Shaping agent for repairing high-strength large-deformation small-drift-diameter casing deformation well and preparation method

Abstract

The invention discloses a shaping agent for repairing a high-strength large-deformation small-drift-diameter casing deformation well and a preparation method, the shaping agent comprises the following components in percentage by mass: 5-10% of aluminum, 3-5% of hexanitrohexaazaisowurtzitane, 5-10% of trinitrotoluene, 4-8% of a composite desensitizing agent, 8-12% of a release agent and the balance of octogen, and the composite desensitizing agent is polyester and microcrystalline wax. Aiming at the problem of small drift diameter of the sleeve caused by deformation of the high-strength sleeve, the invention develops the low-paintless and high-explosive-strength explosive reshaping agent which conforms to the reshaping and repairing of the sleeve, and a traditional beewax or ozokerite type paintless agent is replaced by a composite desensitizing agent consisting of polyester and microcrystalline wax, so that the explosive reshaping agent can be used for reshaping and repairing the sleeve while the paintless feeling of the explosive reshaping agent is greatly reduced. The explosion effect is effectively guaranteed, and the device plays an important role in shaping of the small-drift-diameter casing pipe on an oil field.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield casing repair, in particular to a high-strength, large-deformation, small-diameter casing deformation well repairing plastic medicine and a preparation method thereof. Background Art

[0002] Casing is used to support the well wall of oil and gas wells to ensure the normal operation of the drilling process and the entire oil and gas well after completion. After the casing is lowered and cemented after drilling, the casing in the well begins to be continuously subjected to high temperature and high pressure until the oil and gas production is completed. This process may be accompanied by multiple downhole operations, during which formation creep, formation water corrosion, etc. will affect the quality of the casing, causing the casing to bend, shrink or even break. Such oil wells are collectively referred to as casing change wells, which will affect the production of oil and gas wells and various production increase measures, or even cause them to be scrapped. These casing change wells need to be repaired. At present, casing repair includes mechanical repair (such as channel shaping, drilling, grinding, milling, etc.) and explosive shaping. Mechanical shaping is more effective for relatively low-strength casings such as J55 and N80, but it is difficult to implement mechanical casing repair for high-strength casings such as TP125V, requiring too much equipment and a long construction period, resulting in high well repair costs. The explosive casing repair process has a wider range of adaptability than the mechanical shaping process, greatly simplifies the construction process, and shortens the well repair period.

[0003] Explosive shaping is a means of casing repair. Its mechanism is to use the strong shock wave generated by the explosion of explosives to propagate in the liquid medium in the casing. When the shock wave and the explosive gas reach the inner surface of the casing at the damaged part, an outward pressure wave is generated, causing the casing of the casing deformation section to expand outward, thereby expanding the inner diameter of the casing, allowing the operating tools, pipe strings, etc. to pass through the deformation section, so as to achieve the purpose of shaping and repairing the casing.

[0004] Traditional explosive shaping charges are mainly RDX, TNT, ammonium nitrate explosives, and mixed explosives of RDX and urea nitrate. Conventional oil and gas production uses 5-1 / 2" N80 or J55 casings, with a peak pressure of about 300MPa during the implementation process. The diameter size of the casing after repair can reach more than 100mm. High-strength, deformed small-diameter casings, such as TP125V steel-grade casings, have much higher strength than N80 or J55 steel-grade casings. At the same time, this casing is widely used in deep wells and reservoir formation confining pressure. , the temperature is high, the above-mentioned types of plastic explosives can no longer meet the needs of on-site explosive shaping: RDX has a relatively low temperature resistance, which cannot exceed 120℃; TNT has been preliminarily sorted out and referenced by the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization; the temperature resistance and detonation speed of ammonium nitrate explosives also cannot meet the requirements of on-site application. Therefore, it is necessary to re-develop the plastic explosives suitable for the explosive shaping of this type of casing according to the strength of the high-strength, small-diameter (minimum diameter 50mm) casing after deformation and the application environment of the casing.

[0005] As the single explosive with the best comprehensive performance, Octogen has been widely used in military industry and oil field perforation. Octogen replaces the commonly used RDX explosive in the past to prepare an aluminum-containing mixed explosive with Octogen as the main body, which can effectively improve the detonation velocity of this type of explosive. The explosive has high explosion energy, low mechanical sensitivity, high charge density and good quality. In theory, it can better meet the technical indicators and safety requirements of explosive shaping. However, Octogen has a relatively high sensitivity, which poses great safety hazards in processing, reservoir and transportation. It needs to be reduced in sensitivity before it can be used in explosive shaping. Therefore, the requirements for the detonation agent are relatively high, and the problem of insensitivity cannot be ignored. Beeswax or ozokerite is generally used as a detonating agent in the suppression of mixed explosives. When the amount is small, the insensitivity effect is poor; when the amount is large, the explosive energy of the explosive is weakened, and it is easy to float on the wall, resulting in uneven dispersion. Therefore, it is necessary to further optimize the formula of the explosive from this point of view. Summary of the invention

[0006] In view of the above-mentioned problems, the present invention provides a high-strength, large-deformation, small-diameter casing deformation well repairing shaping agent and a preparation method thereof.

[0007] The technical solution of the present invention is:

[0008] A high-strength, large-deformation, small-diameter casing deformation well repairing plastic medicine, which comprises, by mass percentage, 5-10% aluminum, 3-5% hexanitrohexaazaisowurtzitane, 5-10% trinitrotoluene, 4-8% composite insensitive agent, 8-12% release agent, and the balance is octogen;

[0009] Wherein, the composite desensitizing agent is polyester and microcrystalline wax, and the mass ratio of polyethylene terephthalate and microcrystalline wax in the composite desensitizing agent is 1:2-3.

[0010] Furthermore, the polyester in the composite desensitizing agent is polyethylene terephthalate.

[0011] Description: By using polyethylene terephthalate and microcrystalline wax as a composite desensitizing agent, it is because polyester plays an active liaison role between microcrystalline wax and trinitrotoluene. This effect allows the desensitizing material to be evenly dispersed between the octogen particles and fully fills the gaps between the octogen particles, thereby achieving a better desensitizing effect when the amount used is less than that of beeswax or ozokerite type desensitizing agents.

[0012] Furthermore, the release agent is a graphite release agent.

[0013] The present invention also provides a method for preparing a high-strength, large-deformation, small-diameter casing-change well repairing shaping agent, comprising the following steps:

[0014] S1. Mixing: weigh aluminum powder, hexanitrohexaazaisowurtzitane powder, trinitrotoluene powder, polyester and microcrystalline wax grains, a release agent and octogen powder in order according to mass percentage, mix them evenly, and obtain a mixed powder;

[0015] S2. Pressing: placing the mixed powder in a semi-cylindrical mold with a raised center, and then loading the upper punch, pressing the mixed powder under vacuum conditions, the pressing pressure is 10-15 MPa, the pressing time is 2-3 seconds, and then maintaining the pressure at 8-10 MPa for 30 seconds ± 2 seconds, and removing the mold to obtain an explosive shaping charge column;

[0016] S3. Inspection: The outer diameter, height and inner diameter of the explosive shaping charge column are inspected to meet the requirements of the casing that needs to be shaped.

[0017] Furthermore, the particle sizes of the aluminum powder, hexanitrohexaazaisowurtzitane powder, trinitrotoluene powder, polyester and microcrystalline wax grains, release agent and octogen powder in S1 are all less than 0.6 mm.

[0018] Note: The particle size of raw materials should be kept as fine as possible to improve the preparation success rate and explosion effect.

[0019] Furthermore, the inner diameter of the semi-cylindrical mold in S2 is 36 mm, the height is 180 mm, the diameter of the central protrusion is 7 mm, and the vacuum degree of the vacuum condition is 0.2-0.6 MPa.

[0020] Description: A more compact and high-quality explosive plastic charge is prepared through vacuum pressing and demoulding processes.

[0021] Furthermore, the size requirements of the explosive shaping charge column in S3 are: outer diameter 36mm±0.5mm, height 125mm±0.5mm, inner hole diameter 7mm±0.5mm.

[0022] Description: By optimizing the size requirements of the explosive shaping charge column, it can achieve better results in the explosive repair of small-diameter casing.

[0023] The present invention also provides an application of a high-strength, large-deformation, small-diameter casing deformation well repairing explosive, and the explosive shaping charge is applied to the explosive shaping of TP125V casing.

[0024] Further, the application method is:

[0025] Load the explosive shaping charge column into the shaping tool, lower the shaping tool into the well through the drilling tool, and make the shaping tool pass through the deformation section of the casing. The shaping tool is 1 to 2 meters longer than the deformation section, and the two ends of the shaping tool are respectively 0.5 to 1 meter longer than the upper and lower parts of the shaping section. Detonate by means of pressure from a ground pump truck, and the explosive shaping charge column explodes due to the detonation of the detonating cord. Use the explosion shock wave to impact the deformation section of the casing to cause it to displace toward the formation, thereby achieving diameter expansion.

[0026] Check the shaping effect of the deformed section of the casing. If the casing repair is successful, the construction is completed. If the casing repair does not meet the requirements, a second shaping is performed again until the diameter required for subsequent construction is met.

[0027] Note: For casing with smaller diameter after large deformation, the upper and lower ends of the shaping tool equipped with explosive shaping charge should exceed a part of the deformation section to ensure the shaping effect.

[0028] Furthermore, the shaping tool has an outer diameter of 48 mm and a wall thickness of 5 mm. It is made of a hard alloy aluminum tube. The outside of the shaping tool is grooved with a groove depth of 1 to 2 mm. The shaping tool is fully loaded with explosive shaping charge. A tail plug is installed at the bottom of the shaping tool. The upper end of the shaping tool is a positioning joint. The explosive shaping charge inside the shaping tool is sealed with a sealing ring.

[0029] Note: Grooving is done on the outside of the shaping tool to reduce the size of the shell fragments after the shaping charge explodes. The length of the shaping tool can be adjusted according to the length of the deformation section of the casing to be shaped, and the diameter of the positioning joint is adjusted according to the front end casing size of the deformation section casing. The shaping tool can withstand at least 55MPa pressure.

[0030] The beneficial effects of the present invention are:

[0031] (1) The high-strength, large-deformation, small-diameter shaping agent for repairing deformed casing wells of the present invention aims to solve the problem of small casing diameter caused by deformation of high-strength casing, and develops an explosive shaping agent with low shock sensation and high explosion strength that is suitable for the shaping and repair of such casing. The traditional beeswax or ozokerite type shock agent is replaced by a composite desensitizing agent composed of polyester and microcrystalline wax, thereby greatly reducing the shock sensation of the explosive shaping agent while effectively ensuring the explosion effect, which plays an important role in the shaping of such casing in oil fields.

[0032] (2) The preparation method of the high-strength, large-deformation, small-diameter casing-variable well repair shaping charge of the present invention adopts a constant pressure method to press the internal into a semi-columnar explosive shaping charge column of a certain length and a certain diameter in a charge pressing workshop, and then pack it into boxes and transport it to the site for loading on site. This method has a fast loading speed and good effect, and the type and quantity of the main charge can be adjusted at any time according to needs, greatly improving safety and loading efficiency.

[0033] (3) The present invention also provides a method for on-site application of shaping explosives for repairing high-strength, large-deformation, small-diameter casing deformation wells. When applied to high-strength TP125V casing with a small diameter (minimum diameter 50 mm) after large deformation, the shaping tool size specified in the present invention is used, and the casing can be shaped after 1 to 2 detonations, thereby reducing damage to the cement ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a diagram of the shape of the explosive shaping charge column prepared in Example 6 of the present invention;

[0035] Figure 2 It is a schematic diagram of the testing principle of the detonation velocity instrument in Experimental Example 1 of the present invention;

[0036] Figure 3 It is a drop weight impact sensitivity instrument used in the impact sensitivity test in Experimental Example 1 of the present invention;

[0037] Figure 4 It is a friction sensitivity tester for the friction sensitivity test in Experimental Example 1 of the present invention;

[0038] Figure 5 It is the thermal decomposition curve characteristic of the explosive plastic charge in the temperature resistance test in Experimental Example 1 of the present invention;

[0039] Figure 6 It is the cement target for the confining pressure test in Experimental Example 2 of the present invention;

[0040] Figure 7 It is the appearance diagram of the PT125V bushing after the confining pressure test in Experimental Example 2 of the present invention;

[0041] Figure 8 It is a schematic diagram of the cement sheath structure after the confining pressure test in Experimental Example 2 of the present invention. DETAILED DESCRIPTION

[0042] Example 1

[0043] A high-strength, large-deformation, small-diameter casing deformation well repairing plastic medicine, comprising, by mass percentage, 6% aluminum, 4% hexanitrohexaazaisowurtzitane, 8% trinitrotoluene, 5% composite desensitizing agent, 10% graphite release agent, and the balance is octogen;

[0044] The composite desensitizing agent is polyester and microcrystalline wax, the polyester is polyethylene terephthalate, and the mass ratio of polyethylene terephthalate to microcrystalline wax is 1:2.33, that is, polyethylene terephthalate accounts for 1.5% and microcrystalline wax accounts for 3.5%.

[0045] Example 2

[0046] The difference between this embodiment and embodiment 1 is that:

[0047] A high-strength, large-deformation, small-diameter casing deformation well repairing plastic medicine, comprising, by mass percentage, 5% aluminum, 3% hexanitrohexaazaisowurtzitane, 5% trinitrotoluene, 4% composite desensitizing agent, 8% graphite release agent, and the balance is octogen;

[0048] The composite desensitizing agent is polyester and microcrystalline wax, the polyester is polyethylene terephthalate, and the mass ratio of polyethylene terephthalate to microcrystalline wax is 1:2.

[0049] Example 3

[0050] The difference between this embodiment and embodiment 1 is that:

[0051] A high-strength, large-deformation, small-diameter casing deformation well repairing plastic medicine, comprising, by mass percentage, 10% aluminum, 5% hexanitrohexaazaisowurtzitane, 10% trinitrotoluene, 8% composite desensitizing agent, 12% graphite release agent, and the balance is octogen;

[0052] The composite desensitizing agent is polyester and microcrystalline wax, the polyester is polyethylene terephthalate, and the mass ratio of polyethylene terephthalate to microcrystalline wax is 1:3.

[0053] Example 4

[0054] The difference between this embodiment and embodiment 2 is that:

[0055] The mass ratio of polyethylene terephthalate to microcrystalline wax is 1:2.33, that is, polyethylene terephthalate accounts for 1.5% and microcrystalline wax accounts for 3.5%.

[0056] Example 5

[0057] The difference between this embodiment and embodiment 3 is that:

[0058] The mass ratio of polyethylene terephthalate to microcrystalline wax is 1:2.33, that is, polyethylene terephthalate accounts for 1.5% and microcrystalline wax accounts for 3.5%.

[0059] Note: In the formula of explosive plastic powder, other ingredients except the composite desensitizer can be adjusted within the range given in this application, and the final effect is not much different. The most preferred composite desensitizer is: 5% composite desensitizer, and the mass ratio of polyethylene terephthalate and microcrystalline wax is 1:2.33, that is, polyethylene terephthalate accounts for 1.5% and microcrystalline wax accounts for 3.5%.

[0060] Example 6

[0061] This embodiment is a method for preparing a high-strength, large-deformation, small-diameter casing-change well repairing shaping agent in Embodiment 1, comprising the following steps:

[0062] S1. Mixing: Weigh aluminum powder, hexanitrohexaazaisowurtzitane powder, trinitrotoluene powder, polyester and microcrystalline wax grains, release agent and octogen powder in order according to mass percentage, mix them evenly to obtain a mixed powder, wherein the particle size of the aluminum powder, hexanitrohexaazaisowurtzitane powder, trinitrotoluene powder, polyester and microcrystalline wax grains, release agent and octogen powder is not more than 0.6 mm;

[0063] S2, pressing: placing the mixed powder in a semi-cylindrical mold with a central protrusion, the inner diameter of the semi-cylindrical mold is 36 mm, the height is 180 mm, and the central protrusion diameter is 7 mm, and then loading the upper punch, pressing the mixed powder under vacuum conditions, the vacuum degree of the vacuum conditions is 0.4 MPa, the pressing pressure is 12 MPa, the pressing time is 2.5 s, and then the pressure is maintained at 9 MPa for 30 s, and the mold is removed to obtain an explosive shaping charge column;

[0064] S3. Inspection: The outer diameter, height and inner diameter of the explosive shaping charge column are inspected to meet the casing requirements for shaping. The size requirements of the explosive shaping charge column are: outer diameter 36mm±0.5mm, height 125mm±0.5mm, inner diameter 7mm±0.5mm. Figure 1 shown.

[0065] Example 7

[0066] The difference between this embodiment and embodiment 6 is that:

[0067] S2. During the pressing, the vacuum degree of the vacuum condition is 0.2MPa, the pressing pressure is 10MPa, and the pressing time is 3s. Then the pressure is maintained at 8MPa for 28s, and the mold is removed to obtain the explosive shaping charge column.

[0068] Example 8

[0069] The difference between this embodiment and embodiment 6 is that:

[0070] S2. During the pressing, the vacuum degree of the vacuum condition is 0.6 MPa, the pressing pressure is 15 MPa, and the pressing time is 2 s. Then the pressure is maintained at 10 MPa for 32 s, and the mold is removed to obtain the explosive shaping charge column.

[0071] Example 9

[0072] This embodiment is an application of a high-strength, large-deformation, small-diameter casing modification well repairing shaping charge in embodiment 1. The explosive shaping charge is applied to the explosive shaping of TP125V casing. The application method is as follows:

[0073] Load the explosive shaping charge column into the shaping tool, lower the shaping tool into the well through the drilling tool, and make the shaping tool pass through the deformation section of the casing. The shaping tool is 1.6 meters longer than the deformation section, and the two ends of the shaping tool are 0.8 meters longer than the upper and lower parts of the shaping section respectively. Detonate by means of pressure from a ground pump truck, and the explosive shaping charge column explodes due to the detonation of the detonating cord. Use the explosion shock wave to impact the deformation section of the casing to cause it to displace toward the formation, thereby achieving diameter expansion.

[0074] The shaping tool has an outer diameter of 48 mm and a wall thickness of 5 mm. It is made of a hard alloy aluminum tube. The shaping tool is grooved on the outside with a groove depth of 1 mm. The shaping tool is fully loaded with explosive shaping charges. A tail plug is installed at the bottom of the shaping tool. The upper end of the shaping tool is a positioning joint. The explosive shaping charges inside the shaping tool are sealed with a sealing ring. The shaping tool can withstand a pressure of at least 55 MPa.

[0075] Check the shaping effect of the casing deformation section. If the casing repair is successful, the construction is terminated. If the casing repair does not meet the requirements, a second shaping is performed again until the required diameter for subsequent construction is met. The casing repair meeting the requirements means that the well-drilling tool can smoothly pass through the casing deformation section to reach the artificial well bottom.

[0076] Example 10

[0077] The difference between this embodiment and embodiment 9 is that:

[0078] Load the explosive shaping charge column into the shaping tool, lower the shaping tool into the well through the drilling tool, and make the shaping tool pass through the deformation section of the casing. The shaping tool is 1 meter longer than the deformation section, and the two ends of the shaping tool are 0.5 meters longer than the upper and lower parts of the shaping section respectively. Detonate by means of pressure from a ground pump truck, and the explosive shaping charge column explodes due to the detonation of the detonating cord. Use the explosion shock wave to impact the deformation section of the casing to cause it to displace toward the formation, thereby achieving diameter expansion.

[0079] The shaping tool has an outer diameter of 48 mm and a wall thickness of 5 mm. It is made of a hard alloy aluminum tube. The shaping tool is grooved on the outside with a groove depth of 1.5 mm. The shaping tool is fully loaded with explosive shaping charges. A tail plug is installed at the bottom of the shaping tool. The upper end of the shaping tool is a positioning joint. The explosive shaping charges inside the shaping tool are sealed with a sealing ring. The shaping tool can withstand a pressure of at least 55 MPa.

[0080] Check the shaping effect of the deformed section of the casing. If the casing repair is successful, the construction is completed. If the casing repair does not meet the requirements, a second shaping is performed again until the diameter required for subsequent construction is met.

[0081] Example 12

[0082] The difference between this embodiment and embodiment 9 is that:

[0083] Load the explosive shaping charge column into the shaping tool, lower the shaping tool into the well through the drilling tool, and make the shaping tool pass through the deformation section of the casing. The shaping tool is 2 meters longer than the deformation section, and the two ends of the shaping tool are 1 meter longer than the upper and lower parts of the shaping section respectively. Detonate by means of pressure from a ground pump truck, and the detonation of the explosive shaping charge column by the detonating cord causes the explosion of the explosive shaping charge column. Use the explosion shock wave to impact the deformation section of the casing to cause it to displace toward the formation, thereby achieving diameter expansion.

[0084] The shaping tool has an outer diameter of 48 mm and a wall thickness of 5 mm. It is made of a hard alloy aluminum tube. The shaping tool is grooved on the outside with a groove depth of 2 mm. The shaping tool is fully loaded with explosive shaping charges. A tail plug is installed at the bottom of the shaping tool. The upper end of the shaping tool is a positioning joint. The explosive shaping charges inside the shaping tool are sealed with a sealing ring. The shaping tool can withstand a pressure of at least 55 MPa.

[0085] Check the shaping effect of the deformed section of the casing. If the casing repair is successful, the construction is completed. If the casing repair does not meet the requirements, a second shaping is performed again until the diameter required for subsequent construction is met.

[0086] Experimental Example 1

[0087] We conducted laboratory performance evaluation on the explosive plastic charge prepared in Example 6, including detonation velocity test, impact sensitivity test, friction sensitivity test and temperature resistance test, in order to verify whether the explosive plastic charge of the present invention can effectively ensure the explosion effect while greatly reducing the sense of shock.

[0088] 1. Explosion speed test

[0089] The magnitude of the detonation velocity directly affects the explosion shaping effect. Under the condition of the same amount of explosives, the higher the detonation velocity, the greater the force of the explosion shock wave. The detonation velocity refers to the propagation speed of the detonation wave in the explosive when the explosive is stably detonated. The magnitude of the detonation velocity of the explosive is affected by many factors, especially the energy of the explosive itself, and secondly, it is related to the diameter, density, particle size, shell and additives of the explosive. The detonation of explosives is accompanied by rapid energy changes, and the detonation process involves many disciplines, such as physics, chemistry and fluid dynamics. The detonation wave is a strong shock wave with a rapid chemical reaction zone, and the detonation process is the layer-by-layer transmission process of the detonation wave in the explosive. According to the ideal gas state equation, the detonation propagation conditions and the three conservation laws of energy, mass and momentum, equations can be established to solve the detonation parameters such as detonation pressure, detonation product density, detonation velocity, detonation product point velocity and detonation product temperature. Among these detonation parameters, only the measurement method of detonation velocity is the simplest and most accurate. Therefore, the research on explosives must start with the detonation velocity. The other required related parameters are calculated based on the measured detonation velocity of the explosives, and then the calculated detonation parameters of the explosives are used to continuously optimize the formula and improve performance.

[0090] At present, the commonly used methods for measuring detonation velocity can be divided into three categories, namely: analog method (detonating cord method and detonating tube method), electrical measurement method (resistance wire method and foil probe method, etc.), optical measurement method (optical guide cable method and scanning mirror method, etc.). The present invention adopts an intelligent detonation velocity instrument, which is more convenient to operate and the data obtained is more intuitive. Figure 2 The following is a schematic diagram of the testing principle of the detonation velocity meter. The testing principle of the detonation velocity meter is similar to that of the time meter. Figure 2 The two probes A and B shown are made of copper core enameled wire, and the part inserted into the explosive sample is in a disconnected state. The distance L between the probes A and B is the distance measurement. The distance measurement L can be adjusted according to the experimental conditions and is generally set to 50mm. When the detonation wave propagates to the probe, the detonation product is ionized into positive and negative ions, so that the mutually insulated probes are connected and converted into electrical signals and transmitted to the detonation velocity meter. After the probe A is connected, the detonation velocity meter starts timing, and after the probe B is connected, the detonation velocity meter timing ends, thereby measuring the propagation time t of the detonation wave in the explosive to be tested. The detonation velocity meter automatically calculates the detonation velocity value according to the set distance measurement L and the measured time t. Through measurement, the detonation velocity of the low-detonation-velocity explosive shaping charge column of the formula of the present invention is about 5000m / s, the detonation velocity of the medium-detonation-velocity explosive shaping charge column is 6500m / s, and the detonation velocity of the high-detonation-velocity explosive shaping charge column is about 8000m / s, which can meet the detonation velocity requirements of the main charge in the ground explosion shaping test of TP125V casing with different deformation degrees and the actual application in the well.

[0091] 2. Impact sensitivity test

[0092] Impact sensitivity is one of the important safety indicators of explosives. After the plastic explosives are pressed and formed in the workshop, they must be transported to the site for use. In the process, there are many links such as handling and transportation. In order to ensure safety, impact sensitivity tests must be carried out. The test is carried out using a drop hammer sensitivity tester, such as Figure 3As shown. The sensitivity of explosives is not only affected by the chemical properties of explosives, but also closely related to the crystal characteristics. Crystal characteristics such as material purity, microstructure of the cavities inside the particles, surface defects of particles, particle size and distribution, particle shape and surface smoothness have a significant impact on sensitivity. The change in the shock wave sensitivity of explosives is closely related to the crystal characteristics of explosives. However, in the shock wave sensitivity test, the factors affecting the sensitivity include not only the crystal characteristics of the explosives, but also the bonding agent, the molding method of the explosive shaping charge column, etc. The impact sensitivity of a simple Octogen is usually around 100%, which is very high, and must be desensitized before it can be used in practice. The commonly used desensitizing agent is ozokerite. After adding 5% ozokerite and 10% graphite release agent and other additives to the above explosive formula, the impact sensitivity is 50%, which is still relatively high and needs to be further reduced. Through experimental comparison, the present invention adopts 1.5% polyester plus 3.5% microcrystalline wax as a desensitizing agent. The explosion probability of the main charge of the explosive shaping after adding this formula of desensitizing agent and other additives such as 10% graphite release agent is 0-8% (10Kg / 25cm), and the impact sensitivity is very low, which can meet the safety requirements of on-site explosive shaping.

[0093] 3. Friction sensitivity test

[0094] Friction is one of the most common forms of external stimulation, and the heat generated by friction is also a form of energy that causes a large number of accidents. After the plastic surgery drugs are pressed and formed in the workshop, they must be transported to the site for use. In the process, there are many links such as handling and transportation. In order to ensure safety, friction sensitivity tests must be carried out. The test is carried out using a pendulum sensitivity tester, such as Figure 4 As shown. Factors affecting the friction sensitivity of explosives include the particle size, crystal form, type and content of additives, type of coating material and coating process, eutectic, test temperature, etc. The friction sensitivity of pure Octogen is usually around 100%, which is very high and must be desensitized before it can be used in practice. The commonly used desensitizing agent is ozokerite. After adding 5% ozokerite and 5% release agent and other additives to the above explosive formula, the friction sensitivity is 45%, which is still relatively high and needs to be further reduced. Through experimental comparison, the present invention uses 1.5% polyester plus 3.5% microcrystalline wax as a desensitizing agent. After this formula of desensitizing agent plus 10% graphite release agent and other additives, the friction sensitivity of the main charge is tested to be: 0-20% (90° / 3.92MPa). The friction sensitivity is very low and can meet the safety requirements of on-site explosion shaping.

[0095] 4. Temperature resistance test

[0096] TP125V casing is often used in reservoirs with deep burial depths and high formation temperatures. The ground explosive shaping test is to prepare for future underground use, so the developed shaping agent must take into account the needs of underground applications. It is very necessary to test the temperature resistance of the main charge of explosive shaping. If the temperature resistance is lower than the formation temperature, the explosive will decompose or even die naturally, seriously affecting the construction safety and shaping effect. The temperature resistance is comprehensively evaluated by differential thermal analysis and differential scanning calorimetry (DSC) and constant temperature thermal gravimetry at 165°C. The DSC test is performed according to GJB770B method 502.1 differential thermal analysis and differential scanning calorimetry. The DSC method is used to measure the thermal decomposition characteristics of the propellant from room temperature to 250°C. The test results are as follows Figure 5 shown.

[0097] From the data in the figure, we can see that the propellant begins to decompose endothermically at 163.5℃ and reaches a peak at 204.5℃, which meets the stability requirement at 150℃ as required by the contract. The stability of the main charge at 160℃ for 48 hours was then assessed by the constant temperature thermal weight loss method at 160℃. After the explosive sample was placed at 160℃ for 48 hours, no spontaneous combustion or deformation occurred. The constant temperature thermal weight loss test results are shown in Table 1.

[0098] Table 1 160℃ constant temperature thermal weight loss test results

[0099] Insulation time (h) Weight(g) Weight loss rate (%) 0 4.006g 0 8 3.998 0.1997 24 3.986 0.4992 48 3.978 0.6990

[0100] From the test results in the table, it can be seen that the weight loss rate of the explosive shaping charge of the present invention at 160°C for 48 hours is 0.699%. It can be seen that the thermal weight loss rate of the main charge is small and the thermal stability is good.

[0101] Experimental Example 2

[0102] Next, we test the actual use effect of TP125V casing under three conditions: no confining pressure, confining pressure, and in the well. The results are as follows.

[0103] 1. Ground test without confining pressure

[0104] A TP125V casing was used, threaded and plugged at both ends, and mechanical extrusion was performed to create deformation points. The explosive shaping charge in Example 6 was placed at the extrusion deformation point position, and a ground detonation experiment was performed without any wrapping outside the casing to test the shaping effects of different formula shaping charges on the casing before and after explosion.

[0105] Results of the ground test without confining pressure: After normal detonation, the deformation position has obvious expansion marks (the original diameter after extrusion is about 61mm). The deformation position measured by the caliper is tapered and the diameter after shaping is ≥85mm. The casing is intact, without cracks, etc., and has a good expansion effect on the reduced diameter casing (about 40%) under the condition of no confining pressure outside the casing.

[0106] 2. Ground test with confining pressure

[0107] The TP125V casing is processed according to the requirements, and a 1500-ton press is used to extrude the casing tooling to deform it. After deformation, the maximum internal diameter is 70mm, and the deformation length is ≥200mm. After extrusion, the casing is transported to a site where cement targets can be made, and the cement targets are poured and cured in preparation for the experiment. The production process of the cement target for the confining pressure experiment is as follows: the bottom of the casing with an outer diameter of 13 3 / 8" (P110 casing with an outer diameter of 340mm and a thickness of 12.19mm) is fixed to the cement floor with expansion screws (the casing and the screws are welded together by electric welding), such as Figure 6 As shown, the processed tooling casing is then placed in the middle of the fixed casing and fixed with steel bars to prevent the tooling casing from sliding during the cement pouring process, causing the casing to deviate, thereby affecting the test results. After the tooling casing is fixed, the annulus between the two casings is filled with cement mortar in accordance with the "SY / T5891.1-1999" specification for the production of concrete targets for perforation detection in oil and gas wells and related experimental requirements.

[0108] The results of the confining pressure test show that after normal detonation, the target is basically intact and upright, with obvious signs of expansion on the periphery of the target. The circumference of the target at the deformed part is measured to be about 40 mm longer than that above and below. Figure 7 As shown. After the experiment, the diameter of the internal casing changed from 61mm before the test to 83mm. After cutting open the outer casing and cement ring, the casing was observed to be intact, without cracks. The outer casing expanded, and the maximum measured after cutting was 362mm. The cement ring between the casings was broken and cracked, but the whole was intact. Figure 8 From the data, the combination of high and low detonation velocity charges has a certain expansion effect on the reduced diameter casing under the condition of confining pressure outside the casing (about 39%). The test results are shown in the table below. The expansion effect is obvious and there is no damage to the casing.

[0109] 3. Field experiment

[0110] Field experiment of Well 1#: The shaping process was successful, and the detonation was successful at a pressure of 31.2MPa. After being pulled out, the coiled tubing and tools were found to be intact, the shaping tools were all broken, and the diameter was increased.

[0111] Field test of well 2#: The well was subjected to two explosive shaping operations. According to the method in Example 9, the first shaping section was 3930.0-3931.60 m, and the second shaping section was 3926.43-3929.22 m. Before shaping, the Φ80 mm flat-bottomed mill could barely pass through the deformation section; after shaping, the Φ86 mm flat-bottomed mill could pass through smoothly.

[0112] Field test of Well 3#: The well was reshaped once, and the shaping section was 4609.92-4612.9 (Φ78.587mm logging casing change position). Before the shaping, the Φ80mm flat-bottomed mill passed through the deformation section under 2T pressure. After the shaping, the Φ90mm mill passed smoothly through the well to 5072.3m, which is the artificial well bottom.

Claims

1. A high-strength, large-deformation, small-diameter casing-changing well repairing plastic medicine, characterized in that: According to the mass percentage, it includes 5-10% aluminum, 3-5% hexanitrohexaazaisowurtzitane, 5-10% trinitrotoluene, 4-8% composite desensitizing agent, 8-12% release agent, and the balance is octogen; Wherein, the composite desensitizing agent is polyester and microcrystalline wax, and the mass ratio of polyethylene terephthalate and microcrystalline wax in the composite desensitizing agent is 1:2-3.

2. According to claim 1, a high-strength, large-deformation, small-diameter casing-changing well repairing plastic medicine is characterized in that: The polyester in the composite desensitizing agent is polyethylene terephthalate.

3. The high-strength, large-deformation, small-diameter casing-changing well repairing shaping agent according to claim 1 is characterized in that: The release agent is a graphite release agent.

4. The method for preparing a high-strength, large-deformation, small-diameter casing-change well repairing plastic medicine according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Mixing: weigh aluminum powder, hexanitrohexaazaisowurtzitane powder, trinitrotoluene powder, polyester and microcrystalline wax grains, a release agent and octogen powder in order according to mass percentage, mix them evenly, and obtain a mixed powder; S2. Pressing: placing the mixed powder in a semi-cylindrical mold with a raised center, and then loading the upper punch, pressing the mixed powder under vacuum conditions, the pressing pressure is 10-15 MPa, the pressing time is 2-3 seconds, and then maintaining the pressure at 8-10 MPa for 30 seconds ± 2 seconds, and removing the mold to obtain an explosive shaping charge column; S3. Inspection: The outer diameter, height and inner diameter of the explosive shaping charge column are inspected to meet the requirements of the casing that needs to be shaped.

5. The method for preparing a high-strength, large-deformation, small-diameter casing-changing well repairing plastic medicine according to claim 4 is characterized in that: The particle sizes of the aluminum powder, hexanitrohexaazaisowurtzitane powder, trinitrotoluene powder, polyester and microcrystalline wax grains, release agent and octogen powder in S1 are all less than 0.6 mm.

6. The method for preparing a high-strength, large-deformation, small-diameter casing-changing well repairing plastic medicine according to claim 4 is characterized in that: The inner diameter of the semi-cylindrical mold in S2 is 36 mm, the height is 180 mm, the diameter of the central protrusion is 7 mm, and the vacuum degree of the vacuum condition is 0.2-0.6 MPa.

7. The method for preparing a high-strength, large-deformation, small-diameter casing-changing shaping agent for well repair according to claim 6 is characterized in that: The size requirements of the explosive shaping charge column in S3 are: outer diameter 36mm±0.5mm, height 125mm±0.5mm, inner hole diameter 7mm±0.5mm.

8. The use of a high-strength, large-deformation, small-diameter casing-changing well repairing plastic medicine according to claim 1 is characterized in that: The explosive shaping charge is applied to the explosive shaping of TP125V casing.

9. The use of a high-strength, large-deformation, small-diameter casing-changing well repairing plastic medicine according to claim 8, characterized in that: The application method is: Load the explosive shaping charge column into the shaping tool, lower the shaping tool into the well through the drilling tool, and make the shaping tool pass through the deformation section of the casing. The shaping tool is 1 to 2 meters longer than the deformation section, and the two ends of the shaping tool are respectively 0.5 to 1 meter longer than the upper and lower parts of the shaping section. Detonate by means of pressure from a ground pump truck, and the explosive shaping charge column explodes due to the detonation of the detonating cord. Use the explosion shock wave to impact the deformation section of the casing to cause it to displace toward the formation, thereby achieving diameter expansion. Check the shaping effect of the deformed section of the casing. If the casing repair is successful, the construction is completed. If the casing repair does not meet the requirements, a second shaping is performed again until the diameter required for subsequent construction is met.

10. The use of a high-strength, large-deformation, small-diameter casing-changing well repairing plastic medicine according to claim 9, characterized in that: The shaping tool has an outer diameter of 48 mm and a wall thickness of 5 mm. It is made of a hard alloy aluminum tube. The outside of the shaping tool is grooved with a groove depth of 1 to 2 mm. The shaping tool is fully loaded with explosive shaping charge. A tail plug is installed at the bottom of the shaping tool. The upper end of the shaping tool is a positioning joint. The explosive shaping charge inside the shaping tool is sealed with a sealing ring.

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