gas-oil-water" with high accuracy, fast speed and high stability.

[0007] In order to achieve the above technical objectives, this application adopts the following technical solutions:

[0008] In the first aspect, the present application provides an armored heating composite optical cable, which includes, from the inside to the outside: a first optical transmission unit, an inner metal tube, a second optical transmission unit, and an outer metal tube; the first optical transmission unit is inserted into the inner metal tube and extends along the length direction of the inner metal tube, and the first optical transmission unit includes a first optical fiber and a wire and cable for heating; the second optical transmission unit is covered on the outer wall of the inner metal tube and extends along the length direction of the inner metal tube, and the second optical transmission unit includes a second optical fiber and a metal wire.

[0009] Preferably, the second optical transmission unit is wound and twisted on the outer wall of the inner metal tube along the central axis of the inner metal tube, the second optical transmission unit is spirally wound and twisted on the outer wall of the inner metal tube along the central axis of the inner metal tube, the first optical fiber is a straightened optical fiber arranged in the inner metal tube, and the second optical fiber is a plurality of optical fibers spirally wound on the outer wall of the inner metal tube.

[0010] Preferably, the wires and cables are formed by insulating and connecting wires and cables with different resistance wires or by insulating and welding wires with different resistivities that are customized in sections.

[0011] In a second aspect, the present application provides an application of an armored heating composite optical cable in testing gas-oil-water multi-interface positions in a cavity well.

[0012] On the third aspect, the present application provides an oil and gas layer simulation test device for an armored heating composite optical cable, including a heating power supply, a DTS host, an armored heating composite optical cable and a simulated wellbore. The simulated wellbore is provided with a nitrogen layer, a diesel layer, a brine layer, and a gravel clay layer from top to bottom. The heating power supply and the DTS host are electrically connected through the armored heating composite optical cable, and the armored heating composite optical cable runs through the simulated wellbore.

[0013] Preferably, the simulated wellbore is a column with closed ends, the column includes a through hole for passing the armored heating composite optical cable, and the surface of the column is marked with scales.

[0014] Preferably, the side of the column includes a gas injection and exhaust valve A for forming a nitrogen layer, an oil injection and discharge valve B for forming a diesel layer, and a water injection and discharge valve C for forming a brine layer.

[0015] Preferably, an air injection and exhaust valve D is further included below the water injection and drainage valve C.

[0016] In a fourth aspect, the present application provides a method for detecting and locating gas-oil-water multi-interface positions using an oil and gas layer simulation test device, comprising the following steps:

[0017] S1. Electrically connect the DTS host, armored heating composite optical cable, and heating power supply. Heat the armored heating composite optical cable using the heating power supply and record the current, voltage, and heating time.

[0018] S2. Collect the corresponding Stokes data and anti-Stokes data collected by the DTS host;

[0019] S3. The data collected in step S2 is calculated through a built-in algorithm to obtain the temperature-sensitive characteristic curve and temperature difference change curve along the armored heating composite optical cable, and the convex points and deformed points of the curve are automatically identified to obtain the test interface height T between the brine layer, diesel layer, and nitrogen layer, that is, to obtain the position of the gas-oil-water multi-interface.

[0020] Preferably, the accuracy of the test interface height T is verified, specifically:

[0021] Before step S1, the method further includes step L1. recording the actual interface height h between the brine layer, the diesel layer, and the nitrogen layer of the oil and gas layer simulation test device;

[0022] After step S3, the following steps are also included:

[0023] L2. Adjust the interface heights between the brine layer, diesel layer, and nitrogen layer to m, and calculate the adjusted height difference H1 = mh;

[0024] L3. Use the heating power supply to reheat the armored heating composite optical cable, record the current and voltage values ​​and the heating time, and collect the corresponding Stokes data and anti-Stokes data collected by the DTS host;

[0025] L4. Calculate the data collected in step L3 using a built-in algorithm to obtain the temperature-sensitive characteristic curve and temperature difference curve along the armored heating composite optical cable. Automatically identify convex and deformed points on the curve to obtain the test interface height K between the brine layer, diesel layer, and nitrogen layer, and calculate the test interface height difference H2 = KT.

[0026] L5. Calculate the difference between H2 and H1 to verify the accuracy of the test interface height;

[0027] L6. If the difference between H2 and H1 is less than or equal to 0.5, retain the data of the test interface height T, and the data is valid, that is, the gas-oil-water multi-interface position is obtained.

[0028] The beneficial effects of the present application are as follows: this solution can utilize active heating armor to heat the composite optical cable, thereby causing rapid temperature changes at multiple interfaces such as gas-oil-water; finally, a DTS host is used for analysis and testing to obtain anti-Stokes and temperature difference mutation signal curves, thereby ultimately realizing rapid detection and analysis of multiple interface positions such as "gas-oil-water", with accurate detection results, low cost, strong stability, and a wide measurement range, which can realize gas-oil-water interface testing in large-scale reverse circulation cavity making processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a cross-sectional schematic diagram of an armored heating composite optical cable;

[0030] Figure 2 This is the main view of the armored heating composite optical cable;

[0031] Figure 3 This is a structural diagram of the oil and gas layer simulation test device.

[0032] In the figure: 1. First optical transmission unit; 2. Inner metal tube; 3. Second optical transmission unit; 4. Outer metal tube; 11. First optical fiber; 10. Electric wire and cable; 12. Second optical fiber; 13. Metal wire; 5. Heating power supply; 6. DTS host; 7. Armored heating composite optical cable; 8. Simulated wellbore; 81. Nitrogen layer; 82. Diesel layer; 83. Brine layer; 84. Gravel clay layer; 85. Gas injection and exhaust valve A; 86. Oil injection and drainage valve B; 87. Water injection and drainage valve C; 88. Gas injection and exhaust valve D. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The distributed fiber temperature measurement system (DTS) is based on Raman scattering. Its sensing principle is primarily based on the temperature effect of Raman backscattering in optical fibers and the principle of optical time-domain reflectometry (OTDR). Raman scattering is caused by the energy exchange between thermal vibrations of optical fiber molecules and photons. If some of the optical energy is converted into thermal vibrations, light with a wavelength longer than the source is emitted, known as Stokes light. If some of the thermal vibrations are converted into optical energy, light with a wavelength shorter than the source is emitted, known as anti-Stokes light. Raman scattered light consists of these two different wavelengths. Because anti-Stokes light scattering depends on the number of molecules in an excited state, as the temperature rises, more molecules are in a high-energy state. Therefore, the measured anti-Stokes light intensity is temperature-dependent. Stokes light, on the other hand, is less temperature-dependent. This indicates that the optical signal is modulated by the temperature signal in the optical fiber. By measuring the temperature-dependent anti-Stokes light intensity, temperature information can be obtained. Since the intensity of anti-Stokes light is not only modulated by the temperature signal but also affected by factors such as the attenuation coefficient of the optical fiber itself, light source oscillation, and optical fiber microbending, while Stokes light is only affected by factors of the optical fiber itself, temperature measurement can be achieved by detecting the ratio of the anti-Stokes light and Stokes light intensities in Raman scattered light, and errors caused by factors of the optical fiber itself can be effectively eliminated.

[0035] Based on this, the present invention was created.

[0036] The technical idea of ​​the present invention is as follows: first, an armored heating composite optical cable 7 that can be used for testing multiple "gas-oil-water" interfaces is designed; second, a set of oil and gas layer simulation test equipment that simulates the underground oil and gas formation state or salt cavern well environment is established, and the armored heating composite optical cable 7 is deployed to perform simulation tests; through the heating power supply 5 control module and the DTS host 6, the armored heating composite optical cable 7 is actively heated in the oil and gas layer simulation test device, thereby causing rapid temperature changes at multiple interfaces such as gas-oil-water, and then the DTS host 6 is used in a timely manner to perform analysis and testing, thereby ultimately achieving rapid detection and analysis of multiple interface positions such as "gas-oil-water".

[0037] The present application provides an armored heating composite optical cable 7, which includes, from the inside to the outside, a first optical transmission unit 1, an inner metal tube 2, a second optical transmission unit 3, and an outer metal tube 4; the first optical transmission unit 1 is inserted into the inner metal tube 2 and extends along the length direction of the inner metal tube 2, and the first optical transmission unit 1 includes a first optical fiber 11 and an electric wire and cable 10 for heating; the second optical transmission unit 3 is coated on the outer wall of the inner metal tube 2 and extends along the length direction of the inner metal tube 2, and the second optical transmission unit 3 includes a second optical fiber 12 and a metal wire 13, and the second optical fiber 12 and the metal wire 13 are synchronously coated on the inner metal tube 2.

[0038] In this solution, the number of first optical fiber 11, second optical fiber 12, and wire and cable 10 is greater than or equal to one. First optical fiber 11 and second optical fiber 12 transmit signals between downhole sensors and a surface demodulator. Wire and cable 10 heats first and second optical fibers 11 and 12, while inner and outer metal tubes 2 and 4 provide protection. First and second optical fibers 11 and 12 consist of a core made of transparent material and a surrounding cladding made of silica glass with a slightly lower refractive index than the core. Light signals entering the core are reflected by the cladding interface, serving as the medium for propagation within the core. The optical fiber is comprised of four layers: a high-refractive-index glass core (50 μm diameter) at the center, a low-refractive-index silica glass cladding (125 μm diameter) in the middle, a buffer layer (250 μm diameter), and a reinforcing resin-coated jacket (400 μm diameter). In some embodiments, first and second optical fibers 11 and 12 can be Corning optical fibers with a high-temperature resistance of 150°C. In some embodiments, the first optical fiber 11 is a normally straightened optical fiber, with 2 single-mode and 2 multi-mode fibers / core. The number of second optical fibers 12 can be 4-6, which are wound around the outer wall of the inner metal tube 2. The second optical fiber 12 includes 2 9 / 125μm single-mode fibers / core, 2 50 / 125μm multi-mode fibers / core, and 2 62.5 / 125μm multi-mode fibers / core.

[0039] The second optical transmission unit 3 is wrapped and twisted around the outer wall of the inner metal tube 2 along the central axis. The first optical fiber 11 is a straightened optical fiber laid within the inner metal tube 2. The second optical fiber is a plurality of optical fibers 12 spirally wound around the outer wall of the inner metal tube 2, serving as a reference signal comparison, providing parameter signals and a calculation benchmark for improving the accuracy of subsequent tests. That is, the second optical fiber 12 and the metal wire 13 are synchronously wound around the outer wall of the inner metal tube 2, increasing the length of the optical fibers by winding to improve positioning accuracy. To further improve and meet the high-precision positioning requirements of subsequent DTS testing, an improved structural method of optical fiber wrapped around a central axis of wire and cable 10 is adopted. This method, by wrapping longer and more high-temperature-resistant Corning optical fibers around the central axis within the limited length of the composite optical cable, improves the positioning accuracy of the composite optical cable during testing.

[0040] The inner layer structure of the armored heating composite optical cable contains a straightly laid segmented resistance wire and a reference optical fiber core; the outer layer structure is a spiral wound multi-core optical fiber, which is the fundamental to provide subsequent engineering application test accuracy.

[0041] In some embodiments, two 1.9 mm wire cables 10 and one center straightened first optical fiber 11 are used in the first optical transmission unit 1, the inner layer metal tube 2 is a 4.3 mm seamless steel tube, the second optical transmission unit 3 is a 1.35 mm second optical fiber 12 and a plurality of 1.35 mm steel wires are twisted together in the inner layer metal tube 2, and the outer layer metal tube 4 is an 8 mm or so seamless steel tube; according to a 75 mm pitch, 1 meter is wound 13 times, one circle increases by 17.5 mm in length, and the total increases by 0.227 meters. That is, in the composite optical cable which is originally only 1 meter long, the length of the internal optical fiber can reach 1.227 meters through winding; conversely, even if the positioning accuracy of the optical cable is increased by 0.227 m / 1 m times.

[0042] In other embodiments, three 1.9 mm wire cables 10 and one center straightened first optical fiber 11 are used in the first optical transmission unit 1, the inner layer metal tube 2 is a 4.7 mm seamless steel tube, the second optical transmission unit 3 is a 1.35 mm second optical fiber 12 and a plurality of 1.35 mm steel wires are twisted together in the outer wall of the inner layer metal tube 2, and the outer layer metal tube 4 is an 8.6 mm seamless steel tube; according to a 75 mm pitch, 1 meter is wound 13 times, one circle increases by 19 mm in length, and the total increases by 0.247 meters. That is, in the composite optical cable which is originally only 1 meter long, the length of the internal optical fiber can reach 1.247 meters through winding; conversely, even if the positioning accuracy of the optical cable is increased by 0.247 m / 1 m times.

[0043] In some embodiments, the wire cable 10 is insulated and connected by different resistance wire cables 10, the wire cable 10 is designed in sections, and a certain resistance wire or a resistance wire with greater impedance is added to a specific section according to actual needs, so as to realize segmented heating of the entire armored heating composite optical cable 7, that is, a high-resistance wire is connected in a specified area, the high-resistance wire generates a large amount of heat, the low-resistance wire does not generate heat or generates a small amount of heat, and the insulation of the connection of the two conductors is connected. For example, a 1500 meter long armored heating composite optical cable 7 uses ordinary wire cable 10 in the 0-500 meter section, uses wire cable 10 with a certain resistance wire in the 500-1000 meter section, and uses wire cable 10 with a resistance wire with greater impedance in the 1000-1500 meter section, so as to finally realize segmented heating control of the entire optical cable, that is, the 0-500 meter section does not heat, the 500-1000 meter section slightly heats, and the 1000-1500 meter section intensively heats, thereby realizing segmented heating control of the entire optical cable.

[0044] By calculating the impedance of the heating wires and carefully designing the size and distribution of the resistors, precise control of the cable's heating position, temperature rise, and speed is achieved, improving the current and voltage levels of the wires. The calculation method is as follows: for example, if wire cable 10 has a resistance of 24 ohms per meter and armored heating composite optical cable 7 has two wires laid out within it, connected at the ends to form a loop, and the cable is 1000 meters long and uses a voltage of 300V, then the total power draw is: U*U / R = 300V*300V / 24 ohms*2 = 90,000 / 48 = 1875W. The average power per meter is: 1875W / 1000m = 1.875W / meter.

[0045] The present application provides an application of an armored heating composite optical cable 7 in testing the multi-interface position of gas, oil and water in a cavity well; in actual engineering applications, the armored heating composite optical cable 7 is installed on the outer wall of the outer tube of the dissolution cavity and lowered into the well with the pipe string. The bottom of the pipe string is welded and reinforced, and the optical cable is fixed with a steel belt in the middle and upper part of the pipe string. After the armored heating composite optical cable 7 passes through the bypass of the wellhead casing four-way, the optical fiber head is fused with an optical fiber jumper, and an interface demodulation analyzer is plugged in to heat the armored heating composite optical cable 7 as a whole to test its integrity. Every 50m depth of the armored heating composite optical cable 7 in the well needs to be connected to the ground instrument to measure the optical signal including the light intensity and temperature and the insulation performance of the armored heating composite optical cable 7. Due to the end face reflection of the optical fiber, the optical signal displayed about 5m near the end of the optical fiber is inaccurate. In actual measurement, the signal of this section needs to be filtered out. The downhole armored heating composite optical cable 7 is lowered from the ground into the well along with the pipe string. The original formation temperature value at every 0.5m interval in the well can be recorded using ground equipment; the ground equipment consists of an interface demodulation analyzer and a heating control power supply. The interface demodulation analyzer is used to monitor the real-time temperature of the downhole composite optical cable, and the heating control power supply is used to control the heating temperature of the downhole composite optical cable.

[0046] The present application provides an oil and gas layer simulation test device for an armored heating composite optical cable 7 to simulate the state of underground oil and gas formations or the environment of a salt cavern well. The device includes a heating power supply 5, a DTS host 6, an armored heating composite optical cable 7, and a simulated wellbore 8, wherein the armored heating composite optical cable 7 is used as a test optical cable, and the simulated wellbore 8 is provided with a nitrogen layer 81, a diesel layer 82, a brine layer 83, and a crushed stone clay layer 84 from top to bottom. The heating power supply 5 and the DTS host 6 are electrically connected through the armored heating composite optical cable 7, and the armored heating composite optical cable 7 runs through the simulated wellbore 8.

[0047] As is well known to those skilled in the art, a distributed fiber optic temperature measurement system (DTS) primarily consists of five components: a transmission fiber, a laser light source, a laser beam splitter, an optoelectronic signal analyzer, and a display. In this embodiment, during active heating of the armored heating composite optical cable 7, due to the varying specific heat capacities of different media, such as diesel and brine, their heating and cooling rates also differ, and their temperature sensitivity varies significantly. This results in sudden temperature changes and temperature gradients at interfaces such as those between gas, oil, and water. Therefore, the distributed fiber optic temperature measurement system (DTS) primarily uses this secondary temperature sensitivity to calculate and analyze the precise location and depth variations of multiple gas-oil-water interfaces. The oil and gas layer simulation test device using the distributed optical fiber temperature measurement system DTS combined with the armored heating composite optical cable 7 has the following main advantages: temperature can be measured and monitored in real time and continuously over a long distance; it can effectively reduce the cost per unit of information; the measurement range is relatively wide, with high spatial resolution and high measurement accuracy; it is not affected by flow conditions, is easy to install and maintain, and the monitoring period is flexible and variable; the cross-section is small, which can effectively reduce the space occupied in the wellbore; it is resistant to high temperatures, has no delay, is stable and safe, and is resistant to electromagnetic interference; it has chemical stability and can be used in harsh environments such as rust, humidity, and high temperature.

[0048] The simulated well body 8 is a column with closed ends, which includes a through hole for passing through the armored heating composite optical cable 7, and the surface of the column is marked with scales. In some embodiments, the simulated well body 8 can be an acrylic glass tube with a scale, which is closed at both ends, but has through holes at the upper and lower ends for passing through the armored heating composite optical cable 7, and sealing rings are arranged around the through holes to prevent leakage.

[0049] The side of the column includes a gas injection and exhaust valve A85 for forming a nitrogen layer 81, an oil injection and discharge valve B86 for forming a diesel layer 82, and a water injection and discharge valve C87 for forming a brine layer 83.

[0050] Below the water injection and drainage valve C87, there is also a gas injection and exhaust valve D88 to increase the complexity and instability of each interface, making the simulation environment more realistic.

[0051] The process of forming the underground oil and gas formation state or salt cavern well environment of the oil and gas layer simulation test device of the armored heating composite optical cable 7 is as follows:

[0052] A certain amount of gravel and clay is filled at the bottom of the graduated acrylic glass tube and compacted to form a gravel-clay layer 84 of a certain thickness; the armored heating composite optical cable 7 runs through the entire simulation test device from top to bottom, and the lower end is sealed with acrylic glass glue and sealing rings to prevent leakage, and the heating is controlled by the heating power supply 5 control module; first, brine with a higher liquid level is injected through the water injection and drainage valve C87 to form a water column of a certain height, forming a brine layer 83; then, a certain amount of diesel is slowly injected above the water column through the oil injection and drainage valve B86 to form a certain height. Diesel column, diesel layer 82; finally, a specific gas, such as nitrogen, is injected at the top through the gas injection and exhaust valve A85 to form a nitrogen layer 81, and finally, the interface between nitrogen and diesel, the interface between diesel and brine, and the interface between brine and gravel clay are formed in the glass tube from top to bottom; the position height of the interface between nitrogen and diesel, and the interface between diesel and brine can be adjusted by the three valves A, B, and C; the complexity and instability of each interface can also be increased by adjusting the jet vibration of the gas injection and exhaust valve D88 at the bottom and the floating interference of bubbles.

[0053] In this device, the packaging type of the armored heating composite optical cable 7 depends on the test depth and the specific high-temperature and high-pressure environment. If the depth is within 200 meters in the formation environment, a general soft packaging mode such as GYTA is adopted. If the depth is more than 200 meters in the high-temperature and high-pressure gas storage environment, a mining flame-retardant packaging mode such as MGTSV is adopted. The optical fiber core of the armored heating composite optical cable 7 adopts high-quality DTS dedicated Corning high-temperature optical fiber, which makes the optical fiber temperature and sound sensing effects better. The optical fiber core of the armored heating composite optical cable 7 contains at least two multi-mode optical fibers and two heating resistor wires. One side of the acrylic glass tube is marked with a real scale and corresponds to the actual gas-oil-water interface height position.

[0054] The present application provides a method for detecting and locating the position of gas-oil-water multiple interfaces using an oil and gas layer simulation test device. Before the detection begins, the oil and gas layer simulation test device is first set up. Then, brine with a higher liquid level is injected through the water injection and drainage valve C87 to form a water column of a certain height, forming a brine layer 83; then, a certain amount of diesel is slowly injected above the water column through the oil injection and drainage valve B86 to form a diesel column of a certain height, a diesel layer 82; finally, a specific gas, such as nitrogen, is injected at the top through the gas injection and exhaust valve A85 to form a nitrogen layer 81. Ultimately, the interface between nitrogen and diesel, the interface between diesel and brine, and the interface between brine and gravel clay are formed in the glass tube from top to bottom, thereby simulating the underground oil and gas formation state or salt cavern well environment, and then detection and positioning are performed according to the following steps:

[0055] S1. After ensuring that the surrounding environment is stable and free of interference, electrically connect the DTS host 6, the armored heating composite optical cable 7, and the heating power supply 5. After verifying that all circuits are secure, turn on the heating power supply 5 to heat the armored heating composite optical cable 7. Record the current, voltage, and heating time. In some embodiments, the voltage is 300V, the circuit is 3A, and the heating time is 1 minute.

[0056] S2. After the armored composite optical cable is energized and heated by the heating power supply control module 5, the corresponding Stokes data and anti-Stokes data collected by the DTS host 6 are immediately started to be collected;

[0057] S3. The data collected in step S2 is calculated through a built-in algorithm to obtain the temperature-sensitive characteristic curve and temperature difference change curve along the armored heating composite optical cable 7, and the convex points and deformed points of the curve are automatically identified to obtain the test interface height T between the brine layer 83, the diesel layer 82, and the nitrogen layer 81. The position of the gas-oil-water multi-interface can be timely analyzed and calculated.

[0058] It is worth noting that in step S, the test interface height T includes one or more of the test interface height T1 between the nitrogen layer 81 and the diesel layer 82 and the interface height T2 between the diesel layer 82 and the brine layer 83 .

[0059] The distributed fiber optic temperature measurement system (DTS) host 6 in this solution utilizes a high-sensitivity light source, along with OTDR and OFDR control modules, to enhance the detection accuracy and sensitivity of photoelectric signals from the hardware system. A positioning algorithm based on Brillouin scattering and OFDR is employed to calculate the spectrum of the anti-Stokes and Brillouin signals, generating a more accurate and sensitive temperature feedback signal. This enables accurate temperature measurement and real-time positioning. Theoretically, temperature measurement accuracy can reach 0.1°C, and positioning accuracy can reach 0.2m. Furthermore, automatic recognition technology can be used to precisely capture and control the steep slope of the photoelectric signal. Combined with artificial intelligence algorithms, this technology enables automated and intelligent identification and extraction of gas-oil-water interfaces, eliminating manual selection and control, thereby enabling automated and intelligent identification of multiple gas-oil-water interfaces.

[0060] In order to verify the accuracy of the test interface height T, the following scheme is provided:

[0061] Before step S1, the method further includes: step L1. recording the actual interface heights h between the brine layer 83, the diesel layer 82, and the nitrogen layer 81 at this time using the scale of the acrylic glass tube, for example, the test interface height h1 between the nitrogen layer 81 and the diesel layer 82, and the interface height h2 between the diesel layer 82 and the brine layer 83;

[0062] After step S3, the following steps are also included:

[0063] L2. Use the oil injection and discharge valve B86 and the water injection and discharge valve C87 to adjust the interface heights m between the brine layer 83, the diesel layer 82, and the nitrogen layer 81. The adjusted interface height m includes the interface height m1 between the brine layer 83 and the diesel layer 82, and the interface height m2 between the diesel layer 82 and the nitrogen layer 81. Calculate the adjusted height difference H1 = mh, where m1 corresponds to h1 and m2 corresponds to h2. For example, H1 = m1 - h1 and H1' = m2 - h2.

[0064] L3. After standing for half an hour, the armored heating composite optical cable 7 is heated again using the heating power supply 5 and the gas-oil-water interface position is measured again, the current and voltage values ​​and the power heating time are recorded, and the corresponding Stokes data and anti-Stokes data collected by the DTS host 6 are collected;

[0065] L4. The data collected in step L3 are calculated using a built-in algorithm to obtain a temperature-sensitive characteristic curve and a temperature difference change curve along the armored heating composite optical cable 7. The convex points and deformed points of the curve are automatically identified to obtain the test interface height K between the brine layer 83, the diesel layer 82, and the nitrogen layer 81. The test interface height K includes the interface height K1 between the brine layer 83 and the diesel layer 82, and the interface height K2 between the diesel layer 82 and the nitrogen layer 81. The test interface height difference H2=KT is also calculated, where K1 corresponds to T1 and K2 corresponds to T2, for example, H1=K1-T1 and H1'=K2-T2.

[0066] L5. Calculate the difference between H2 and H1 to verify the accuracy of the test interface height;

[0067] L6. If the difference between H2 and H1 is less than or equal to 0.5, retain the data of the test interface height T, turn off the power, release and store brine and diesel in a safe location through the oil injection and discharge valve A and water injection and discharge valve B respectively, save the test data and comparative analysis results, and obtain the gas-oil-water multi-interface position positioning.

[0068] In some embodiments, the accuracy error of the DTS host 6 is 0.5 meters, so the accuracy error of the difference test between H2 and H1 is also within 0.5 meters. The armored heating composite optical cable 7 is heated within 1 minute. The analysis result of the DTS host 6 is real-time, so the interface test time is about 1 minute.

[0069] In some embodiments, the accuracy error of the DTS host 6 is within 0.2 meters, so the test accuracy error of the interface between diesel and brine is also within 0.2 meters. The temperature measurement accuracy can theoretically reach 0.1°C and the positioning accuracy can reach 0.2m.

[0070] In summary, this solution is based on the armored heating composite optical cable 7 using the oil and gas layer simulation test device to instantaneously heat the oil-water-gas multi-interface with temperature difference changes to achieve intelligent identification of the gas-oil-water interface.

[0071] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. An armored heating composite optical cable, characterized in that: From the inside to the outside, the optical transmission device comprises: a first optical transmission unit (1), an inner metal tube (2), a second optical transmission unit (3), and an outer metal tube (4); the first optical transmission unit (1) is inserted into the inner metal tube (2) and extends along the length direction of the inner metal tube (2), and the first optical transmission unit (1) comprises a first optical fiber (11) and a heating wire and cable (10); the second optical transmission unit (3) is coated on the outer wall of the inner metal tube (2) and extends along the length direction of the inner metal tube (2), and the second optical transmission unit (3) comprises a second optical fiber (12) and a metal wire (13); the second optical transmission unit (3) is spirally wound and twisted on the outer wall of the inner metal tube (2) along the central axis of the inner metal tube (2), and the first optical fiber (11) is arranged on the inner metal tube. (2) straightened optical fiber, the second optical fiber is a plurality of optical fibers (12) spirally wound on the outer wall of the inner metal tube (2); the electric wire and cable (10) is made of electric wire and cable (10) with different resistance wires through insulation connection or segmented customized electric wires with different resistivity through insulation welding; the segmented heating of the electric wire and cable (10) is achieved by different resistance wires: ordinary electric wire and cable (10) is used in the section of scale 0-500 meters, electric wire and cable (10) with a certain resistance wire is used in the section of scale 500-1000 meters, and electric wire and cable (10) with a larger resistance wire impedance can be used in the section of scale 1000-1500 meters; the second optical fiber and the metal wire are synchronously wound on the outer wall of the inner metal tube; the electric wire and cable (10) is used to heat the first optical fiber (11) and the second optical fiber (12).

2. Use of the armored heating composite optical cable according to claim 1 in testing gas-oil-water multi-interface positions in a cavity well.

3. An oil and gas layer simulation test device using the armored heating composite optical cable according to claim 1, characterized in that: The invention comprises a heating power supply (5), a DTS host (6), an armored heating composite optical cable (7), and a simulated wellbore (8), wherein the simulated wellbore (8) is provided with a nitrogen layer (81), a diesel layer (82), a brine layer (83), and a crushed clay layer (84) in sequence from top to bottom, and the heating power supply (5) and the DTS host (6) are electrically connected via the armored heating composite optical cable (7), and the armored heating composite optical cable (7) runs through the simulated wellbore (8).

4. The oil and gas layer simulation test device according to claim 3, characterized in that: The simulated wellbore (8) is a column with closed ends, the column comprising a through hole for passing the armored heating composite optical cable (7), and the surface of the column is marked with scales.

5. The oil and gas layer simulation test device according to claim 4, characterized in that: The side of the column includes a gas injection and exhaust valve A (85) for forming a nitrogen layer (81), an oil injection and discharge valve B (86) for forming a diesel layer (82), and a water injection and discharge valve C (87) for forming a brine layer (83).

6. The oil and gas layer simulation test device according to claim 5, characterized in that: An air injection and exhaust valve D (88) is also provided below the water injection and drainage valve C (87).

7. A method for detecting and locating gas-oil-water multi-interface positions using the oil and gas layer simulation test device according to claim 3, characterized in that: The following steps are involved: S1. Electrically connect the DTS host (6), the armored heating composite optical cable (7) and the heating power supply (5), and use the heating power supply (5) to heat the armored heating composite optical cable (7), and record the current and voltage values ​​and the power-on heating time; S2. Collect the corresponding Stokes data and anti-Stokes data collected by the DTS host (6); S3. The data collected in step S2 are calculated by a built-in algorithm to obtain the temperature-sensitive characteristic curve and the temperature difference change curve along the armored heating composite optical cable (7), and the convex points and deformed points of the curve are automatically identified to obtain the test interface height T between the brine layer (83), the diesel layer (82), and the nitrogen layer (81), that is, to obtain the position of the gas-oil-water multi-interface.

8. The method for detecting and locating the position of gas-oil-water multiple interfaces according to claim 7, characterized in that: It also includes verifying the accuracy of the test interface height T, specifically: Before step S1, the method further includes step L1. recording the actual interface height h between the brine layer (83), the diesel layer (82), and the nitrogen layer (81) of the oil and gas layer simulation test device; After step S3, the following steps are also included: L2. Adjust the interface height between the brine layer (83), the diesel layer (82), and the nitrogen layer (81) to m, and calculate the adjusted height difference H1=mh; L3. Reheating the armored heating composite optical cable (7) using the heating power supply (5), recording the current and voltage values ​​and the power-on heating time, and collecting the corresponding Stokes data and anti-Stokes data collected by the DTS host (6); L4. Calculate the data collected in step L3 using a built-in algorithm to obtain a temperature-sensitive characteristic curve and a temperature difference change curve along the armored heating composite optical cable (7), automatically identify convex points and deformed points of the curve, and obtain the test interface height K between the brine layer (83), the diesel layer (82), and the nitrogen layer (81), and calculate the test interface height difference H2=KT; L5. Calculate the difference between H2 and H1 to verify the accuracy of the test interface height; L6. If the difference between H2 and H1 is less than or equal to 0.5, retain the data of the test interface height T, and the data is valid, that is, the gas-oil-water multi-interface position is obtained.

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