Temperature drift correction system and correction method for photoelectric composite cable

Abstract

The invention discloses a temperature drift correction system and correction method for a photoelectric composite cable. The method comprises the following steps: step 1, installing a plurality of heating devices on the photoelectric composite cable at intervals; 2, the photoelectric composite cable with the heating device is put into the well bottom, the heating device is started, the photoelectric composite cable is heated, the temperatures of different monitoring points of the photoelectric composite cable are collected through the heating device, and the temperatures of the different monitoring points of the photoelectric composite cable are collected through the photoelectric composite cable; step 3, establishing a temperature correction chart of each monitoring point by using the temperature collected by the heating device and the photoelectric composite cable; and 4, correcting the DTS temperature monitored under normal conditions by using the temperature correction plate. Heating devices are additionally arranged at fixed intervals on the whole-well-section optical cable, the heating temperature is adjusted, and a temperature drift correction reference point is changed into a whole well section from an original single point; and establishing a temperature drift correction method and a chart under different depths and different temperature and pressure environments to realize accurate correction of the DTS temperature of the optical fiber.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum geophysical exploration and development, and specifically relates to a DTS temperature correction system and correction method for an optoelectronic composite cable, and in particular to a system and method for petroleum well logging. Background Art

[0002] With the deepening of exploration and development, various oil fields have generally adopted horizontal well staged fracturing technology to increase the production of single wells, but there has been a lack of effective means to dynamically monitor and evaluate the production capacity of horizontal wells. In recent years, distributed optical fiber logging (DTS / DAS) technology has the advantages of small size, light weight, anti-vibration, anti-interference, low power consumption, high sensitivity, ultra-high temperature and pressure resistance, etc., and has received widespread attention from users. Its application surface, application scenarios and application scale are constantly expanding, such as shale oil and gas horizontal well dynamic output monitoring, fracturing monitoring, water plugging guidance, etc. The rapid development of distributed optical fiber logging dynamic monitoring technology makes horizontal well staged fracturing monitoring and evaluation possible, and is expected to become a technical tool to guide production logging to the middle and high end. However, at the same time, the optical fiber is affected by the fluctuation of the excitation light source, the unreasonable setting of the refractive index, the state of the optical cable in the drum and extension, the temperature and pressure environment, etc., resulting in temperature drift in DTS logging, affecting the quality of DTS data and limiting the further development of optical fiber logging. During existing fiber optic logging, a storage-type thermometer and pressure gauge is simultaneously lowered into the bottom of the optical fiber to achieve full monitoring of the bottom hole temperature and pressure data. The bottom hole temperature data monitored by the gauge is used as a reference to perform overall correction of the DTS temperature. This method can have a certain effect in vertical wells and absolutely horizontal wells, but because the actual refractive index of the optical fiber is greatly affected by the well inclination, and there is no clear influence relationship between the degree of bending of the optical cable and the existing well inclination, the optical fiber refractive index parameter in the existing acquisition software can only be set to a fixed value. The unreasonable setting of the refractive index restricts the accuracy of DTS data acquisition, resulting in general application effects in oil and water wells with large changes in inclination. In addition, the optical cable is affected by the wellbore ambient temperature and pressure, and will undergo certain changes in the fiber layer, resulting in different offsets in the DTS monitoring temperature value under different temperature and pressure environments. Therefore, it is urgent to develop a new temperature drift correction method to solve the technical bottlenecks of low accuracy and poor stability of fiber optic DTS logging. Summary of the invention

[0003] The present invention provides a temperature drift correction system and correction method for an optoelectronic composite cable, which can obtain the real DTS temperature response characteristics of a wellbore and realize temperature drift correction for oil and water wells with large inclination changes.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A temperature drift correction system for an optoelectronic composite cable comprises a heating device and a collection system. The plurality of heating devices comprise a heating part and a control part. The heating parts are installed at intervals outside the optoelectronic composite cable to be corrected. The control part of the heating device is used to control the heating temperature and heating time of the heating device. The collection system is used to collect the temperature of the optoelectronic composite cable.

[0006] Furthermore, the heating device is conical.

[0007] Furthermore, the heating device covers the optical fiber probe.

[0008] Furthermore, a heating device is provided every 50 to 100 meters.

[0009] A method for correcting temperature drift of an optoelectronic composite cable comprises the following steps:

[0010] Step 1: Install multiple heating devices at intervals on the photovoltaic composite cable;

[0011] Step 2: lower the photoelectric composite cable with a heating device into the bottom of the well, turn on the heating device to heat the photoelectric composite cable, collect the temperature of each monitoring point of the photoelectric composite cable through the heating device, and collect the DTS temperature of each monitoring point of the photoelectric composite cable;

[0012] Step 3: Using the temperature collected by the heating device and the optoelectronic composite cable, establish a temperature correction chart for each monitoring point;

[0013] Step 4: Use the temperature calibration chart obtained in step 3 to calibrate the monitored DTS temperature.

[0014] Furthermore, in step 2, the maximum heating temperature of the heating device is greater than the original formation temperature.

[0015] Furthermore, in step 2, the maximum heating temperature of the heating device is 5°C-10°C above the original formation temperature.

[0016] Furthermore, in step 2, the lowest heating temperature of the heating device is the temperature of the wellhead constant temperature zone.

[0017] Furthermore, in step 2, the heating device monitors from the highest temperature downwards.

[0018] Furthermore, in step 2, the heating device adjusts the heating temperature in steps of 0.5°C-1°C.

[0019] Furthermore, in step 2, each monitoring point is monitored for 2 minutes to 5 minutes.

[0020] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0021] Compared with the prior art, the optical cable of the present invention uses a composite optical cable, and heating devices are added at fixed intervals through the composite optical cable of the entire well section. After power is turned on, the temperature of the heating device can be adjusted and fixed, and the temperature of the location where the heating device is located and the temperature measured by the optical cable itself are obtained, thereby further enriching the collected data information and realizing that the reference point for temperature drift correction is changed from the original single point to the entire well section.

[0022] Furthermore, the heating device is conical, which facilitates the lowering of the optoelectronic composite cable.

[0023] Furthermore, the heating device is covered on the optical fiber probe, so that the heating position and the measuring position of the optoelectronic composite cable are wirelessly close to each other, thereby improving the accuracy of the calibration.

[0024] Compared with the prior art, the method described in the present invention further enriches the collected data information by adding heating devices at fixed intervals in the optical cables of the entire well section, and then adjusting and fixing the temperature of the heating devices, so as to change the reference point of temperature drift correction from the original single point to the entire well section; the composite optical cable is powered on and heated before formal monitoring, and the temperature drift correction method and chart under different depths and different temperature and pressure environments are established to achieve accurate correction of optical fiber DTS temperature. It can effectively solve the technical bottleneck problems such as low optical fiber DTS logging accuracy and poor measurement stability, and lay the foundation for further promoting the large-scale application of optical fiber logging in various oil fields.

[0025] Furthermore, the maximum heating temperature of the heating device is 5°C-10°C above the original formation temperature, and the minimum heating temperature is the temperature of the wellhead constant temperature zone, ensuring that all temperature ranges that need to be corrected can be covered.

[0026] Furthermore, the heating device monitors downward from the highest temperature, so that the temperature of the heating device is always higher than the temperature of the formation where it is located, thereby avoiding being affected by the formation temperature and improving the correction accuracy.

[0027] Furthermore, the heating device adjusts the heating temperature in steps of 0.5°C-1°C, and measures as many temperatures as possible to improve the calibration accuracy.

[0028] Furthermore, each monitoring point is monitored for 2-5 minutes, and the temperature value is collected after the temperature becomes constant, so that the correction result is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the DTS temperature collection and correction scheme for composite optical cables;

[0030] Figure 2 This is a schematic diagram of the temperature correction plate;

[0031] Figure 3 This is the waterfall diagram of a well before DTS correction;

[0032] Figure 4 This is the waterfall diagram after DTS correction for a certain well;

[0033] Figure 5 This is the temperature matching diagram of the storage opening and closing curves of a certain well.

[0034] In the attached figure: 1. logging vehicle; 2. photoelectric composite cable; 3. heating device; 4. storage instrument; 5. casing; 6. formation. DETAILED DESCRIPTION

[0035] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] The present invention proposes a DTS correction method based on a photoelectric composite cable, which adopts a photoelectric composite cable + heating device mode for monitoring; during data collection, the highest bottom hole temperature is first determined by a storage instrument 4, and then the heating device is powered, and the temperature is adjusted from the highest temperature to the wellhead constant temperature layer temperature in sequence, and DTS temperature monitoring is performed on each heating point; using DTS monitoring data, combined with a linear interpolation method, a temperature drift correction method and a chart (in a tabular form) are established at different positions and different temperature and pressure environments in the entire well section.

[0038] The technical solution adopted by the present invention is:

[0039] On the one hand, the present invention provides a temperature drift correction system for an optoelectronic composite cable, which is composed as follows: an acquisition system and an optoelectronic composite cable equipped with a constant temperature heating device. A heating device 3 is arranged every 100 meters on the optoelectronic composite cable. The shape of the heating device 3 is conical. After the heating device is powered, it can be accurately heated to a specified temperature; the optical fiber logging operation is completed with the help of auxiliary equipment such as a ground acquisition system, a logging vehicle, and wellhead tools. The acquisition system is used to measure the DTS monitoring temperature. Before the formal logging of the optical fiber, the calibration monitoring is performed. The acquisition system is installed on the logging vehicle 1. The logging vehicle 1 is also provided with a controller and a power supply for the heating device 3. The wellhead tool is a tool or equipment for lowering the optoelectronic composite cable with a heating device into the well.

[0040] On the other hand, the present invention provides a method for correcting temperature drift of an optoelectronic composite cable, comprising the following steps:

[0041] Step 1: Design a photovoltaic composite cable with a constant temperature heating device;

[0042] The photoelectric composite cable comprises a photoelectric composite cable body and a heating device 3 fixed on the photoelectric composite cable body at intervals of 100 m. The heating device 3 is an electric heating device.

[0043] Step 2: Design a constant temperature heating monitoring solution for temperature correction monitoring;

[0044] The constant temperature heating monitoring scheme is: with 5°C above the original formation temperature as the highest temperature, the wellhead constant temperature zone temperature (temperature at 130m underground) as the lowest temperature, and a temperature interval of 1°C, the heating device 3 is powered to heat it, and monitoring is carried out from the highest temperature downwards, with each temperature point monitored for 2 minutes, focusing on recording the heating temperature of the heating device 3 and the corresponding DTS sampling point monitoring temperature, and establishing a relationship chart between the constant heating temperature and the DTS monitoring temperature at each monitoring depth point for subsequent DTS monitoring temperature correction.

[0045] Step 3: Lower the optoelectronic composite cable into the casing 5 at the bottom of the well, and perform calibration monitoring according to the constant temperature heating monitoring scheme designed in step 2:

[0046] First, according to the constant temperature heating monitoring scheme designed in step 2, the heating device 3 is started to heat the optoelectronic composite cable, and the heating temperature is collected and recorded at the same time;

[0047] Then, the power supply to the heating device 3 is stopped, and according to the construction design, normal DTS temperature monitoring is performed through the optical fiber probe on the optoelectronic composite cable, and monitoring records are kept.

[0048] Step 4: Using the heating temperature of the heating device 3 and the DTS monitoring temperature, establish a temperature correction chart for each depth point;

[0049] Step 5: Use the temperature calibration chart obtained in step 4 to calibrate the DTS temperature monitored under normal conditions.

[0050] Example

[0051] The present invention is described in detail below in conjunction with the accompanying drawings and specific implementation cases. The target well is a horizontal fracturing well of XXXX shale oil in XX oil field, and the original formation temperature (i.e., the highest bottom temperature) is 130° C., as follows:

[0052] This embodiment uses an optoelectronic composite cable for optical fiber monitoring, on which a heating device 3 is arranged every 100 meters. The heating device 3 adopts a double cone shape to facilitate the lowering of the optoelectronic composite cable. The heating device 3 covers the optical fiber probe and can heat to a specified temperature; the specific shape is as follows Figure 1 shown.

[0053] During data collection, the storage instrument 4, namely, the pressure gauge, first measures the pressure at the location and the change of pressure and temperature over time. The pressure curve is used for interpretation, the highest bottom hole temperature is determined, and the heating scheme is adjusted according to the pressure.

[0054] Design a constant temperature heating monitoring scheme. Set the highest temperature of the constant temperature device as 5℃ (135℃) above the original formation temperature, the lowest temperature as the wellhead constant temperature zone temperature (25℃), and the temperature interval as 1℃. Power the heating device 3 and monitor from the highest temperature downwards. Each temperature monitoring point is monitored for 2 minutes. Record the heating temperature of the heating device 3 and the corresponding DTS sampling point monitoring temperature. The specific monitoring scheme is shown in Table 1. 5300 in Table 1 is the bottom depth of the well.

[0055] Table 1 Monitoring plan

[0056] Heater Depth Heater temperature Heater temperature adjustment interval 100m 135-25℃ 1℃ 200m 135-25℃ 1℃ 300m 135-25℃ 1℃ 400m 135-25℃ 1℃ 500m 135-25℃ 1℃ 600m 135-25℃ 1℃ 700m 135-25℃ 1℃ 800m 135-25℃ 1℃ 900m 135-25℃ 1℃ 1000m 135-25℃ 1℃ 1100m 135-25℃ 1℃ 1200m 135-25℃ 1℃ 1300m 135-25℃ 1℃ 1400m 135-25℃ 1℃ 1500m 135-25℃ 1℃ 1600m 135-25℃ 1℃ 1700m 135-25℃ 1℃ 1800m 135-25℃ 1℃ 1900m 135-25℃ 1℃ 2000m 135-25℃ 1℃ 2100m 135-25℃ 1℃ 2200m 135-25℃ 1℃ 2300m 135-25℃ 1℃ 2400m 135-25℃ 1℃ 2500m 135-25℃ 1℃ 2600m 135-25℃ 1℃ 2700m 135-25℃ 1℃ 2800m 135-25℃ 1℃ 2900m 135-25℃ 1℃ 3000m 135-25℃ 1℃ 3100m 135-25℃ 1℃ 3200m 135-25℃ 1℃ 3300m 135-25℃ 1℃ 3400m 135-25℃ 1℃ 3500m 135-25℃ 1℃ 3600m 135-25℃ 1℃ 3700m 135-25℃ 1℃ 3800m 135-25℃ 1℃ 3900m 135-25℃ 1℃ 4000m 135-25℃ 1℃ 4100m 135-25℃ 1℃ 4200m 135-25℃ 1℃ 4300m 135-25℃ 1℃ 4400m 135-25℃ 1℃ 4500m 135-25℃ 1℃ 4600m 135-25℃ 1℃ 4700m 135-25℃ 1℃ 4800m 135-25℃ 1℃ 4900m 135-25℃ 1℃ 5000m 135-25℃ 1℃ 5100m 135-25℃ 1℃ 5200m 135-25℃ 1℃ 5300m 135-25℃ 1℃

[0057] The casing 5 is lowered into the formation 6, and the optoelectronic composite cable with the heating device 3 is lowered to the bottom of the well through the casing 5. Pre-test monitoring is carried out according to the design. After the monitoring is completed, the power supply to the heating device 3 is stopped. According to the construction design, normal DTS temperature monitoring is carried out and monitoring records are kept. Due to the large amount of data, only part of the monitoring records are shown, as shown in Table 2.

[0058] Table 2 Monitoring records

[0059]

[0060]

[0061]

[0062] Establish a chart of the relationship between the constant heating temperature and the DTS monitoring temperature at each monitoring depth point for subsequent DTS monitoring temperature correction. Figure 2 The figure shows the relationship between the heater temperature and the DTS monitoring temperature at a depth of 5300. Figure 2 Similar to the correction plate shown, a correction plate is established for each depth point.

[0063] The DTS temperature monitored under normal conditions is corrected using the established temperature correction chart. The DTS curve of a well before correction is as follows: Figure 3 As shown in the figure, the left side is the well opening curve, and the right side is the well closing curve. The well opening curve and the well closing curve are quite different. Figure 4 As shown in the figure, the corrected switch well curve is consistent with the production law. Figure 5 The storage instrument 4 shown has basically the same matching relationship for monitoring the temperature profile of the switch well.

[0064] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A temperature drift correction system for an optoelectronic composite cable, characterized in that: It comprises a heating device (3) and a collection system, wherein a plurality of the heating devices (3) comprise a heating part and a control part, wherein the heating parts are installed at intervals outside the optoelectronic composite cable to be calibrated, the control part of the heating device (3) is used to control the heating temperature and heating time of the heating device, and the collection system is used to collect the temperature of the optoelectronic composite cable.

2. The temperature drift correction system for an optoelectronic composite cable according to claim 1, characterized in that: The heating part of the heating device (3) is conical.

3. The temperature drift correction system for an optoelectronic composite cable according to claim 1, characterized in that: The heating part of the heating device (3) covers the optical fiber probe.

4. The temperature drift correction system for an optoelectronic composite cable according to claim 1, characterized in that: The heating part of the heating device (3) is arranged every 50 meters to 100 meters.

5. A method for correcting temperature drift of an optoelectronic composite cable, characterized in that: The following steps are involved: Step 1: Installing a plurality of heating devices (3) at intervals on the photovoltaic composite cable; Step 2: lowering the optoelectronic composite cable with the heating device (3) into the bottom of the well, turning on the heating device (3) to heat the optoelectronic composite cable, collecting the temperature of each monitoring point of the optoelectronic composite cable through the heating device (3), and collecting the DTS monitoring temperature of each monitoring point of the optoelectronic composite cable; Step 3: Using the temperature collected by the heating device (3) and the optoelectronic composite cable, establish a temperature correction chart for each monitoring point; Step 4: Use the temperature calibration chart obtained in step 3 to calibrate the monitored DTS monitoring temperature.

6. The method for correcting temperature drift of an optoelectronic composite cable according to claim 4, characterized in that: In step 2, the maximum heating temperature of the heating device (3) is greater than the original formation temperature.

7. A method for correcting temperature drift of an optoelectronic composite cable according to claim 4 or 5, characterized in that: In step 2, the maximum heating temperature of the heating device (3) is 5°C-10°C above the original formation temperature.

8. The method for correcting temperature drift of an optoelectronic composite cable according to claim 4, characterized in that: In step 2, the lowest heating temperature of the heating device (3) is the temperature of the wellhead isothermal zone.

9. The method for correcting temperature drift of an optoelectronic composite cable according to claim 4, characterized in that: In the step 2, the heating device (3) monitors the temperature from the highest temperature downwards.

10. A method for correcting temperature drift of an optoelectronic composite cable according to claim 4 or 8, characterized in that: In step 2, the heating device (3) adjusts the heating temperature in steps of 0.5°C-1°C.

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