A logging device based on multi-dimensional imaging of a flexible detector

Abstract

The present invention discloses a logging device based on multi-dimensional imaging of a flexible detector, belonging to the technical field of oil and gas exploration. The present invention includes a housing, in which a main control board, a motor, an X-ray generator unit, a transformer, an X-ray flexible detector, a photoelectric conversion circuit, a data storage unit, and a voltage regulator are sequentially connected. After the present invention uses a bendable X-ray flexible detector to replace the traditional flat detector, the area of the detector occupied by the instrument is reduced, and at the same time, the acquisition of X-ray energy for arc-shaped irregular objects is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas exploration, and relates to a logging device based on multi-dimensional imaging of a flexible detector. Background Art

[0002] In X-ray backscatter imaging: X-rays have the characteristics that their energy cannot be optically focused, they are not affected by the material density during transmission, the radiation will not be refracted due to the change in the fluid density through which it passes, and it will not be refracted by small bubbles or mixtures of water and oil, which is very beneficial for downhole use. A beam of X-rays is collimated to form a narrow beam that produces a fine spot illumination on the target object, and data collection is achieved through a detector array system. Both the X-ray source and the detector are located on the same side of the object to be detected, and photons will pass through the barrier, scatter from the object, and then pass through the barrier again and enter the detector. The contrast of the X-ray backscatter image comes from the difference in the number of photons scattered by the object of interest and the background object. When the object of interest scatters strongly and the background material does not scatter, the backscatter imaging effect is the best, such as metals or organic objects in the air. The processes of evaluating and inspecting the formation of cuttings, microbially induced corrosion, and material defects in traditional wellbores and downhole casings are complex, time-consuming, and very expensive. In order to obtain more effective information, downhole picture information is batch obtained through a backscatter imaging device, so as to further analyze the structural composition of the downhole formation.

[0003] In the existing X-ray backscatter imaging logging device, the source collimator of the X-ray generating device adopts a fixed and unidirectional emission structure, and continuous X-rays are emitted along the wellbore circumference by the rotation of a motor, and a physical reaction occurs with the wellbore wall. First, due to the limitation that traditional flat panel detectors cannot be bent and folded, a single detector cannot be made into a cylindrical shape to detect the wellbore circumference. Generally, multiple flat panel detectors are spliced into a cylindrical detector array in a certain way, and relevant images are calculated later through the information collected by each detector. Therefore, in the current X-ray backscatter imaging logging device, the direction of the source collimator cannot be adjusted, and thus the optimal angle between the collimator and the wellbore wall and the detector cannot be automatically adjusted, which limits the imaging quality in different downhole environments. Second, there are obvious creases at the joints during the splicing process of traditional flat panel detectors, which leads to more serious scattering at the joints and is not conducive to three-dimensional X-ray imaging of curved or irregular target objects. In addition, the X-ray detectors in today's logging devices are manufactured on a glass substrate, making the overall mass large, easy to break, and difficult to transport, which restricts the precise measurement in small-diameter downhole environments. Summary of the Invention

[0004] The object of the present invention is to provide a logging device based on multi-dimensional imaging of a flexible detector, so as to solve the technical problems existing in traditional logging devices, such as limited detection range, complex structure, and image distortion of objects.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A logging device based on multi-dimensional imaging of a flexible detector includes a housing, a main control board, a motor, an X-ray generator unit, a transformer, an X-ray flexible detector, a photoelectric conversion circuit, a data storage unit, and a voltage regulator that are sequentially connected inside the housing; a lower plug is connected to one end of the housing where the voltage regulator is located, and the voltage regulator passes through the housing and is connected to the lower plug; an instrument hanging wall is provided at one end of the housing where the main control board is located.

[0007] The X-ray generator unit includes an X-ray emission source spectrum and n collimator devices arranged equidistantly on the X-ray emission source spectrum. There are n valves for controlling the opening or closing of the collimators inside the X-ray emission source spectrum, and the valves are connected to the collimators one by one.

[0008] The X-ray flexible detector includes an annular flexible substrate and a detector crystal array arranged on the flexible substrate. The detector crystal array is formed by sequentially arranging multiple detector crystals closely; a shielding cover for isolating the flexible detector from the X-ray source is sleeved outside the X-ray flexible detector, and there is a gap between the inner wall of the shielding cover of the X-ray source and the X-ray flexible detector.

[0009] Furthermore, the above-mentioned logging device based on multi-dimensional imaging of a flexible detector is also connected to an image processing and reconstruction unit, and the image processing and reconstruction unit is connected to the data storage unit; the density of the formation of the well wall to be detected and the elemental content are deduced according to the energy distribution information provided by the data storage unit, and after converting them into digital images, well wall imaging information for logging analysis is formed.

[0010] Furthermore, the collimator is an adjustable collimator, which consists of a large ball, a small ball, and a columnar collimator rod; the large ball is sleeved on the outer wall of the small ball and rotates around the small ball, and rotates and seals the small ball; the small ball is provided with a first opening and a second opening, and the second opening is arranged on the opposite side of the first opening and communicates with the first opening to form an outgoing particle channel during the rotation of the large ball; one end of the columnar collimator rod is inserted into the first opening and matches the diameter of the first opening, and the other end is inserted into the X-ray emission source spectrum.

[0011] Even further, the first opening is a circular opening, and the second opening is a 150° square opening. By setting two openings with different shapes, the angle of the continuous X-ray along the direction of the second opening can be adjusted.

[0012] Further, the flexible substrate is made of polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), or polyethylene naphthalate (PEN), and the detector crystal is made of CsPbBr3, Cs2TeI6, Ni-DABDT, or PbI2.

[0013] Furthermore, the size of the detector crystal array is 480×1640; each detector is square, and its pixel size is 100×100μm 2 _.

[0014] Further, while ensuring the detection effect, the overall size of the flexible detector is minimized, and the cost is lower. Among the detector crystal arrays, the spatial positions of individual detector crystals should meet:

[0015] Vector x,y,z = ((R1 + 0.5*cryst dz ) * cos(dphi i,j ), (R1 + 0.5*cryst dz ) * sin(dphi i,j ), i*cryst dx )

[0016] where Vector x,y,z represents the spatial position of an individual detector crystal, R1 represents the inner diameter of the flexible detector, and cryst dx , cryst dy , cryst dz represent the length, width, and height of an individual detector crystal respectively, dphi i,j represents the rotation angle of an individual crystal, and i, j represent the i-th row and j-th column of detector crystals.

[0017] Further, the shielding cover is made of a beryllium window. By using the beryllium window, the energy of X-rays directly reaching the detector from the source in the backscattering of X-rays is effectively reduced.

[0018] Further, the value range of n is 4 ≤ n ≤ 12.

[0019] After adopting the above technical solutions, the present invention has the following beneficial effects:

[0020] 1. Using a bendable X-ray flexible detector instead of a flat panel detector reduces the area occupied by the detector in the instrument and improves the acquisition of X-ray energy for curved and irregular objects.

[0021] 2. In the X-ray generator unit, there are n valves for controlling the opening or closing of collimators in the X-ray emission source spectrum. The valves are connected to the collimators one by one. By controlling the valves, the opening range of the collimators can be controlled according to the actual well logging requirements.

[0022] 3. The collimator of the X-ray generator unit is an adjustable collimator. With this unique collimator structure, the instrument can not only perform circumferential detection downhole, but also control the emission angle by rotating left and right to "focus" on the best angle of backscattering with the detector array, achieving a better imaging effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a design drawing of the rotatable collimation device of the X-ray backscattering instrument: (a) is the assembly drawing of the multi-directional X-ray collimation device, and (b) and (c) are the rotatable diagrams at different angles;

[0024] Figure 2 It is a schematic diagram of the modeling of the nanoscale annular flexible X-ray detector array;

[0025] Figure 3 It is a schematic diagram of the structure of the flexible detector imaging logging device of the present invention;

[0026] Figure 4 It is a diagram of the image processing and data analysis interface of the terminal upper computer in the embodiment;

[0027] Figure 5 It is a schematic diagram of the downhole transmission device of the X-ray backscattering flexible detector in the embodiment;

[0028] Figure 6 It is a flowchart of the X-ray backscattering imaging device in the embodiment;

[0029] Figure 7 It is a diagram of the imaging result of the flexible detector simulating downhole objects in the embodiment;

[0030] Figure 8 It is a comparison diagram of the detection efficiency of different flexible crystal materials. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be described in detail below with reference to the drawings and embodiments.

[0032] Figure 3 It is a schematic diagram of the structure of the flexible detector imaging logging device of the present invention. As Figure 3 shown, a logging device based on multi-dimensional imaging of a flexible detector provided in this embodiment includes a housing, in which a main control board, a motor, an X-ray generator unit, a transformer, an X-ray flexible detector, a photoelectric conversion circuit, a data storage unit, and a voltage regulator are sequentially connected; a lower plug is connected to one end of the housing where the voltage regulator is located, and the voltage regulator passes through the housing and is connected to the lower plug; an instrument hanging wall is provided at one end of the housing where the main control board is located.

[0033] Figure 1Design drawing of a rotatable collimation device for an X-ray backscattering instrument: (a) is the assembly drawing of a multi-directional X-ray collimation device, and (b) and (c) are schematic diagrams of rotation at different angles. As Figure 1 shown, the X-ray generator unit includes an X-ray emission source spectrum and 6 collimator devices equidistantly arranged on the X-ray emission source spectrum. There are 6 valves for controlling the opening or closing of the collimators in the X-ray emission source spectrum, and the 6 valves are connected to the 6 collimators in one-to-one correspondence. The collimator is an adjustable collimator, which consists of a large ball, a small ball, and a columnar collimation rod; the large ball is sleeved on the outer wall of the small ball and rotates around the small ball as the axis, and the small ball is rotationally sealed; the small ball is provided with a first opening and a second opening, and the second opening is arranged on the opposite side of the first opening and communicates with the first opening to form an outgoing particle channel during the rotation of the large ball; one end of the columnar collimation rod is inserted into the first opening and matches the diameter of the first opening, and the other end is inserted into the X-ray emission source spectrum. The two openings provided on the small ball have different shapes, where the first opening is a circular opening and the second opening is a 150° square opening, and the left-right rotation angle is controlled by an external collimation servo.

[0034] The collimator device of this embodiment solves the drawback of the single emission direction of the conventional collimation device. When in use, by rotating the large ball, the instrument can perform circumferential detection around the wellbore, and at the same time, the emission angle can be controlled by left-right rotation to "focus" on the best backscattering angle with the detector array. During implementation, the working states of the n collimators arranged on the X-ray emission source spectrum are controlled by the valves connected thereto. Generally, the more collimators in a single cycle, the finer the acquired imaging information, and more two-dimensional pictures can be obtained, which is helpful for subsequent three-dimensional reconstruction. Affected by construction technology and cost, the number of collimators should be controlled to be greater than or equal to 4 and less than or equal to 12, and 6 is preferred in this embodiment.

[0035] Figure 2 Schematic diagram of modeling a nanoscale annular flexible X-ray detector array. As Figure 2 shown, the X-ray flexible detector includes an annular flexible substrate and a detector crystal array arranged on the flexible substrate. The size of the detector crystal array is 480×1640. It is composed of multiple detector crystals arranged closely in sequence. Each detector is square, and its pixel size is 100×100μm 2The flexible substrate is made of materials such as polyvinyl alcohol (PVA), polyester (PET), polyimide (PI), or polyethylene naphthalate (PEN). The detector crystal can be selected from CsPbBr3, Cs2TeI6, Ni-DABDT, or PbI2. In this embodiment, polyester (PET, C10H8O4, 1.38 g / cm3) or polyimide (PIs, C35H28N2O7, 1.47 g / cm3) is used as the substrate. An organic material is used to achieve bending at an angle and it is made into a ring shape so that it can correspond to the collimator in the axial direction. The detector crystal is selected as CsPbBr3. During production, it can be sprayed on the substrate through a chemical process. In the embodiment, in order to make the X-ray flexible detector have the smallest size, the lowest cost, and the best detection effect, requirements need to be made on the spatial position of a single detector crystal. Specifically:

[0036] The overall size of the X-ray flexible detector is related to the relative arrangement position of the single detector crystal array, the bending angle of the detector, and the size of a single crystal. Let the three-dimensional sizes of a single crystal be dx, dy, and dz respectively, and the detector matrix size be m×n. When the bending angle of the flexible detector is θ, in order to achieve close arrangement, the angle dphi that each corresponding pixel needs to rotate is: i,j ,:

[0037] dphi i,j = θ start + j*θ / n (1)

[0038] Since the crystal has a certain thickness, the inner diameter and outer diameter of the curved surface corresponding to the bent detector are R1 and R2 respectively. Through calculation, the corresponding inner and outer radii of the curved surface can be obtained according to the bending angle and the size of the crystal:

[0039]

[0040]

[0041] Since the array is arranged in sequence, the spatial position of a single crystal in a complete detector array can be expressed by formula (4):

[0042] Vector x,y,z = ((R1 + 0.5*cryst dz ) * cos(dphi i,j ), (R1 + 0.5*cryst dz ) * sin(dphi i,j ), i*cryst dx ) (4)

[0043] In this embodiment, a shielding cover is sleeved outside the X-ray flexible detector to separate the detector from the X-ray source. By isolating the X-ray source and the flexible detector, the energy directly reaching the detector from the source in the X-ray backscattering is effectively reduced. The above logging device based on multi-dimensional imaging of the flexible detector is also connected with an image processing and reconstruction unit, and the image processing and reconstruction unit is connected with a data storage unit; the density of the formation of the well wall to be detected and the element content are deduced according to the energy distribution information provided by the data storage, and then after being converted into a digital image, well wall imaging information for logging analysis is formed. The image processing and reconstruction unit of this embodiment is completed by the upper computer terminal. Figure 4 It is the image processing and data analysis interface diagram of the upper computer terminal in this embodiment. As Figure 4 shown, the information provided by the data storage unit is sliced through a series of pictures on the upper computer terminal, and finally the image reconstruction of the complete well wall is realized through the reconstruction algorithm.

[0044] Figure 6 The detailed process of logging using the above logging device is shown, as Figure 6 shown, including the following steps:

[0045] Step 1: As Figure 5 shown, fix the instrument on the wall with a cable rope, place the logging device of this embodiment downhole, and transmit it to the designated detection area through the transmission device.

[0046] Step 2: After the logging device of this embodiment is transmitted to the relevant area, turn on the X-ray emission source spectrum. The X-ray emission source spectrum generates continuous X-rays. The X-rays irradiate the formation after passing through the collimator. During the irradiation process, the logging device of this embodiment rotates 360 degrees along with the cable and rises slowly continuously to ensure that the formation is irradiated in all directions. Set the angular velocity of the motor rotation to ω (rad / s), the vertical velocity to v z (m / s), the number of selected collimators to n, the time for scanning one cycle around the wellbore to t = 2π / ωn, the length of the annular detector to H. In the same time, v z = H / t = H / (2π / ωn), and then the vertical velocity v z is obtained. The relationship between the vertical velocity v z and the motor angular velocity ω, the number of collimators 6, each collimator is equipped with a source collimator servo for controlling the rotation angle in the left and right directions, and the length of the annular detector is v

[0047] Step 3: The X-rays after irradiation are detected by the annular flexible detector array after being absorbed and scattered by the formation and well fluid. Among them, the low-energy X-rays emitted by the source react with the formation to generate characteristic X-rays, which are received by the CsPbBr3 flexible detector. The relevant information detected is transmitted to the data storage unit, and at the same time, the data in the data storage unit is continuously transmitted to the host computer terminal via the data line.

[0048] Step 4: The host computer terminal performs combination based on the two-dimensional image information provided by the data storage unit to achieve three-dimensional reconstruction, forming complete wellbore imaging information.

[0049] In order to verify the advantage of the bendable flexible detector compared to the flat detector in imaging irregular curved surface geometries in the above logging device. Figure 7 It is the imaging result diagram of the flexible detector in the embodiment simulating downhole objects. As Figure 7 shown, in this embodiment, a semi-circular ring geometry with five defects at different positions is simulated, and the traditional flat detector and the bendable flexible detector are used for imaging respectively. Compared with the problem that the flat detector cannot completely image the defects, that is, the flat detector shows 3 defects and the edge distortion and scattering are relatively serious, the flexible detector used in the logging device of this embodiment can completely image the shapes and positions of the five defects, and at the same time, the influence of imaging distortion is improved. This shows that the imaging of downhole irregular objects in this embodiment is optimized.

[0050] Figure 8 It is the comparison diagram of the detection efficiency of different flexible crystal materials. As Figure 8 shown, by comparing the detection efficiencies of the flexible detector crystals (CsPbBr3, Cs2TeI6) used in this embodiment and the traditional detector crystals (NaI, CsI), the detection efficiency of the detector crystal CsPbBr3 used in this logging device reaches 95% at a crystal thickness of 10 mm, and the detection efficiency of the NaI detector used in the existing logging device is 80% at the same thickness. Therefore, the logging device of this embodiment effectively improves the detection and energy acquisition of X-rays.

[0051] It is not difficult to see from the above embodiments that the logging device provided by the present invention is based on the limitations of current downhole imaging devices, mainly improves the X-ray collimator and detector, and perfects the image automatic processing platform based on the existing logging device. By designing an X-ray collimator device with adjustable directions in multiple directions, the X-ray coverage range is increased, and at the same time, the optimal irradiation angle for different downhole environments is adapted. By converting the traditional flat panel detector into an angle-bendable flexible detector, the problem of serious scattering between flat panel detectors and poor imaging effect is solved. In addition, the flexible crystal material composed of nanoscale crystal materials has the advantages of small particle size, easy preparation and good combination of various materials, which provides feasibility for the large-scale production and application of large-area, flexible and ultrasensitive X-ray detectors.

Claims

1. A logging device based on multi-dimensional imaging of a flexible detector, comprising a housing, a main control board, a motor, an X-ray generator unit, a transformer, an X-ray flexible detector, a photoelectric conversion circuit, a data storage unit, and a voltage regulator that are sequentially connected within the housing; a lower plug is connected to one end of the housing where the voltage regulator is located, and the voltage regulator passes through the housing and is connected to the lower plug; an instrument hanging wall is provided at one end of the housing where the main control board is located; characterized in that: The X-ray generator unit includes an X-ray emission source spectrum and n collimator devices arranged at equal distances around the X-ray emission source spectrum. There are n valves for controlling the opening or closing of the collimators inside the X-ray emission source spectrum, and the valves are connected to the collimators one by one; The X-ray flexible detector includes an annular flexible substrate and a detector crystal array arranged on the flexible substrate. The detector crystal array is formed by arranging multiple detector crystals closely in sequence; An outer shield is provided outside the X-ray flexible detector for isolating the flexible detector from the X-ray source, and there is a gap between the inner wall of the shield of the X-ray source and the X-ray flexible detector; The collimator is an adjustable collimator, which consists of a large ball, a small ball and a cylindrical collimating rod; The large ball is sleeved on the outer wall of the small ball and rotates around the small ball, and rotates and seals the small ball; The small ball is provided with a first opening and a second opening. The second opening is arranged on the opposite side of the first opening and communicates with the first opening to form an outgoing particle channel during the rotation of the large ball; One end of the cylindrical collimating rod is inserted into the first opening and matches the aperture of the first opening, and the other end is inserted into the X-ray emission source spectrum; The first opening is a circular opening, and the second opening is a 150° square opening. By setting two openings with different shapes, the angle of the continuous X-ray along the direction of the second opening can be adjusted.

2. The logging device based on multi-dimensional imaging of a flexible detector according to claim 1, characterized in that: The flexible detector imaging logging device based on X-ray backscattering is also connected with an image processing and reconstruction unit, and the image processing and reconstruction unit is connected with a data storage unit; According to the energy distribution information provided by the data storage unit, the density and elemental content of the formation of the detected well wall are deduced, and after converting them into digital images, well wall imaging information for logging analysis is formed.

3. The logging device based on multi-dimensional imaging of a flexible detector according to claim 1, characterized in that: The flexible substrate is made of materials such as polyvinyl alcohol (PVA), polyester (PET), polyimide (PI) or polyethylene naphthalate (PEN), and the detector crystal is selected from CsPbBr3, Cs2TeI6, Ni-DABDT or PbI2.

4. The logging device based on multi-dimensional imaging of a flexible detector according to claim 1, characterized in that: The size of the detector crystal array is 480×1640; each detector is square, and its pixel size is 100×100 µm 2 .

5. The logging device based on multi-dimensional imaging of a flexible detector according to claim 1, characterized in that: During the array process of the detector crystals, the spatial positions of individual detector crystals should meet: Among them, Vector x,y,z represents the spatial position of a single detector crystal, R 1 represents the inner diameter of the flexible detector, cryst dx 、 cryst dy 、cryst dz respectively represent the length, width, and height of a single detector crystal, dphi (i,j) represents the rotation angle of a single crystal, i,j represents the i row j column of detector crystals.

6. The logging device based on multi-dimensional imaging of a flexible detector according to claim 1, characterized in that: The shield is made of a beryllium window.

7. The logging device based on multi-dimensional imaging of a flexible detector according to any one of claims 1 to 6, characterized in that: The value range of n is 4 ≤ n ≤ 12.

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