A downhole corrosion monitor, monitoring method, system and application

Abstract

The invention discloses a downhole corrosion monitor, a monitoring method, a system and an application. The monitor comprises a receiving assembly and a hanging piece monitoring mechanism; the receiving assembly comprises: an upper joint, an upper cylinder sleeve, a receiving short joint, a lower cylinder sleeve, a lower joint, a guide cylinder, a positioning short joint and a rotating guide body which are connected in sequence; the receiving short joint is provided with an eccentric hole for accommodating the hanging piece monitoring mechanism and a through hole which is connected with the eccentric hole; the guide cylinder is nested in the upper cylinder sleeve and connected with the receiving short joint, and a first guide groove is provided on the guide cylinder, and the first guide groove matches the position of the eccentric hole; the positioning short joint is nested in the lower cylinder sleeve and the lower joint, and is connected with the lower cylinder sleeve; the rotating guide body is nested in the positioning short joint and connected with the positioning short joint, and a second guide groove is provided on the rotating guide body, and the second guide groove and the first guide groove are located on one side of the central axis of the receiving assembly; the upper joint and the lower joint are used for externally connecting oil pipes, and the hanging piece monitoring mechanism is used for being assembled in the eccentric hole by a bailer or for being lifted out of the eccentric hole by a bailer.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas production, in particular to the technical field of pipe column corrosion monitoring, and in particular to a downhole corrosion monitor, a monitoring method, a system and applications. Background Art

[0002] During the development of oil fields, the pH value of the injected water in the water injection wells will be adjusted according to actual needs. When the injected water is adjusted to be slightly acidic, it will corrode the casing, tubing and various tools in the well. In order to grasp the degree of corrosion, it is necessary to monitor the corrosion rate of the tubing in the water injection well. It is necessary to send hanging pieces with the same metal material composition as the casing, tubing and various tools into the water injection well. By analyzing and evaluating the corrosion degree of the hanging pieces, the corrosion status of the entire water injection well can be judged to guide the adjustment of the operation cycle of the water well tubing to avoid corrosion and failure of tubing and tools or even breakage due to corrosion, resulting in major repairs.

[0003] At present, downhole corrosion monitoring technologies for water injection wells can be divided into two categories: fixed and removable. The fixed type is lowered into the well with the tubing string, and can monitor the corrosion conditions of the environment inside and outside the oil pipe respectively. However, there are defects such as the removal of the hanging piece requires the moving of the tubing string and the difficulty in adjusting the monitoring cycle, so the corrosion conditions in the oil pipe cannot be monitored in real time. The removable type will stick the monitor in the gap between the inner wall of the oil pipe and be thrown or fished out by a special throwing and fishing tool. Although it does not need to be sent in and taken out with the tubing string, the production channel in the oil pipe is occupied after it is put into the oil pipe, affecting normal production, and other operations cannot be carried out during the monitoring period. Therefore, the existing downhole corrosion monitoring technology cannot obtain downhole corrosion information at any time and flexibly, cannot provide the data required for safe production of oil fields in a timely manner, and cannot meet the production needs of oil fields. Summary of the invention

[0004] In order to solve the deficiency that the existing downhole corrosion monitoring technology cannot flexibly monitor the downhole corrosion condition, and to realize a downhole corrosion monitoring scheme that can flexibly and conveniently monitor the downhole corrosion condition, can remove and replace the monitoring hanging piece without moving the pipe string, and does not affect the normal production operation, the present invention provides a downhole corrosion monitor, a monitoring method, a system and an application.

[0005] In a first aspect, an embodiment of the present invention provides a downhole corrosion monitor, which may include: a receiving assembly and a hanging piece monitoring mechanism detachably assembled in the receiving assembly;

[0006] Wherein, the receiving assembly may include: an upper joint, an upper cylinder sleeve, a receiving short section, a lower cylinder sleeve, a lower joint, a guide cylinder, a positioning short section and a rotating guide body connected in sequence;

[0007] The receiving short section is cylindrical, an eccentric hole for accommodating the hanging piece monitoring mechanism is opened in the long axis direction of the receiving short section, and a through hole communicating with the eccentric hole is opened on the inner wall of the receiving short section;

[0008] The guide cylinder is nested in the upper cylinder sleeve and connected to the receiving short section, and a first guide groove is formed on the guide cylinder, and the first guide groove matches the position of the eccentric hole;

[0009] The positioning nipple is nested in the lower cylinder sleeve and the lower joint, and is connected to the lower cylinder sleeve;

[0010] The rotating guide body is nested in the positioning short section and connected to the positioning short section, and a second guide groove is provided on the rotating guide body, and the second guide groove and the first guide groove are located on one side of the central axis of the receiving assembly;

[0011] The upper joint and the lower joint are used for externally connecting oil pipes, and the hanging piece monitoring mechanism is used for being assembled in the eccentric hole by a bailer or for being taken out from the eccentric hole by a bailer.

[0012] In one embodiment, the hanging piece monitoring mechanism may include: a casting and fishing component and a hanging piece monitoring component;

[0013] The casting and fishing assembly may include: a casting and fishing head, a back cap, a connecting short section, a cam and a spring;

[0014] The back cap and the connecting short section are detachably connected, a through slot is provided in the middle of the connecting short section, and the cam is rotatably fixed in the through slot;

[0015] The scooping head is nested inside the back cap and the connecting short section, one end of the scooping head extends out of the back cap for external connection with the scooping device, and the other end extends into the through slot to cooperate with the cam;

[0016] A step is provided in the middle of the fishing head, the spring is nested on the outside of the fishing head, one end of the spring abuts against the step, and the other end abuts against the back cap;

[0017] The hanging piece monitoring assembly is connected to an end of the connecting short section away from the back cap;

[0018] In the launching operation, the bailer is connected with the back cap to lower the hanging piece monitoring mechanism into the well, the hanging piece monitoring mechanism is sent to the eccentric hole along the first guide groove, the bailer is lifted up, the spring compresses the bailing head so that the bailing head acts on the cam, so that the long end of the cam extends out of the through groove and is limited on the eccentric hole, and the bailer is separated from the back cap to realize the launching operation of the hanging piece monitoring mechanism;

[0019] During the lifting operation, the bailer is connected to the bailing head, the bailing head is lifted and the spring is compressed to separate the bailing head from the cam, and the bailing head is further lifted to release the cam from the eccentric hole to realize the lifting operation of the hanging piece monitoring mechanism.

[0020] In one embodiment, the hanging plate monitoring assembly may include: a loading nipple, a hanging plate, and a loading bolt;

[0021] The loading short section is threadedly connected to the connecting short section. One end of the loading short section away from the connecting short section is conical. The middle of the loading short section is hollowed out. The hanging piece is fixed to the hollow part of the loading short section through the loading bolt.

[0022] In one embodiment, the receiving short section is provided with a slot inside the eccentric hole, the slot is located on a side of the through hole close to the first guide groove, and the positions of the slot and the through hole match;

[0023] When the long end of the cam extends out of the through slot, the long end of the cam can be engaged in the clamping slot, so as to limit the casting and fishing assembly through the clamping slot.

[0024] In one embodiment, a first recessed angle of an axial cross section of the slot close to one end of the through hole is greater than 90°, and a second recessed angle away from one end of the through hole is not greater than 90°.

[0025] In one embodiment, a plurality of annular grooves are formed on the outer side of one end of the dredging head away from the cam, and the axial cross-section of the annular grooves is triangular, and the annular grooves are used to cooperate with the clamping and pressing head of the dredging device;

[0026] One end of the catching head matched with the cam is provided with a boss, and the cam is provided with a locking groove matched with the boss.

[0027] In one embodiment, the receiving assembly may further include: a first screw, a second screw, a third screw, a fourth screw, a fifth screw, a first bolt, and a second bolt;

[0028] The upper joint, the upper cylinder sleeve, the receiving nipple, the lower cylinder sleeve and the lower joint are threadedly connected in sequence; the upper joint and the upper cylinder sleeve are fixed by the first screw, the upper cylinder sleeve and the receiving nipple are fixed by the second screw, the receiving nipple and the lower cylinder sleeve are fixed by the third screw, and the lower cylinder sleeve and the lower joint are fixed by the fourth screw;

[0029] The guide cylinder abuts against the end surface of the receiving short section and is connected by a first bolt;

[0030] The positioning nipple is connected to the lower cylinder sleeve via a fifth screw;

[0031] The rotary guide body and the positioning short section are connected via the second bolt.

[0032] In one embodiment, the downhole corrosion monitor may further include: a cable-controlled monitoring mechanism, the cable-controlled monitoring mechanism being located between the upper joint and the upper cylinder sleeve;

[0033] The cable control monitoring mechanism may include: an electrode assembly, a cable assembly, a temperature and pressure assembly, a main control circuit board and a sheath;

[0034] The electrode assembly may include: an electrode connector, an electrode control board, an electrode, an electrode fixing head, a sealing pressure ring, an electrode sealing ring and a spacer; one end of the electrode connector is connected to the upper cylinder sleeve, and the other end is connected to the upper connector; the electrode control board is welded to the electrode connector; a T-shaped through hole is opened in the long axis direction of the electrode connector, the electrode is located in the T-shaped through hole, and one end of the electrode close to the upper cylinder sleeve extends out of the T-shaped through hole; the spacer, the electrode sealing ring and the sealing pressure ring are nested on the outside of the electrode and are located in the T-shaped through hole, the electrode fixing head is nested on the outside of the electrode and connected to the T-shaped through hole and limits the sealing pressure ring; the electrode control board is electrically connected to the electrode for collecting the electrical signal monitored by the electrode;

[0035] The upper joint is provided with a through hole and a mounting hole in the long axis direction, and the cable assembly may include: a cable and a cable sealing head, the cable is located in the through hole, and the cable sealing head is installed on the mounting hole;

[0036] The temperature and pressure assembly may include: a temperature sensor, a temperature control board, a pressure sensor and a pressure control board, wherein the temperature sensor and the pressure sensor are mounted on the end surface of the electrode joint close to the upper cylinder sleeve, the temperature control board and the pressure control board are respectively welded to the electrode joint, and the temperature control board is electrically connected to the temperature sensor, and the pressure control board is electrically connected to the pressure sensor;

[0037] The main control circuit board is welded on the electrode connector and is electrically connected to the cable, the electrode control board, the temperature control board, and the pressure control board respectively;

[0038] The sheath is nested on the outside of the electrode assembly and is located between the upper connector and the electrode connector.

[0039] In a second aspect, an embodiment of the present invention provides a downhole corrosion monitoring method, which is implemented according to the downhole corrosion monitor of the first aspect, and includes:

[0040] The upper joint and the lower joint in the receiving assembly of the downhole corrosion monitor are respectively connected to the oil pipe, and the downhole corrosion monitor is lowered into the target well through the wellhead operation machine; wherein the hanging piece monitoring mechanism included in the downhole corrosion monitor is assembled on the receiving assembly, or assembled on the receiving assembly through a bailer after being lowered into the target well;

[0041] After the set monitoring time is reached, the hanging monitoring mechanism is taken out by a scooping device, and the hanging pieces in the hanging monitoring mechanism are disassembled to evaluate the corrosion status and calculate the corrosion rate by weight loss method;

[0042] According to the preset monitoring cycle, the hook monitoring mechanism loaded with new hooks is lowered into the target well using the bailer to continue underground corrosion monitoring.

[0043] In one embodiment, the above-mentioned downhole corrosion monitoring method may further include:

[0044] Real-time monitoring of corrosion rate and temperature and pressure is performed through the cable-controlled monitoring mechanism in the downhole corrosion monitor;

[0045] The corrosion rate real-time monitoring is corrected by the corrosion rate result obtained by the weight loss method using the hanging plate to determine the underground corrosion rate under actual working conditions.

[0046] In a third aspect, an embodiment of the present invention provides a downhole corrosion monitoring system, which may include: an oil pipe, a bailer, a wellhead operating machine, and at least one downhole corrosion monitor as described in the first aspect;

[0047] Both ends of the downhole corrosion monitor are connected to the oil pipe respectively;

[0048] The wellhead operation machine is used to lower the oil pipe and the downhole corrosion monitor to a preset well section in the target well;

[0049] The downhole corrosion monitor is used for downhole corrosion monitoring. When the set monitoring time is reached, the hanging plate monitoring mechanism in the downhole corrosion monitor is taken out by the bailer, and the hanging plates in the hanging plate monitoring mechanism are disassembled to evaluate the corrosion status and calculate the corrosion rate by the weight loss method.

[0050] In a fourth aspect, an embodiment of the present invention provides an application of a downhole corrosion monitor in downhole corrosion monitoring, wherein the downhole corrosion monitor is the downhole corrosion monitor as described in the first aspect.

[0051] The beneficial effects of the above technical solution provided in the embodiments of the present invention include at least:

[0052] In the embodiment of the present invention, a downhole corrosion monitor, monitoring method, system and application are provided. The receiving component and the hanging plate monitoring mechanism of the downhole corrosion monitor can be lowered into the predetermined position in the well along with the water injection pipe string operation. After the monitoring period is over, the hanging plate on the hanging plate monitoring mechanism needs to be taken out to evaluate the corrosion status or calculate the corrosion rate. The hanging plate monitoring mechanism is directly fished out by a fishing device without lifting the entire water injection pipe string, and the monitoring period can be flexibly adjusted as needed. The above-mentioned receiving component in this embodiment can retain the complete production channel in the oil pipe, and both water injection production and monitoring operations can be carried out normally during the monitoring period; further, multiple above-mentioned downhole corrosion monitors can be used at the same time to evaluate the corrosion rates of various metal materials in the downhole production environment, and suitable pipes and downhole tools can be further screened, which has important guiding significance for the safe production of oil fields.

[0053] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0054] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0056] Figure 1 This is one of the structural diagrams of the downhole corrosion monitor provided in the embodiment of the present invention;

[0057] Figure 2 A structural diagram of a hanging piece monitoring mechanism provided in an embodiment of the present invention;

[0058] Figure 3 for Figure 1 Cross-section view in the AA direction;

[0059] Figure 4 for Figure 1 Cross-section along the middle BB direction;

[0060] Figure 5 for Figure 1 Cross-sectional view in the mid-CC direction;

[0061] Figure 6 for Figure 1 Cross-section in the middle DD direction;

[0062] Figure 7A structural diagram of a clamping slot on a receiving short section provided in an embodiment of the present invention;

[0063] Figure 8 This is the second structural diagram of the downhole corrosion monitor provided in the embodiment of the present invention;

[0064] Fig. 9 A structural diagram of a cable control monitoring mechanism provided in an embodiment of the present invention;

[0065] Fig.10 for Fig. 9 Cross-section in the EE direction;

[0066] Fig.11 for Figure 8 Cross-section view in the FF direction;

[0067] Fig.12 for Fig. 9 Cross-section along the mid-GG direction;

[0068] Fig.13 It is a structural schematic diagram of a downhole corrosion monitoring system provided in an embodiment of the present invention;

[0069] Among them, 1-downhole corrosion monitor; 2-oil pipe; 3-bailer; 4-wellhead operation machine;

[0070] 11- receiving component; 12- hanging piece monitoring mechanism; 13- cable control monitoring mechanism;

[0071] 111-upper joint; 112-upper cylinder sleeve; 113-receiving short joint; 114-lower cylinder sleeve; 115-lower joint; 116-guide cylinder; 117-positioning short joint; 118-rotating guide body; 1101-first screw; 1102-second screw; 1103-third screw; 1104-fourth screw; 1105-fifth screw; 1106-first bolt; 1107-second bolt;

[0072] 1111-through hole; 1112-mounting hole; 1131-eccentric hole; 1132-through hole; 1133-slot; 1161-first guide groove; 1181-second guide groove;

[0073] 121-casting and fishing assembly; 122-hanging monitoring assembly;

[0074] 1211-casting and fishing head; 1212-back cap; 1213-connecting short section; 1214-cam; 1215-spring;

[0075] 12111-step; 12112-annular groove; 12113-boss; 12131-through groove; 12141-long end; 12142-locking groove; 11331-first recessed angle; 11332-second recessed angle;

[0076] 1221-loading short section; 1222-hanging piece; 1223-loading bolt;

[0077] 131-electrode assembly; 132-cable assembly; 133-temperature pressing assembly; 134-main control circuit board; 135-sheath;

[0078] 1311-electrode connector; 1312-electrode control board; 1313-electrode; 1314-electrode fixing head; 1315-sealing pressure ring; 1316-electrode sealing ring; 1317-spacer; 13111-T-shaped through hole;

[0079] 1321-cable; 1322-cable sealing head;

[0080] 1331-temperature sensor; 1332-temperature control board; 1333-pressure sensor; 1334-pressure control board. DETAILED DESCRIPTION

[0081] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0082] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", "far", "near", "front", "back" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0083] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0084] In the prior art, the application publication number is CN110836950A, and the invention name is "Corrosion Monitoring Device and Pipeline for Corrosion Monitoring of Water Injection Wells", which discloses a corrosion monitoring scheme for water injection wells. The corrosion monitoring device mainly includes a fixing part, a monitoring core and a plugging core. During the application process, the corrosion monitoring device monitors the corrosion rate through the monitoring body, that is, the first monitoring part in the monitoring body is exposed to the first monitoring through hole for monitoring the corrosion rate of the water injected into the pipe sleeve annulus between the oil pipe and the casing; the second monitoring part in the monitoring body is exposed to the second monitoring through hole for monitoring the corrosion rate of the water injected into the fixing part connected to the oil pipe. After the corrosion monitoring device is pulled out, it is also necessary to use a plugging core to seal the eccentric hole in the fixing part to avoid the pipeline annulus and the oil pipe from being connected and unable to operate normally. Furthermore, the first monitoring part and the second monitoring part in the corrosion monitoring device are both columnar, and the pipe sleeve annulus and the eccentric hole monitored by it are blocked by a packer or a water distributor at the top and bottom, resulting in the two monitoring parts actually monitoring the corrosion rate of the water injected into the closed chamber.

[0085] After actual use and research, the inventor found that the corrosion monitoring device has at least the following drawbacks: First, after the monitoring core is pulled out after completing the monitoring operation, in order to ensure normal operation, it is necessary to use a plugging core to seal the eccentric hole, which adds a set of pipe string operation procedures; second, because the two monitoring components actually monitor the corrosion rate of the injected water in the closed chamber, rather than monitoring under the flow state, which is not the actual working condition on site, the corrosion rate monitoring value is equivalent to the laboratory static simulation, which is an order of magnitude different from the actual working condition, resulting in a large difference in monitoring data; third, because the pipe string corrosion is mostly corroded from the inside to the outside, and the cylindrical monitoring component itself will seal the fluid channel, the existing corrosion monitoring device cannot timely understand the corrosion rate of the injected water under the working condition on site. In view of the above problems, the present invention is proposed to provide a downhole corrosion monitor, monitoring method, system and application that overcomes the above problems or at least partially solves the above problems.

[0086] In an embodiment of the present invention, a downhole corrosion monitor is provided. Figure 1 to Figure 13As shown, the downhole corrosion monitor 1 may include: a receiving assembly 11 and a hanging piece monitoring mechanism 12 detachably assembled in the receiving assembly 11; wherein the receiving assembly 11 may include: an upper joint 111, an upper cylinder sleeve 112, a receiving short section 113, a lower cylinder sleeve 114, a lower joint 115, and a guide cylinder 116, a positioning short section 117 and a rotating guide body 118 connected in sequence; the receiving short section 113 is cylindrical, and an eccentric hole 1131 for accommodating the hanging piece monitoring mechanism 12 is opened in the long axis direction of the receiving short section 113, and a through hole 1132 communicating with the eccentric hole 1131 is opened on the inner wall of the receiving short section 113; the guide cylinder 116 is nested in the upper cylinder sleeve 112 and connected to the receiving short section 113, and the guide cylinder 116 is connected to the lower cylinder sleeve 114. A first guide groove 1161 is provided on the guide tube 116, and the first guide groove 1161 matches the position of the eccentric hole 1131; the positioning short section 117 is nested in the lower cylinder sleeve 114 and the lower joint 115, and is connected to the lower cylinder sleeve 114; the rotating guide body 118 is nested in the positioning short section 117 and is connected to the positioning short section 117, and a second guide groove 1181 is provided on the rotating guide body 118, and the second guide groove 1181 and the first guide groove 1161 are located on one side of the central axis of the receiving component 11; the upper joint 111 and the lower joint 115 are used for externally connecting the oil pipe 2, and the hanging piece monitoring mechanism 12 is used to be assembled in the eccentric hole 1131 through the bailer 3 or to be lifted out from the eccentric hole 1131 through the bailer 3.

[0087] It should be noted that the receiving assembly 11 is used as a carrier of the hanging piece monitoring mechanism 12. It is connected up and down by the oil pipe 2 during the application process. Since it is not connected to the outer pipeline annulus, there is no need to perform a plugging operation after the hanging piece monitoring mechanism 12 is pulled out, which saves a pipe string operation process. It should also be noted that the bailer used in this embodiment is an existing bailer, and its specific structure and working principle can refer to the application publication number CN118462092A, and the invention name is "A multi-cast bailer". In the embodiment of the present invention, when using the multi-cast bailer, the escort head of the bailer is used in the process of delivering the hanging piece monitoring mechanism 12, and the delivery head of the bailer is used in the process of pulling out the hanging piece monitoring mechanism 12.

[0088] In the embodiment of the present invention, the receiving component 11 and the hanging piece monitoring mechanism 12 of the downhole corrosion monitor 1 can be lowered into the predetermined position in the well along with the water injection pipe string operation. After the monitoring period is over, it is necessary to take out the hanging piece 1222 on the hanging piece monitoring mechanism 12 to evaluate the corrosion status or calculate the corrosion rate. The hanging piece monitoring mechanism 12 can be directly fished out by the throwing device 3 without taking out the entire water injection pipe string, and the monitoring period can be flexibly adjusted as needed. The above-mentioned receiving component 11 in this embodiment can retain the complete production channel in the oil pipe 2, and both water injection production and monitoring operations can be carried out normally during the monitoring period; further, multiple above-mentioned downhole corrosion monitors 1 can be used at the same time to evaluate the corrosion rates of various metal materials in the downhole production environment, and suitable pipes and downhole tools can be further selected, which has important guiding significance for the safe production of oil fields.

[0089] Compared with the corrosion monitoring device in the prior art application publication number CN110836950A, the downhole corrosion monitor 1 provided in the embodiment of the present invention has the following advantages: first, the receiving component 11 hanging the hanging monitoring mechanism 12 or removing the hanging monitoring mechanism 12 will not affect production, while the prior art must use a plugging core for plugging after removing the monitoring core, which is bound to have an additional pipe string operation process; second, because the pipeline annulus in the prior art is a closed chamber and the electrochemical environment in the pipeline annulus is relatively stable, the prior art monitors the corrosion rate in the closed chamber, which is significantly reduced in accuracy compared with the corrosion rate in the flow state, that is, the normal production environment, which is monitored in the embodiment of the present invention; third, because the lowering position and number of the downhole corrosion monitor 1 in the embodiment of the present invention can be flexibly adjusted and combined, it can realize simultaneous monitoring or different period monitoring of multiple well sections, so as to achieve the purpose of monitoring the corrosion status of the water injection well at any time, and provide detailed data and information for oilfield development adjustment.

[0090] In one embodiment, referring to Figure 1 and Figure 2As shown, the hanging piece monitoring mechanism 12 may include: a casting and fishing assembly 121 and a hanging piece monitoring assembly 122; the casting and fishing assembly 121 may include: a casting and fishing head 1211, a back cap 1212, a connecting short section 1213, a cam 1214 and a spring 1215; the back cap 1212 and the connecting short section 1213 are detachably connected, a through groove 12131 is provided in the middle of the connecting short section 1213, and the cam 1214 is rotatably fixed in the through groove 12131; the casting and fishing head 1211 is nested in the back cap 1212 and the connecting short section On the inner side of the section 1213, one end of the dredging head 1211 extends out of the back cap 1212 for externally connecting the dredging device 3, and the other end extends into the through slot 12131 to cooperate with the cam 1214; a step 12111 is provided in the middle of the dredging head 1211, and a spring 1215 is nested on the outer side of the dredging head 1211, one end of the spring 1215 abuts against the step 12111, and the other end abuts against the back cap 1212; the hanging piece monitoring assembly 122 is connected to the end of the connecting short section 1213 away from the back cap 1212; combined Fig.13 As shown, in the dropping operation, the bailer 3 is connected to the back cap 1212 to lower the hanging piece monitoring mechanism 12 into the well, and the hanging piece monitoring mechanism 12 is sent to the eccentric hole 1131 along the first guide groove 1161, and the spring 1215 of the bailer 3 is lifted up to compress the bailing head 1211 so that the bailing head 1211 acts on the cam 1214, so that the long end 12141 of the cam 1214 extends out of the through groove 12131 and is limited on the eccentric hole 1131, and the bailer 3 is separated from the back cap 1212 to realize the dropping operation of the hanging piece monitoring mechanism 12; in the pulling out operation, the bailer 3 is connected to the bailing head 1211, the bailing head 1211 is lifted up and the spring 1215 is compressed so that the bailing head 1211 is separated from the cam 1214, and the bailing head 1211 is continuously lifted up to release the cam 1214 from the limit of the eccentric hole 1131 to realize the pulling out operation of the hanging piece monitoring mechanism 12.

[0091] Compared with the first scooping component in the corrosion monitoring device of the prior art, the scooping component 121 of the hanging piece monitoring mechanism 12 in the embodiment of the present invention abandons the reset spring 1215 on the cam 1214, and realizes the limiting and releasing of the cam 1214 by changing the structural relationship between the cam 1214 and the eccentric hole 1131.

[0092] In one embodiment, referring to Figure 1 and Figure 2 As shown, the hanging piece monitoring assembly 122 may include: a loading short section 1221, a hanging piece 1222 and a loading bolt 1223; the loading short section 1221 is threadedly connected to the connecting short section 1213, the end of the loading short section 1221 away from the connecting short section 1213 is conical, the middle part of the loading short section 1221 is hollow, and the hanging piece 1222 is fixed to the hollow part of the loading short section 1221 by the loading bolt 1223.

[0093] The hanging piece monitoring assembly 122 of the downhole corrosion monitor 1 of the embodiment of the present invention improves the loading short section 1221, abandons the original mounting rod structure, and replaces the cylindrical monitoring component with a sheet-shaped monitoring component. In this way, the fluid flow space is increased by cooperating with the hollow loading short section 1221 and the sheet-shaped hanging piece 1222. Compared with the monitoring through holes opened around the eccentric hole in the prior art (single contact surface or single monitoring orientation), it is more in line with the actual working environment.

[0094] In one embodiment, referring to Figure 1 and Figure 2 As shown, the receiving short section 113 is provided with a slot 1133 inside the eccentric hole 1131, and the slot 1133 is located on the side of the through hole 1132 close to the first guide slot 1161, and the positions of the slot 1133 and the through hole 1132 match each other; when the long end 12141 of the cam 1214 extends out of the through slot 12131, the long end 12141 of the cam 1214 can be engaged in the slot 1133, so as to limit the casting assembly 121 through the slot 1133. In a specific embodiment, referring to Figure 7 As shown, the first concave angle 11331 of the axial cross section of the slot 1133 close to the end of the through hole 1132 is greater than 90°, and the second concave angle 11332 away from the end of the through hole 1132 is not greater than 90°. It should be noted that the first concave angle 11331 can be as follows Figure 7 As shown in (A) or (B), the first recessed angle 11331 is a straight obtuse angle, or it can be Figure 7 As shown in (C) or (D), the first recessed angle 11331 is a smoothly transitioned angle, which is not specifically limited in the embodiment of the present invention.

[0095] In this embodiment, the structure of the above-mentioned slot 1133 can ensure that the cam 1214 can be stably engaged with the slot 1133 when it is squeezed by the catching head 1211. After the catching head 1211 is lifted up, the cam 1214 will no longer be squeezed. When the catching assembly 121 is lifted up, the cam 1214 will rotate from the end close to the through hole 1132 and disengage from the above-mentioned slot 1133.

[0096] In one embodiment, referring to Figure 1 and Figure 2As shown, a plurality of annular grooves 12112 are provided on the outer side of one end of the dredging head 1211 away from the cam 1214, and the axial cross section of the annular grooves 12112 is triangular, and the annular grooves 12112 are used to cooperate with the clamping and pressing head of the dredging device 3; a boss 12113 is provided on the end of the dredging head 1211 that cooperates with the cam 1214, and a locking groove 12142 that cooperates with the boss 12113 is provided on the cam 1214. In this embodiment, the axial cross section of the annular grooves 12112 on the dredging head 1211 is triangular, and such annular grooves 12112 are convenient for matching with the clamping and pressing head of the dredging device 3 and clamping more tightly; at the same time, the boss 12113 provided on the dredging head 1211 can effectively cooperate with the locking grooves 12142 on the cam 1214, and the travel limit of the cam 1214 can be achieved through the slot 1133 after the cam 1214 rotates to a certain angle.

[0097] In another embodiment, also referring to Figure 1 As shown, the receiving assembly 11 may also include: a first screw 1101, a second screw 1102, a third screw 1103, a fourth screw 1104, a fifth screw 1105, a first bolt 1106 and a second bolt 1107; the upper joint 111, the upper cylinder sleeve 112, the receiving short section 113, the lower cylinder sleeve 114 and the lower joint 115 are threadedly connected in sequence; the upper joint 111 is fixed to the upper cylinder sleeve 112 by the first screw 1101, and the upper cylinder sleeve 112 and the receiving short section 113 are fixed to the upper cylinder sleeve 114 by the first screw 1101. 13 is fixed by a second screw 1102, the receiving short section 113 and the lower cylinder sleeve 114 are fixed by a third screw 1103, and the lower cylinder sleeve 114 and the lower joint 115 are fixed by a fourth screw 1104; the guide cylinder 116 abuts against the end surface of the receiving short section 113 and is connected by a first bolt 1106; the positioning short section 117 is connected to the lower cylinder sleeve 114 by a fifth screw 1105; and the rotating guide body 118 is connected to the positioning short section 117 by a second bolt 1107. In the embodiment of the present invention, the various components are further connected by screws or bolts, which enhances the stability of the connection between the components and is more suitable for complex working conditions in underground wells.

[0098] In a detailed embodiment, referring to Figure 1 to Figure 7As shown, the downhole corrosion monitor 1 in the embodiment of the present invention includes a receiving assembly 11 and a hanging piece monitoring mechanism 12, wherein the lower end of the upper joint 111 in the receiving assembly 11 is threadedly connected to the upper end of the upper cylinder sleeve 112, the lower end of the upper cylinder sleeve 112 is threadedly connected to the upper end of the receiving short section 113, the lower end of the receiving short section 113 is threadedly connected to the upper end of the lower cylinder sleeve 114, and the lower end of the lower cylinder sleeve 114 is threadedly connected to the upper end of the lower joint 115, thus forming the periphery of the receiving assembly 11. In addition, the upper end surface of the receiving short section 113 is connected to the guide cylinder 116 by a first bolt 1106, and the rotating guide body 118 is fixed to the inner wall of the positioning short section 117 by a second bolt 1107; the first guide groove 1161 provided on the guide cylinder 116 matches the position of the eccentric hole 1131 provided on the receiving short section 113 ... rotating guide body 118 is fixed to the inner wall of the positioning short section 117 by a second bolt 1107; the rotating guide body 118 is fixed to the inner wall of the positioning short section 117 by a second bolt 1107; the rotating guide body 118 is fixed to the inner wall of the positioning short section 117 by a second bolt 1107; the rotating guide body 118 is Fig.13 As shown, the bailer 3 can slide into the eccentric hole 1131 provided on the receiving short section 113 along the first guide groove 1161 provided on the guide cylinder 116 to release the hanging piece monitoring mechanism 12. Further, the upper joint 111 and the upper cylinder sleeve 112, the upper cylinder sleeve 112 and the receiving short section 113, the receiving short section 113 and the lower cylinder sleeve 114, the lower cylinder sleeve 114 and the lower joint 115, and the positioning short section 117 and the lower cylinder sleeve 114 are fixed with corresponding screws, that is, they are fixed by the first screw 1101, the second screw 1102, the third screw 1103, the fourth screw 1104, and the fifth screw 1105 respectively to prevent the connection thread from loosening, and sealing rings are installed between the components to prevent leakage at the connection.

[0099] The hanging piece monitoring mechanism 12 in the downhole corrosion monitor 1 includes a casting and fishing assembly 121 and a hanging piece monitoring assembly 122, wherein the casting and fishing assembly 121 may include: a casting and fishing head 1211, a back cap 1212, a connecting short section 1213, a cam 1214 and a spring 1215; the casting and fishing head 1211 is sleeved inside the back cap 1212 and the connecting short section 1213, the spring 1215 is sleeved on the outside of the casting and fishing head 1211, and the back cap 1212 and the connecting short section 1213 are connected by threads; the hanging piece monitoring assembly 122 may include: a loading short section 1221, a hanging piece 1222 and a loading bolt 1223; the loading short section 1221 and the connecting short section 1213 are connected by threads, the cam 1214 is fixed to the inner side of the connecting short section 1213 by a cam shaft (at the center of the cam in the figure), and the hanging piece 1222 is fixed to the inside of the loading short section 1221 by a loading bolt 1223. After the hanging piece monitoring mechanism 12 is put into operation, the cam 1214 is stuck in the slot 1133 of the eccentric hole 1131 in the receiving short section 113 to prevent the hanging piece monitoring mechanism 12 from sliding upward along the eccentric hole 1131 in the receiving short section 113 .

[0100] Combination Figure 1 to Figure 7As shown, the above-mentioned underground corrosion monitor 1 in the embodiment of the present invention is put into operation and pulled out operation as follows: after the hanging piece monitoring mechanism 12 is pulled out of the ground, it is necessary to put in the hanging piece 1222 or replace the hanging piece 1222 to monitor the underground corrosion condition again. Fig.13 As shown, firstly, the bailer 3 and the hanging piece monitoring mechanism 12 are assembled, and the clamping and pressing head of the bailer 3 is connected to the raised part at the upper end of the back cap 1212 (the raised part of the back cap in the figure), and the bailer 3 and the hanging piece monitoring mechanism 12 are driven by the wellhead operation machine to be sent to the bottom of the receiving component 11, and then the bailer 3 is lifted up, and the side wall switch on the side wall of the bailer 3 will collide with the lower end surface of the lower joint 115 in the receiving component 11 so that the side arm of the bailer 3 is released, and the clamping and pressing head on the side arm delivers or fishes out the hanging piece monitoring mechanism 12. Continue to lift the dredger 3 so that its side arm passes a distance above the upper end of the guide cylinder 116, and then lower the dredger 3. After the side arm switch of the dredger 3 descends to the upper end of the rotating guide body 118, it will slide down and rotate along the spiral surfaces on both sides of the top of the rotating guide body 118, thereby driving the entire dredger 3 to slide down and rotate. When the side arm switch of the dredger 3 slides and rotates to the lower end of the spiral surface of the rotating guide body 118, the side arm of the dredger 3 will align with the first guide groove 1161 on the guide cylinder 116, and will also align with the eccentric hole 1131 on the receiving short section 113. At this time, continue to lower the dredger 3, and the side arm switch of the dredger 3 will slide down along the opening groove of the rotating guide body 118 without rotating. Continue to lower the dredger 3, and its side arm will slide down along the first guide groove 1161 on the guide cylinder 116 with the entire delivery assembly until it enters the eccentric hole 1131 on the receiving short section 113. When the cam 1214 of the casting and fishing assembly 121 in the hanging piece monitoring mechanism 12 enters the eccentric hole 1131 on the receiving short section 113, since the radius of the long end 12141 of the cam 1214 is larger than the radius of the eccentric hole 1131 on the receiving short section 113, the long end 12141 of the cam 1214 will rotate upward due to the constraint of the eccentric hole 1131 on the receiving short section 113 until the long end 12141 of the cam 1214 can slide into the eccentric hole 1131 on the receiving short section 113. After the long end 12141 of the cam 1214 slides over the upper end surface of the slot 1133 of the eccentric hole 1131 of the receiving short section 113, it will hit the upper end surface, so that the casting and fishing assembly 121 cannot slide upward. Thereafter, the bailer 3 is lifted up. Since the bailing assembly 121 is locked by the cam 1214, the lifting force exceeds the friction force between the clamping and pressing head on the side arm and the raised portion on the back cap 1212. Then, the bailer 3 is separated from the hanging piece monitoring mechanism 12, and the launching operation is completed.

[0101] After the monitoring cycle is completed, it is necessary to remove the hanging piece monitoring mechanism 12, and the wellhead operation machine will lower the bailer 3 into the well. The clamping and pressing head of the bailer 3 will be connected with the annular groove 12112 on the bailer head 1211. After the bailer head 1211 is lifted up, the spring 1215 is compressed, and the boss 12113 at the lower end of the bailer head 1211 is separated from the locking groove 12142 of the cam 1214. When the boss 12113 at the lower end of the bailer head 1211 moves out of the maximum diameter of the axial section of the cam 1214, the cam 1214 loses its constraint and support, and the limit is released to allow free rotation. Continuing to lift the bailer head 1211 can drive the bailer assembly 121 to slide out of the eccentric hole 1131 that receives the short section 113. After the hanging piece monitoring mechanism 12 is lifted out of the wellhead, the hanging piece 1222 can be removed by unscrewing the loading bolt 1223 on the ground, and the hanging piece 1222 is sent to the laboratory for corrosion status evaluation and corrosion rate measurement, so as to achieve the purpose of monitoring the downhole corrosion status. Since the inner diameter of the area where the downhole corrosion monitor 1 is located is consistent with the inner diameter of the oil pipe 2 after the bailer 3 is lifted out of the wellhead, the normal water injection work and the subsequent measurement and adjustment operation are not affected. The hanging piece 1222 can be fished out at any time during the monitoring period, and the monitoring period is flexible and adjustable.

[0102] In another alternative embodiment, referring to Figure 8~Figure 12As shown, the above-mentioned downhole corrosion monitor 1 may also include: a cable-controlled monitoring mechanism 13, which is located between the upper joint 111 and the upper cylinder sleeve 112; the cable-controlled monitoring mechanism 13 may include: an electrode assembly 131, a cable assembly 132, a temperature-pressure assembly 133, a main control circuit board 134 and a sheath 135; the electrode assembly 131 may include: an electrode joint 1311, an electrode control board 1312, an electrode 1313, an electrode fixing head 1314, a sealing pressure ring 1315, an electrode sealing ring 1316 and a spacer 1317; one end of the electrode joint 1311 is connected to the upper cylinder sleeve 112, and the other end is connected to the upper joint 1 11 connection; the electrode control board 1312 is welded on the electrode connector 1311; a T-shaped through hole 13111 is opened in the long axis direction of the electrode connector 1311, the electrode 1313 is located in the T-shaped through hole 13111, and the end of the electrode 1313 close to the upper cylinder sleeve 112 extends out of the T-shaped through hole 13111; the spacer 1317, the electrode sealing ring 1316, and the sealing pressure ring 1315 are nested on the outside of the electrode 1313 and are located in the T-shaped through hole 13111, and the electrode fixing head 1314 is nested on the outside of the electrode 1313 and connected to the T-shaped through hole 13111 and limits the sealing pressure ring 1315; The electrode control board 1312 is electrically connected to the electrode 1313 and is used to collect the electrical signal monitored by the electrode 1313; the upper connector 111 is provided with a through hole 1111 and a mounting hole 1112 in the long axis direction, and the cable assembly 132 may include: a cable 1321 and a cable sealing head 1322, the cable 1321 is located in the through hole 1111, and the cable sealing head 1322 is installed on the mounting hole 1112; the temperature and pressure assembly 133 may include: a temperature sensor 1331, a temperature control board 1332, a pressure sensor 1333 and a pressure control board 1334, the temperature sensor 1331 and the pressure sensor 1333 are installed Installed on the end face of the electrode connector 1311 close to the upper cylinder sleeve 112, the temperature control board 1332 and the pressure control board 1334 are respectively welded on the electrode connector 1311, and the temperature control board 1332 is electrically connected to the temperature sensor 1331, and the pressure control board 1334 is electrically connected to the pressure sensor 1333; the main control circuit board 134 is welded on the electrode connector 1311, and is respectively electrically connected to the cable 1321, the electrode control board 1312, the temperature control board 1332, and the pressure control board 1334; the sheath 135 is nested on the outside of the electrode assembly 131, and is located between the upper connector 111 and the electrode connector 1311.

[0103] The cable control monitoring mechanism 13 in the embodiment of the present invention is used to monitor the downhole temperature, pressure and corrosion rate in real time. The electrode 1313 in the electrode assembly 131 may include a working electrode, a reference electrode and an auxiliary electrode. The three electrodes 1313 are respectively fixed and sealed in the T-shaped through hole 13111 opened on the electrode connector 1311 by three groups of electrode fixing heads 1314, sealing pressure rings 1315, electrode sealing rings 1316 and spacers 1317. The three electrodes 1313 are respectively electrically connected to the electrode control board 1312 to control the voltage and current required by the three electrodes 1313 respectively, and measure the voltage change between the electrode 1313 and the environmental medium through the three electrodes 1313. The electrode control board 1312 is also used to record the above voltage change and compare the reaction current difference between the working electrode and the reference electrode to characterize the corrosion rate of the working electrode, thereby realizing real-time monitoring of the corrosion rate in the medium environment in the well. The main control circuit board 134 in this embodiment is connected to the cable 1321, and the ground control equipment provides the required power to the main control circuit board 134 through the cable 1321. The temperature sensor 1331 and the pressure sensor 1333 monitor the temperature and pressure of the medium environment in the well in real time, and send the real-time monitored temperature and pressure data to the main control circuit board 134 through the temperature control board 1332 and the pressure control board 1334. The main control circuit board 134 records and stores the real-time monitored corrosion rate, temperature and pressure data of the medium environment in the well, and uploads the above data to the ground control equipment (not shown in the figure) in real time.

[0104] It should be noted that, since the corrosion rate in the downhole medium environment monitored in real time by the electrode assembly 131 in the embodiment of the present invention is not the most accurate, the corrosion rate monitored by the weight loss method of the hanging piece 1222 can also be corrected in this embodiment to achieve the purpose of accurate real-time monitoring. Fig.10 and Fig.11 As shown, the specific positions of the working electrode, reference electrode and auxiliary electrode in the embodiment of the present invention are not limited.

[0105] Based on the same inventive concept, an embodiment of the present invention further provides a downhole corrosion monitoring method, which is implemented according to the downhole corrosion monitor described above, combined with Figure 1 to Figure 13 As shown, the method may include the following steps:

[0106] Step 1, connect the upper joint 111 and the lower joint 115 in the receiving assembly 11 of the downhole corrosion monitor 1 to the oil pipe 2 respectively, and lower it into the target well through the wellhead operation machine 4; wherein, the hanging plate monitoring mechanism 12 included in the downhole corrosion monitor 1 is assembled on the receiving assembly 11, or assembled on the receiving assembly 11 through the bailer 3 after being lowered into the target well.

[0107] Step 2: After the set monitoring time is reached, the hanging piece monitoring mechanism 12 is taken out through the scooping device 3, and the hanging piece 1222 in the hanging piece monitoring mechanism 12 is disassembled to evaluate the corrosion condition and calculate the corrosion rate through the weight loss method.

[0108] Step 3: according to the preset monitoring cycle, the hanging piece monitoring mechanism 12 loaded with the new hanging piece 1222 is lowered into the target well using the bailer 3 to continue the downhole corrosion monitoring.

[0109] In another optional embodiment, the above-mentioned downhole corrosion monitoring method may further include the following steps:

[0110] Step 4: Real-time monitoring of corrosion rate and temperature and pressure is performed through the cable-controlled monitoring mechanism 13 in the downhole corrosion monitor 1.

[0111] Step 5: Correct the real-time monitoring of the corrosion rate by using the corrosion rate result obtained by the weight loss method using the hanging plate 1222 to determine the underground corrosion rate under the actual working conditions.

[0112] Based on the same inventive concept, an underground corrosion monitoring system is also provided in an embodiment of the present invention. Fig.13 As shown, the system may include: an oil pipe 2, a bailer 3, a wellhead operating machine 4 and at least one of the above-mentioned downhole corrosion monitors 1; both ends of the downhole corrosion monitor 1 are respectively connected to the oil pipe 2; the wellhead operating machine 4 is used to lower the oil pipe 2 and the downhole corrosion monitor 1 to a preset well section in the target well; the downhole corrosion monitor 1 is used to perform downhole corrosion monitoring, and after reaching a set monitoring time, the hanging piece monitoring mechanism 12 in the downhole corrosion monitor 1 is taken out by the bailer 3, and the hanging piece 1222 in the hanging piece monitoring mechanism 12 is disassembled to evaluate the corrosion condition and calculate the corrosion rate by the weight loss method.

[0113] Based on the same inventive concept, an embodiment of the present invention further provides an application of a downhole corrosion monitor in downhole corrosion monitoring. The downhole corrosion monitor is the downhole corrosion monitor in the above embodiment.

[0114] The specific implementation and beneficial effects of the downhole corrosion monitoring method, downhole corrosion monitoring system and downhole corrosion monitor involved in the embodiments of the present invention in downhole corrosion monitoring can refer to the specific introduction of the downhole corrosion monitor in the above embodiments, and the embodiments of the present invention will not be repeated here.

[0115] Obviously, various changes and modifications may be made to the present invention by those skilled in the art without departing from the spirit and scope of the present invention. The present disclosure is not limited to the precise structure described above and shown in the accompanying drawings, and various changes and modifications may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims. Thus, if these changes and modifications of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and modifications.

Claims

1. A downhole corrosion monitor, characterized in that: include: A receiving assembly, a hanging piece monitoring mechanism and a cable control monitoring mechanism detachably assembled in the receiving assembly; The receiving assembly includes: an upper joint, an upper cylinder sleeve, a receiving short section, a lower cylinder sleeve, a lower joint, a guide cylinder, a positioning short section and a rotating guide body connected in sequence; The receiving short section is cylindrical, an eccentric hole for accommodating the hanging piece monitoring mechanism is opened in the long axis direction of the receiving short section, and a through hole communicating with the eccentric hole is opened on the inner wall of the receiving short section; The guide cylinder is nested in the upper cylinder sleeve and connected to the receiving short section, and a first guide groove is formed on the guide cylinder, and the first guide groove matches the position of the eccentric hole; The positioning nipple is nested in the lower cylinder sleeve and the lower joint, and is connected to the lower cylinder sleeve; The rotating guide body is nested in the positioning short section and connected to the positioning short section, and a second guide groove is provided on the rotating guide body, and the second guide groove and the first guide groove are located on one side of the central axis of the receiving assembly; The upper joint and the lower joint are used for external oil pipes, and the hanging piece monitoring mechanism is used to be assembled in the eccentric hole by a bailer or to be taken out from the eccentric hole by a bailer; The cable control monitoring mechanism is located between the upper joint and the upper cylinder sleeve; the cable control monitoring mechanism includes: an electrode assembly, a cable assembly, a temperature and pressure assembly, a main control circuit board and a sheath; The electrode assembly comprises: an electrode joint, an electrode control board, an electrode, an electrode fixing head, a sealing pressure ring, an electrode sealing ring and a spacer; one end of the electrode joint is connected to the upper cylinder sleeve, and the other end is connected to the upper joint; the electrode control board is welded to the electrode joint; a T-shaped through hole is opened in the long axis direction of the electrode joint, the electrode is located in the T-shaped through hole, and one end of the electrode close to the upper cylinder sleeve extends out of the T-shaped through hole; the spacer, the electrode sealing ring and the sealing pressure ring are nested on the outside of the electrode and are located in the T-shaped through hole, the electrode fixing head is nested on the outside of the electrode and connected to the T-shaped through hole and limits the sealing pressure ring; the electrode control board is electrically connected to the electrode for collecting the electrical signal monitored by the electrode; The upper joint is provided with a through hole and a mounting hole in the long axis direction, and the cable assembly comprises: a cable and a cable sealing head, the cable is located in the through hole, and the cable sealing head is installed on the mounting hole; The temperature and pressure assembly comprises: a temperature sensor, a temperature control board, a pressure sensor and a pressure control board, wherein the temperature sensor and the pressure sensor are mounted on the end surface of the electrode joint close to the upper cylinder sleeve, the temperature control board and the pressure control board are respectively welded to the electrode joint, and the temperature control board is electrically connected to the temperature sensor, and the pressure control board is electrically connected to the pressure sensor; The main control circuit board is welded on the electrode connector and is electrically connected to the cable, the electrode control board, the temperature control board, and the pressure control board respectively; The sheath is nested on the outside of the electrode assembly and is located between the upper connector and the electrode connector.

2. The downhole corrosion monitor according to claim 1, characterized in that: The hanging piece monitoring mechanism comprises: a casting and catching component and a hanging piece monitoring component; The casting and fishing assembly comprises: a casting and fishing head, a back cap, a connecting short section, a cam and a spring; The back cap and the connecting short section are detachably connected, a through slot is provided in the middle of the connecting short section, and the cam is rotatably fixed in the through slot; The scooping head is nested inside the back cap and the connecting short section, one end of the scooping head extends out of the back cap for external connection with the scooping device, and the other end extends into the through slot to cooperate with the cam; A step is provided in the middle of the fishing head, the spring is nested on the outside of the fishing head, one end of the spring abuts against the step, and the other end abuts against the back cap; The hanging piece monitoring assembly is connected to an end of the connecting short section away from the back cap; In the launching operation, the bailer is connected with the back cap to lower the hanging piece monitoring mechanism into the well, the hanging piece monitoring mechanism is sent to the eccentric hole along the first guide groove, the bailer is lifted up, the spring compresses the bailing head so that the bailing head acts on the cam, so that the long end of the cam extends out of the through groove and is limited on the eccentric hole, and the bailer is separated from the back cap to realize the launching operation of the hanging piece monitoring mechanism; During the lifting operation, the bailer is connected to the bailing head, the bailing head is lifted and the spring is compressed to separate the bailing head from the cam, and the bailing head is further lifted to release the cam from the eccentric hole to realize the lifting operation of the hanging piece monitoring mechanism.

3. The downhole corrosion monitor according to claim 2, characterized in that: The hanging plate monitoring assembly comprises: a loading nipple, a hanging plate and a loading bolt; The loading short section is threadedly connected to the connecting short section. One end of the loading short section away from the connecting short section is tapered. The middle of the loading short section is hollowed out. The hanging piece is fixed to the hollow part of the loading short section through the loading bolt.

4. The downhole corrosion monitor according to claim 2, characterized in that: The receiving short section is provided with a slot inside the eccentric hole, the slot is located on a side of the through hole close to the first guide groove, and the positions of the slot and the through hole match; When the long end of the cam extends out of the through slot, the long end of the cam can be engaged in the clamping slot, so as to limit the casting and fishing assembly through the clamping slot.

5. The downhole corrosion monitor according to claim 4, characterized in that: A first recessed angle of the axial cross section of the clamping groove close to one end of the through hole is greater than 90°, and a second recessed angle away from one end of the through hole is not greater than 90°.

6. The downhole corrosion monitor according to claim 2, characterized in that: A plurality of annular grooves are formed on the outer side of one end of the bailing head away from the cam, wherein the axial cross section of the annular grooves is triangular and the annular grooves are used to cooperate with the clamping and pressing head of the bailing device; One end of the catching head matched with the cam is provided with a boss, and the cam is provided with a locking groove matched with the boss.

7. The downhole corrosion monitor according to any one of claims 1 to 6, characterized in that: The receiving assembly further comprises: a first screw, a second screw, a third screw, a fourth screw, a fifth screw, a first bolt and a second bolt; The upper joint, the upper cylinder sleeve, the receiving nipple, the lower cylinder sleeve and the lower joint are threadedly connected in sequence; the upper joint and the upper cylinder sleeve are fixed by the first screw, the upper cylinder sleeve and the receiving nipple are fixed by the second screw, the receiving nipple and the lower cylinder sleeve are fixed by the third screw, and the lower cylinder sleeve and the lower joint are fixed by the fourth screw; The guide cylinder abuts against the end surface of the receiving short section and is connected by a first bolt; The positioning nipple is connected to the lower cylinder sleeve via a fifth screw; The rotary guide body and the positioning short section are connected via the second bolt.

8. A method for monitoring underground corrosion, characterized in that: The downhole corrosion monitoring method is implemented according to the downhole corrosion monitor according to any one of claims 1 to 7, and the method comprises: The upper joint and the lower joint in the receiving assembly of the downhole corrosion monitor are respectively connected to the oil pipe, and the downhole corrosion monitor is lowered into the target well through the wellhead operation machine; wherein the hanging piece monitoring mechanism included in the downhole corrosion monitor is assembled on the receiving assembly, or assembled on the receiving assembly through a bailer after being lowered into the target well; After the set monitoring time is reached, the hanging monitoring mechanism is taken out by a scooping device, and the hanging pieces in the hanging monitoring mechanism are disassembled to evaluate the corrosion status and calculate the corrosion rate by weight loss method; According to the preset monitoring cycle, the hook monitoring mechanism loaded with new hooks is lowered into the target well using the bailer to continue underground corrosion monitoring.

9. The method according to claim 8, characterized in that Also includes: Real-time monitoring of corrosion rate and temperature and pressure is performed through the cable-controlled monitoring mechanism in the downhole corrosion monitor; The corrosion rate real-time monitoring is corrected by the corrosion rate result obtained by the weight loss method using the hanging plate to determine the underground corrosion rate under actual working conditions.

10. A downhole corrosion monitoring system, characterized in that: include: An oil pipe, a bailer, a wellhead operating machine and at least one downhole corrosion monitor as described in any one of claims 1 to 7; Both ends of the downhole corrosion monitor are connected to the oil pipe respectively; The wellhead operation machine is used to lower the oil pipe and the downhole corrosion monitor to a preset well section in the target well; The downhole corrosion monitor is used for downhole corrosion monitoring. When the set monitoring time is reached, the hanging plate monitoring mechanism in the downhole corrosion monitor is taken out by the bailer, and the hanging plates in the hanging plate monitoring mechanism are disassembled to evaluate the corrosion status and calculate the corrosion rate by the weight loss method.

11. An application of a downhole corrosion monitor in downhole corrosion monitoring, characterized in that: The downhole corrosion monitor is the downhole corrosion monitor according to any one of claims 1 to 7.

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