CN107916922B - Downhole fish detection method and device based on flexible array pressure sensor - Google Patents

Abstract

The invention relates to a method and a device for detecting underground fish based on a flexible array type pressure sensor, and belongs to the technical field of oilfield workover operation. The lower part of the weighting block is connected with an underground vertical transmission mechanism through a connecting device, the underground horizontal transmission mechanism is fixedly connected with the inside of a shell of the underground vertical transmission mechanism, the lower part of the underground vertical transmission mechanism is connected with a flexible array type pressure sensing probe, and a logging cable is connected with the upper part of the weighting block and penetrates through the underground vertical transmission mechanism to be connected with the flexible array type pressure sensing probe. The underground cable has the advantages that the underground cable is novel in structure, and the underground cable is low in underground operation period, time and labor cost; the flexible array type pressure sensing probe and the fish roof are used for contact type detection, the piezoresistive cantilever beam sensing array is utilized and embedded into the polyimide insulating elastic film, so that the reliability is high, the structure is compact, and the operation is convenient.

Description

Downhole fish detection method and device based on flexible array pressure sensor

Technical Field

The present invention belongs to the technical field of oilfield well repair operations, and in particular relates to a method and device for detecting fish falling into a well, and specifically to a method and device for detecting fish falling into a well based on a flexible array pressure sensor.

Background Art

Every year, oil and water wells are shut down due to fish dropping or casing misalignment caused by rock fractures, resulting in serious losses. Therefore, well repair operations such as salvaging and unstuck wells are needed to restore oil well production. Among them, the detection and identification of the shape and position of fish dropping or misaligned casing in the well is the first and most critical step, and its detection accuracy provides an important guarantee for the success rate of subsequent well repair operations.

At present, the methods used for downhole fish detection mainly include contact traditional lead mold printing, ultrasonic imaging detection, and downhole video system. Traditional lead mold printing method: Since the lead mold is pressurized to contact with the fish top to cause plastic deformation, the pressurized printing can only be printed once and cannot be repeated; the lead mold is transported through the connected drill pipe column or oil pipe column, and the operation cycle of lifting and lowering is long, the efficiency is low, and the time and labor costs are increased. Downhole video method: Due to the complex and changeable media in the well, the mixture of crude oil, impurities, mud, etc. causes sound wave attenuation and affects the lens' detection of fallen fish, and the cost is high. Ultrasonic imaging detection: Since the ultrasonic probe needs to continuously adjust the vertical distance between the probe and the fish top and the rotation angle to transmit and receive signals point by point to ensure that the collected signal covers the entire shape of the fish top, the detection efficiency is low, the equipment is complex and the precision requirements are high, the cost is high, and the imaging accuracy is not high due to the well medium and electromagnetic interference.

In summary, the technical methods and equipment currently used for downhole fish detection have limitations and shortcomings in detection accuracy, operation efficiency, operating difficulty and cost.

Summary of the invention

The present invention provides a method and device for detecting fallen fish in a well based on a flexible array pressure sensor, so as to solve the existing problems of low accuracy in identifying fallen fish, low efficiency in detecting operation and large amount of operation engineering.

The technical solution adopted by the present invention is a method for detecting fish falling in a well based on a flexible array pressure sensor, comprising the following steps:

Step 1: Lower the flexible array pressure sensor probe to the top of the fish through the logging cable;

Step 2: drive the stepper motor to drive the disc cam transmission mechanism to control the follower rods uniformly distributed in the horizontal plane to move radially to the inner wall of the casing to complete the guidance and fixation of the detection device;

Step 3: Drive the linear motor to drive the transmission rod, control the axial movement of the flexible array pressure sensing probe, complete the contact between the force transmission protection contact and the fish top, use the oil inlet channel and cavity structure to achieve the internal and external static pressure self-balancing of the downhole force transmission protection contact, and obtain the fish top contact displacement information through the piezoresistive cantilever beam sensor array;

Step 4: Condition and convert the resistance change signal collected by the piezoresistive film, and transmit it to the host computer via a cable to achieve high-precision imaging and recognition of the position and contour of the fallen fish.

During the process of lowering the pressure sensing detection device in step one of the present invention, when the flexible array pressure sensing probe contacts the top of the fish, the contact state can be judged by the sudden increase in pressure imaging data transmitted to the host computer and the resistance encountered in the lowering of the cable. The cable lowering operation is stopped, and then the detection device is lifted up 10 to 20 cm.

In step 2 of the present invention, a stepper motor is used to control the radial travel of the circumferentially uniformly distributed driven rod, straighten the shell, and fix it to the inner wall of the casing; wherein the end of the driven rod is a hemispherical high-temperature and corrosion-resistant rubber, and the curvature of the hemisphere is consistent with the curvature of the inner wall of the casing, so as to increase the contact area between the end of the driven rod and the inner wall of the casing, and increase the friction between the end and the inner wall of the casing.

In step four of the present invention: the upper computer on the well uses software to perform real-time imaging of the fish falling downhole. In order to obtain higher-precision imaging information of the fish top, the detection device can be lifted, and the contact speed between the flexible array pressure sensor probe and the fish top can be adjusted to perform secondary contact imaging. The above operation is repeated until the errors of the fish falling position and contour obtained three times in a row are within the allowable range, and then compared with the existing technical data related to the well repair operation to complete the identification of the fish falling downhole.

A downhole fish detection device based on a flexible array pressure sensor: the lower part of the weight block is connected to the downhole vertical transmission mechanism through a connecting device, the downhole horizontal transmission mechanism is fixedly connected to the inside of the shell of the downhole vertical transmission mechanism, the lower part of the downhole vertical transmission mechanism is connected to the flexible array pressure sensing probe, the logging cable is connected to the upper part of the weight block, and passes through the downhole vertical transmission mechanism to connect to the flexible array pressure sensing probe.

The structure of the underground vertical transmission mechanism of the present invention is as follows: the linear motor is fixed in the housing, the output shaft of the linear motor is connected to the transmission rod through threads, and the end of the transmission rod is welded to the flexible array pressure sensing probe.

The structure of the underground horizontal transmission mechanism described in the present invention is: the stepper motor is fixed to the housing by bolt 1, the output shaft of the stepper motor is connected to the gear shaft on the driving gear by key 1, the driving gear and the driven gear constitute a gear pair, the sleeve performs axial positioning on the driven gear, the driven gear is fixedly connected to the transmission shaft by key 2, the disc cam with a groove is fixed to the transmission shaft by key 3, the transmission shaft is supported in the housing by a bearing, and circumferentially uniformly distributed driven rods are arranged in the groove of the disc cam.

The structure of the flexible array pressure sensing probe described in the present invention is: the substrate is welded to the thermal insulation cover, the circuit board is fixed on the top of the thermal insulation cover, the wires are respectively connected to the circuit board and the polyimide film, the annular side wall of the substrate is processed with an oil inlet hole, and a filter plug is provided at the port of the oil inlet hole. The upper end of each force transmission protection contact is processed with an annular inclined surface and is connected to the substrate through a sealing rubber ring. The oil inlet hole is communicated with the upper surface of each force transmission protection contact, and the oil action area on the upper and lower surfaces of the force transmission protection contact is equal. The pressure isolation plate is bonded to the groove on the upper surface of the substrate, the polyimide film is bonded to the top of the pressure isolation plate, the piezoresistive cantilever beam sensing array is embedded in the flexible polyimide film, the lower end of the elastic force transmission column is bonded to the upper end of the force transmission protection contact, the upper end passes through the hole wall of the pressure isolation plate, and the top is connected to the polyimide film.

The structure of the piezoresistive cantilever beam sensor array of the present invention is as follows: a _SiO2 insulating substrate is disposed above a Si substrate, one end of the piezoresistive cantilever beam is connected to the insulating substrate, and a piezoresistive film is disposed above the cantilever beam.

The force-bearing length of the piezoresistive cantilever beam of the present invention is L ₂ , and the diameter of the elastic force-transmitting column is d. When L ₂ ≈0.3d, the sensitivity reaches the maximum.

The beneficial effects of the present invention are:

(1) The lowering and lifting of the pressure sensing detection device of the present invention is achieved through cables. Compared with the traditional method of transporting lead molds through drill pipe strings or oil pipe strings, it has the advantages of short downhole operation cycle, high efficiency, saving time and labor costs, etc.

(2) The fish-falling detection device of the present invention can provide real-time feedback on the position and shape of the fish falling downhole, and can control the contact state between the detection device and the top of the fish through the host computer, thereby improving the accuracy of fish-falling detection. Compared with the traditional lead mold, the contact between the flexible array pressure sensor and the top of the fish is elastic deformation, which can be printed multiple times, that is, reused.

(3) The present invention uses a flexible array pressure sensor probe to perform contact detection with the fish top, utilizes a piezoresistive cantilever beam sensor array, and embeds it into an insulating elastic film of polyimide. Compared with downhole non-contact television and ultrasonic imaging, the present invention has strong resistance to environmental media and electromagnetic interference, has a high signal-to-noise ratio, can achieve high-precision fish detection, has high reliability, and is more efficient than point-by-point detection by ultrasonic probes. It has a compact structure, is simple to operate, and has low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic structural diagram of the present invention;

FIG2a is a schematic structural diagram of a downhole horizontal transmission mechanism of the present invention;

FIG2 b is a schematic diagram of the initial state of the driven rod of the present invention;

FIG2c is a schematic diagram of the guide fixing state of the driven rod of the present invention;

FIG3 is a schematic diagram of the structure of a flexible array pressure sensing probe according to the present invention;

FIG4 is a schematic diagram of the distribution of the piezoresistive cantilever beam sensor array of the present invention;

FIG5 is a schematic diagram of the structural force of the piezoresistive cantilever beam sensing unit of the present invention;

FIG6 is a curve diagram showing the relationship between the sensitivity of the present invention and the ratio of the cantilever beam force length;

In the figure: 1, flexible array pressure sensor probe, 101, force transmission protection contact, 102, sealing rubber ring, 103, substrate, 104, filter plug, 105, oil inlet, 106, elastic force transmission column, 107, pressure isolation plate, 108, polyimide film, 109, circuit board, 110, piezoresistive cantilever beam sensor array, 1101, piezoresistive film, 1102, piezoresistive cantilever beam, 1103, SiO _2. Insulating substrate, 1104. Si substrate, 111. Wire, 112. Thermal insulation cover, 2. Downhole vertical transmission mechanism, 201. Transmission rod, 202. Linear motor 203. Shell, 204. Line, 3. Downhole horizontal transmission mechanism, 301. Stepper motor, 302. Bolt one, 303. Key one, 304. Driving gear, 305. Sleeve, 306. Driven gear, 307. Key two, 308. Driven rod, 309. Disc cam, 310. Key three, 311. Transmission shaft, 312. Bearing, 4. Connecting device, 401. Bolt two, 402. Bolt three, 403. Sealing rubber, 5. Weight block, 6. Logging cable, 7. Upper computer, 8. Downhole fish drop, 9. Casing.

DETAILED DESCRIPTION

As shown in FIG. 1 and FIG. 2a to FIG. 2c, a method for detecting fish in a well based on a flexible array pressure sensor comprises the following steps:

Step 1: lowering the flexible array pressure sensing probe 1 to above the fish 8 via the logging cable 6;

Step 2: Drive the stepper motor 301 to drive the disc cam transmission mechanism to control the follower rods 308 uniformly distributed in the horizontal plane to move radially to the inner wall of the sleeve 9 to complete the guidance and fixation of the detection device;

Step 3: Drive the linear motor 202 to drive the transmission rod 201, control the axial movement of the flexible array pressure sensing probe 1, complete the contact between the force transmission protection contact 101 and the fish drop top, use the oil inlet channel and the cavity structure to achieve the internal and external static pressure self-balancing of the downhole force transmission protection contact, and obtain the contact displacement information of the fish drop top through the piezoresistive cantilever beam sensing array 110;

Step 4: Condition and convert the resistance change signal collected by the piezoresistive film 1101, and transmit it to the host computer 7 via a cable to achieve high-precision imaging and recognition of the position and contour of the fish;

During the process of lowering the pressure sensing detection device in step 1, when the flexible array pressure sensing probe 1 contacts the top of the fish landing, the contact state can be judged by the sudden increase of the pressure imaging data transmitted to the host computer and the resistance of the cable lowering, the cable lowering operation is stopped, and then the detection device is lifted up by 10 to 20 cm;

In the step 2, the radial stroke of the circumferentially uniformly distributed driven rod is controlled by a stepper motor to straighten the housing and fix it to the inner wall of the sleeve 9; wherein the end of the driven rod is a hemispherical rubber that is resistant to high temperature and corrosion, and the curvature of the hemisphere is consistent with the curvature of the inner wall of the sleeve, so as to increase the contact area between the end of the driven rod and the inner wall of the sleeve, and increase the friction between the end and the inner wall of the sleeve;

In the step 4, the upper computer 7 on the well performs real-time imaging of the downhole fish detection through software. To obtain higher-precision imaging information of the fish top, the detection device can be lifted, and the contact speed between the flexible array pressure sensing probe and the fish top can be adjusted to perform secondary contact imaging. The above operation is repeated until the error of the fish position and contour obtained three times in a row is within the allowable range, and then compared with the existing technical data related to the well repair operation to complete the identification of the downhole fish;

The output signal of the piezoresistive cantilever beam is collected, filtered and amplified by the conditioning circuit, and then the A/D conversion circuit module is performed. Then the communication interface module transmits the signal to the well through the logging cable 6, filters and amplifies it, and finally transmits it to the host computer 7 through the communication interface. The algorithm is used in the Labview software to filter, calibrate, interpolate and fit the image.

As shown in Figure 1, a downhole fish detection device based on a flexible array pressure sensor is provided, wherein the lower portion of the weight block 5 is connected to the downhole vertical transmission mechanism 2 through a connecting device 4, the downhole horizontal transmission mechanism 3 is fixedly connected to the inside of a shell 203 of the downhole vertical transmission mechanism 2, and the lower portion of the downhole vertical transmission mechanism 2 is connected to a flexible array pressure sensing probe 1; a logging cable 6 is connected to the upper portion of the weight block 5, and passes through the downhole vertical transmission mechanism 2 to connect to the flexible array pressure sensing probe 1.

The structure of the downhole vertical transmission mechanism 2 is as follows: the linear motor 202 is fixed in the housing 203, the output shaft of the linear motor 202 is connected to the transmission rod 201 by threads, and the end of the transmission rod 201 is welded to the flexible array pressure sensing probe 1 to realize the axial movement of the sensing probe;

The connecting device 4 includes a second bolt 401, a third bolt 402 and a sealing rubber 403. The housing 203 is connected by the second bolt 401 and sealed by the sealing rubber 403 which is resistant to high temperature and corrosion. The weight block 5 is fixed to the housing 203 by the third bolt 402. The geometric shape of the weight block 5 is designed so that the center of gravity of the pressure sensing detection device is located on the central axis of rotation of the inner wall of the sleeve 9, so that the detection device can be smoothly lowered.

The structure of the underground horizontal transmission mechanism 3 is as follows: the stepper motor 301 is fixed to the housing 203 by a bolt 302, the output shaft of the stepper motor 301 is connected to the gear shaft on the driving gear 304 by a key 303, the driving gear 304 and the driven gear 306 form a gear pair, the sleeve 305 performs axial positioning on the driven gear, the driven gear 306 is fixedly connected to the transmission shaft 311 by a key 307, the disc cam 309 with a groove is fixed to the transmission shaft 311 by a key 310, the transmission shaft 311 is supported in the housing by a bearing 312, and the groove of the disc cam 309 is provided with circumferentially uniformly distributed driven rods 308;

As shown in FIG2a, in the downhole horizontal transmission mechanism 3, the stepper motor 301 drives the grooved disc cam 309 through a gear pair, thereby driving the circumferentially uniformly distributed follower rods 308 to move radially. One end of the follower rod 308 is stuck in the groove of the disc cam 309, and the other end is wrapped with high temperature and corrosion resistant rubber; as shown in FIGS. 2b and 2c, the two position states of the follower rod 308 are controlled by the stepper motor 301. When the follower rod 308 moves from the initial state to the guided fixed state (the farthest point from the rotation center of the cam), the straightening and fixation of the sensor detection device is completed.

As shown in FIG3 , the structure of the flexible array pressure sensing probe 1 is as follows: a substrate 103 is welded with a thermal insulation cover 112, a circuit board 109 is fixed on the top of the thermal insulation cover 112, a wire 111 is connected to the circuit board 109 and a polyimide film 108 respectively, an annular side wall of the substrate 103 is processed with an oil inlet hole 105, and a filter plug 104 is provided at the port of the oil inlet hole 105 to filter out suspended impurities in the oil well to avoid blockage of the internal channel, and an annular bevel is processed on the upper end of each force transmission protection contact 101. The surface is connected to the base 103 through the sealing rubber ring 102, ensuring that the force transmission protection contact 101 moves in the vertical direction of the inner wall of the cavity without falling off, the oil introduction hole 105 is connected to the upper surface of each force transmission protection contact 101, and the oil action area on the upper and lower surfaces of the force transmission protection contact 101 is equal, so that the inside and outside of the flexible array pressure sensing probe 1 always maintain the self-balance of the static oil pressure during the lowering process, avoiding the influence of the static oil pressure of the downhole oil on the sensor measurement result. The detection device works stably and the detection data is reliable; the pressure isolation plate 107 is bonded in the groove on the upper surface of the substrate 103, and the polyimide film 108 is bonded to the upper part of the pressure isolation plate 107. On the one hand, the pressure isolation plate 107 can prevent the oil pressure from being transmitted to the piezoresistive cantilever beam sensor array 110, and on the other hand, the overload force acting on the force transmission protection contact 101 can be transmitted to the substrate through the pressure isolation plate 107 to realize the overload protection function of the sensor and make the sensor work reliably; the piezoresistive cantilever beam sensor The array 110 is embedded in the flexible polyimide film 108 to optimize the flexibility and mechanical properties of the sensor; the lower end of the elastic force transmission column 106 is bonded to the upper end of the force transmission protection contact 101, the upper end passes through the hole wall of the pressure isolation plate 107, and the top is connected to the polyimide film 108 to realize the force transmission between the downhole fish top and the piezoresistive cantilever beam sensor array 110. The elastic force transmission column 106 can not only play a certain buffering role, but also realize the flexibility of the sensor to adapt to the uneven surface of the fish top.

The structure of the piezoresistive cantilever beam sensor array 110 is as follows: a _SiO2 insulating substrate 1103 is located above a Si substrate 1104, one end of a piezoresistive cantilever beam 1102 is connected to the insulating substrate 1103, and a piezoresistive film 1101 is located above the cantilever beam 1102.

As shown in FIG4 , the piezoresistive cantilever beam sensor array 110 is processed on a high temperature resistant insulator silicon (SOI) substrate using a microsystem processing technology MEMS, so that the sensor array has good mechanical and electrical characteristics, and the central axis of each piezoresistive cantilever beam 1102 is at an angle of 45 degrees to the rotation centerline of the oil inlet 105 to increase the spatial resolution of the sensor array. At the same time, based on the existing technical data of downhole fish dropping, the present invention designs the spatial resolution of the piezoresistive cantilever beam sensor array to be 5 mm while ensuring that small objects also have high detection accuracy.

The force-bearing length of the piezoresistive cantilever beam 1102 (acted by the elastic force transmission column 106 ) is L ₂ , and the diameter of the elastic force transmission column 106 is d. When L ₂ ≈0.3d, the sensitivity of the sensor reaches the maximum.

As shown in FIG5 , after the force transmission protection contact 101 contacts the top of the fish, the elastic force transmission column 106 is first compressed and deformed, and then the elastic force transmission column 106 transmits the force to the end of the piezoresistive cantilever beam structure. The piezoresistive cantilever beam 1102 is fixed on the pressure isolation plate 107 through the _SiO2 insulating substrate 1103 and the Si substrate 1104. Finally, the shape and position information of the fallen fish is obtained through the resistance change rate of the piezoresistive film 1101 on the piezoresistive cantilever beam, and the relationship between the vertical displacement of the force transmission protection contact 101 (caused by the contact with the surface of the fallen fish) and the resistance change rate output by the piezoresistive film 1101 is established. The specific calculation formula is:

Since E ₂ >> E ₃ , E ₂ is the Young's modulus (200 Gpa) of the piezoresistive cantilever beam 1102 , and E ₃ is the Young's modulus (3-4 Gpa) of the polyimide film 108 , it can be regarded as that the force F of the elastic force transmission column 106 is fully applied to the end of the piezoresistive cantilever beam 1102 with a uniformly distributed load q; where h, △z ₁ , d, and E ₁ are the height, deformation, diameter, and Young's modulus of the elastic force transmission column 106 , respectively; L ₂ is the force-bearing length of the cantilever beam structure 1102 ;

The bending moment equation M(x) of the piezoresistive cantilever beam 1102 subjected to uniform load is:

The equivalent bending moment _Me acting on the piezoresistive film 1101 is:

The surface stress σ of the piezoresistive film 1101 is:

Wherein, L, w, t are the length, width, and thickness of the cantilever beam structure 1102, respectively; _L1 is the length of the piezoresistive film 1101, wherein L= _L1 + _L2 , I is the moment of inertia of the cantilever beam structure 1102,

The deflection curve approximation equation of the beam structure is:

When 0≤x≤LL ₂ , the rotation angle equation θ ₁ (x) and the deflection equation v ₁ (x) of the piezoresistive cantilever beam 1102 are:

When LL ₂ ≤x≤L, the rotation angle equation θ ₁ (x) and the deflection equation v ₁ (x) of the piezoresistive cantilever beam 1102 are:

Where, E ₂ is the Young's modulus of the piezoresistive cantilever beam 1102, and x is the distance from the fixed end of the cantilever beam;

By the boundary conditions:

v ₁ (0) = 0, θ ₁ (0) = 0, v ₁ (LL ₂ ) = v ₂ (LL ₂ ), θ ₁ (LL ₂ ) = θ ₂ (LL ₂ );

We can get the constants C ₁ , D ₁ , C ₂ , D ₂ :

C ₁ = 0, D ₁ = 0;

Wherein, Δz ₂ is the deflection of the end of the piezoresistive cantilever beam 1102, and k _l is the equivalent stiffness of the right end of the piezoresistive cantilever beam 1102, because:

Where △z is the overall displacement of the sensor in the vertical direction caused by the fish top shape;

The sensitivity s of the sensor can be obtained as:

Wherein, μ, ε, λ are respectively the transverse Poisson's ratio, longitudinal strain, and piezoresistance coefficient of the piezoresistive film; △R and R are respectively the resistance change amount and initial resistance value of the piezoresistive film 1101 caused by the fish top shape.

The sensor sensitivity can be maximized by optimizing the parameters in the sensor sensitivity S expression;

In this embodiment, the fixed parameter values are:

E ₁ =2GPa, E ₂ =200GPa, d =5mm, t =0.8mm, L ₁ =1mm,

w = 2 mm, h = 12 mm;

纵坐标为传感器的灵敏度S，传感器的灵敏度呈现先增大后减小的趋势，可得到

时，传感器的灵敏度达到最大，因此取压阻式悬臂梁1102受弹性传力柱的载荷长度为弹性传力柱直径的0.3倍。By optimizing the parameter L ₂ , we get the curve shown in Figure 6 , where the horizontal axis is

The ordinate is the sensitivity S of the sensor. The sensitivity of the sensor increases first and then decreases.

When , the sensitivity of the sensor reaches the maximum, so the load length of the piezoresistive cantilever beam 1102 subjected to the elastic force transmission column is taken as 0.3 times the diameter of the elastic force transmission column.

Claims (7)

1. Underground fish detection device based on flexible array formula pressure sensor, its characterized in that: the lower part of the weighting block is connected with an underground vertical transmission mechanism through a connecting device, the underground horizontal transmission mechanism is fixedly connected with the inside of a shell of the underground vertical transmission mechanism, and the lower part of the underground vertical transmission mechanism is connected with a flexible array type pressure sensing probe; the logging cable is connected with the upper part of the weighting block and penetrates through the underground vertical transmission mechanism to be connected with the flexible array type pressure sensing probe;

the structure of the underground vertical transmission mechanism is as follows: the linear motor is fixed in the shell, an output shaft of the linear motor is connected with the transmission rod through threads, and the end part of the transmission rod is welded with the flexible array type pressure sensing probe;

the structure of the underground horizontal transmission mechanism is as follows: the stepping motor is fixed on the shell through a first bolt, an output shaft of the stepping motor is connected with a gear shaft on the driving gear through a first key, the driving gear and the driven gear form a gear pair, the sleeve is used for axially positioning the driven gear, the driven gear is fixedly connected with the transmission shaft through a second key, a disc cam with a groove is fixed on the transmission shaft through a third key, the transmission shaft is supported in the shell through a bearing, and driven rods uniformly distributed in the circumferential direction are arranged in the grooves of the disc cam;

the structure of the flexible array type pressure sensing probe is as follows: the base body is welded with the heat insulation cover, the circuit board is fixed at the top of the heat insulation cover, the lead is respectively connected with the circuit board and the polyimide film, the annular side wall of the base body is provided with an oil guiding hole, the port of the oil guiding hole is provided with a filter plug, the upper end of each force transmission protection contact is provided with an annular inclined plane and connected with the base body through a sealing rubber ring, the oil guiding hole is communicated with the upper surface of each force transmission protection contact, the oil liquid acting areas of the upper surface and the lower surface of the force transmission protection contact are equal, the heat insulation plate is bonded in a groove on the upper surface of the base body, the polyimide film is bonded above the heat insulation plate, the piezoresistive cantilever beam sensing array is embedded in the flexible polyimide film, the lower end of the elastic force transmission column is bonded with the upper end of the force transmission protection contact, and the upper end of the elastic force transmission column penetrates through the hole wall of the heat insulation plate, the top of the heat insulation plate is connected with the polyimide film in a propping mode.

2. A device for detecting a fish in a well based on a flexible array pressure sensor as claimed in claim 1, wherein: the piezoresistive cantilever beam sensing array has the structure that: above the Si substrate is SiO ₂ One end of the piezoresistive cantilever beam is connected with the insulating substrate, and the piezoresistive film is positioned above the cantilever beam.

3. The device of claim 2, wherein the piezoresistive cantilever has a stress length ofL ₂ The diameter of the elastic force transmission column isd，When (when)L ₂ ≈0.3dAt this point the sensitivity is maximized.

4. A method for detecting a well fish by using the flexible array type pressure sensor according to any one of claims 1 to 3, comprising the steps of:

step one: lowering a flexible array type pressure sensing probe to the upper part of the fish through a logging cable;

step two: the driving stepping motor drives the disc cam transmission mechanism to control the driven rods uniformly distributed in the circumferential direction in the horizontal plane to radially move to the inner wall of the sleeve, so that the guiding and fixing of the detection device are completed;

step three: the linear motor is driven to drive the transmission rod, the axial movement of the flexible array type pressure sensing probe is controlled, the contact between the force transmission protection contact and the fish roof is completed, the oil guiding holes are communicated with the upper surface of each force transmission protection contact, the oil acting areas of the upper surface and the lower surface of the force transmission protection contact are equal, the self-balancing of static oil pressure inside and outside the flexible array type pressure sensing probe is always maintained in the lowering process, and the contact displacement information of the fish roof is obtained through the piezoresistive cantilever sensing array;

step four: the resistance change signals acquired by the piezoresistive film are conditioned and converted, and are transmitted to an upper computer through a cable, so that high-precision imaging and identification of the position and the outline of the fish are realized.

5. The method of probing as recited in claim 4 wherein: in the first step, when the flexible array type pressure sensing probe contacts the fish roof in the process of lowering the pressure sensing detection device, the contact state can be judged by suddenly increasing pressure imaging data transmitted to the upper computer and lowering the cable when the cable is blocked, the cable lowering operation is stopped, and then the detection device is lifted up by 10-20 cm.

6. The method of probing as recited in claim 4 wherein: in the second step, radial strokes of driven rods uniformly distributed circumferentially are controlled by a stepping motor, and the shell is straightened and fixed on the inner wall of the sleeve; the end part of the driven rod is hemispherical high-temperature-resistant corrosion-resistant rubber, and the curvature of the hemisphere is consistent with that of the inner wall of the sleeve, so that the contact area between the end part of the driven rod and the inner wall of the sleeve is increased, and the friction between the end part and the inner wall of the sleeve is increased.

7. The method according to claim 4, wherein in the fourth step: the method comprises the steps that an uphole upper computer detects the underground fish to form images in real time through software, in order to obtain fish top imaging information with higher accuracy, a detection device can be lifted, the contact speed of a flexible array type pressure sensing probe and the fish top is adjusted, secondary contact imaging is carried out, the operation is repeated until errors of the position and the outline of the fish obtained continuously for three times are within an allowable range, and then the errors are compared with related technical data of the existing well repair operation, so that identification of the underground fish is completed.

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