CN110487891A - A kind of casing damage detection method, device and system based on transient electromagnetic emission array - Google Patents

Abstract

The embodiment of the invention discloses a kind of casing damage detection method, device and system based on transient electromagnetic emission array；The device includes: that control remote short section and at least one transmitting receive pipe nipple；Wherein, each transmitting receives pipe nipple, the transient electromagnetic sensor array of described device radial direction is parallel to comprising one, the transient electromagnetic sensor array includes a transient electromagnetic emission array and a transient electromagnetic receiving transducer, the transient electromagnetic emission array includes multiple transmitting array elements, each transmitting array element uses corresponding emission current by the control command of the control remote short section, so that the emitted energy of the emission array focuses to setting regions in desired cannula.

Description

A casing damage detection method, device and method based on a transient electromagnetic emission array system

technical field

The embodiments of the present invention relate to the technical field of oil and gas field equipment detection, and in particular to a casing damage detection method, device and system based on a transient electromagnetic emission array.

Background technique

With the increase of the service life of casings put into production in oil and gas fields at home and abroad, coupled with factors such as formation stress and chemical corrosion, most oil and gas casings have varying degrees of damage, such as diameter shrinkage, deformation, corrosion and rupture. These damages will directly affect the production and service life of oil and gas wells. By detecting the damage of the casing, the change and damage of the oil and gas well body structure can be found in time, which has a great effect on the prevention and maintenance of the casing. At present, the logging technology using the transient electromagnetic method has been widely used because it will not damage the wellbore during the logging process and has good logging performance.

Transient electromagnetic method is also called time domain electromagnetic method (TEM, Time domain electromagnetic methods). Its principle is to use artificial pulse current in the transmitting coil to transmit a transient primary pulse electromagnetic field to the ground. The primary magnetic field is generated when it encounters the surrounding medium. The eddy current ring forms a secondary magnetic field. During the intermittent period of the primary pulse magnetic field, the secondary eddy current field is observed by the coil or the ground electrode, and the formation conductivity information is obtained by analyzing the attenuation law of the received signal and inversion.

Limited by the small space and high temperature and high pressure environment of oil and gas wells, the signal-to-noise ratio of the received signal measured by the transient electromagnetic method seriously affects its detection performance. The current conventional scheme usually adopts coaxial multi-turn transmitting and receiving coils wound around the magnetic core or air core to improve the signal-to-noise ratio, and by detecting different crack shapes, it is proved that the longitudinal sensor is better than the transverse sensor in detecting large areas. it is good. However, with the increase in the number of turns of the longitudinal multi-turn coil sensor, the length of the sensor and the distance between the transmitting coil and the receiving coil will also increase, which will cause serious distortion of the received signal model and seriously affect the accuracy of nondestructive testing. In addition, there are some schemes that use a transient electromagnetic casing damage detection system with multiple receiving probes and a single transmitting probe, and use the relationship between the received signals of each element of the receiving array to eliminate the model caused by the transmitting and receiving distance through array signal processing. Distortion, improve the signal-to-noise ratio.

However, the number of receiving array elements in the receiving array cannot be infinitely increased, because as the number of receiving array elements increases, the distance between the newly added receiving probe and the transmitting probe is getting farther and farther, resulting in an increase in the signal-to-noise ratio. lower. It can be seen that after the number of receiving probes has increased to a certain extent, adding more receiving probes has little effect on improving the overall signal-to-noise ratio of the casing damage detection system. Therefore, it is currently necessary to increase the signal-to-noise ratio within a limited probe length.

Contents of the invention

In order to solve the above technical problems, the embodiments of the present invention expect to provide a casing damage detection method, device and system based on a transient electromagnetic emission array, which can obtain a higher signal-to-noise ratio and better performance.

Technical scheme of the present invention is realized like this:

In the first aspect, an embodiment of the present invention provides a casing damage detection device based on a transient electromagnetic emission array, the device includes: a control remote transmission sub-section and at least one transmitting and receiving sub-section; wherein,

Each of the transmitting and receiving short sections includes a transient electromagnetic sensor array parallel to the radial direction of the device, and the transient electromagnetic sensor array includes a transient electromagnetic transmitting array and a transient electromagnetic receiving probe. The variable electromagnetic emission array includes a plurality of emission elements, and each emission element adopts the corresponding emission current through the control command of the remote transmission sub-section, so that the emission energy of the emission array can be focused to the set area in the target casing .

In the second aspect, an embodiment of the present invention provides a casing damage detection system based on a transient electromagnetic emission array, the system includes: a host computer and the casing damage detection system based on a transient electromagnetic emission array described in the first aspect device; of which,

The host computer is connected to the device through a cable, and the host computer is configured to send the transmission current required by each transmitting array element to the device; and receive the summary information sent by the receiving probe in the device, the The summary information includes the measurement signal detected by the receiving probe and the ambient temperature information of the device; and, according to the measurement signal, the damage state of the set area in the target casing is determined.

In a third aspect, an embodiment of the present invention provides a casing damage detection method based on a transient electromagnetic emission array, and the method is applied to the casing damage detection system based on a transient electromagnetic emission array described in the second aspect. The methods described include:

transmitting current to a set area of the target casing based on at least one transmitting array; wherein the transmitting current of each transmitting array is used to focus the transmitting energy of the transmitting array to the set area;

Detection of the measurement signal by the receiving probe;

Determining the damage state of a set area within the target sleeve based on the measurement signal.

Embodiments of the present invention provide a casing damage detection method, device, and system based on a transient electromagnetic emission array; since the emission array composed of multiple emission array elements is used, the emission signal can be focused, avoiding the use of a single emission probe As a result, the direction and magnitude of the emission current are uncontrollable, and a higher signal-to-noise ratio and better performance can be obtained.

Description of drawings

Fig. 1 is a schematic composition diagram of a casing damage detection device based on a transient electromagnetic emission array provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of the composition of a transmitting and receiving short section provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of a detection comparison provided by an embodiment of the present invention;

Fig. 4 is a schematic diagram of the composition of a control remote transmission sub-section provided by an embodiment of the present invention;

Fig. 5 is a schematic composition diagram of another casing damage detection device based on a transient electromagnetic emission array provided by an embodiment of the present invention;

Fig. 6 is a schematic composition diagram of a casing damage detection system based on a transient electromagnetic emission array provided by an embodiment of the present invention;

Fig. 7 is a schematic composition diagram of another casing damage detection system based on a transient electromagnetic emission array provided by an embodiment of the present invention;

Fig. 8 is a schematic diagram of a working model of a casing damage detection device based on a transient electromagnetic emission array provided by an embodiment of the present invention;

FIG. 9 is a schematic diagram of a simulation provided by an embodiment of the present invention;

Fig. 10 is a schematic flowchart of a casing damage detection method based on a transient electromagnetic emission array provided by an embodiment of the present invention;

Fig. 11 is a schematic diagram of a specific implementation flow of a casing damage detection method based on a transient electromagnetic emission array provided by an embodiment of the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention.

At present, in the conventional method of detecting casing damage by using the transient electromagnetic method, a single transmitting element is usually used to transmit current, and a receiving array composed of multiple receiving elements receives the transient electromagnetic signal; the array signal processing is used to eliminate the gap caused by the transmitting and receiving distance. Model distortion, improve signal-to-noise ratio. But at the same time, there is a defect that the number of array elements in the receiving array cannot be increased infinitely, and after the number of receiving probes increases to a certain extent, adding more probes has little effect on improving the overall signal-to-noise ratio of the system.

Based on the above problems, the embodiments of the present invention expect to be able to focus the transmitted energy to the region of interest by increasing the number of transmitting array elements, improve the signal-to-noise ratio of the signal, and thus effectively detect the damage of the casing. Referring to FIG. 1 , it shows a casing damage detection device 1 based on a transient electromagnetic emission array provided by an embodiment of the present invention. The device 1 includes: a control remote transmission sub-section 11 and at least one transmitting and receiving sub-section 12 Wherein, as shown in Figure 2, each of the transmitting and receiving short joints 12 includes a transient electromagnetic sensor array parallel to the radial direction of the device 1, and the transient electromagnetic sensor array includes a transient electromagnetic emission array 121 and a transient electromagnetic receiving probe 122, the transient electromagnetic emission array 121 includes a plurality of emission array elements 1211, and each emission element 1211 adopts a corresponding emission current through the control command of the remote transmission short section 11, In order to focus the emission energy of the emission array 121 to a set area in the target cannula.

It should be noted that in the specific implementation process, as shown in Figure 2, taking a single transmitting array element as an example, both the transmitting array element and the receiving probe can be electromagnetic coils with different diameters, magnetic cores and winding turns. Therefore, it has different detection ranges and performances, and is suitable for different detection environments. It can be understood that the casing damage detection device 1 based on the transient electromagnetic emission array may contain one or more transmitting and receiving short joints 12, and when there are multiple transmitting and receiving short joints 12, each transmitting and receiving short joint 12 The transmitting array 121 can form a large transmitting array to improve the detection capability.

In addition, as shown in Figure 3, the detection direction of the single transmitting probe in the upper part of the figure cannot be focused in the longitudinal direction, while the transmitting array in the lower part of the figure, since each transmitting element in the transmitting array adopts a different size And the emission current in different directions, so that the emission energy can be focused on a certain area in the longitudinal direction compared with a single emission probe, and a higher signal-to-noise ratio and better performance can be obtained.

Combining the technical solutions shown in Figure 1 and Figure 2, referring to Figure 4, the control remote transmission short joint 11 includes a temperature measurement part 111, a data transmission part 112, a control circuit part 113 and a power supply part 114;

Wherein, the temperature measurement part 111 is configured to monitor the current ambient temperature of the device 1;

The data transmission part 112 is configured to receive the emission current required by each emission element sent by the host computer, and the measurement signal detected by the receiving probe; and, monitor the measurement signal and the temperature measurement part After the ambient temperature information is summarized, the summary information is carried on the cable through the coupling capacitor; and, the summary information is sent to the host computer through the cable;

The control circuit part 113 is configured to send a control command to the transmitting and receiving sub-section 12 according to the transmission current required by each transmitting element sent by the host computer, and the control command is used to control the transmitting and receiving sub-section 12 The interval between transmitting and receiving signals;

The power supply part 114 is configured to provide electric energy to the control remote transmission sub-section and the transmitting and receiving sub-section.

For the above implementation, in the specific implementation process, the temperature measurement part 111 may include a temperature sensor and its peripheral circuit, which can monitor the ambient temperature of the device 1 downhole in real time, so as to ensure the normal operation of the device 1 . The data transmission part 112 can not only receive the transmitting current required by each transmitting array element sent by the host computer, but also receive the transient electromagnetic signal measured by the receiving probe 122 in the transmitting and receiving short section 12, and measure The signal and the temperature information measured by the temperature measuring part 111 are packaged and summarized together, and the summarized data is carried on the single-core cable through the coupling capacitor, and sent to the host computer via the single-core cable. The control circuit part 113 sends control commands to the transmitting and receiving short joints 12 according to the transmission current required by each transmitting element sent by the host computer, so as to control one or more transmitting and receiving short joints 12 to transmit and receive signals according to a certain time interval , the above-mentioned one or more transmitting and receiving sub-sections 12 can be controlled by different control signals, for example, controlling the remote transmission sub-sections 11 can send corresponding control signals in time sequence to ensure that each transmitting and receiving sub-sections 12 do not interfere with each other, and the data has sequence upload. The power supply part 114 includes two DC-DC power supply modules and a plurality of integrated regulator tubes to provide electric energy for the control remote transmission sub-section 11 and the transmitting and receiving sub-section 12 .

Regarding the above technical solution, in a possible implementation manner, referring to FIG. 5 , the device 1 further includes: a bridle 13 for connecting the device 1 with a cable.

For the above technical solution, in a possible implementation, referring to Fig. 5, the device 1 also includes: an upper centralizer 14 and a lower centralizer 15 located at both ends of the device, so as to ensure that the device 1 is always Stay on the axis of the wellbore.

Combining the above two possible implementations, specifically, Fig. 5 shows the specific style when the device 1 is realized, the bridle 13 is used to connect the device 1 and the single-core cable, and can ensure the cable core and control of the single-core cable The communication on-off of the remote transmission sub-section 11 and the insulation of the power supply circuit are good, and can be disassembled and connected quickly, so that the logging work can be carried out smoothly. The upper and lower centralizers 14 and 15 are located at both ends of the device 1, and the centralizers of different sizes can be replaced according to the size of the borehole, so that the device 1 can always be kept at the axial center of the borehole during the logging process, that is, the instantaneous The variable electromagnetic sensor is always kept at the axial center of the wellbore, so that the transmitting and receiving coils of the transient electromagnetic sensor in the transmitting and receiving sub-section 12 are concentric circles with the borehole, casing and cement layer, so as to avoid the transient electromagnetic sensor from being in the well logging The eccentricity and shaking during the lowering and lifting process will cause detection errors.

Through the above elaboration on the casing damage detection device 1 based on the transient electromagnetic emission array, the above casing damage detection device 1 based on the transient electromagnetic emission The signal is focused to avoid the uncontrollable direction and size of the emission current caused by the use of a single emission probe, which can obtain a higher signal-to-noise ratio and better performance.

Based on the same inventive concept as the aforementioned technical solution, see FIG. 6 , which shows a casing damage detection system 6 based on a transient electromagnetic emission array provided by an embodiment of the present invention. The system 6 includes: a host computer 61 and the aforementioned The casing damage detection device 1 based on the transient electromagnetic emission array described in the technical solution; wherein,

The host computer 61 is connected to the device 1 through a cable 62, and the host computer 61 is configured to send to the device 1 the transmission current required by each transmitting array element; The summary information includes the measurement signal detected by the receiving probe and the ambient temperature information of the device; and, according to the measurement signal, the damage state of the set area in the target casing is determined.

In the specific implementation process, it should be noted that the host computer 61 may include a data transmission part, a data processing part, a depth calculation part and an image display part. The depth calculation part can monitor the depth information of the downhole instrument in real time, and at the same time read the prior knowledge of the casing installation, estimate the structure of the casing at the current depth of the device 1, and calculate the emission array elements of the device 1 according to the current casing structure The desired emission current is sent to device 1. At the same time, the data transmission part can receive and save the detection data uploaded by the device 1, and the data processing part combines the casing structure at the current depth and the emission current of each transmitting array element to judge whether the casing at the current depth is damaged, and if there is damage , to quantify the damage. The casing structure at the current depth, real-time damage detection results and historical detection results can all be intuitively displayed through the image display part using curves and spectral intensity diagrams.

In addition, in the specific implementation process, as shown in FIG. 6 , the device 1 can be sequentially connected with a logging drawworks 63 and a host computer 61 through a single-core cable 62 . The logging drawworks 63 control device 1 is lifted and lowered at a required speed in the well. The single-core cable 62 is used to transport the device 1, supply power to the device 1, transmit the emission current information of each transmitting element calculated by the host computer 61 to the device 1, and transmit the control to the host computer 61. The temperature information measured by the remote transmission sub-section 11 and the transient electromagnetic signal collected by the transmitting and receiving sub-section 12. In most conventional implementation processes, the upper computer 61 can be arranged in the logging drawworks 63, as shown in Figure 7, the casing damage detection device 1 based on the transient electromagnetic emission array is in the well, from the inside to the outside in order of the casing , cement layer and formation.

For the technical solution shown in FIG. 6, in a possible implementation manner, the upper computer 61 is configured as:

The emission current required by each emission array is determined according to the prior information of the target casing; wherein, the emission current required by each emission array is used to focus the emission energy of the emission array to the set area;

The damage state of the set area is determined according to the prior information and the measurement signal detected by the receiving probe.

It should be noted that the transmission current required by each element of the transmitting array is calculated based on the prior information of the casing structure at the depth of the downhole tool, so as to control the energy emitted by the transmitting array to focus on the area of interest and improve the signal accuracy. SNR. The receiving probe in the transmitting and receiving sub-joint receives the transient electromagnetic signal and sends it to the host computer. The host computer combines the prior information of the casing structure and the emission current information of each transmitting array element to determine whether the casing is damaged, and through the casing damage Detection method specific scale damage. At the same time, the upper computer constantly detects the temperature information of the downhole instrument measured by the control remote transmission nipple to ensure the normal operation of the downhole instrument.

For the above implementation, preferably, the prior information of the target casing includes the prior wall thickness of the target casing, and correspondingly, the host computer 61 is configured as:

determining the measured wall thickness of the set area according to the measured signal detected by the receiving probe;

judging whether the transmit energy of the transmit array is focused to the set area according to the relationship between the measured wall thickness and the prior wall thickness;

If it is not focused to the set area, re-determine the emission current required by each emission array according to the measured wall thickness, and send the re-determined emission current required by each emission array element to the device;

If focusing on the set area, judge whether there is damage in the set area according to the relationship between the measured wall thickness and the set measurement threshold;

If the measured wall thickness is smaller than the set measurement threshold, it is determined that there is no damage in the set area;

If the measured wall thickness is not smaller than the set measurement threshold, it is determined that damage exists in the set area, and the degree of damage in the set area of the target sleeve is measured according to the measured wall thickness.

It should be noted that, in order to illustrate the feasibility of the foregoing implementation manner, the embodiments of the present invention are demonstrated through the following content.

In order to simplify the demonstration process, the casing, cement layer and formation are modeled as homogeneous media with different electrical conductivity, magnetic permeability and permittivity, and the working model of casing damage detection device 1 based on transient electromagnetic emission array As shown in Figure 8, the media of each layer are iron core, air, casing, cement layer and formation, and the corresponding electrical conductivity, magnetic permeability and permittivity are (μ ₁ , ε ₁ , σ ₁ ), ( μ ₂ ,ε ₂ ,σ ₂ ), (μ ₃ ,ε ₃ ,σ ₃ ), (μ ₄ ,ε ₄ ,σ ₄ ) and (μ ₅ ,ε ₅ ,σ ₅ ); the radii are r ₁ , r ₂ , r ₃ , r ₄ , r ₅ , where the formation radius r ₅ is infinite. The centers of the transmitting array and the receiving probe are located at the coordinate origin, and N transmitting array elements are distributed in the z-axis direction, and their distances from the receiving probe are z ₁ , z ₂ , . . . , z _N . Refer to Figure 6 or Figure 7 for the overall structural framework of the system.

According to Maxwell's equations:

Among them, D is the electric displacement vector, E is the electric field intensity vector, J is the current density, B is the magnetic induction intensity vector, and H is the magnetic field intensity vector. Solving the above equation can obtain the magnetic field strength at the inner radius r of the first layer of medium where the receiving probe is located as

Among them, z=[z ₁ z ₂ ... z _N ] _1×N , I=[I ₁ I ₂ ... I _N ] _1×N , In is the emission current of the _nth emission element, d=r ₃ - r ₂ is the casing thickness, H _n is the magnetic field intensity of the nth transmitting element, expressed as

Among them, I ₀ (*) represents the 0th order complex Bessel function of the first kind, T _n is the number of turns of the nth transmitting element, C is the transmission coefficient, which is related to the geometric parameters of the formation, and x and λ are The introduced variable satisfies λ ² -x ² =μ ₁ ε ₁ ω ² -iμ ₁ σ ₁ ω.

Then the induced electromotive force received by the receiving probe can be expressed in the time domain as:

U(t,z,d,I)=I ^T Q(t,z,d) (5)

In the formula, Q(t,z _n ,d)=[Q(t,z ₁ ,d) Q(t,z ₂ ,d) ... Q(t,z _N ,d)], Q(t,z _n ,d) is the induced electromotive force acting on the receiving probe when the transmitting current of the nth transmitting array element is 1A.

It can be known from formula (5) that by changing the emission current of each transmitting element, the induced electromotive force of the receiving probe can be adjusted, that is, the transmitting energy at the cross section of the receiving probe can be adjusted. Utilizing this feature, the emission current of each emission element can be adjusted to an appropriate value, so that the emission energy can be concentrated in the set area of interest. In the case of independent and identical distribution of environmental noise, the situation of energy accumulation can be reflected in the intensity of induced electromotive force. Therefore, in order to achieve emission focusing, the area of M can be set up along the z direction with the origin as the center, and each area is set to have receiving probes with the same number of turns, and then the induced electromotive force of the receiving probe in the set area of interest is strong In addition, the induction electromotive force of the receiving probe in other areas is weak, so as to realize the emission focus.

Then the induced electromotive force of the receiving probe in the mth area is U _m (t,z _m ,d,I)=I ^T Q(t,z _m ,d) (6)

Where z _m =[z _1,m z _2,m ... z _N,m ] _1×N , z _n,m is the distance from the nth transmitting array element to the receiving probe in the mth area.

Then the vector composed of the induced electromotive force of the receiving probes in the M areas is:

U _1-M (t,I,d,z)=I ^T ·Q _1-M (t,d,z) (7)

Among them, Q _1-M (t,d,z)=[Q ₁ (t,d,z ₁ ) Q ₂ (t,d,z ₂ ) … Q _M (t,d,z _M )] _N×M .

Taking the transmitting signal focused on the p area as an example, it is necessary to control the transmitting current of each transmitting array element so that the induced electromotive force U _p (t,z _p ,d,I) of the receiving probe in the p area remains unchanged, while the other areas The induced electromotive force of the receiving probe is the smallest. The emission current of each emission element can be calculated according to the Linearly Constrained Minimum-Variance (LCMV) criterion, as shown in Equation 8

in,

Solutions have to:

Then the transmission current of each transmitting array element can be calculated through the above formula 9, so that the transmission energy can be concentrated in the p region of interest, thereby improving the signal-to-noise ratio.

Fig. 9 is a simulation schematic diagram of the above technical solution, 800 receiving areas are set up along the z direction, as shown in the abscissa in Fig. 9, and the detection area of interest is set as the middle receiving area. The ordinate is the normalized induced electromotive force. Figure 9 compares the detection scheme of the traditional single transmitting probe with the technical scheme of the embodiment of the present invention, where the number of array elements used is 3, 5, 300. It can be seen from the comparison that with the technical solution of the embodiment of the present invention, even if only 3 array elements are used, the emission energy can be well focused on the area of interest, and as the number of emission elements increases, the emission energy The performance of focusing will also be further improved. However, due to the limited space in the underground, the increase in the number of transmitting array elements will greatly increase the hardware complexity of the system and the size of the instrument. Therefore, in the actual application process, an appropriate number of array elements can be used according to the actual situation and detection needs.

Based on the same inventive concept as the technical solution described in the foregoing embodiments, see FIG. 10 , which shows a casing damage detection method based on a transient electromagnetic emission array provided by an embodiment of the present invention, and the method is applied to the foregoing technologies The casing damage detection system based on the transient electromagnetic emission array described in the scheme, the method includes:

S101: Transmitting current to a set area of the target casing based on at least one transmitting array; wherein, the transmitting current of each transmitting array is used to focus the transmitting energy of the transmitting array to the set area;

S102: detecting the measurement signal through the receiving probe;

S103: Determine a damage state of a set area in the target cannula according to the measurement signal.

It can be understood that the technical solution shown in Figure 10 can be realized by the casing damage detection system based on the transient electromagnetic emission array described in the foregoing embodiments. Therefore, the embodiment of the present invention provides a transient electromagnetic emission array-based The casing damage detection method of the present invention has the same technical advantages and effects as the casing damage detection system based on the transient electromagnetic emission array described in the foregoing embodiments, and will not be described in detail in the embodiments of the present invention.

In a possible implementation manner, the transmitting current to a set area of the target casing based on at least one transmitting array includes:

The emission current required by each emission array is determined according to the prior information of the target casing; wherein, the emission current required by each emission array is used to focus the emission energy of the emission array to the set area;

Correspondingly, the determining the damage state of the set area in the target casing according to the measurement signal includes: determining the damage state of the set area according to the prior information and the measurement signal detected by the receiving probe .

For the above implementation, preferably, the determining the damage state of the set area according to the prior information and the measurement signal detected by the receiving probe includes:

determining the measured wall thickness of the set area according to the measured signal detected by the receiving probe;

judging whether the transmit energy of the transmit array is focused to the set area according to the relationship between the measured wall thickness and the prior wall thickness;

If it is not focused to the set area, re-determine the emission current required by each emission array according to the measured wall thickness, and send the re-determined emission current required by each emission array element to the device;

If focusing on the set area, judge whether there is damage in the set area according to the relationship between the measured wall thickness and the set measurement threshold;

If the measured wall thickness is smaller than the set measurement threshold, it is determined that there is no damage in the set area;

If the measured wall thickness is not smaller than the set measurement threshold, it is determined that damage exists in the set area, and the degree of damage in the set area of the target sleeve is measured according to the measured wall thickness.

It should be noted that, based on the above technical solution, in the specific implementation process, the process is shown in Figure 11. In the specific implementation process, the area is set as the p area, and the process may include:

S111: Obtain the current depth and the prior knowledge d _x of the casing wall thickness;

S112: Calculate the emission current of each emission element through the prior knowledge of the casing wall thickness at the current depth;

At this time, through S112, the emitted energy is concentrated in the p-region of interest. And since the emitted energy is all concentrated in the p region, a relatively good transient electromagnetic induction signal can be obtained as long as the receiving probe is arranged in the p region.

S113: Using the measurement signal detected by the receiving probe to invert and measure the wall thickness d _c ;

Specifically, the receiving induced electromotive force of the receiving probe in the p area can be expressed as:

U _p (t,z _p ,d,I)=I ^T ·Q _p (t,z _p ,d)

The measured wall thickness d _c can be calculated by bringing the emission current and other parameters of each emission array element into the above formula.

S114: judging whether effective focusing is completed;

Specifically, compare the measured wall thickness with the prior knowledge d _x of the casing wall thickness here, and obtain the wall thickness difference here d _s =d _c -d _x ; compare the wall thickness difference d _s and Set the threshold d _sy . When d _s <d _sy , it means that there is not much difference between the measured wall thickness and the prior wall thickness. At this time, it shows that the emission current of each transmitting array element calculated by the prior wall thickness is relatively accurate, and more effective emission focusing is realized. At this time, the measured wall thickness can be used to judge the damage of the casing. If effective focusing is achieved, go to S115, and judge whether there is damage to the casing by comparing the measured wall thickness with the set measurement threshold d _sz . When d _s <d _sz , it means that the value of the measured wall thickness is within the range of measurement error, there is no damage or little damage to the casing, and the process ends. On the contrary, it means that there is a certain damage to the casing, so S116 can be executed to quantify the current casing damage degree in combination with the casing damage judged at the depth during the historical measurement process and the value of the measured wall thickness.

Conversely, when d _s ≥ d _sy , it means that the gap between the measured wall thickness and the prior wall thickness is relatively large. At this time, the emission current of each transmitting element calculated by the prior wall thickness is not suitable for the wall thickness environment at this time. Effective transmit focusing cannot be achieved. Then go to S117 at this time: use the measured wall thickness to recalculate the emission current of each transmitting array element, and return to S113 to use the receiving probe signal to invert the new measured wall thickness, that is, to measure the casing damage by re-focusing. That is to say, if it is judged that effective emission focusing has not been achieved, it is necessary to bring the measured wall thickness into formula (10), recalculate the emission current of each emission element, and use the calculation results to re-emit signals to measure casing damage. Using the received induced electromotive force to repeat S113, calculate the second measured wall thickness through the formula U _p (t, z _p , d, I) = I ^T Q _p (t, z _p , d), and judge the focusing situation, If effective focusing is completed in the second transmission, go to S115 to judge the damage of the casing. On the contrary, if the effective focusing is still not completed, repeat S117, recalculate the emission current, and emit the signal measurement sleeve again until the effective emission focusing is completed or the number of emission reaches a certain threshold.

It should be noted that: the technical solutions described in the embodiments of the present invention can be combined arbitrarily if there is no conflict.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (10)

1. A casing damage detection apparatus based on a transient electromagnetic emission array, the apparatus comprising: controlling the remote transmission short section and the at least one transmitting and receiving short section; wherein,

each transmitting and receiving short section comprises a transient electromagnetic sensor array parallel to the radial direction of the device, the transient electromagnetic sensor array comprises a transient electromagnetic transmitting array and a transient electromagnetic receiving probe, the transient electromagnetic transmitting array comprises a plurality of transmitting array elements, and each transmitting array element adopts corresponding transmitting current through a control command for controlling the remote transmitting short section so as to focus transmitting energy of the transmitting array to a set region in a target casing.

2. The device of claim 1, wherein the control telemetry sub comprises a temperature measurement portion, a data transmission portion, a control circuit portion and a power supply portion;

wherein the temperature measuring part is configured to monitor the current ambient temperature of the device;

the data transmission part is configured to receive the transmitting current required by each transmitting array element sent by the upper computer and the measuring signal detected by the receiving probe; the measurement signal and the environmental temperature information monitored by the temperature measurement part are collected and then carried on a cable through a coupling capacitor; the summarized information is sent to an upper computer through the cable;

the control circuit part is configured to send a control command to the transmitting and receiving short section according to the transmitting current required by each transmitting array element sent by the upper computer, and the control command is used for controlling the interval time of transmitting and receiving signals of the transmitting and receiving short section;

the power supply part is configured to supply electric energy to the control telemetry sub and the transmitting and receiving sub.

3. The apparatus of claim 1, further comprising: a bridle for connecting the device with a cable.

4. The apparatus of claim 1, further comprising: and the upper centralizer and the lower centralizer are positioned at two ends of the device so as to ensure that the device is always kept at the axial center position of the borehole in the well.

5. A transient electromagnetic emission array based casing damage detection system, the system comprising: an upper computer and the transient electromagnetic emission array based casing damage detection device of any one of claims 1 to 4; wherein,

the upper computer is connected with the device through a cable and is configured to send transmitting current required by each transmitting array element to the device; receiving summary information sent by a receiving probe in the device, wherein the summary information comprises a measuring signal detected by the receiving probe and environmental temperature information of the device; and determining the damage state of the set region in the target casing according to the measurement signal.

6. The system of claim 5, wherein the upper computer is configured to:

determining the transmitting current required by each transmitting array according to the prior information of the target casing; wherein, the emission current required by each emission array is used for focusing the emission energy of the emission array to the set region;

and determining the damage state of the set region according to the prior information and the measurement signal detected by the receiving probe.

7. The system of claim 6, wherein the a priori information of the target cannula includes a priori wall thickness of the target cannula, and accordingly, the host computer is configured to:

determining the measured wall thickness of the set area according to the measuring signals detected by the receiving probe;

judging whether the emission energy of the emission array is focused to the set region or not according to the relation between the measured wall thickness and the prior wall thickness;

if the measured wall thickness is not focused to the set area, re-determining the emission current required by each emission array according to the measured wall thickness, and sending the re-determined emission current required by each emission array element to the device;

if the measured wall thickness is focused to the set area, judging whether the set area is damaged or not according to the relation between the measured wall thickness and the set measurement threshold value;

if the measured wall thickness is smaller than the set measurement threshold, determining that no damage exists in the set region;

and if the measured wall thickness is not less than the set measurement threshold, determining that the set region is damaged, and measuring the damage degree of the set region of the target casing according to the measured wall thickness.

8. A casing damage detection method based on a transient electromagnetic emission array is applied to the casing damage detection system based on the transient electromagnetic emission array of any one of claims 5 to 7, and the method comprises the following steps:

emitting current to a set region of a target casing based on at least one emitting array; wherein the emission current of each emission array is used for focusing the emission energy of the emission array to the set region;

detecting a measurement signal by a receiving probe;

and determining the damage state of the set region in the target casing according to the measurement signal.

9. The method of claim 8, wherein said transmitting a current to a set region of a target casing based on at least one transmit array comprises:

determining the transmitting current required by each transmitting array according to the prior information of the target casing; wherein, the emission current required by each emission array is used for focusing the emission energy of the emission array to the set region;

correspondingly, the determining the damage state of the set region in the target casing according to the measurement signal comprises: and determining the damage state of the set region according to the prior information and the measurement signal detected by the receiving probe.

10. The method according to claim 9, wherein the determining the lesion state of the set region according to the prior information and the measurement signals detected by the receiving probe comprises:

determining the measured wall thickness of the set area according to the measuring signals detected by the receiving probe;

judging whether the emission energy of the emission array is focused to the set region or not according to the relation between the measured wall thickness and the prior wall thickness;

if the measured wall thickness is not focused to the set area, re-determining the emission current required by each emission array according to the measured wall thickness, and sending the re-determined emission current required by each emission array element to the device;

if the measured wall thickness is focused to the set area, judging whether the set area is damaged or not according to the relation between the measured wall thickness and the set measurement threshold value;

if the measured wall thickness is smaller than the set measurement threshold, determining that no damage exists in the set region;

and if the measured wall thickness is not less than the set measurement threshold, determining that the set region is damaged, and measuring the damage degree of the set region of the target casing according to the measured wall thickness.