A method and apparatus for correcting the physical location of distributed optical fiber data in a well

Abstract

The application provides a distributed optical fiber data well physical position correction method and device, and belongs to the optical fiber sensing technical field.The method comprises the following steps: determining the physical point depth of the optical fiber at the well mouth and the well end; knocking the optical fiber at the well mouth, collecting the knocking signal; obtaining the knocking optical fiber response superposition channel; picking up the peak position of the optical fiber knocking position and the optical fiber end response on the knocking optical fiber response superposition channel; and performing physical position calibration on the optical fiber data depth.Through actual test, the method can accurately calibrate the physical position of the optical fiber data in the well.

Description

Technical Field

[0001] This invention belongs to the field of optical fiber sensing technology, specifically relating to a method and apparatus for correcting the physical position of distributed optical fiber data in a well. Background Technology

[0002] Distributed fiber optic sensing (DAS) technology, as an emerging and transformative technology, has developed rapidly in fields such as oil and gas exploration and development and engineering monitoring, but there are still some problems that need to be solved.

[0003] During DAS measurements, the actual physical location of the optical fiber is not entirely determined due to several factors. First, the spatial location of the DAS sensor is determined by the fiber's refractive index, the speed of light, and the arrival time of Rayleigh scattering. Because of significant differences in fiber deployment environments—for example, large temperature gradients in wells, and other environmental factors—the speed of light in the fiber may deviate slightly, leading to accumulated errors in the DAS measurement location determined by these methods. Second, to prevent fiber breakage, the fiber core is made relatively loose and redundant during manufacturing. This excessive core filling also results in the actual length of the fiber exceeding the length of the cable, causing errors in the measured physical location. Furthermore, the fiber cannot be completely straightened during deployment. For example, during deployment outside drilling casing, as the casing rotates in the well, the fiber inevitably develops some spirals or even entanglement outside the casing, causing the actual cable length to exceed the depth reached with the casing.

[0004] Therefore, before fiber optic cables are put into formal use, their physical length and actual measurement location need to be recalibrated. Currently, the commonly used calibration method involves calibrating the fiber's position using physical points or markers at known depths or locations. Linear interpolation is then performed between these calibrated points. These physical points include specially made beacons for calibration and physical points whose measurement locations can be determined to elicit a fiber response. However, in practice, the production of special beacons is costly and the construction conditions are demanding. Furthermore, physical points whose measurement locations can be determined to elicit a fiber response are not easily found when deploying cables in wells. Therefore, there is an urgent need to research a calibration method that can guarantee the accuracy of the measurement location in DAS data. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and provide a method and device for correcting the physical position of distributed optical fiber data in the well, thereby ensuring the measurement position accuracy of DAS data.

[0006] One of the objectives of this invention is to provide a method for correcting the physical location of distributed optical fiber data in a well.

[0007] The second objective of this invention is to provide a device for correcting the physical location of distributed optical fiber data in a well.

[0008] A third objective of this invention is to provide a computer-readable storage medium.

[0009] The fourth objective of this invention is to provide a computer device.

[0010] This invention is achieved through the following technical solution:

[0011] The first aspect of this invention provides a method for correcting the physical location of distributed optical fiber data in a well, specifically including the following steps:

[0012] Determine the physical depth of the fiber optic cable at the wellhead and in the well.

[0013] The optical fiber was tapped at the wellhead to collect the tapping signal;

[0014] Obtain the superimposed channel of the strike fiber response;

[0015] Pick the fiber tapping position and the peak position of the fiber end response on the fiber tapping response superposition channel;

[0016] Physical location calibration of fiber optic data depth.

[0017] Further improvements of the present invention are in:

[0018] The specific operations for determining the physical point depth of the optical fiber at the wellhead and its end in the well include:

[0019] By using fiber optic deployment data, the physical depths of the fiber optic cables at the wellhead and the ends within the well are obtained. These depths are then used as known inputs. Let A be the location of the fiber optic cable at the wellhead, and d be the corresponding depth. A The fiber optic cable ends at point B in the well, corresponding to a depth of d. B .

[0020] A further improvement of the present invention is that:

[0021] The specific operation of striking the optical fiber at the wellhead and collecting the striking signal is as follows:

[0022] At wellhead location A, the optical fiber was struck multiple times. Each time the optical fiber was struck, a striking signal was collected and recorded.

[0023] The tapping signal includes the channel number, acquisition time, and amplitude value.

[0024] A further improvement of the present invention is that,

[0025] The specific operations for obtaining the superimposed channel of the struck fiber response include:

[0026] ① For the tapping signal collected in step S2, take one channel and calculate the root mean square amplitude of the sample amplitude values ​​of all collection times on the channel;

[0027] ② Repeat step ①, iterate through all channels, and calculate the root mean square amplitude of all acquisition times on each channel;

[0028] ③ Output the root mean square amplitude of all channels in channel order. The output value is the superimposed channel of the strike fiber response.

[0029] A further improvement of the present invention is that:

[0030] The specific operations for picking up the fiber tapping position and the peak position of the fiber end response on the fiber tapping response superposition channel include:

[0031] On the superimposed channel of the impact fiber response obtained in step S3, the channel number corresponding to the maximum root mean square amplitude at wellhead position A is picked as the channel number of the wellhead impact position, denoted as i. A ;

[0032] On the superimposed channel of the striking fiber response obtained in step S3, the channel number corresponding to the maximum value of the root mean square amplitude jump at position B at the end of the well is taken as the channel number of the fiber end position, denoted as i. B .

[0033] A further improvement of the present invention is that:

[0034] The specific operations for physically calibrating the depth of fiber optic data include:

[0035] Calculate the number of channels i between the channels corresponding to positions A and B. N :

[0036] i N =i B -i A

[0037] Calculate the actual physical location of each channel on the optical fiber:

[0038] d i =d A +(ii A )×(d B -d A ) / i N

[0039] Where i refers to the fiber channel number; d i This refers to the actual physical location of the i-th channel; i N It represents the number of channels between position A and position B.

[0040] A further improvement of the present invention is that:

[0041] Before collecting the impact signal by tapping the optical fiber at the wellhead, the process also includes: redundancy demodulation of the optical fiber data, specifically as follows:

[0042] The demodulation start channel and demodulation end channel of the optical fiber are set to be more than the actual number of channels of the optical fiber, that is, the demodulation recording space output channels of the optical fiber have redundancy.

[0043] The demodulation start channel refers to the first channel of optical fiber acquisition and output.

[0044] The demodulation end channel refers to the last channel of fiber optic acquisition and output.

[0045] A second aspect of the present invention provides a well-drilled physical location correction device for distributed optical fiber data, comprising:

[0046] Depth determination unit: used to determine the physical point depth of the fiber optic cable at the wellhead and in the well.

[0047] The striking signal acquisition unit, connected to the depth determination unit, is used to strike the optical fiber at the wellhead and acquire the striking signal.

[0048] The overlay acquisition unit is connected to the impact signal acquisition unit and is used to acquire the overlay of the impact fiber response;

[0049] A position picking unit, connected to the superposition channel acquisition unit, is used to pick up the fiber striking position and the peak position of the fiber end response on the fiber striking response superposition channel.

[0050] A position calibration unit, connected to the position pickup unit, is used to physically calibrate the depth of the optical fiber data.

[0051] A third aspect of the present invention provides a computer-readable medium storing at least one computer-executable program, which, when executed by the computer, causes the computer to perform steps in the well physical location correction method for distributed optical fiber data as described above.

[0052] A fourth aspect of the present invention provides a computer device including a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the well physical location correction method for distributed optical fiber data as described above.

[0053] Compared with the prior art, the beneficial effects of the present invention are:

[0054] This invention first obtains the physical depth of the optical fiber at the wellhead and the end of the fiber in the well using optical fiber deployment data. Then, the optical fiber is tapped at the wellhead to obtain the tapping signal. Based on the tapping signal, the tapping fiber response superposition channel is obtained. The peak position of the fiber tapping position and the peak position of the fiber end response are picked up on the tapping fiber response superposition channel. Finally, the physical position of the optical fiber data depth is calibrated based on the fiber tapping position and the peak position of the fiber end response, ensuring the measurement position accuracy of DAS data.

[0055] Actual tests show that the method of the present invention can accurately pinpoint the physical location of optical fiber data in the well. Attached Figure Description

[0056] Figure 1 This is a flowchart of a method for correcting the physical location of distributed optical fiber data in a well, provided by the present invention;

[0057] Figure 2 This is a diagram showing the relationship between optical fiber and demodulation channel;

[0058] Figure 3 It is the knock signal after DAS redundancy demodulation;

[0059] Figure 4 It is a pickup diagram of the tapping signal and the response at the end of the optical fiber. Detailed Implementation

[0060] The present invention will now be described in further detail with reference to the accompanying drawings:

[0061] This invention addresses the problem that the actual physical location of the fiber optic measurement point is uncertain during data acquisition in distributed optical fiber sensing (DAS) due to the influence of the fiber material, cabling process, and deployment process, which introduces errors into the DAS data measurement results. It provides a method for correcting the physical location of distributed optical fiber data in the well, ensuring the accuracy of the DAS data measurement location.

[0062] An embodiment of the well physical location correction method for distributed optical fiber data is as follows:

[0063]

Example 1

[0064] like Figure 1 As shown, the method includes the following steps:

[0065] Step 1: Determine the physical depth of the fiber optic cable at the wellhead and its end in the well:

[0066] The specific operations include:

[0067] By using fiber optic deployment data, the physical depths of the fiber optic cables at the wellhead and the ends within the well are obtained. These depths are then used as known inputs. Let A be the location of the fiber optic cable at the wellhead, and d be the corresponding depth. AThe fiber optic cable ends at point B in the well, corresponding to a depth of d. B .

[0068] The fiber optic deployment data is known data obtained through measurement during the fiber optic well installation process, and will not be elaborated further here.

[0069] The second step is to perform redundancy demodulation on the fiber optic data:

[0070] The demodulation start channel and demodulation end channel of the optical fiber are set to be more than the actual number of channels of the optical fiber, that is, the demodulation recording space output channel of the optical fiber has redundancy; the relationship between the optical fiber and the demodulation channels is shown in Figure 2.

[0071] The fiber demodulation start channel refers to the first channel of fiber acquisition and output.

[0072] The demodulation end channel refers to the last channel of fiber optic acquisition and output.

[0073] The fiber optic data here refers to the signals collected by the fiber optic cables from each channel.

[0074] Fiber redundancy demodulation is used because before the physical position of the fiber is corrected, it's impossible to accurately determine which channels on the fiber are within the effective data acquisition range. To ensure all effective data is acquired, more channels are demodulated before and after the fiber's start and end. After the physical position is corrected, redundancy is not needed during actual data acquisition; only the fiber channels within the effective signal acquisition range need to be acquired. Without redundancy, incomplete acquisition of effective signal channels may occur.

[0075] The third step is to tap the optical fiber at the wellhead and collect the tapping signal.

[0076] The specific steps are as follows:

[0077] At wellhead location A, the optical fiber was struck multiple times. Each time the optical fiber was struck, a striking signal was collected and recorded.

[0078] The tapping signal includes the channel number, acquisition time, and amplitude value.

[0079] Step 4: Obtain the superimposed track of the strike fiber response:

[0080] The specific operations include:

[0081] ① For the tapping signal collected in the third step, take one channel and calculate the root mean square amplitude of the sample amplitude values ​​of all collection times on the channel;

[0082] ② Repeat step ①, iterate through all channels, and calculate the root mean square amplitude of all acquisition times on each channel;

[0083] ③ Output the root mean square amplitude of all channels in channel order. The output value is the superimposed channel of the strike fiber response.

[0084] Step 5: Pick the fiber tapping position and the peak position of the fiber end response on the fiber tapping response superposition channel:

[0085] The specific operations include:

[0086] On the stacked channel of the impact fiber response obtained in the fourth step, the channel number corresponding to the maximum root mean square amplitude at wellhead position A is picked as the channel number of the wellhead impact position, denoted as i. A ;

[0087] On the superimposed channel of the strike fiber response obtained in the fourth step, the channel number corresponding to the maximum value of the root mean square amplitude jump at position B at the end of the well is taken as the channel number of the fiber end position, denoted as i. B .

[0088] The principle behind steps three, four, and five is:

[0089] The physical location of the strike and the physical location of the fiber optic end are both known. After the strike, there will be a signal response on the fiber optic. By establishing a correspondence between the channel number of the channel with the strongest signal response and the known physical location of the strike, the channel number corresponding to the wellhead location A on the fiber optic is determined. Due to the end scattering effect at the end of the fiber optic, the signal will have a large jump. The fiber optic channel number of this jump is also established with the actual physical location of the fiber optic end, thus determining the channel number corresponding to point B on the fiber optic.

[0090] Step 6: Physically determine the depth of the fiber optic data.

[0091] The specific operations include:

[0092] ① Calculate the number of channels i between the channels corresponding to positions A and B. N :

[0093] i N =i B -i A

[0094] ② Calculate the actual physical location of each channel on the optical fiber:

[0095] d i =d A +(ii A )×(d B -d A ) / i N

[0096] Where i refers to the fiber channel number; d i This refers to the actual physical location of the i-th channel; iN It represents the number of channels between position A and position B.

[0097] This step determines the physical location of two channels on the optical fiber, calculates the physical interval between two adjacent channels, and uses this interval to calculate the physical location of all channels in sequence, ultimately determining the physical location of all channels.

[0098] like Figure 3 The image shows the raw data collected by redundant demodulation after the optical fiber deployed in the well was struck at the wellhead. The striking signal and the noise response at the end of the optical fiber can be clearly seen from the data.

[0099] Figure 4 Yes Figure 3 The signal calculation is performed on the superimposed track of the impact fiber response, and the channel number and physical point location of the wellhead impact position and fiber end position are identified on the superimposed track, where the wellhead channel number i A =120, depth d A =0 meters; fiber optic end channel number i B =810, depth d B = 689 meters.

[0100] Table 1 shows the correction results for the physical point locations of the above data from the wellhead to the fiber optic terminal section.

[0101] Table 1

[0102] Fiber Channel Number Location of fiber optic physical point (meters) 120 0.00 121 1.00 122 2.00 123 3.00 124 3.99 125 4.99 126 5.99 127 6.99 128 7.99 129 8.99 …… …… 800 679.01 801 680.01 802 681.01 803 682.01 804 683.01 805 684.01 806 685.01 807 686.00 808 687.00 809 688.00 810 689.00

[0103] The present invention also provides a device for correcting the physical location in a well for distributed optical fiber data, and an embodiment of the device is as follows:

[0104]

Example 2

[0105] The well-ground physical location correction device for distributed optical fiber data includes:

[0106] Depth determination unit: used to determine the physical point depth of the fiber optic cable at the wellhead and in the well.

[0107] The striking signal acquisition unit, connected to the depth determination unit, is used to strike the optical fiber at the wellhead and acquire the striking signal.

[0108] The overlay acquisition unit is connected to the impact signal acquisition unit and is used to acquire the overlay of the impact fiber response;

[0109] A position picking unit, connected to the superposition channel acquisition unit, is used to pick up the fiber striking position and the peak position of the fiber end response on the fiber striking response superposition channel.

[0110] A position calibration unit, connected to the position pickup unit, is used to physically calibrate the depth of the optical fiber data.

[0111] The present invention also provides a computer-readable medium, embodiments of which are as follows:

[0112]

Example 3

[0113] The computer-readable storage medium stores at least one computer-executable program, which, when executed by the computer, causes the computer to perform the steps in the well physical location correction method for distributed optical fiber data as described above.

[0114] The present invention also provides a computer device, embodiments of which are as follows:

[0115]

Example 4

[0116] The computer device includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, causes the processor to perform the steps of the well physical location correction method for distributed optical fiber data as described above.

[0117] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and RAMbus dynamic RAM (RDRAM), etc.

[0118] The above technical solution is only one embodiment of the present invention. For those skilled in the art, based on the principles disclosed in the present invention, it is easy to make various types of improvements or modifications, and not limited to the technical solutions described in the specific embodiments of the present invention. Therefore, the foregoing description is only a preferred option and is not restrictive.

Claims

1. A method for correcting the physical location in a well of distributed optical fiber data, characterized in that, Specifically, the following steps are included: Step 1: Determine the physical depth of the fiber optic cable at the wellhead and its end within the well. Specific operations include: By using fiber optic deployment data, the physical depths of the fiber optic cables at the wellhead and their ends within the well are obtained. These depths are then used as known inputs, and the location of the fiber optic cable at the wellhead is denoted as... A The corresponding depth is d A The fiber optic cable is located at its end in the well. B The corresponding depth is d B ; Step 2: Tap the optical fiber at the wellhead and collect the tapping signal; Step 3, obtaining the superimposed path of the strike fiber response, includes the following specific operations: (1) For the knocking signal collected in step S2, take one channel and calculate the root mean square amplitude of the sample amplitude values ​​of all collection times on the channel. (2) Repeat step (1) to traverse all channels and calculate the root mean square amplitude of all acquisition times on each channel; (3) Output the root mean square amplitude of all channels in channel order. The output value is the superimposed channel of the strike fiber response. Step 4: Pick the peak position of the fiber tapping location and the peak position of the fiber end response on the fiber tapping response superposition channel. Specific operations include: On the superimposed path of the knocking fiber response obtained in step S3, at the wellhead position A The channel number corresponding to the maximum root mean square amplitude is taken as the channel number of the wellhead tapping position, denoted as . i A ; On the superimposed path of the knocking fiber response obtained in step S3, at the end of the well. B The channel number corresponding to the largest initial value of the root mean square amplitude is taken as the channel number of the fiber optic end position, denoted as . i B ; Step 5: Physically locate the depth of the fiber optic data. Specific operations include: Calculate the number of channels between the channels corresponding to positions A and B. i N : i N = i B - i A Calculate the actual physical location of each channel on the optical fiber: d i = d A + ( ii A )×( d B - d A ) / i N in, i This refers to the fiber channel number; d i It refers to the first i The actual physical location of each channel; i N It represents the number of channels between position A and position B.

2. The method for correcting the physical location in a well for distributed optical fiber data according to claim 1, characterized in that, The specific operation of striking the optical fiber at the wellhead and collecting the striking signal is as follows: At the wellhead location A The optical fiber is struck multiple times. A striking signal is collected and recorded for each pair of optical fibers struck once. The tapping signal includes the channel number, acquisition time, and amplitude value.

3. The method for correcting the physical location of distributed optical fiber data in a well according to claim 1, characterized in that, Before collecting the impact signal by tapping the optical fiber at the wellhead, the process also includes: redundancy demodulation of the optical fiber data, specifically as follows: The demodulation start channel and demodulation end channel of the optical fiber are set to be more than the actual number of channels of the optical fiber, that is, the demodulation recording space output channels of the optical fiber have redundancy. The demodulation start channel refers to the first channel of optical fiber acquisition and output. The demodulation end channel refers to the last channel of fiber optic acquisition and output.

4. A well-based physical position correction device for distributed optical fiber data, characterized in that, The apparatus for performing the well-drilled physical location correction method for distributed optical fiber data according to any one of claims 1-3, the apparatus comprising: Depth determination unit: used to determine the physical point depth of the fiber optic cable at the wellhead and in the well. The striking signal acquisition unit, connected to the depth determination unit, is used to strike the optical fiber at the wellhead and acquire the striking signal. The overlay acquisition unit is connected to the impact signal acquisition unit and is used to acquire the overlay of the impact fiber response; A position picking unit, connected to the superposition channel acquisition unit, is used to pick up the fiber striking position and the peak position of the fiber end response on the fiber striking response superposition channel. A position calibration unit, connected to the position pickup unit, is used to physically calibrate the depth of the optical fiber data.

5. A computer-readable medium, characterized in that, The computer-readable storage medium stores at least one computer-executable program, which, when executed by the computer, causes the computer to perform the steps in the well physical location correction method for distributed optical fiber data as described in any one of claims 1-3.

6. A computer device comprising a memory and a processor, the memory storing a computer program that, when executed by the processor, causes the processor to perform the steps of the well physical location correction method for distributed optical fiber data as described in any one of claims 1-3.

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