CN115356199A - Method for evaluating hydrogen sulfide stress corrosion resistance sensitivity of oil well pipe - Google Patents
Method for evaluating hydrogen sulfide stress corrosion resistance sensitivity of oil well pipe Download PDFInfo
- Publication number
- CN115356199A CN115356199A CN202210908043.4A CN202210908043A CN115356199A CN 115356199 A CN115356199 A CN 115356199A CN 202210908043 A CN202210908043 A CN 202210908043A CN 115356199 A CN115356199 A CN 115356199A
- Authority
- CN
- China
- Prior art keywords
- sample
- test
- stress corrosion
- hydrogen sulfide
- fracture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000007797 corrosion Effects 0.000 title claims abstract description 77
- 238000005260 corrosion Methods 0.000 title claims abstract description 77
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 229910000037 hydrogen sulfide Inorganic materials 0.000 title claims abstract description 54
- 239000003129 oil well Substances 0.000 title claims abstract description 42
- 230000035945 sensitivity Effects 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims description 33
- 238000012360 testing method Methods 0.000 claims abstract description 98
- 239000000463 material Substances 0.000 claims abstract description 33
- 238000012545 processing Methods 0.000 claims abstract description 14
- 239000012085 test solution Substances 0.000 claims abstract description 11
- 238000007789 sealing Methods 0.000 claims abstract description 5
- 239000000243 solution Substances 0.000 claims description 17
- 238000005259 measurement Methods 0.000 claims description 12
- 230000003321 amplification Effects 0.000 claims description 2
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 2
- 238000009864 tensile test Methods 0.000 abstract description 14
- 238000011156 evaluation Methods 0.000 abstract description 7
- 238000001514 detection method Methods 0.000 abstract description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 238000004381 surface treatment Methods 0.000 description 10
- 238000005336 cracking Methods 0.000 description 9
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- 229910052717 sulfur Inorganic materials 0.000 description 6
- 239000011593 sulfur Substances 0.000 description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 239000004519 grease Substances 0.000 description 5
- 239000002932 luster Substances 0.000 description 5
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 229910052979 sodium sulfide Inorganic materials 0.000 description 2
- GRVFOGOEDUUMBP-UHFFFAOYSA-N sodium sulfide (anhydrous) Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009533 lab test Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052976 metal sulfide Inorganic materials 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000012086 standard solution Substances 0.000 description 1
- 239000010913 used oil Substances 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/56—Investigating resistance to wear or abrasion
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/006—Crack, flaws, fracture or rupture
- G01N2203/0067—Fracture or rupture
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
- G01N2203/0647—Image analysis
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/02—Details not specific for a particular testing method
- G01N2203/06—Indicating or recording means; Sensing means
- G01N2203/067—Parameter measured for estimating the property
- G01N2203/0676—Force, weight, load, energy, speed or acceleration
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Biodiversity & Conservation Biology (AREA)
- Ecology (AREA)
- Environmental & Geological Engineering (AREA)
- Environmental Sciences (AREA)
- Testing Resistance To Weather, Investigating Materials By Mechanical Methods (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
Abstract
The invention provides an evaluation method for hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe, which comprises the following steps: processing a sample into a set size, and pretreating the surface of the sample; mounting the sample on a stretching device in a reaction kettle, adding a proper amount of test solution into the reaction kettle, and sealing the reaction kettle; adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to 50-80% yield strength value of the test sample; after the test sample is stabilized, a slow tensile loading test is carried out at a set strain rate until the test sample is broken, and a test result is recorded; and (4) taking out the fractured tensile sample, and selecting the area of the step crack plane with the largest area on the fracture to evaluate the stress corrosion resistance of the oil well pipe material through fracture morphology observation. The slow tensile test result is accurately analyzed by using the step crack parameters on the fracture, so that the aim of quantitatively analyzing the stress corrosion resistance sensitivity of the oil well pipe material is fulfilled, the test period is shortened, and the detection efficiency is improved.
Description
Technical Field
The invention relates to the technical field of corrosion tests, in particular to an evaluation method for hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe.
Background
In recent years, with the exploration and development of oil and gas wells in ultra-deep, ultra-high temperature and ultra-high corrosion harsh environments, the working condition environment of the oil and gas wells generally has the characteristics of high temperature, high pressure, high CO2, high H2S, high Cl and high salinity, and the stress corrosion cracking failure of oil well pipes is caused by the complex and harsh working conditions and the special operation process, so that the normal production and operation of oil and gas fields are seriously influenced. In particular, in the exploration and exploitation process of sulfur-containing oil and gas resources, the used oil well pipe is easy to generate hydrogen sulfide stress corrosion cracking, which is low-stress brittle fracture, the crack propagation speed is high, the fracture has burstiness, the risk coefficient is highest, and major accidents and casualties are easy to cause.
In view of the above situation, relevant standards are established at home and abroad to reduce the risk caused by hydrogen Sulfide Stress Corrosion Cracking (SSCC), and the SSCC resistance of the oil well pipe is strictly detected and evaluated. Standard tensile tests (method A) are specified in NACE Standard TM0177-2005 indoor tests of metal sulfide stress corrosion cracking resistance and stress corrosion cracking resistance in H2S environment and GB/T4157-2006 laboratory tests of metal special form environmental cracking resistance in hydrogen sulfide environment, the hydrogen sulfide stress corrosion resistance performance is determined by the fracture time in the experimental period, products which do not fracture after exceeding 720H are qualified, products which fracture within 720H are unqualified, and the test result only can give failure and non-failure information. Similarly, a four-point bending loading test in the ASTM G39-99 standard is also a common method for evaluating the stress corrosion resistance of the oil well pipe, a standard solution of the method A is adopted, a product which is not broken within 720h is qualified, a product which is broken within 720h is unqualified, whether cracks exist on the surface of a sample which is not broken is observed by a magnifying lens of 10 times, and the test result can only give out failure and non-failure information. The methods have the defects of harsh test conditions, long test period and test results, and can only give failure and non-failure information, the hydrogen sulfide stress corrosion resistance grade of a non-failure sample cannot be evaluated, other test means are required to be combined for comprehensive evaluation, the test period is prolonged, and the test cost is increased.
Therefore, a new method is needed to be found, which can quickly and accurately evaluate the hydrogen sulfide stress corrosion resistance of the oil well pipe material, shorten the test period and reduce the test cost. The slow-rate tensile test is fast, accurate, high in reproducibility, and has a lot of obtained parameter information, so that the slow-rate tensile test is widely used by extensive researchers, and is one of the more mature and more advanced standard methods for researching stress corrosion at present. When the hydrogen sulfide stress corrosion resistance of the oil well pipe is evaluated by a slow tensile test, fracture morphology and a stress corrosion cracking sensitivity index are generally adopted for evaluation, and if the fracture morphology is a brittle fracture characteristic or the stress corrosion cracking sensitivity index is larger than a certain value (generally 25%), the oil well pipe material is generally considered to have stress corrosion cracking sensitivity in a corresponding research system.
However, in the actual test process, the fracture morphology is often found to be a ductile fracture or mixed fracture mechanism, the stress corrosion sensitivity index calculated by using the elongation after fracture, the shrinkage after fracture and the yield strength loss ratio is lower than 25%, the material is generally considered to have no stress corrosion sensitivity, but a stepped crack platform appears near the fracture circumference, which indicates that the material actually has obvious stress corrosion sensitivity, and the stress corrosion sensitivity is not consistent with the test result. In addition, even if two materials with the same stress corrosion sensitivity index have larger difference of actual stress corrosion resistance, particularly step cracks in the fracture morphology perpendicular to the stretching direction are distributed along the circumferential direction, and the size and the number of the step cracks are obviously different, so that the hydrogen sulfide stress corrosion resistance of the materials is not favorable for accurately evaluating.
Based on the above, the invention is provided for accurately and quickly evaluating the hydrogen sulfide stress corrosion resistance of the oil well pipe material.
Disclosure of Invention
In order to overcome the defects in the background technology, the invention provides an evaluation method for the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe, which can quickly and accurately evaluate the hydrogen sulfide stress corrosion resistance of an oil well pipe material, and can accurately analyze the slow tensile test result by using the step crack plane parameters on a fracture, thereby achieving the purpose of quantitatively evaluating the stress corrosion resistance sensitivity of the oil well pipe material, shortening the test period and improving the detection efficiency.
In order to achieve the purpose, the invention adopts the following technical scheme:
an evaluation method for the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe comprises the following steps:
step 1: processing a sample into a set size, and pretreating the surface of the sample;
and 2, step: mounting the sample on a stretching device in a reaction kettle, adding a proper amount of test solution into the reaction kettle, and sealing the reaction kettle;
and 3, step 3: adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to 50-80% yield strength value of the test sample;
and 4, step 4: after the test sample is stabilized, a slow tensile loading test is carried out at a set strain rate until the test sample is broken, and a test result is recorded;
and 5: and finally, taking out the fractured tensile sample, removing corrosion products on the surface of the sample and the fracture, and selecting the area of the step crack plane with the largest area on the fracture to evaluate the stress corrosion resistance of the oil well pipe material through fracture morphology observation.
Further, the strain of the slow tensile loading testRate of 1X 10 -7 ～5×10 -5 mm/s。
Further, the strain rate of the rapid stretching is more than or equal to 1 x 10 -4 mm/s。
Further, the evaluating the stress corrosion resistance of the oil well pipe material in the step 5 specifically comprises the following steps:
1) The crack propagation direction is along the step crack plane, and the crack propagates from the outer surface of the sample to the center along the radius and simultaneously propagates along the circumferential direction;
2) The fracture appearance observation adopts a laser confocal microscope, the amplification factor is 20-100, the fracture surface is uneven, step cracks appear in the circumferential direction, and meanwhile, the distance between a workbench and a lens is adjusted to ensure that the fracture appearance of a sample is clear and the step crack area is accurately measured;
3) The step crack plane selects the largest area on the fracture to measure the step crack area;
4) Selecting a vertical projection area for calculating the area of the step crack;
5) The plane shape of the step crack is an ellipse, the stress corrosion resistance is related to the maximum vertical projection area S of the step crack, the formula of the stress corrosion sensitivity R is simplified to be R = K R/b S, wherein b is the length of the minor axis of the ellipse, namely the radial crack propagation depth, R is the radius of a slow tensile sample test area, and K is a constant.
Further, the slow tensile loading test is loaded along the length direction of the sample, and the tensile direction is parallel to the length direction of the sample.
Further, the stretching direction of the slow tensile loading test is vertical to the plane of the step crack, and the stretching direction is vertical to the crack propagation direction and has a difference of 90 degrees.
Furthermore, the test solution is a Nace standard A solution, and the concentration of hydrogen sulfide is 0-3500 ppm.
Compared with the prior art, the invention has the beneficial effects that:
the invention tests the stress corrosion resistance of the oil well pipe material in a service environment or a simulated actual environment, evaluates the stress corrosion resistance sensitivity of the oil well pipe material through fracture morphology observation and the area of a step crack plane, further evaluates the practicability of the oil well pipe material in a specific working condition environment, and guides material selection and equipment maintenance.
Drawings
FIG. 1 is a vertical projection of a fracture specimen at zero hydrogen sulfide concentration for an embodiment of the present invention
FIG. 2 is a macroscopic stereogram of a fracture sample when the concentration of hydrogen sulfide is zero in the embodiment of the invention;
FIG. 3 is a vertical projection of a fracture specimen at a hydrogen sulfide concentration of 1000ppm for an embodiment of the invention;
FIG. 4 is a macroscopic view of the fracture specimen at a hydrogen sulfide concentration of 1000ppm for an example of the present invention;
FIG. 5 is a vertical projection of a fracture specimen at a hydrogen sulfide concentration of 3500ppm for an embodiment of the invention;
FIG. 6 is a macroscopic view of a fracture sample with a hydrogen sulfide concentration of 3500ppm according to an embodiment of the present invention;
FIG. 7 is a graph of the radial width b of the crack plane of the step and the elliptical perpendicular projected area S of an embodiment of the present invention.
Detailed Description
The following detailed description of the present invention will be made with reference to the accompanying drawings.
An evaluation method for the hydrogen sulfide stress corrosion resistance sensitivity of an oil well pipe comprises the following steps:
step 1: processing a sample into a set size, and pretreating the surface of the sample;
and 2, step: mounting the sample on a stretching device in a reaction kettle, adding a proper amount of test solution into the reaction kettle, and sealing the reaction kettle; the test solution is Nace standard A solution, and the concentration of hydrogen sulfide is 0-3500 ppm.
And 3, step 3: adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to 50-80% yield strength value of the test sample; the strain rate of the rapid stretching is more than or equal to 1 multiplied by 10 -4 mm/s。
And 4, step 4: after the test sample is stabilized, a slow tensile loading test is carried out at a set strain rate until the test sample is broken, and a test result is recorded; the strain rate of the slow tensile loading test is 1 multiplied by 10 -7 ～5×10 -5 mm/s。
And 5: and finally, taking out the fractured tensile sample, removing corrosion products on the surface of the sample and the fracture, and selecting the area of the step crack plane with the largest area on the fracture through fracture morphology observation to evaluate the stress corrosion resistance of the oil well pipe material.
The method specifically comprises the following steps:
1) The crack propagation direction is along the step crack plane, and the crack propagates from the outer surface of the sample to the center along the radius and simultaneously propagates along the circumferential direction;
2) The fracture appearance observation adopts a laser confocal microscope, the magnification is 20-100, the fracture surface is uneven, step cracks appear in the circumferential direction, and meanwhile, the distance between a workbench and a lens is adjusted to ensure that the fracture appearance of a sample is clear and the step crack area is accurately measured;
3) The step crack plane selects the largest area on the fracture to measure the step crack area;
4) Selecting a vertical projection area for calculating the area of the step crack;
5) As shown in fig. 7, the planar shape of the stepped crack is an ellipse, the stress corrosion resistance is related to the maximum vertically projected area S of the stepped crack, and the stress corrosion sensitivity R is simplified to R = kr/bss, where b is the length of the minor axis of the ellipse, i.e., the radial crack propagation depth, R is the radius of the slow tensile specimen test area, and K is a constant.
The fracture appearance is observed by a microscope, the magnification is 20-100, when the step crack is small, the magnification is large, when the step crack is large, the magnification is small, the sample fracture appearance is completely presented, and the step crack area is accurately measured.
The slow tensile loading test is loaded along the length direction of the sample, and the tensile direction is parallel to the length direction of the sample. The stretching direction of the slow stretching loading test is vertical to the plane of the step crack, and the stretching direction is vertical to the crack propagation direction and has a difference of 90 degrees.
Example 1
The test material is a 110-grade sulfur-resistant oil well pipe, the yield strength is 800Mpa, and the method consists of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack area measurement.
The sample processing in the step I is to process the test material into a proper cylindrical tensile sample with the length of 72mm, the diameter of a test area of 6.40mm and the surface smoothness of 0.3 mu m;
the surface treatment in the step II is to clean the sample in the step I by ultrasonic waves, and the sample is respectively cleaned in acetone and absolute ethyl alcohol once for removing residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to adopt a slow strain rate tensile testing machine, the test temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, the reaction kettle is closed, high-purity nitrogen is introduced to remove oxygen for 2 hours, the concentration of hydrogen sulfide in the solution is 0, a sample is loaded to 600Mpa in advance, the sample is kept in an elastic stress deformation stage, and then the sample is subjected to 5 x 10 -6 The slow tensile loading test is started at the strain rate of mm/s, after the test is finished, the test result is recorded, the fractured tensile sample is taken out, corrosion products on the surface of the sample and the fracture are removed, the surface of the sample is ensured to present metallic luster, and the fracture appearance is clear;
and in the step IV, fracture morphology observation and step crack area measurement are performed by vertically placing a fractured tensile sample on an objective table by using a laser confocal microscope, wherein the tensile direction is vertical to the plane of the objective table, the distance between the fracture sample and a lens is properly adjusted, the magnification is 100 times, the fracture morphology is shot after focusing is clear, the fracture is in a cup cone shape and belongs to ductile fracture without stress corrosion, the step crack area S is marked as 0, a stress corrosion sensitivity formula R =3R/b S is introduced, and the test result is shown in Table 1.
Example 2
The test material is a 110-grade sulfur-resistant oil well pipe, the yield strength is 800Mpa, and the method consists of sample I processing, II surface treatment, III slow tensile loading test, IV fracture morphology observation and step crack area measurement.
The sample processing in the step I is to process the test material into a proper cylindrical tensile sample, wherein the length of the sample is 72mm, the diameter of a test area is 6.40mm, and the surface finish degree is 0.3 mu m;
the surface treatment in the step II is to wash the sample in the step I by ultrasonic waves, and the sample is washed in acetone and absolute ethyl alcohol respectively for one time so as to remove residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to adopt a slow strain rate tensile testing machine, inject Nace standard A solution into a reaction kettle, introduce high-purity nitrogen to remove oxygen for 2 hours, add a proper amount of analytically pure sodium sulfide, ensure the concentration of hydrogen sulfide in the solution to be 1000ppm after full reaction, seal the reaction kettle, load the sample to 600Mpa in advance, keep the sample in an elastic stress deformation stage, and then follow 5 × 10 -6 The slow tensile loading test is started at the strain rate of mm/s, after the test is finished, the test result is recorded, the fractured tensile sample is taken out, corrosion products on the surface of the sample and the fracture are removed, the surface of the sample is ensured to present metallic luster, and the fracture appearance is clear;
and IV, fracture morphology observation and step crack area measurement in the step IV are carried out by vertically placing a fractured tensile sample on an objective table by adopting a laser confocal microscope, wherein the tensile direction is vertical to the plane of the objective table, properly adjusting the distance between the fracture sample and a lens, the magnification is 100 times, photographing the fracture morphology after focusing is clear, selecting the largest step crack plane, and calculating the radial width b and the elliptical vertical projection area S (mm) of the step crack plane through matched software, wherein the radial width b and the elliptical vertical projection area S (mm) of the step crack plane are shown in figures 3-4 2 ) The formula R =3R/b × S for stress corrosion sensitivity was introduced, and the test results are shown in table 1.
Example 3
The test material is a 110-grade sulfur-resistant oil well pipe, the yield strength is 800Mpa, and the method consists of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack area measurement.
The sample processing in the step I is to process the test material into a proper cylindrical tensile sample, wherein the length of the sample is 72mm, the diameter of a test area is 6.40mm, and the surface finish degree is 0.3 mu m;
the surface treatment in the step II is to clean the sample in the step I by ultrasonic waves, and the sample is respectively cleaned in acetone and absolute ethyl alcohol once for removing residues and grease on the surface of the sample;
the slow tensile loading test in the step III adopts a slow strain rate tensile testing machine, the testing temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, the reaction kettle is closed, high-purity nitrogen is firstly introduced to remove oxygen for 2 hours, then high-purity hydrogen sulfide gas (99.99%) is introduced until the solution is saturated, the concentration of hydrogen sulfide in the solution is 3500ppm at room temperature and normal pressure, a sample is loaded to 600Mpa in advance, the sample is kept at an elastic stress deformation stage, and then the sample is loaded according to 5 x 10 -6 The slow tensile loading test is started at the strain rate of mm/s, after the test is finished, the test result is recorded, the fractured tensile sample is taken out, corrosion products on the surface of the sample and the fracture are removed, the surface of the sample is ensured to present metallic luster, and the fracture appearance is clear;
step IV, fracture appearance observation and step crack area measurement are carried out by vertically placing a fractured tensile sample on an objective table by using a laser confocal microscope, wherein the tensile direction is vertical to the plane of the objective table, properly adjusting the distance between a fracture and a lens, the magnification is 100 times, taking the fracture appearance after focusing is clear, selecting the largest step crack plane, and calculating the radial width b and the elliptical vertical projection area S (mm) of the step crack plane through matched software, wherein the radial width b and the elliptical vertical projection area S (mm) of the step crack plane are shown in figures 5-6 2 ) The formula R =3R/b × S for stress corrosion sensitivity was introduced, and the test results are shown in table 1.
TABLE 1 Slow tensile test results for oil well pipes at different hydrogen sulfide concentrations
From the above test results, it can be seen that: in a Nace standard A solution, when the concentration of hydrogen sulfide is zero, the oil well pipe material is not subjected to stress corrosion, a fracture is in a cup cone shape and belongs to ductile fracture, the sensitivity index of the stress corrosion is 0, the sensitivity index of the stress corrosion of the oil well pipe material is increased from 56.75 to 86.37 with the increase of the concentration of the hydrogen sulfide, the fracture appearance presents step cracks, and the fracture appearance has obvious stress corrosion characteristics which are similar to the conventional calculation results of the sensitivity of the stress corrosion, such as the elongation loss ratio and the fracture time loss ratio. The method realizes the measurement of the hydrogen sulfide stress corrosion resistance sensitivity index of the oil well pipe, and more accurately and comprehensively evaluates the stress corrosion resistance of the oil well pipe material through fracture morphology observation and step crack area calculation.
Example 4
The samples used in the test were two types of sulfur-resistant oil country tubular goods A and B, which were two different types of oil country tubular goods (for example, oil country tubular goods different in material and different in rolling, heat treatment, and the like, and the same explanation is given here in the following examples). The method comprises the steps of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack area measurement.
The sample processing in the step I is to process the test material into a proper cylindrical tensile sample with the length of 72mm, the diameter of a test area of 6.40mm and the surface smoothness of 0.3 mu m;
the surface treatment in the step II is to wash the sample in the step I by ultrasonic waves, and the sample is washed in acetone and absolute ethyl alcohol respectively for one time so as to remove residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to adopt a slow strain rate tensile testing machine, the test temperature is room temperature, a Nace standard A solution is injected into a reaction kettle, the reaction kettle is closed, high-purity nitrogen is firstly introduced to remove oxygen for 2 hours, then high-purity hydrogen sulfide gas (99.99%) is introduced until the solution is saturated, the concentration of hydrogen sulfide in the solution is 3500ppm at room temperature and normal pressure, and then the hydrogen sulfide concentration is 1 x 10 -7 Strain rate in mm/s onset of slow draw plusCarrying out a test, recording a test result after the test is finished, taking out a fractured tensile sample, removing corrosion products on the surface of the sample and a fracture, and ensuring that the surface of the sample presents metallic luster and the fracture is clear in appearance;
and IV, fracture morphology observation and step crack area measurement in the step IV are carried out by vertically placing a fractured tensile sample on an objective table by adopting a laser confocal microscope, wherein the tensile direction is vertical to the plane of the objective table, properly adjusting the distance between a fracture and a lens, the magnification is 80 times, photographing the fracture morphology after focusing is clear, selecting the largest step crack plane, and calculating the radial width b and the elliptical vertical projection area S (mm) of the step crack plane through matched software 2 ) The formula of stress corrosion sensitivity R =3R/b × S is introduced, the test results are shown in table 2, and the analysis shows that: the stress corrosion sensitivity is in the order of high to low; b is>A。
Table 2 slow tensile test results of oil well pipes
Example 5
The samples used in the test were A and B sulfur-resistant oil country tubular goods, which were two different oil country tubular goods (for example, oil country tubular goods of different materials or different processes such as rolling and heat treatment, and the same explanations are given in the following examples). The method comprises the steps of sample I processing, surface treatment II, slow tensile loading test III, fracture morphology observation IV and step crack area measurement.
The sample processing in the step I is to process the test material into a proper cylindrical tensile sample, wherein the length of the sample is 72mm, the diameter of a test area is 6.40mm, and the surface finish degree is 0.3 mu m;
the surface treatment in the step II is to clean the sample in the step I by ultrasonic waves, and the sample is respectively cleaned in acetone and absolute ethyl alcohol once for removing residues and grease on the surface of the sample;
the slow tensile loading test in the step III is to inject Nace standard A solution into a slow strain rate tensile testing machineIntroducing high-purity nitrogen into a reaction kettle to remove oxygen for 2 hours, adding a proper amount of analytically pure sodium sulfide, fully reacting to ensure that the concentration of hydrogen sulfide in the solution is 1000ppm, sealing the reaction kettle, and then carrying out reaction according to 5 x 10 -5 The method comprises the following steps of (1) starting a slow tensile loading test at a strain rate of mm/s, recording a test result after the test is finished, taking out a fractured tensile sample, removing corrosion products on the surface and fracture of the sample, and ensuring that the surface of the sample presents metallic luster and the fracture appearance is clear;
and IV, fracture morphology observation and step crack area measurement in the step IV are carried out by vertically placing a fractured tensile sample on an objective table by adopting a laser confocal microscope, wherein the tensile direction is vertical to the plane of the objective table, properly adjusting the distance between a fracture and a lens, the magnification is 80 times, photographing the fracture morphology after focusing is clear, selecting the largest step crack plane, and calculating the radial width b and the elliptical vertical projection area S (mm) of the step crack plane through matched software 2 ) The formula of stress corrosion sensitivity R =3R/b × S is introduced, the test results are shown in table 3, and the analysis shows that: the stress corrosion sensitivity is in the order of high to low; b is>A。
TABLE 3 Slow tensile test results for oil well pipes
The above embodiments are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the above embodiments. The methods used in the above examples are conventional methods unless otherwise specified.
Claims (7)
1. The method for evaluating the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe is characterized by comprising the following steps of:
step 1: processing a sample into a set size, and pretreating the surface of the sample;
step 2: mounting the sample on a stretching device in a reaction kettle, adding a test solution into the reaction kettle, and sealing the reaction kettle;
and step 3: adjusting the concentration of hydrogen sulfide in the test solution, and quickly stretching and preloading the hydrogen sulfide to 50-80% yield strength value of the test sample;
and 4, step 4: after the test sample is stabilized, a slow tensile loading test is carried out at a set strain rate until the test sample is broken, and a test result is recorded;
and 5: and finally, taking out the fractured tensile sample, removing corrosion products on the surface of the sample and the fracture, and selecting the step crack plane with the largest area on the fracture to evaluate the stress corrosion resistance of the oil well pipe material through fracture morphology observation.
2. The method for evaluating the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe according to claim 1, wherein the strain rate of the slow tensile loading test is 1 x 10 -7 ～5×10 -5 mm/s。
3. The method according to claim 1, wherein the strain rate of the rapid elongation is 1 x 10 or more -4 mm/s。
4. The method for evaluating the stress corrosion resistance sensitivity of the oil well pipe to the hydrogen sulfide according to claim 1, wherein the evaluating the stress corrosion resistance performance of the oil well pipe material in the step 5 specifically comprises the following steps:
1) The crack propagation direction is along the step crack plane, and the crack propagates from the outer surface of the sample to the center along the radius and simultaneously propagates along the circumferential direction;
2) The fracture appearance observation adopts a laser confocal microscope, the amplification factor is 20-100, the fracture surface is uneven, a step crack plane appears in the circumferential direction, and meanwhile, the distance between a workbench and a lens is adjusted to ensure that the fracture appearance of a sample is clear and the step crack area is accurately measured;
3) The step crack plane selects the step crack with the largest area on the fracture for measurement;
4) Selecting a vertical projection area for calculating the area of the step crack;
5) The plane shape of the step crack is an ellipse, the stress corrosion resistance is related to the maximum vertical projection area S of the step crack, the formula of the stress corrosion sensitivity R is simplified to be R = K R/b S, wherein b is the length of the minor axis of the ellipse, namely the radial crack propagation depth, R is the radius of a slow tensile sample test area, and K is a constant.
5. The method for evaluating the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe according to claim 1, wherein the slow tensile load test is loaded along the length direction of the sample, and the tensile direction is parallel to the length direction of the sample.
6. The method for evaluating the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe according to claim 1, wherein the stretching direction of the slow tensile loading test is perpendicular to the step crack plane, and the stretching direction is perpendicular to the crack propagation direction and is different from the crack propagation direction by 90 degrees.
7. The method for evaluating the hydrogen sulfide stress corrosion resistance sensitivity of the oil well pipe according to claim 1, wherein the test solution is a Nace standard A solution, and the concentration of hydrogen sulfide is 0-3500 ppm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210908043.4A CN115356199A (en) | 2022-07-29 | 2022-07-29 | Method for evaluating hydrogen sulfide stress corrosion resistance sensitivity of oil well pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210908043.4A CN115356199A (en) | 2022-07-29 | 2022-07-29 | Method for evaluating hydrogen sulfide stress corrosion resistance sensitivity of oil well pipe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115356199A true CN115356199A (en) | 2022-11-18 |
Family
ID=84031067
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210908043.4A Pending CN115356199A (en) | 2022-07-29 | 2022-07-29 | Method for evaluating hydrogen sulfide stress corrosion resistance sensitivity of oil well pipe |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115356199A (en) |
-
2022
- 2022-07-29 CN CN202210908043.4A patent/CN115356199A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US11788951B2 (en) | Testing method to evaluate cold forming effects on carbon steel susceptibility to hydrogen induced cracking (HIC) | |
| CN105891093B (en) | A kind of detection method of ferromagnetic metal material resistance against hydrogen cracking performance | |
| CN111982705A (en) | Economical anti-H2S-CO2Stress corrosion performance testing method for oil well pipe | |
| KR20170104779A (en) | Method for Predicting Mechanical Properties of Steel Pipe | |
| CN115356200A (en) | Oil well pipe hydrogen sulfide stress corrosion resistance sensitivity testing method based on fracture sample | |
| CN103439473A (en) | Assessment method for state of heating surface of 12Cr1MoV steel | |
| CN110763758B (en) | Method for determining relation between defects and fatigue performance based on nondestructive testing | |
| CN106769439B (en) | A kind of test method of line steel hot rolling roll bending yield strength | |
| CN113884430A (en) | Comprehensive evaluation method and device for metal corrosion degree based on image recognition | |
| CN115356199A (en) | Method for evaluating hydrogen sulfide stress corrosion resistance sensitivity of oil well pipe | |
| CN110646306B (en) | Method for evaluating segregation of continuous casting billet through hardness | |
| CN113053471A (en) | Method for nondestructive online detection of Brinell hardness of fan main shaft | |
| CN113486458A (en) | DEFORM simulation-based method for predicting influence of anisotropy on steel bending cracking | |
| Chaouadi et al. | Fracture toughness characterization of vessel forging with hydrogen flaked specimens | |
| CN103103920A (en) | Manufacturing method for tempering cable clip applied to suspension bridge | |
| CN113125258A (en) | Method for measuring mechanical property of metal material | |
| CN109916737A (en) | A method of test oil well pipe anti-stress corrosion performance | |
| CN115931567B (en) | Stress corrosion sensitivity assessment method and system for welded component | |
| Andrews et al. | Variation of the fracture toughness of a high-strength pipeline steel under cathodic protection | |
| CN114184488B (en) | Quick testing method for service life of optical cable of oil well | |
| Kula et al. | Investigating fatigue strength of vacuum carburized 17CrNi6-6 steel using a resonance high frequency method | |
| CN117168978A (en) | Corrosion pit volume-based evaluation method for hydrogen sulfide stress corrosion resistance of oil well pipe | |
| CN115655938A (en) | Conversion method of hardness in Rich and Brinell of P91 steel | |
| CN114894647B (en) | Alloy pre-film elastic modulus testing method and application thereof | |
| Jończyk et al. | The Selected Measurement Problems in the Aspect of the Non-Destructive Testing of the Gear Wheels and the other Parts |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |