Method for evaluating the inner diameter of a casing by electromagnetic logging of a well

Abstract

The application discloses an electromagnetic flaw detection well logging calculation method for evaluating the inner diameter of a sleeve of a nickel-based material oil pipe, and comprises the following steps: according to the electromagnetic flaw detection well logging curve characteristics, selecting a probe measurement value sensitive to the pipe string deformation; and substituting the measurement value into an electromagnetic flaw detection calculation sleeve inner diameter formula to obtain the minimum inner diameter value of the deformation section sleeve. The beneficial effect is that the technical problem of quantitative calculation of the deformation of the outer sleeve of the nickel-based material oil pipe is solved, and the relative error of the calculation is small. Compared with the prior art, the method has the characteristics of simple evaluation sleeve deformation mode and high evaluation accuracy.

Description

Technical Field

[0001] This invention relates to the field of oil well logging technology, and in particular to an electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing. Background Technology

[0002] Electromagnetic flaw detection logging is widely used as an important means of inspecting the technical condition of oil and casing. However, conventional electromagnetic flaw detection logging evaluation technology can only provide information on oil (casing) defects and remaining wall thickness, and cannot quantitatively evaluate the degree of casing deformation or calculate the casing inner diameter through the tubing.

[0003] Therefore, how to provide a calculation method for quantitatively evaluating the technical condition of tubular columns has become an important technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides an electromagnetic flaw detection logging calculation method for evaluating the inner diameter of the casing of nickel-based tubing, in order to meet the production needs of accurately evaluating the deformation of the outer casing and predicting construction risks without moving the production tubing string.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] An electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing includes the following steps:

[0007] Based on the characteristics of electromagnetic flaw detection logging curves, select probe measurement values ​​that are sensitive to tubing deformation;

[0008] Substituting the measured value into the formula for calculating the inner diameter of the casing using electromagnetic flaw detection, the minimum inner diameter of the deformed section of the casing is calculated.

[0009] Preferably, the selection of probe measurement values ​​that are sensitive to tubular deformation includes:

[0010] Evaluate several segments of the deformed casing;

[0011] The calculation yields the minimum inner diameter value of the deformed section sleeve, including:

[0012] Calculate the minimum inner diameter of each of the deformed sleeve segments.

[0013] Preferably, before selecting the probe measurement value that is sensitive to tubing deformation, the method further includes performing electromagnetic flaw detection logging under well conditions with a tubing production string.

[0014] Preferably, before selecting the probe measurement value that is sensitive to the deformation of the tubing, the method further includes:

[0015] Establish an interpretation model for electromagnetic flaw detection of nickel-based oil pipes;

[0016] The formula for calculating the inner diameter of the casing was determined by applying ground simulation test data.

[0017] Preferably, the step of establishing an interpretation model for electromagnetic flaw detection of nickel-based tubing includes:

[0018] Treating the induced electromotive force of the double-layer tubing string as the induced electromotive force of the single-layer casing, and based on Faraday's law of electromagnetic induction, an interpretation model for the casing deformation in electromagnetic flaw detection of nickel-based tubing is established:

[0019] D=aε -b (1)

[0020] Where D is the outer diameter of the casing, ε is the induced electromotive force, a is a coefficient related to the material of the oil (casing) tube, the structural characteristics of the instrument, etc., and b is a correction coefficient related to pressure, temperature, and the relative geometric position of the oil and casing.

[0021] Preferably, the step of establishing the interpretation model for electromagnetic flaw detection of nickel-based tubing further includes:

[0022] Based on the induced current J O The formulas for calculating magnetic field strength B and induced electromotive force ε are obtained respectively:

[0023] Induced current:

[0024]

[0025] Magnetic field strength:

[0026]

[0027] Induced electromotive force:

[0028]

[0029] Outer diameter of the sleeve with variable section:

[0030]

[0031] Where T is the sleeve thickness; μ is the permeability; σ is the conductivity; χm is the volume magnetic susceptibility; D is the outer diameter of the sleeve; d is the inner diameter of the sleeve; ε is the induced electromotive force; J is the induced current; J0 is the steady current; The loop's cyclic vector; The magnetic field strength in the circuit; λ is the rate of change of magnetic flux; K is the attenuation coefficient; S1 is the area of ​​a single coil; N is the number of turns of the coil; t is time; b is a correction coefficient related to pressure, temperature, and the relative geometric position of the oil (casing) pipe.

[0032] Preferably, the method of determining the casing inner diameter calculation formula using ground simulation test data includes:

[0033] Based on the quantitative evaluation and interpretation model of nickel-based tubing casing and the results of ground simulation tests, a quantitative evaluation and interpretation chart of nickel-based tubing casing was drawn.

[0034] The formula for calculating the inner diameter of the casing was determined by applying regression analysis.

[0035] Preferably, the step of drawing a quantitative evaluation and interpretation chart of nickel-based tubing casing variations based on the quantitative evaluation and interpretation model and ground simulation test results includes:

[0036] Based on the measured value ε of the simulated extruded casing deformation section obtained from the ground simulation experiment and the experimental data of the corresponding casing inner diameter, an electromagnetic flaw detection logging curve of the casing deformation section of the experimental well was plotted.

[0037] Based on the measured value ε and the experimental data of the corresponding casing inner diameter, the electromagnetic flaw detection logging curves of the casing deformation section of the experimental well are deformed at multiple points. The relationship curve between the electromagnetic flaw detection measured value ε and the casing inner diameter d is plotted in a rectangular coordinate system.

[0038] The electromagnetic flaw detection casing variation interpretation model for nickel-based tubing is quantitatively derived based on the relationship curve between the electromagnetic flaw detection measurement value ε and the casing inner diameter d.

[0039] Preferably, the method of using regression analysis to determine the formula for calculating the inner diameter of the casing includes:

[0040] The induced electromotive force change rate ε% is introduced into the casing deformation quantitative calculation chart. Based on the casing deformation interpretation model for electromagnetic flaw detection of nickel-based tubing, the relationship between the induced electromotive force change rate ε% and the casing inner diameter d is obtained through regression analysis of the measured value ε and the corresponding casing inner diameter d; where...

[0041] Rate of change of induced electromotive force:

[0042]

[0043] The relationship between the rate of change of induced electromotive force ε% and the inner diameter of the bushing d: d = a(ε%) -b ;(12)

[0044] Where d is the inner diameter of the bushing; ε% is the rate of change of induced electromotive force.

[0045] Preferably, after substituting the formula for calculating the inner diameter of the casing using electromagnetic flaw detection to obtain the minimum inner diameter value of the deformed section of the casing, the method further includes:

[0046] The minimum inner diameter of the deformed section casing was compared with the well logging interpretation results of the forty-arm diameter under the condition of empty casing, and the relative error rate of the inner diameter calculation of the deformed section was obtained.

[0047] As can be seen from the above technical solution, the electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing provided by this invention establishes an interpretation model for electromagnetic flaw detection logging of nickel-based tubing to quantitatively evaluate casing deformation in production wells using electromagnetic flaw detection logging. Furthermore, based on ground simulation experiments, a calculation chart for the casing inner diameter of nickel-based tubing using electromagnetic flaw detection was drawn, and the calculation method for the casing inner diameter was determined. The beneficial effect is that this method solves the technical problem of quantitatively calculating the deformation of the outer casing of nickel-based tubing, with the relative calculation error controlled within 5%. Compared with existing technologies, it has the advantages of simple evaluation method and high evaluation accuracy. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 Electromagnetic flaw detection logging curves of the casing deformation section provided in the embodiment of the present invention for the electromagnetic flaw detection logging calculation method for evaluating the inner diameter of the casing of nickel-based tubing.

[0050] Figure 2 This is an interpretation model diagram of the electromagnetic flaw detection sleeve for nickel-based tubing provided in an embodiment of the present invention;

[0051] Figure 3 This invention provides a diagram for calculating the inner diameter of the casing for electromagnetic flaw detection of nickel-based tubing.

[0052] Figure 4 A comparison diagram of the electromagnetic flaw detection results of well X1 and the diameter of well 40 arms provided in this embodiment of the invention;

[0053] Figure 5 A comparison diagram of the electromagnetic flaw detection results of well X2 and the diameter of the 40-arm well provided in this embodiment of the invention;

[0054] Figure 6 A comparison diagram of the electromagnetic flaw detection results of well X3 and the diameter of well 24 provided in this embodiment of the invention;

[0055] Figure 7 The quantitative chart provided in this embodiment of the invention is a statistical chart of the relative error of the inner diameter of the casing.

[0056] Figure 8 A flowchart illustrating the calculation of the deformed casing inner diameter using an electromagnetic flaw detection logging method for evaluating the casing inner diameter of nickel-based tubing, as provided in an embodiment of the present invention.

[0057] Figure 9 for Figure 8 The first process expansion diagram is selected before the probe measurement values ​​that are sensitive to the deformation of the tubing are selected;

[0058] Figure 10 for Figure 8 Expanded flowchart for calculating the minimum inner diameter of the deformed section sleeve;

[0059] Figure 11 for Figure 8 The second process expansion diagram is selected before the probe measurement value that is sensitive to the deformation of the tubing is selected;

[0060] Figure 12 for Figure 8 The third process expansion diagram is selected before the probe measurement value that is sensitive to the deformation of the tubing is selected. Detailed Implementation

[0061] This invention discloses an electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing. By determining the calculation method for the casing inner diameter, it solves the technical problem of quantitatively calculating the deformation of the outer casing of nickel-based tubing, and has the characteristics of simple evaluation method and high accuracy of results.

[0062] In summary, this invention provides a method for quantitatively evaluating the inner diameter of the deformed section of the outer casing of nickel-based tubing using electromagnetic flaw detection logging technology, comprising the following specific steps:

[0063] 1. Establish an interpretation model for electromagnetic flaw detection of nickel-based oil pipes.

[0064] Given that nickel-based alloy tubing exhibits non-magnetic or weakly magnetic characteristics, when the inner tubing string is made of nickel-based material, the induced electromotive force (EMF) ε in a double-layer tubing string structure is equivalent to that in a single-layer tubing string structure. Experimental data shows that when the casing is undamaged and undeformed, the measured amplitude of the induced EMF ε remains unchanged. However, when the casing is deformed but undamaged, only the inner diameter increases or decreases, causing a change in the geometric position of the casing wall relative to the probe. Consequently, the measured amplitude of the induced EMF ε decreases or increases accordingly, indicating a close correlation between the degree of casing deformation and the ε value.

[0065] When the casing is regarded as an infinitely long cylindrical straight conductor, since the permeability μ, conductivity σ and wall thickness T of the casing are constant, the relationship between the induced electromotive force generated in the receiving coil and the outer diameter D of the casing can be obtained according to Faraday's law of electromagnetic induction. An interpretation model for electromagnetic flaw detection of nickel-based oil pipes is established, as shown in equation (1).

[0066] D=aε -b (1)

[0067] In the formula: ε is the induced electromotive force; D is the outer diameter of the casing; a is a coefficient related to the material of the oil (casing) tube, the structural characteristics of the instrument, etc.; b is a correction coefficient related to pressure, temperature, and the relative geometric position of the oil and casing.

[0068] 2. Determine the formula for calculating the inner diameter of the casing using ground simulation test data.

[0069] Through the casing deformation section simulated in the experimental well, the measurement curves of probe A and probe C and the measured value of induced electromotive force ε were analyzed. In order to reduce the error caused by the logging instrument and the downhole pressurized environment, the induced electromotive force change rate ε% was introduced into the casing deformation quantitative calculation chart. Based on the casing deformation interpretation model of electromagnetic flaw detection for nickel-based tubing, the relationship between the induced electromotive force change rate ε% and the casing inner diameter d was obtained through regression analysis of the experimental data, as shown in equations (2) and (3):

[0070] A: Casing inner diameter d = 407.6 (ε%) -0.394 (2)

[0071] C: Inner diameter of the casing d = 151.2 (ε%) -0.105 (3)

[0072] In the formula, d is the inner diameter of the sleeve; ε% is the rate of change of induced electromotive force.

[0073] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0074] The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing provided in this embodiment of the invention is described in [reference needed]. Figure 8 The steps include:

[0075] S010. Based on the characteristics of the electromagnetic flaw detection logging curve, select the probe measurement value that is sensitive to the deformation of the tubing string;

[0076] S020. Substitute the measured value into the formula for calculating the inner diameter of the casing in electromagnetic flaw detection to calculate the minimum inner diameter of the deformed section of the casing.

[0077] It should be noted that when performing electromagnetic flaw detection logging on the completed tubing string, in step S010, a probe measurement value that is sensitive to tubing string deformation is selected based on the characteristics of the electromagnetic flaw detection logging curve, ensuring the accuracy of the measurement value. In step S020, this measurement value is substituted into the electromagnetic flaw detection formula for calculating the casing inner diameter to obtain the minimum inner diameter value of the deformed section of the casing. This value can be compared with the original inner diameter of the casing to evaluate the degree of casing deformation. Compared with existing technologies, this method has the advantages of simple evaluation methods and accurate evaluation results.

[0078] As a preferred option, see Figure 9 and Figure 10 Select probe measurements that are sensitive to tubular deformation, including:

[0079] S011. Evaluate several segments of the casing deformation section;

[0080] The minimum inner diameter of the deformed section sleeve is calculated, including:

[0081] S021. Calculate the minimum inner diameter of several deformed casing sections. This comparison of multiple data points further reduces evaluation errors, thereby improving the accuracy of the evaluation and providing practical data and technical support for the formulation and implementation of well workover measures.

[0082] Further, see Figure 11 Before selecting probe measurements sensitive to tubing deformation, the process also includes electromagnetic flaw detection logging under well conditions with tubing production strings. This design allows for a consistent comparison of the evaluation results of the tubing string under well conditions with tubing production strings and those under well conditions without casing, ensuring higher accuracy in the interpretation results.

[0083] To optimize the above technical solution, see [link / reference]. Figure 12 Before selecting probe measurements that are sensitive to tubular deformation, the following steps are also included:

[0084] S310. Establish an interpretation model for electromagnetic flaw detection of nickel-based oil pipes;

[0085] S210. Determine the formula for calculating the inner diameter of the casing using ground simulation test data.

[0086] It should be noted that in step S310, considering that nickel-based alloy tubing exhibits non-magnetic or weakly magnetic characteristics, when the inner tubing string is made of nickel-based material, the induced electromotive force ε of the double-layer tubing string structure is equivalent to that of the single-layer tubing string structure. Experimental data shows that when the casing is undamaged and undeformed, the measured amplitude of the induced electromotive force ε remains unchanged. When the casing is deformed but undamaged, only the inner diameter increases or decreases, and the geometric position of the casing wall relative to the probe changes, the measured amplitude of the induced electromotive force ε decreases or increases accordingly. The degree of casing deformation is closely related to the ε value; thus, an interpretation model for electromagnetic flaw detection of nickel-based tubing casing deformation is established.

[0087] In step S210, the measured curve morphology and the induced electromotive force measurement value ε are analyzed using the casing deformation section simulated in the experimental well. Based on the interpretation model of casing deformation for nickel-based tubing electromagnetic flaw detection, the casing inner diameter calculation formula is determined through regression analysis of the experimental data. This design scheme features a high correlation between the model and the degree of casing deformation and high reliability of the evaluation results.

[0088] As a preferred option, an interpretation model for electromagnetic flaw detection of nickel-based tubing is established, including:

[0089] Treating the induced electromotive force of the double-layer tubing string as the induced electromotive force of the single-layer casing, and based on Faraday's law of electromagnetic induction, an interpretation model for the casing deformation in electromagnetic flaw detection of nickel-based tubing is established:

[0090] D=aε -b ; (1)

[0091] Where D is the outer diameter of the casing, ε is the induced electromotive force, a is a coefficient related to the material of the oil (casing) tube, the structural characteristics of the instrument, etc., and b is a correction coefficient related to pressure, temperature, and the relative geometric position of the oil and casing.

[0092] It should be noted that when the casing is regarded as an infinitely long cylindrical straight conductor, since the permeability μ, conductivity σ and wall thickness T of the casing are constant, the relationship between the induced electromotive force generated in the receiving coil and the outer diameter D of the casing can be obtained according to Faraday's law of electromagnetic induction, and the casing variation interpretation model of electromagnetic flaw detection of nickel-based oil pipe as shown in Equation (1) can be established.

[0093] Furthermore, the interpretation model for electromagnetic flaw detection of nickel-based tubing also includes:

[0094] Based on the induced current J O The formulas for calculating magnetic field strength B and induced electromotive force ε are obtained respectively:

[0095] Induced current:

[0096]

[0097] Magnetic field strength:

[0098]

[0099] Induced electromotive force:

[0100]

[0101] Inner diameter of the sleeve with variable section:

[0102]

[0103] Where T is the sleeve thickness; μ is the permeability; σ is the conductivity; χm is the volume magnetic susceptibility; D is the outer diameter of the sleeve; d is the inner diameter of the sleeve; ε is the induced electromotive force; J is the induced current; Jo is the steady current; is the loop cyclic vector; and is the magnetic field strength in the loop. λ is the rate of change of magnetic flux; K is the attenuation coefficient; S1 is the area of ​​a single coil; N is the number of turns of the coil; t is time; b is a correction coefficient related to pressure, temperature, and the relative geometric position of the oil (casing) pipe.

[0104] It should be noted that when a DC current J0 is applied to the transmitting coil, a stable magnetic field with a magnetic field strength of H is generated around the solenoid. For a multi-layered tubing string consisting of tubing and casing in a production well, the steady magnetic field will induce a current J0 in the tubing and casing, as shown in equation (4). The tubing (casing) is considered as an infinitely long cylindrical straight conductor. When the DC current is disconnected, the magnetic field strength generated by the induced current is calculated, as shown in equation (5). The induced electromotive force ε generated in the receiving coil that decays with different times is calculated, as shown in equation (6).

[0105] Since the magnetic permeability μ of the inner nickel-based tubing is much smaller than that of the outer steel casing, its magnetic induction intensity B is close to 0. From equation (6), we can know that: ε 内 ≈0, at this time the induced electromotive force of the double-layer tube can be regarded as the induced electromotive force of the single-layer sleeve, that is: ε 总 =ε 内 +ε 外 ≈ε 外 Calculate the diameter of the sleeve in the variable section, see formula (7);

[0106] Among them, let Then equation (7) can be simplified to equation (1), that is .

[0107] To optimize the above technical solution, ground simulation test data was used to determine the formula for calculating the inner diameter of the casing, including:

[0108] Based on the quantitative evaluation and interpretation model of nickel-based tubing casing deformation and the results of ground simulation tests, a quantitative evaluation and interpretation chart of nickel-based tubing casing deformation is drawn; including: based on the measured value ε of the simulated extruded casing deformation section obtained from the ground simulation test and the experimental data of the corresponding casing inner diameter, an electromagnetic flaw detection logging curve of the casing deformation section of the experimental well is drawn.

[0109] Based on the measured value ε and the experimental data of the corresponding casing inner diameter, the relationship curve between the electromagnetic flaw detection measured value ε and the casing inner diameter d was plotted in a rectangular coordinate system at multiple deformations in the electromagnetic flaw detection logging curve of the casing deformation section of the experimental well.

[0110] A quantitative interpretation model for electromagnetic flaw detection of nickel-based tubing was developed based on the relationship curve between the electromagnetic flaw detection measurement value ε and the casing inner diameter d.

[0111] The formula for calculating the casing inner diameter was determined using regression analysis. This included: introducing the induced electromotive force (EMF) change rate ε% into the casing deformation quantitative calculation chart; based on the electromagnetic flaw detection casing deformation interpretation model for nickel-based tubing; and through regression analysis of the measured value ε and the corresponding casing inner diameter d, obtaining the relationship between the induced EMF change rate ε% and the casing inner diameter d; where:

[0112] Rate of change of induced electromotive force:

[0113]

[0114] The relationship between the rate of change of induced electromotive force ε% and the inner diameter of the bushing d: d = a(ε%) -b ;(12)

[0115] Where d is the inner diameter of the casing, and ε% is the rate of change of induced electromotive force. Introducing the rate of change ε% into the quantitative interpretation chart of casing deformation increases the weight of the deformation rate in the calculation formula, thereby reducing the impact of errors caused by logging instruments and the downhole pressurized environment.

[0116] The electromagnetic flaw detection logging calculation method for evaluating the inner diameter of nickel-based tubing provided by this invention, after substituting the formula for calculating the inner diameter of the casing using electromagnetic flaw detection to obtain the minimum inner diameter value of the deformed section of the casing, further includes:

[0117] By comparing the minimum inner diameter of the deformed section casing with the well logging interpretation results of the forty-arm diameter under the condition of empty casing, the relative error rate of the inner diameter calculation of the deformed section is obtained.

[0118] The solution will be further described below with reference to specific embodiments.

[0119] This invention provides a method for quantitatively evaluating the inner diameter of the deformed section of the outer casing in electromagnetic flaw detection logging of nickel-based tubing, comprising the following specific steps:

[0120] 1. Establish a quantitative evaluation and interpretation model for nickel-based tubing casing.

[0121] Nickel-based alloy tubing exhibits non-magnetic or weakly magnetic characteristics. Based on Faraday's law of electromagnetic induction, a quantitative evaluation and interpretation model for the casing variation of nickel-based tubing is established.

[0122] 2. Conduct ground simulation tests and develop a quantitative interpretation chart of the casing inner diameter under well completion conditions.

[0123] Ground simulation tests based on electromagnetic flaw detection and logging technology were conducted. Based on the quantitative evaluation and interpretation model of nickel-based tubing casing variation and the results of ground simulation tests, quantitative evaluation and interpretation charts of nickel-based tubing casing variation were drawn, and regression analysis was used to determine the calculation formula for the casing inner diameter.

[0124] The invention includes the following specific steps:

[0125] 1. Establish an interpretation model for electromagnetic flaw detection of nickel-based oil pipes.

[0126] A DC current J is applied to the transmitting coil. O A stable magnetic field with a strength of H is generated around the solenoid. For a multi-layered tubing string consisting of tubing and casing in a production well, the steady magnetic field induces a current J in the tubing and casing. O Calculate the induced current J O See equation (4):

[0127]

[0128] Treating the oil (casing) tube as an infinitely long cylindrical straight conductor, the magnetic field strength generated by the induced current is calculated after the DC current is disconnected, as shown in equation (5):

[0129]

[0130] The induced electromotive force ε generated in the receiving coil and decaying with different times is calculated, as shown in equation (6):

[0131]

[0132] Since the magnetic permeability μ of the inner nickel-based tubing is much smaller than that of the outer steel casing, its magnetic induction intensity B is close to 0. From equation (6), we can know that: ε 内 ≈0, at this time the induced electromotive force of the double-layer tube can be regarded as the induced electromotive force of the single-layer sleeve, that is: ε 总 =ε 内 +ε 外 ≈ε 外 The diameter of the sleeve section is calculated using equation (7):

[0133]

[0134] make:

[0135] Equation (7) can be simplified to:

[0136] D=aε -b ; (8)

[0137] In the above formulas: T is the sleeve thickness; μ is the permeability; σ is the conductivity; χm is the volume magnetic susceptibility; D is the outer diameter of the sleeve; d is the inner diameter of the sleeve; ε is the induced electromotive force; J is the induced current; Jo is the steady current; The loop's cyclic vector; The magnetic field strength in the circuit; λ is the rate of change of magnetic flux; K is the attenuation coefficient; S1 is the area of ​​a single coil; N is the number of turns of the coil; t is time; b is a correction coefficient related to pressure, temperature, and the relative geometric position of the oil (casing) pipe.

[0138] Equation (1) expresses the functional relationship between the outer diameter D of the casing and the induced electromotive force ε, which is the calculation model for the inner diameter of the casing in electromagnetic flaw detection logging of nickel-based tubing.

[0139] 2. Conduct ground simulation tests and develop quantitative interpretation charts of casing inner diameter under well completion conditions.

[0140] 2.1 Conducting ground simulation tests of electromagnetic flaw detection logging for nickel-based tubing

[0141] Technical specifications for tubing and casing used in simulation experiments: Tubing specifications: 3in (88.9mm*6.45mm); material is weakly magnetic nickel-based alloy; includes 1 coupling. Casing specifications: 7in (177.8mm*12.65 / 11.51mm); material is ordinary alloy (SM-C110); includes 3 couplings, one intact casing section, and three casing sections with known defects.

[0142] Defects in the experimental casing manufacturing process: 6 sections of casing deformed, 2 cracks (1 transverse crack, 1 longitudinal crack), 2 corrosions, and 5 perforations. The design of defects in the experimental tubing is shown in Appendix 1.

[0143]

[0144]

[0145] Table 1. Design of Deformation and Damage of Casing String in Experimental Wells

[0146] Ground simulation experiment scheme: Measurements were conducted at a velocity of 260 m / h under a vertically centered configuration with a tubing + casing double-layer string structure, and experimental data were recorded. The electromagnetic flaw detection logging curves for the deformed section of the casing in the experimental well are attached. Figure 1Among them, in Figure 1 The information above is A (00-3900), BB (-200-2600), B (350-2800), and C (100-750).

[0147] 2.2 Experimental Data Analysis

[0148] The measured values ​​ε and corresponding inner diameters of six simulated casing deformation sections in the simulated experimental well were fitted, and the relationship curve between the electromagnetic flaw detection measured value ε and the inner diameter d of the casing was plotted in a rectangular coordinate system.

[0149] Simulation data analysis shows that the curves of each probe in the casing extrusion deformation section exhibit an increasing degree of bending, and the degree of deformation is directly proportional to the measured value ε. Based on the experimental data, an interpretation model for the casing deformation in nickel-based tubing electromagnetic flaw detection was established (see attached). Figure 2 .

[0150] 2.3 Develop quantitative interpretation charts and fit the formula for calculating the inner diameter of the casing.

[0151] Based on the interpretation model of casing deformation in electromagnetic flaw detection of nickel-based tubing, the rate of change ε% of the induced electromotive force measured by probes A and C in the deformed section compared to the baseline value is introduced into the quantitative interpretation chart of casing deformation. This increases the weight of the deformation rate in the calculation formula and reduces the influence of errors caused by logging instruments and the downhole pressurized environment. The resulting chart for calculating the inner diameter of casing in electromagnetic flaw detection of nickel-based tubing is shown in the appendix. Figure 3 .

[0152] The rate of change of induced electromotive force, ε%, is shown in equation (9):

[0153]

[0154] By interpreting the data regression of the chart, the calculation formula for the inner diameter of the sleeve of the electromagnetic flaw detection system for nickel-based oil pipe is obtained, as shown in equations (8) and (9):

[0155] Inner diameter of probe A's sleeve: d = 407.6(ε%) - 0.394; (10)

[0156] The inner diameter of the probe C sleeve is: d = 151.2(ε%) - 0.105; (11)

[0157] Where: d—inner diameter of the sleeve; ε%—rate of change of induced electromotive force.

[0158] Example 1

[0159] The reliability of the model was verified by referring to the logging results of the 40-arm caliper well of Well X1. The completion tubing of Well X1 was Φ88.9mm*6.45mm nickel-based alloy tubing, and the production casing was Φ177.8mm*12.65mm.

[0160] After the casing string was installed, electromagnetic flaw detection logging was performed on the well. Based on the characteristics of the electromagnetic flaw detection logging curves, the probe measurements that are sensitive to casing deformation were selected and substituted into the electromagnetic flaw detection formula for calculating the casing inner diameter to obtain the minimum inner diameter value of the deformed section. Four casing deformation sections were evaluated: 4680-4692m, 4722-4727m, 4740-4746m, and 4786-4790m. The calculated minimum inner diameters of the casing in these deformed sections were 139.58mm, 143.31mm, 142.14mm, and 144.93mm, respectively. A comparison with the interpretation results of the 40-arm caliper logging under uncased well conditions is shown in the appendix. Figure 4 Among them, in Figure 4 The information above is as follows:

[0161]

[0162]

[0163] The comparison of the results shows that:

[0164] (1) The two evaluations of the casing deformation section were consistent, and the interpretation accuracy rate was 100%;

[0165] (2) The relative errors of the calculated inner diameter of the casing in the four deformed sections were 0.85%, 1.50%, 1.47% and 0.24%, respectively. The relative error rate of the calculated inner diameter of the deformed section was less than 5%, as shown in Appendix Table 2.

[0166]

[0167] Table 2. Comparison of Interpretation Results of Casing Deformation in Well X1

[0168] Example 2

[0169] The reliability of the model was verified by referring to the logging results of the 40-arm caliper well of Well X2. The completion tubing of Well X2 was Φ88.9mm*6.45mm nickel-based alloy tubing, and the production casing was Φ177.8mm*12.65mm.

[0170] After the casing string was installed, electromagnetic flaw detection logging was performed on the well. Based on the characteristics of the electromagnetic flaw detection logging curves, the probe measurement value that most sensitively reflects casing deformation was selected and substituted into the electromagnetic flaw detection formula for calculating the casing inner diameter to obtain the minimum inner diameter value of the deformed section. Four casing deformation sections were evaluated: 4014-4032m, 4081-4104m, 4227-4269m, and 4310-4321m. The calculated minimum inner diameters of the casing in these deformed sections were 141.62mm, 142.93mm, 140.53mm, and 139.49mm, respectively. A comparison with the interpretation results of the 40-arm caliper logging under uncased well conditions is shown in the appendix. Figure 5 Among them, in Figure 5The main text information above is as follows:

[0171]

[0172]

[0173] The comparison of the results shows that:

[0174] (1) The two evaluations of the casing deformation section were consistent, and the interpretation accuracy rate was 100%;

[0175] (2) The relative errors of the inner diameter of the deformed section of the casing are 2.23%, 1.44%, 2.64%, and 3.19%, respectively. The relative error rate of the inner diameter of the deformed section is less than 5%, as shown in Appendix Table 3.

[0176]

[0177] Table 3. Comparison of Interpretation Results of Casing Deformation in Well X2

[0178] Example 3

[0179] The accuracy of the model was analyzed based on the electromagnetic flaw detection and 24-arm caliper logging interpretation results before and after the X3 well tubing was installed. The completion tubing of the X3 well was Φ88.9mm*6.45mm nickel-based alloy tubing, and the production casing was Φ177.8mm*11.51mm.

[0180] 1. Electromagnetic flaw detection logging was performed on well X3 before the tubing string was pulled in.

[0181] Electromagnetic flaw detection logging was conducted under the condition of a well with a production tubing string. Based on the characteristics of the electromagnetic flaw detection logging curve, the measurement value of probe A2 was selected and substituted into the electromagnetic flaw detection quantitative interpretation chart. The inner diameter of the production casing was obtained through calculation formula. Three casing deformation sections were evaluated: 2906-2975m, 2990-3030m, and 3050-3057m, respectively. The minimum inner diameters of the casing in the deformation sections were calculated to be 130.62mm, 135.96mm, and 146.82mm, respectively.

[0182] 2. After the tubing string was pulled out, a 24-arm caliper logging was performed on well X3.

[0183] 24-arm caliper logging was conducted under uncased well conditions. Based on the 24-arm caliper imaging logging data, three casing deformation sections were evaluated: 2911-2967m, 2992-3029m, and 3052-3057.5m. The minimum inner diameters of the casing in these deformation sections were measured to be 130.12mm, 134.74mm, and 144.08mm, respectively. A comparison of the two interpretation results is attached. Figure 6 .

[0184] in, Figure 6 The information above is:

[0185]

[0186] 3. Compared with the interpretation results of the tubing string before and after the interpretation, the interpretation chart has higher accuracy.

[0187] The interpretation results of the 24-arm caliper logging data under uncased well conditions were compared and analyzed with the casing inner diameter values ​​of the deformed sections calculated using the electromagnetic flaw detection logging quantitative interpretation chart before the tubing string was pulled in. The two evaluations of the casing deformation sections showed consistency. The relative errors of the casing inner diameters of the three deformed sections were 0.38%, 0.91%, and 1.9%, respectively, with a relative error rate of less than 5%. See the appendix for relative error statistics. Figure 7 The results of the explanation are shown in Appendix Table 4.

[0188]

[0189] Table 4. Comparison of Casing Deformation Interpretation Results in Well X3

[0190] Comparative example:

[0191] In the example, the electromagnetic flaw detection logging data of well X3 before the casing string was pulled out was interpreted and evaluated using conventional interpretation methods. The electromagnetic flaw detection interpretation software could only calculate the casing wall thickness and qualitatively evaluate the casing deformation, but could not calculate the inner diameter of the deformed section of the casing. The interpretation results are shown in Appendix Table 5.

[0192]

[0193] Table 5. Interpretation Results of Electromagnetic Flaw Detection of Deformed Section of Casing in Well X3 using Conventional Interpretation Methods

[0194] In summary, the beneficial effects of this invention are as follows:

[0195] 1. An electromagnetic flaw detection logging interpretation model for evaluating the casing inner diameter of nickel-based tubing was established. This model is applicable to the quantitative evaluation of casing variation in production wells using electromagnetic flaw detection logging of weakly magnetic or non-magnetic tubing.

[0196] 2. Based on ground simulation tests, a calculation chart for the inner diameter of the casing of nickel-based tubing electromagnetic flaw detection was drawn, and the calculation method for the inner diameter of the casing was determined. This method solved the technical problem of quantitative calculation of the deformation of the outer casing of nickel-based tubing, and the relative error of the calculation was controlled within 5%.

[0197] 3. As can be seen from the examples, the relative error of the casing inner diameter calculated using the new method is less than 5%.

[0198] The advantages of this invention are:

[0199] The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter through the tubing has no existing research results in the field of well condition detection research at home and abroad. This technology saves the cost of gas well tubing monitoring operations and avoids construction risks, and is the main development direction for future well condition detection research.

[0200] Applying electromagnetic flaw detection logging technology to calculate the casing inner diameter through the tubing allows for quantitative evaluation of the tubing string's technical condition and prediction of construction risks without moving the production tubing string. This provides practical data and technical support for the formulation and implementation of well workover measures, and is a technical challenge that oil (gas) fields urgently need to overcome.

[0201] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0202] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for calculating the inner diameter of casing in nickel-based tubing using electromagnetic flaw detection logging, characterized in that, Including the following steps: Establish an interpretation model for electromagnetic flaw detection of nickel-based oil pipes; The formula for calculating the inner diameter of the casing was determined using ground simulation test data. Based on the characteristics of electromagnetic flaw detection logging curves, select probe measurement values ​​that are sensitive to tubing deformation; Substitute the probe measurement value into the electromagnetic flaw detection formula for calculating the inner diameter of the casing to obtain the minimum inner diameter value of the deformed section casing. The establishment of the interpretation model for electromagnetic flaw detection of nickel-based oil pipes includes: Treating the induced electromotive force of the double-layer tubing string as the induced electromotive force of the single-layer casing, and based on Faraday's law of electromagnetic induction, an interpretation model for the casing deformation in electromagnetic flaw detection of nickel-based tubing is established: ； （1） Where D is the outer diameter of the casing, ε is the measured value of the induced electromotive force, a is a coefficient related to the material of the tubing and casing and the structural characteristics of the instrument; b is a correction coefficient related to pressure, temperature and the relative geometric position of the oil and casing. The establishment of the interpretation model for electromagnetic flaw detection of nickel-based tubing also includes: Based on the induced current J O The formulas for calculating magnetic field strength B and induced electromotive force ε are obtained respectively: Induced current: ; (4) Magnetic field strength: ; (5) Induced electromotive force: 　　　 （6） Outer diameter of the sleeve with variable section: ; (7) Where T is the sleeve thickness; μ is the permeability; σ is the conductivity; χm is the volume magnetic susceptibility; D is the outer diameter of the sleeve; d is the inner diameter of the sleeve; ε is the induced electromotive force; J is the induced current; J0 is the steady current; is the loop's cyclic vector; B is the magnetic field strength in the loop; λ is the rate of change of magnetic flux; K is the hysteresis constant; S1 is the area of ​​a single coil; N is the number of turns of the coil; t is time; b is a correction factor related to pressure, temperature, and the relative geometric position of the tubing and casing.

2. The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing according to claim 1, characterized in that, The selection of probe measurements that are sensitive to tubular deformation includes: The calculation yields the minimum inner diameter value of the deformed section sleeve, including: Calculate the minimum inner diameter of each of the deformed sleeve segments.

3. The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing according to claim 1, characterized in that, Before selecting the probe measurement value that is sensitive to tubing deformation, the method also includes: performing electromagnetic flaw detection logging under well conditions with oil tubing production tubing.

4. The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing according to claim 1, characterized in that, The formula for calculating the inner diameter of the casing is determined using ground simulation test data, including: Based on the quantitative evaluation and interpretation model of nickel-based tubing casing and the results of ground simulation tests, a quantitative evaluation and interpretation chart of nickel-based tubing casing was drawn. The formula for calculating the inner diameter of the casing was determined by applying regression analysis.

5. The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing according to claim 4, characterized in that, The quantitative evaluation and interpretation charts for nickel-based tubing casing variations, based on the nickel-based tubing casing variation quantitative evaluation and interpretation model and ground simulation test results, include: Based on the measured value of induced electromotive force ε of the simulated extruded casing deformation section and the experimental data of the corresponding casing inner diameter obtained from the ground simulation experiment, an electromagnetic flaw detection logging curve of the casing deformation section of the experimental well was plotted. Based on the measured value of induced electromotive force ε and the experimental data of the corresponding casing inner diameter, the relationship curve between the measured value of induced electromotive force ε and the casing inner diameter d in electromagnetic flaw detection is plotted in a rectangular coordinate system at multiple deformations in the electromagnetic flaw detection logging curve of the casing deformation section in the experimental well. The interpretation model of the casing variation in the electromagnetic flaw detection of nickel-based tubing is quantitatively based on the relationship curve between the measured value of induced electromotive force ε in the electromagnetic flaw detection and the inner diameter d of the casing.

6. The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing according to claim 4, characterized in that, The method of using regression analysis to determine the formula for calculating the inner diameter of the casing includes: The induced electromotive force (EMF) change rate ε% is introduced into the casing deformation quantitative calculation chart. Based on the casing deformation interpretation model for electromagnetic flaw detection of nickel-based tubing, the relationship between the induced EMF change rate ε% and the casing inner diameter d is obtained through regression analysis of the experimental data of the measured EMF value ε and the corresponding casing inner diameter d; where: Rate of change of induced electromotive force: ; (9) The relationship between the rate of change of induced electromotive force ε% and the inner diameter of the bushing d: d = a(ε%) -b ;(12) Where d is the inner diameter of the bushing; ε% is the rate of change of induced electromotive force.

7. The electromagnetic flaw detection logging calculation method for evaluating the casing inner diameter of nickel-based tubing according to claim 1, characterized in that, After substituting the formula for calculating the inner diameter of the casing using electromagnetic flaw detection, and obtaining the minimum inner diameter value of the deformed section of the casing, the following steps are also included: The minimum inner diameter of the deformed section casing was compared with the well logging interpretation results of the forty-arm diameter under the condition of empty casing, and the relative error rate of the inner diameter calculation of the deformed section was obtained.

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