CN100548559C - A kind of 13Cr oil well-pipe test object preparation method - Google Patents

Abstract

The present invention relates to a kind of 13Cr oil well-pipe test object preparation method, with the oil pipe of test, bevel for welding is processed at two ends, processes circumferential equally distributed plug welding hole, some edges apart from bevel for welding end face 100mm distance; One end of two test chucks is processed into groove and developmental tube welding, and other end outside or inside are processed with screw thread, are connected with testing equipment; Plug weld root and chuck weld together, and side and developmental tube link together; Along the uniform circle reinforcement of pipe, material is a low-alloy high-strength steel, and is a plurality of uniform along pipe one circle, adopts angle welding and chuck and developmental tube to link together; At high temperature, high pressure, repeatedly under the load test condition, welding point is intact, when having solved the actual loading test of 13Cr oil pipe and the connectivity problem of chuck, adopt screw thread+glue sealing structure, reliability and success rate height, the test period is short, increase work efficiency, reduced experimentation cost.

Description

A kind of preparation method of 13Cr oil well pipe test object

technical field

The invention relates to a method for preparing a test object by welding a 13Cr martensitic stainless steel oil well oil pipe or casing with a chuck of 35CrMo or 30CrMo or the like.

Background technique

In the process of oil and gas production, materials are often in high temperature, high pressure environment and multiphase flow corrosive medium where gas, water, hydrocarbon and solid coexist. Corrosion is one of the main failure modes of metal materials. The oil and gas development and processing industry has always been one of the industries with relatively serious corrosion, and almost involves various types of corrosion. The loss caused by corrosion problems is huge every year. Strengthening corrosion protection can bring huge economic benefits to the petroleum industry, and the use of materials with excellent corrosion resistance is one of the main directions for corrosion protection.

The Kela gas field in the Tarim Oilfield contains a relatively high concentration of corrosive media. A large number of 13Cr oil well pipes are used downhole, including two types. The typical chemical composition is shown in Table 1. Due to the high temperature, high pressure and corrosive environment, the quality requirements of the pipe are very high, and the test and evaluation of the performance of the pipe is an effective means to ensure the quality of the engineering pipe.

Table 1 Typical chemical composition (wt%) of two kinds of 13Cr stainless steel

elements C Si Mn P S Cr Mo Ni V Ordinary 13Cr 0.18 0.33 0.48 0.020 0.001 12.94 0.013 0.10 0.048  Super 13Cr 0.029 0.40 0.20 0.021 0.005 12.79 0.98 4.46 0.03

When carrying out the physical test evaluation of 13Cr oil well pipe, both ends need to be connected with the chuck, and then it can be connected to the test equipment. During the high-pressure sealing test, the collet also acts as a seal for the plug. According to the technology provided by foreign suppliers, this structure cannot be welded, and it needs to adopt a threaded + glue sealing structure, which is used in laboratories of foreign manufacturers. We conducted physical experiments on three oil well pipes according to the technology provided by foreign countries. Two of them failed in the thread + glue seal structure, and the test failed. It is connected by welding, and the requirement for welding is that it cannot break or leak in the weld seam or heat-affected zone during the test. There are three main requirements for the performance of welded joints: (1) welding defects such as cracks should not occur in the weld seam and heat-affected zone; (2) the weld seam must have sufficient strength to prevent brittle fracture and fatigue cracking. The composition and metallurgical properties of the two materials, 13Cr oil well pipe and 35CrMo material chuck, are very different, and both are martensitic structures, and the weldability is very poor. Will the heat-affected zone of the 13Cr material soften or embrittle significantly after welding, can the two materials be well combined (whether a weld without metallurgical defects can be formed), and whether the performance of the joint can meet the test requirements (it cannot be welded Fracture or leakage at the joint) is the difficulty and key point in determining the welding process.

Contents of the invention

The purpose of the present invention is to solve the connection problem of 13Cr stainless steel material and 35CrMo or 30CrMo material by welding process, and ensure that the welded joint will not leak or break during high temperature, high pressure pressure test and axial tension or compression test.

The materials involved in the invention are 13Cr stainless steel oil well pipes and 35CrMo or 30CrMo chucks for testing, and the chucks also play the role of plug sealing when the high-pressure sealing test is carried out.

Specific technical features include:

(1) Structure: Firstly, the two ends of the tested oil well pipe are processed into welding grooves, and a number of plug welding holes uniformly distributed along the circumference are processed at a distance of 100mm from the end face of the welding groove; one end of the two test chucks is processed into a slope The mouth is welded to the test pipe, and the other end is threaded externally or internally, and connected to the test equipment; the root of the plug welding seam is welded to the chuck, and the side is connected to the test pipe; a circle of reinforcing ribs is uniformly distributed along the pipe, and the material It is a general low-alloy high-strength steel, and several are evenly distributed along the pipe circle, and are connected with the chuck and the test pipe by fillet welds;

(2) Welding method: use arc welding, the equipment is a DC welding machine, the polarity is reversed, the welding material is a ferrite-austenite duplex stainless steel electrode, and the chemical composition of the deposited metal is as follows by weight percentage: C ≤0.04%, Cr 21.0-23.5%, Ni 8.5-10.5%, Mo 2.5-3.5%, Mn 0.5-2.0%, Si≤0.9%, P≤0.04%, S≤0.03%, N 0.08 -0.20%, Cu≤0.75% and the balance is Fe;

The typical mechanical properties of the weld metal of this welding material can reach a yield strength of 612MPa, a tensile strength of 855MPa, an elongation of 27%, and a Charpy impact energy of -20°C of 50J.

(3) Preheat the workpiece before welding, start welding when the temperature reaches 150-200°C, and control the interlayer temperature between 150-250°C during the welding process;

Because the collet is thick, the workpiece must be heated thoroughly during preheating and postheating, otherwise the temperature will drop rapidly, and cracks may appear in the weld or heat-affected zone.

(4) The diameter of the electrode is 3.2mm. The principle of welding parameter selection is the current of the appropriate size, the arc should be as low as possible (the arc voltage is small), and the electrode should not swing as much as possible. Under the premise of good fusion, try to use fast welding speed, the recommended welding current is 90-120A, and control the welding line energy in the range of 0.5-1.0kJ/mm.

(5) Firstly, weld the main load-bearing weld. After the groove is fully welded, the weld must have at least 2mm of reinforced height, and the edge of the test tube weld must be parallel to the bead weld. The electrode cannot swing during welding, and the width is about 10mm ( The purpose is to improve the shape distribution and stress state of the weak zone in the heat-affected zone of the test tube).

(6) To weld the plug welding seam, first of all, ensure that the root and the chuck are well fused, and secondly, pay attention to stop and cool after each layer is welded, clean up the welding slag and spatter, and then weld the next layer to ensure good fusion .

(7) When the tensile strength level of the 13Cr oil well pipe reaches 850MPa or more, according to the stress situation at the welded joint during the test, use reinforcing ribs (about 200mm in length, about 80mm in width, about 10-20mm in thickness, and about 100mm in spacing) , the number depends on the diameter of the pipe, and it is evenly distributed along the pipe circle) for reinforcement. The welding of the reinforcing rib adopts the same welding consumables and process parameters, and a fillet weld is welded at the root, and the height of the welding foot is 10-15mm.

(8) After the welding work is completed, wait for the welding part to cool to about 150°C, and keep it warm for 30 minutes (be careful not to cool below 100°C), so as to promote the martensitic transformation of the welding heat-affected zone and ensure the strength of the joint. Then heat the weld seam and the 100mm range on both sides to about 400°C, keep it warm for 1 to 2 hours, and then air cool.

After many physical tests, especially under the conditions of high temperature, high pressure, and repeated loading tests, the welded joints are intact, which proves that the welding process is feasible, and the connection problem between the 13Cr oil pipe and the chuck during the physical test is solved. Compared with the screw thread + glue seal structure, the technology adopted by the invention has higher reliability and success rate, shortens the test cycle, improves work efficiency, and reduces the test cost. The technology is leading at home and abroad. Accumulated technology and experience for our unit's oil well pipe physical test, improved the technical ability of China National Petroleum Corporation, and guaranteed the quality of oilfield pipes.

Description of drawings

Fig. 113 Schematic diagram of weld structure between Cr oil well pipe and test chuck.

Among them: 1 oil well pipe, 2 test chuck, 3 main bearing weld, 4 plug weld, 5 reinforcement

Detailed ways

Example 1

There are two kinds of materials to be welded in the present invention, one is 13Cr stainless steel oil well pipe, and the other is a 35CrMo or similar material chuck used in the test for high pressure sealing test, the chuck also acts as a plug. Specific technical features include:

In the structural form shown in Figure 1, first, the two ends of the tested oil well pipe 1 are processed into welding grooves, and a number of plug welding holes uniformly distributed along the circumferential direction are processed at a distance of 100mm from the end face of the welding groove; One end of the head 2 is processed into a groove and the groove of the test pipe is welded into the main load-bearing weld 3, and the other end is threaded externally or internally to connect with the test equipment; It is connected with the test tube; a circle of reinforcing ribs 5 is evenly distributed along the tube, and the material is general low-alloy high-strength steel, and a plurality of them are evenly distributed along the tube, and are connected with the chuck and the test tube by fillet welds;

(2) Manual arc welding is used as the welding method, the equipment is a DC hammer, and the polarity is reversed (the electrode is connected to the positive). The welding material is ferritic-austenitic duplex stainless steel electrode, and the chemical composition (weight percentage) of the deposited metal is shown in the table below. The weld metal of this welding material can reach a yield strength of 612MPa, a tensile strength of 855MPa, an elongation of 27%, and a Charpy impact energy of -20°C of 50J.

C Cr Ni Mo mn Si P S N Cu ≤0.04 21.0-23.5 8.5-10.5 2.5-3.5 0.5-2.0 ≤0.9 ≤0.04 ≤0.03 0.08-0.20 ≤0.75

(3) The workpiece should be preheated before welding. Welding starts when the temperature reaches 150-200°C, and the interlayer temperature is controlled between 150-250°C during the welding process. Because the collet is thick, the workpiece must be heated thoroughly during preheating and postheating, otherwise the temperature will drop rapidly, and cracks may appear in the weld or heat-affected zone.

(4) The diameter of the electrode is 3.2mm. The principle of selecting welding parameters is the current of the appropriate size, the arc should be as low as possible (the arc voltage is small), and the electrode should not swing as much as possible. If the swing does not exceed 3 times the diameter of the electrode core. Under the premise of ensuring good fusion, try to use fast welding speed, the recommended welding current is 90-120A, and control the welding line energy in the range of 0.5-1.0kJ/mm.

(5) First, carry out the welding of the main load-bearing weld 3. After the groove is fully welded, the weld must have a reinforced height of at least 2mm, and 2 welds shall be surfacing parallel to the edge of the test pipe weld. The electrode cannot swing during welding, and the width is about 10mm (the purpose is to improve the shape and stress state of the distributed weak zone in the heat-affected zone of the test tube).

(6) To weld the plug welding seam, first of all, ensure that the root and the chuck are well fused, and secondly, pay attention to stop and cool after each layer is welded, clean up the welding slag and spatter, and then weld the next layer to ensure good fusion .

(7) When the tensile strength level of the 13Cr oil well pipe reaches 850MPa or more, according to the stress situation at the welded joint during the test, use reinforcing ribs (about 200mm in length, about 80mm in width, about 10-20mm in thickness, and about 100mm in spacing) , the number depends on the diameter of the pipe, and it is evenly distributed along the pipe circle) for reinforcement. The welding of the reinforcing rib adopts the same welding consumables and process parameters, and a fillet weld is welded at the root, and the height of the welding foot is 10-15mm.

(8) After the welding work is completed, wait for the welding part to cool to about 150°C, and keep it warm for 30 minutes (be careful not to cool below 100°C), so as to promote the martensitic transformation of the welding heat-affected zone and ensure the strength of the joint. Then heat the weld seam and 100mm on both sides to about 400°C for 1 to 2 hours and then air cool;

The content range of the chromium (Cr) element in the oil well pipe material is 12-18% by weight.

Example 2

型号为KO-13Cr-110FOX油管(普通13Cr不锈钢)采用实施例1工艺进行夹头焊接，在内压下进行5种参数的拉伸或压缩试验：(1)拉伸载荷为130,000kg，内压为0，持续时间5分钟，未发生任何泄漏和开裂；(2)拉伸载荷为89,400kg，内压为86.2MPa，持续时间5分钟，未发生任何泄漏和开裂；(3)压缩载荷为50,800kg，内压为109MPa，持续时间5分钟，未发生任何泄漏和开裂；(4)压缩载荷为90,000kg，内压为82.7MPa，持续时间5分钟，未发生任何泄漏和开裂；(5)压缩载荷为130,000kg，内压为0，载荷持续时间5分钟，在保载过程中，油管发生失稳变形，而焊接接头完好。The specifications produced by a Japanese company are

The model is KO-13Cr-110FOX oil pipe (ordinary 13Cr stainless steel) using the process of Example 1 for chuck welding, and carrying out tensile or compression tests of 5 parameters under internal pressure: (1) The tensile load is 130,000kg, and the internal pressure 0 for 5 minutes without any leakage or cracking; (2) Tensile load of 89,400kg and internal pressure of 86.2MPa for 5 minutes without any leakage or cracking; (3) Compression load of 50,800 kg, with an internal pressure of 109MPa for 5 minutes, without any leakage or cracking; (4) a compression load of 90,000kg, with an internal pressure of 82.7MPa, for 5 minutes, without any leakage or cracking; (5) compression The load is 130,000kg, the internal pressure is 0, and the load lasts for 5 minutes. During the loading process, the oil pipe is unstable and deformed, but the welded joint is intact.

Example 3

型号为KO-HP1-13Cr110 FOX的套管(超级13Cr不锈钢)，利用实施例1工艺进行夹头焊接，进行内压循环与热循环试验。加压介质为干燥氮气，利用气泡瓶检测试样泄漏情况，加压速率＜34MPa/Min。共进行两种参数的试验，试样编号分别为1Z和2Z。1Z试样在177℃，试验压力为64.5MP，2Z试样在室温，试验压力为87.9MPa，按规定试验方法循环一周时间，均未发生泄漏现象。The specifications produced by a Japanese company are

The bushing (super 13Cr stainless steel) with the model number KO-HP1-13Cr110 FOX was welded by the process of Example 1, and the internal pressure cycle and thermal cycle tests were carried out. The pressurization medium is dry nitrogen, and the leakage of the sample is detected by using a bubble bottle, and the pressurization rate is <34MPa/Min. A total of two parameters were tested, and the sample numbers were 1Z and 2Z. The 1Z sample was at 177°C, the test pressure was 64.5MPa, the 2Z sample was at room temperature, the test pressure was 87.9MPa, and the test method was cycled for one week according to the prescribed test method, and no leakage occurred.

After the test, continue to increase the test pressure until the sample fails. The internal pressure of the 1Z sample reached 131.6MPa, and the internal pressure of the 2Z sample reached 131.2 (2Z) MPa. The pipe body exploded, which was higher than the minimum yield strength of the casing internal pressure specified in the casing technical conditions. The pressure is 87.1MPa, and the welded joints are intact.

Claims (1)

1, a kind of 13Cr oil well-pipe test object preparation method is characterized in that:

To test with 13Cr stainless steel oil well pipe and the test weld together with 35CrMo material chuck,

Concrete technology comprises:

(1) structure: at first with the oil pipe of test, bevel for welding is processed at two ends, processes circumferential equally distributed plug welding hole, some edges apart from bevel for welding end face 100mm distance; One end of two test chucks is processed into groove and the welding of test tubing, and other end outside or inside are processed with screw thread, are connected with testing equipment; Plug weld root and chuck weld together, and side and developmental tube link together; Along the uniform circle reinforcement of pipe, material is general low-alloy high-strength steel, and is a plurality of uniform along pipe one circle, adopts angle welding and chuck and developmental tube to link together;

(2) welding method: select arc welding for use, equipment is DC welder, polarity is reversal connection, welding material is selected the ferritic-austenitic diphasic stainless steel electrode for use, and the chemical composition of its deposited metal is as follows by weight percentage: C≤0.04%, Cr are that 21.0-23.5%, Ni are that 8.5-10.5%, Mo are that 2.5-3.5%, Mn are that 0.5-2.0%, Si≤0.9%, P≤0.04%, S≤0.03%, N are that 0.08-0.20%, Cu≤0.75% and surplus are Fe;

(3) will carry out preheating to workpiece before the weldering, temperature begins welding when reaching 150～200 ℃, and the Control Welding Process interlayer temperature is between 150～250 ℃;

(4) adopting core diameter is 3.2mm, and welding selects for use arc voltage little, and welding current is 90～120A, and the control weld heat input is at 0.5～1.0kJ/mm;

(5) at first carry out the welding of main strength weld, groove welding completely back weld seam will have 2mm to strengthen height, and at the parallel built-up welding 2 road weld seams of developmental tube weld edge, the welding rod swing width is less than 10mm during welding;

(6) carry out the welding of plug weld, root and chuck fusion, the every layer of cooling of stopping after weld cleaned out welding slag and splashed, and welds one deck then;

(7) reach 850MPa when above when the intensity rank of oil well pipe, adopt length 200mm, width 80mm, thickness 10～20mm, the reinforcement of spacing 100mm, quantity decide on caliber, and is uniform along pipe one circle, encloses angle welding, foot welding height 10～15mm in root weldering one;

(8) after welding job is finished, wait for that the welding position is cooled to about 150 ℃, be incubated 30 minutes, then weld seam and each 100mm scope of weld seam both sides are heated to 400 ℃, be incubated air cooling after 1～2 hour.