Method and system for determining commodity inspection tolerance of special thread parameters of oil casing

Abstract

The invention discloses an oil casing special thread parameter commodity inspection tolerance determination method and system, and the method comprises the steps: measuring the thread parameters of a plurality of oil casing special thread joints by different detection personnel, carrying out the A-class standard uncertainty evaluation through a statistical method, and obtaining the repetitive standard uncertainty component of the detection personnel; obtaining a standard uncertainty component of the indication error of the measuring tool and a standard uncertainty component of the standard block; based on the repetitive standard uncertainty component of the detection personnel, the standard uncertainty component of the indication error of the measuring tool and the standard uncertainty component of the standard block, determining the synthesis standard uncertainty; determining a measurement error; the average increment of thread parameters before and after thread surface treatment of the special threaded joint of the oil casing is determined; and determining the commodity inspection tolerance of the special thread parameter of the oil casing based on the measurement error and the average increment. According to the method, the relational expression of the oil casing special thread parameter commodity inspection tolerance and the design tolerance is scientifically and reasonably established.

Description

Technical Field

[0001] The invention belongs to the technical field of oil casing, and in particular relates to a method and system for determining commercial inspection tolerance of special thread parameters of oil casing. Background Art

[0002] Special threaded joints for oil casing and tubing have been increasingly widely used due to their advantages such as high connection strength and good sealing performance. With the increasing number of suppliers and types of buckle types, many difficulties have been brought to the on-site acceptance and quality control of special threads. At present, the inspection items, on-site acceptance tolerances, inspection methods and measuring tools of special thread parameters are all provided by suppliers, and they are also different for different manufacturers. In order to improve the pass rate of on-site commodity inspection, most manufacturers intend to relax the on-site acceptance tolerances for key parameters such as sealing diameter and thread median diameter, and the relaxation range of each manufacturer is not uniform. However, the relaxed commodity inspection tolerances lack theoretical data support and relevant experimental verification and evaluation. It is difficult to determine whether the quality of special threaded joints for oil casing and tubing can be guaranteed by acceptance according to the commodity inspection tolerances provided by the supplier. The formulation of commodity inspection tolerances has always been the focus of controversy between oil fields and suppliers. Summary of the invention

[0003] In view of the above problems, the present invention discloses a method for determining the commercial inspection tolerance of special thread parameters of oil casing, comprising the following steps:

[0004] Different inspectors measured the thread parameters of several special threaded joints of oil casing and pipes, and used statistical methods to evaluate the type A standard uncertainty, and obtained the standard uncertainty component of the inspector's repeatability;

[0005] Obtain the standard uncertainty component of the gauge indication error and the standard uncertainty component of the standard block;

[0006] Determine the combined standard uncertainty based on the standard uncertainty component of the repeatability of the tester, the standard uncertainty component of the gauge indication error, and the standard uncertainty component of the standard block;

[0007] Determine the measurement error based on the combined standard uncertainty;

[0008] Determine the average increment of thread parameters before and after thread surface treatment of special threaded joints of oil casing;

[0009] Based on the measurement error and average increment, the inspection tolerance of special thread parameters of oil casing is determined.

[0010] Furthermore, the combined standard uncertainty is determined by the following formula:

[0011]

[0012] Among them, u cis the combined standard uncertainty; u2 is the standard uncertainty component of the repeatability of the inspector; u2 is the standard uncertainty component of the indication error of the measuring instrument; u3 is the standard uncertainty component of the standard block.

[0013] Furthermore, the measurement error is determined by an expanded uncertainty;

[0014] The expanded uncertainty is determined by the following formula:

[0015] U=ku c ;

[0016] U is the expanded uncertainty; k is the coverage factor, which is 2; and the confidence probability is 95%.

[0017] Furthermore, the measurement error is determined by the following formula:

[0018] U m = = 2u c

[0019] Among them, U m is the measurement error.

[0020] Furthermore, the specific steps of determining the average increment of thread parameters of the special threaded joint of oil casing before and after the thread surface treatment are as follows:

[0021] Several special threaded joints of oil casing and tubing from the same batch were randomly selected to test the thread parameter tolerances before and after the thread surface treatment at the field end. The thread parameters of each thread before and after the thread surface treatment were tested with a set sample capacity, and the average increment of the thread parameters before and after the thread surface treatment was calculated.

[0022] Furthermore, the surface treatment includes phosphating treatment, sandblasting treatment, copper plating treatment and hot-dip galvanizing treatment.

[0023] Furthermore, the inspection tolerance of the special thread parameters of the oil casing is determined by the following formula:

[0024] Commodity inspection tolerance = design tolerance + m + b

[0025] Among them, U b is the average increment.

[0026] Furthermore, the thread parameters include a sealing surface diameter and a thread pitch diameter.

[0027] The present invention also discloses a system for determining the commercial inspection tolerance of special thread parameters of oil casing, comprising:

[0028] The inspection unit is used for different inspectors to measure the thread parameters of several special threaded joints of oil casing and pipes, and to evaluate the Class A standard uncertainty using statistical methods to obtain the standard uncertainty component of the inspector's repeatability;

[0029] An evaluation unit, used to obtain the standard uncertainty component of the measuring tool indication error and the standard uncertainty component of the standard block;

[0030] The combined standard uncertainty unit is used to determine the combined standard uncertainty based on the standard uncertainty component of the repeatability of the tester, the standard uncertainty component of the measuring instrument indication error and the standard uncertainty component of the standard block;

[0031] a determination unit for determining a measurement error based on a combined standard uncertainty;

[0032] Average increment unit, used to determine the average increment of thread parameters before and after thread surface treatment of special threaded joints of oil casing;

[0033] The inspection tolerance unit is used to determine the inspection tolerance of special thread parameters of oil casing based on measurement error and average increment.

[0034] Furthermore, the inspection tolerance of the special thread parameters of the oil casing is determined by the following formula:

[0035] Commodity inspection tolerance = design tolerance + m + b

[0036] Among them, U b is the average increment.

[0037] Compared with the prior art, the embodiments of the present invention have at least the following advantages: by adopting statistical methods and experimental methods, the magnitude of the influence degree of each influencing factor on the commercial inspection tolerance can be accurately calculated, and finally the commercial inspection tolerance of the mean value of the diameter deviation of the thread sealing surface of the Φ177.8×10.36mm casing internal thread and external thread is scientifically and accurately determined by the method of the present invention; the present invention can scientifically and reasonably establish the relationship between the commercial inspection tolerance and the design tolerance of the special thread parameters of the oil casing, which has important guiding significance for improving the commercial inspection acceptance and quality control level of the thread parameters of the special threaded joints of the oil casing.

[0038] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 A flow chart showing a method for determining the commercial inspection tolerance of special thread parameters of oil casing according to an embodiment of the present invention is shown;

[0041] Figure 2 A statistical diagram of the diameter deviation of the sealing surface of a Φ177.80×10.36 mm oil casing before and after phosphating according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Figure 1 The flowchart of the method for determining the inspection tolerance of special thread parameters of oil casing according to an embodiment of the present invention is shown. Figure 1 As shown, a method for determining the commercial inspection tolerance of special thread parameters of oil casing proposed by the present invention comprises the following steps:

[0044] Different inspectors measured the thread parameters of several special threaded joints of oil casing and pipes, and used statistical methods to evaluate the type A standard uncertainty, and obtained the standard uncertainty component of the inspector's repeatability; the type A standard uncertainty evaluation is evaluated by statistical analysis methods, and its standard uncertainty u is equivalent to the standard deviation σ obtained from the series of observations, that is, u = σ;

[0045] Obtain the standard uncertainty component of the measuring tool indication error and the standard uncertainty component of the standard block; illustratively, obtain them based on the calibration certificates of the measuring tool and the standard block.

[0046] Determine the combined standard uncertainty based on the standard uncertainty component of the repeatability of the tester, the standard uncertainty component of the gauge indication error, and the standard uncertainty component of the standard block;

[0047] Based on the combined standard uncertainty, the measurement error is determined; the measurement error includes the error of the inspector during measurement, the error of the measuring tool indication and the error of the standard block;

[0048] Determine the average increment of thread parameters before and after thread surface treatment of special threaded joints of oil casing;

[0049] Based on the measurement error and average increment, the inspection tolerance of special thread parameters of oil casing is determined.

[0050] In order to make the commercial inspection tolerance of special thread parameters of oil casing have a scientific and essential basis, the present invention proposes a method for determining the commercial inspection tolerance of special thread parameters of oil casing. On the basis of the design tolerance of thread parameters of special threaded joints of oil casing, the main factors affecting the difference between commercial inspection tolerance and design tolerance are evaluated by the method of statistical measurement uncertainty assessment. The average increment of thread parameters caused by surface treatment is evaluated by batch detection and statistical analysis of thread parameters before and after factory surface treatment, and finally the commercial inspection tolerance is determined by quantitative superposition of various influencing factors. The present invention can well solve the problem of no scientific method for commercial inspection tolerance of special thread parameters of oil casing.

[0051] In some embodiments, the combined standard uncertainty is determined by the following formula:

[0052]

[0053] Among them, u c is the combined standard uncertainty; u1 is the standard uncertainty component of the repeatability of the inspector; u2 is the standard uncertainty component of the indication error of the measuring instrument; and u3 is the standard uncertainty component of the standard block.

[0054] In some embodiments, the measurement error is determined by an expanded uncertainty;

[0055] The expanded uncertainty is determined by the following formula:

[0056] U=ku c (2)

[0057] U is the expanded uncertainty; the confidence probability is 95%; k is the coverage factor, which is 2.

[0058] The probability of using only the synthetic standard uncertainty being true is only 68%. In actual work, such as high-precision comparisons and measurements related to production safety and health, the confidence probability of the measurement result interval required is higher, so it is necessary to use the expanded uncertainty.

[0059] In some embodiments, the measurement error is determined by the following formula:

[0060] U m =U=2u c (3)

[0061] Among them, Um is the measurement error.

[0062] In some embodiments, the specific steps of determining the average increment of thread parameters before and after the thread surface treatment of the special threaded joint of oil casing are as follows:

[0063] Several special threaded joints of oil casing produced in the same batch in the factory were randomly selected to test the thread parameter tolerance before and after the thread surface treatment at the field end. The thread parameters of each end before and after the thread surface treatment were tested with a set sample capacity, and the average increase of the thread parameters before and after the thread surface treatment was counted.

[0064] In some embodiments, the surface treatment includes phosphating, sandblasting, copper plating and hot-dip galvanizing.

[0065] In some embodiments, the inspection tolerance of the special thread parameters of the oil casing is determined by the following formula:

[0066] Commodity inspection tolerance = design tolerance + U m +U b (4)

[0067] Among them, U b is the average increment.

[0068] Among them, in formula (4), for the external thread of the special threaded joint of the oil casing without sandblasting, there is no influence of the surface coating, so the determination of the commercial inspection tolerance of the external thread does not require the calculation of the average increment. In this case, U b =0.

[0069] The invention scientifically and reasonably establishes the relationship between the commercial inspection tolerance and the design tolerance of the special thread parameters of the oil casing, which has important guiding significance for improving the commercial inspection acceptance and quality control level of the thread parameters of the special thread joints of the oil casing, and can truly solve the problem that there is no scientific calculation method for the commercial inspection tolerance of the special thread parameters of the oil casing.

[0070] In some embodiments, the thread parameters include a sealing face diameter and a thread pitch diameter.

[0071] Example 1

[0072] Determination of the inspection tolerance of the mean value of the diameter deviation of the external thread sealing surface of a certain type of Φ177.8×10.36mm casing.

[0073] Implementation process: ① Three inspectors measured the mean deviation of the sealing surface diameter of 6 groups of Φ177.8×10.36mm casing external threads, and calculated the mean standard deviation of the sealing surface diameter deviation of each group of threads (see Table 1). The statistical method was used to evaluate the Class A standard uncertainty, and the maximum value of the mean standard deviation of the 6 groups of sealing surface diameter deviations was 0.0104mm for evaluation. The actual measurement of the mean deviation of the sealing surface diameter was based on a single measurement value as the measurement result, so u1=0.0104mm.

[0074] Table 1 External thread (male end) sealing surface diameter detection and statistical results

[0075]

[0076] ② According to the calibration report of the threaded sealing surface diameter gauge, the standard uncertainty component of the indication error is u2 = 0.006mm. According to the calibration report of the sealing surface diameter standard block, the standard uncertainty component of the standard block is u3 = 0.002mm.

[0077] ③ Calculate the combined standard uncertainty u using formula (1) c =0.012.

[0078] ④Measurement error U m =2u c =0.024.

[0079] ⑤ It is known that the design tolerance of the mean deviation of the external thread sealing surface diameter of the Φ177.8×10.36mm sleeve is ±0.050mm. According to formula (4), the inspection tolerance is calculated as ±0.050+(±0.024)=±0.074mm. (Note: External thread U b =0).

[0080] Example 2

[0081] Determination of the inspection tolerance of the mean deviation of the internal thread sealing surface diameter of a certain type of Φ177.8×10.36mm casing.

[0082] Implementation process: ① Three inspectors measured the mean deviation of the sealing surface diameter of 6 groups of internal threads of a certain thread type Φ177.8×10.36mm casing, and calculated the mean standard deviation of the sealing surface diameter deviation of each group of threads (see Table 2). The statistical method was used to evaluate the Class A standard uncertainty, and the maximum value of the mean standard deviation of the sealing surface diameter deviation of the 6 groups of threads was 0.0076mm for evaluation. The actual measurement of the mean deviation of the sealing surface diameter of the thread is based on a single measurement value as the measurement result, so u1=0.0076mm.

[0083] Table 2 Internal thread (coupling) sealing surface diameter detection and statistical results

[0084]

[0085] ② According to the calibration report of the threaded sealing surface diameter gauge, the standard uncertainty component of the indication error is u2 = 0.006mm. According to the calibration report of the sealing surface diameter standard block, the standard uncertainty component of the standard block is u3 = 0.002mm.

[0086] ③ Calculate the combined standard uncertainty u using formula (1) c =0.010mm.

[0087] ④Measurement error U m =2u c =0.020mm.

[0088] ⑤ 22 Φ177.8×10.36mm sleeves of this buckle type were randomly selected at the production site, and 50 sets of sealing surface diameter deviation values ​​were tested at different positions of each internal thread (coupling). The sealing surface diameter deviations after machining and surface treatment (phosphating) were tested respectively. The changes in the mean values ​​of the sealing surface diameter deviations before and after surface treatment (phosphating) were statistically analyzed. The statistical results are as follows: Figure 2 As shown, U b =-0.010.

[0089] ⑥ It is known that the design tolerance of the mean deviation of the internal thread sealing surface diameter of the Φ177.8×10.36mm casing is ±0.050mm. According to formula (4), the commercial inspection tolerance is calculated as ±0.050+(±0.020)+(-0.010)=-+00..0086mm.

[0090] It can be seen from Examples 1 and 2 that by using statistical methods and experimental methods, the magnitude of the influence of each influencing factor on the commercial inspection tolerance can be accurately calculated, and ultimately the commercial inspection tolerance of the mean value of the diameter deviation of the internal and external thread sealing surfaces of the Φ177.8×10.36mm casing is scientifically and accurately determined by the present invention.

[0091] Based on the above method for determining the commercial inspection tolerance of special thread parameters of oil casing, the present invention further proposes a system for determining the commercial inspection tolerance of special thread parameters of oil casing, comprising:

[0092] The inspection unit is used for different inspectors to measure the thread parameters of several special threaded joints of oil casing and pipes, and to evaluate the Class A standard uncertainty using statistical methods to obtain the standard uncertainty component of the inspector's repeatability;

[0093] An evaluation unit, used to obtain the standard uncertainty component of the measuring tool indication error and the standard uncertainty component of the standard block;

[0094] The combined standard uncertainty unit is used to determine the combined standard uncertainty based on the standard uncertainty component of the repeatability of the tester, the standard uncertainty component of the measuring instrument indication error and the standard uncertainty component of the standard block;

[0095] a determination unit for determining a measurement error based on a combined standard uncertainty;

[0096] Average increment unit, used to determine the average increment of thread parameters before and after thread surface treatment of special threaded joints of oil casing;

[0097] The inspection tolerance unit is used to determine the inspection tolerance of special thread parameters of oil casing based on measurement error and average increment.

[0098] In some embodiments, the inspection tolerance of the special thread parameters of the oil casing is determined by the following formula:

[0099] Commodity inspection tolerance = design tolerance + m + b

[0100] Among them, U b is the average increment.

[0101] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present disclosure, the size of the serial number of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present disclosure. The serial numbers of the embodiments of the present disclosure are for description only and do not represent the advantages and disadvantages of the embodiments.

[0102] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining the commercial inspection tolerance of special thread parameters of oil casing, characterized in that: The following steps are involved: Different inspectors measured the thread parameters of several special threaded joints of oil casing and pipes, and used statistical methods to evaluate the type A standard uncertainty, and obtained the standard uncertainty component of the inspector's repeatability; Obtain the standard uncertainty component of the gauge indication error and the standard uncertainty component of the standard block; Determine the combined standard uncertainty based on the standard uncertainty component of the repeatability of the tester, the standard uncertainty component of the gauge indication error, and the standard uncertainty component of the standard block; Determine the measurement error based on the combined standard uncertainty; Determine the average increment of thread parameters before and after thread surface treatment of special threaded joints of oil casing; Based on the measurement error and average increment, the inspection tolerance of special thread parameters of oil casing is determined.

2. The method for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 1 is characterized in that: The combined standard uncertainty is determined by the following formula: Among them, u c is the combined standard uncertainty; u2 is the standard uncertainty component of the repeatability of the inspector; u2 is the standard uncertainty component of the indication error of the measuring instrument; u3 is the standard uncertainty component of the standard block.

3. The method for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 1 is characterized in that: The measurement error is determined by the expanded uncertainty; The expanded uncertainty is determined by the following formula: U=ku c ; U is the expanded uncertainty; k is the coverage factor, which is 2; and the confidence probability is 95%.

4. The method for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 3 is characterized in that: The measurement error is determined by the following formula: IN m =U=2u c Among them, U m is the measurement error.

5. The method for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 1 is characterized in that: The specific steps of determining the average increment of thread parameters before and after the thread surface treatment of the special threaded joint of the oil casing are as follows: Several special threaded joints of oil casing and tubing from the same batch were randomly selected to test the thread parameter tolerances before and after the thread surface treatment at the field end. The thread parameters of each thread before and after the thread surface treatment were tested with a set sample capacity, and the average increment of the thread parameters before and after the thread surface treatment was calculated.

6. The method for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 5 is characterized in that: The surface treatment includes phosphating treatment, sandblasting treatment, copper plating treatment and hot-dip galvanizing treatment.

7. The method for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 1 is characterized in that: The inspection tolerance of the special thread parameters of the oil casing is determined by the following formula: Commodity inspection tolerance = design tolerance + U m +U b Among them, U b is the average increment.

8. The method for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 1 is characterized in that: The thread parameters include the sealing surface diameter and the thread pitch diameter.

9. A system for determining the commercial inspection tolerance of special thread parameters of oil casing, characterized in that: include: The inspection unit is used for different inspectors to measure the thread parameters of several special threaded joints of oil casing and pipes, and to evaluate the Class A standard uncertainty using statistical methods to obtain the standard uncertainty component of the inspector's repeatability; An evaluation unit, used to obtain the standard uncertainty component of the measuring tool indication error and the standard uncertainty component of the standard block; The combined standard uncertainty unit is used to determine the combined standard uncertainty based on the standard uncertainty component of the repeatability of the tester, the standard uncertainty component of the measuring instrument indication error and the standard uncertainty component of the standard block; a determination unit for determining a measurement error based on a combined standard uncertainty; Average increment unit, used to determine the average increment of thread parameters before and after thread surface treatment of special threaded joints of oil casing; The inspection tolerance unit is used to determine the inspection tolerance of special thread parameters of oil casing based on measurement error and average increment.

10. The system for determining the commercial inspection tolerance of special thread parameters of oil casing according to claim 9, characterized in that: The inspection tolerance of the special thread parameters of the oil casing is determined by the following formula: Commodity inspection tolerance = design tolerance + U m +U b Among them, U b is the average increment.

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