Device and method capable of monitoring corrosion and scaling of oil casing with sucker rod

Abstract

The invention discloses a device and method capable of monitoring corrosion and scaling of an oil casing with a sucker rod. The device comprises an oil pipe pup joint arranged on an oil pipe and a corrosion coupon support arranged on a dosing tail pipe, the oil pipe pup joint comprises an oil pipe pup joint body, an oil pipe pup joint upper end and an oil pipe pup joint lower end, the oil pipe pup joint body is of a circular tube structure with two open ends, and double-layer annular corrosion coupon bodies are arranged on the oil pipe pup joint body. Comprising an outer-layer annular corrosion coupon arranged on an oil pipe pup joint body and an inner-layer annular corrosion coupon arranged on the inner wall of the oil pipe pup joint body and is used for monitoring the corrosion conditions of a sleeve and an oil pipe, and the corrosion coupon is fixed to a corrosion coupon support and fixed to a dosing tail pipe through a bolt structure. According to the method, component analysis of water produced by a to-be-monitored well and an indoor corrosion simulation experiment are combined, and the corrosion coupon is mounted at a determined corrosion monitoring part, so that the corrosion condition of an oil pipe and a sleeve in an oil-gas well is monitored on the premise of not influencing normal operation of the oil-gas well.

Description

Technical Field

[0001] The invention relates to the technical field of corrosion and protection of metal materials, and in particular to a device and method for monitoring corrosion and scaling of an oil casing with a sucker rod. Background Art

[0002] As the main old oil fields enter the late stage of development, the water content of the produced crude oil increases rapidly. In recent years, with the development of high (acid) gas fields, shale oil, CO2 flooding, ultra-deep oil fields, etc., the corrosion environment is severe, and the corrosion, scaling and perforation risks of oil pipes and casings in oil and gas wells increase. This makes it very important to monitor the corrosion of oil pipes and casings and determine the specific location of corrosion monitoring in order to understand the corrosion and scaling conditions of oil and gas wells and formulate corrosion control strategies.

[0003] During the oilfield production process, multiple pumping rods in the oil pipe are sequentially connected to the piston extending to the underground oil layer, and the oil is pumped through reciprocating motion. Depending on the nature of the produced water and gas in the reservoir, the oil pipe and casing may corrode, and the corrosion conditions of the oil pipe and casing at different depths are different, making the location of the corrosion monitoring point particularly important. If too few corrosion monitoring points are set, there will be local perforations that are not detected, resulting in the shutdown of the oil and gas well. However, too many corrosion monitoring points cannot be set. It is necessary to reasonably set corrosion monitoring points and monitor key key parts.

[0004] In summary, the layout of corrosion monitoring points is very important for understanding the actual corrosion status of oil pipes and casings. In addition, the hanging corrosion hanger cannot affect the normal production operations of the oil pipes, casings and sucker rods in the oil and gas wells, and cannot affect the flow state of the medium in the oil pipes and casings. Therefore, it is urgent to propose a device and method for monitoring the corrosion and scaling of oil casings with sucker rods, so as to realize the monitoring of the corrosion of oil pipes and casings in oil and gas wells without interfering with the normal production of oil and gas wells. Summary of the invention

[0005] The corrosion monitoring devices currently used in oil pipes or casings of oil and gas wells will affect the flow of media in the oil pipes or casings, and are difficult to be used for monitoring corrosion in oil casings with sucker rods. In addition, the prior art has not yet involved a method for determining key positions for monitoring corrosion and scaling of oil pipes and casings in oil and gas wells. The present invention proposes a device and method for monitoring corrosion and scaling of oil casings with sucker rods, which realizes the monitoring of corrosion and scaling of oil pipes or casings at any depth in oil and gas wells without affecting the normal production operation of the oil and gas wells, thereby laying a foundation for corrosion prevention and control of oil and gas wells.

[0006] The present invention specifically adopts the following technical solutions:

[0007] A device capable of monitoring corrosion and scaling of an oil casing with a sucker rod, comprising an oil pipe short-circuit arranged on the oil pipe and a corrosion hanging piece bracket arranged on a dosing tail pipe;

[0008] The oil pipe short connection includes an oil pipe short connection body, an oil pipe short connection upper end portion and an oil pipe short connection lower end portion;

[0009] The tubing short-circuit body is a circular tubular structure with two ends open. The upper end of the tubing short-circuit is arranged at the top of the tubing short-circuit body and is integrally formed with the tubing short-circuit body. The lower end of the tubing short-circuit is arranged at the bottom of the tubing short-circuit body and is threadedly connected with the tubing short-circuit body.

[0010] The tubing short-circuit body is provided with a double-layer annular corrosion hanging plate, which includes an outer annular corrosion hanging plate and an inner annular corrosion hanging plate. The outer annular corrosion hanging plate is provided on the outer wall of the tubing short-circuit body to monitor the corrosion conditions inside the casing and outside the tubing, and the inner annular corrosion hanging plate is provided on the inner wall of the tubing short-circuit body to monitor the corrosion conditions inside the tubing.

[0011] The outer annular corrosion hanging piece includes a lower outer test ring, a middle outer test ring and an upper outer test ring. The lower outer test ring, the middle outer test ring and the upper outer test ring are sequentially sleeved on the outer wall of the tubing short-circuit body in order from bottom to top. The middle outer test ring is set as an annular corrosion hanging piece. An outer isolation ring is set between the lower outer test ring and the middle outer test ring and between the middle outer test ring and the upper outer test ring. The upper outer test ring and the lower outer test ring are both sealed with the outer wall of the tubing short-circuit body through an outer sealing ring.

[0012] The inner annular corrosion hanging piece includes a lower inner test ring, a middle inner test ring and an upper inner test ring, which are arranged on the inner wall of the tubing short-circuit body in order from bottom to top, the middle inner test ring is arranged as an annular corrosion hanging piece, inner isolation rings are arranged between the lower inner test ring and the middle inner test ring and between the middle inner test ring and the upper inner test ring, and the upper inner test ring and the lower inner test ring are sealed with the inner wall of the tubing short-circuit body through inner sealing rings;

[0013] The corrosion hanging piece bracket is made of non-metallic material and is arranged on the dosing tail pipe. The corrosion hanging piece is fixed on the corrosion hanging piece bracket.

[0014] Preferably, both ends of the oil pipe short circuit are threadedly connected to the oil pipe.

[0015] Preferably, the outer diameter of the oil pipe short connection is the same as the outer diameter of the oil pipe, and the inner diameter of the oil pipe short connection is the same as the inner diameter of the oil pipe.

[0016] Preferably, reinforcing ribs are provided inside the oil pipe short-circuit body.

[0017] Preferably, the reinforcing rib is in a circular ring shape.

[0018] Preferably, the outer isolation ring and the inner isolation ring are both made of non-metallic materials.

[0019] Preferably, the sizes of the lower outer test ring, the middle outer test ring, the upper outer test ring and the outer isolation ring are the same, and the inner diameters of the lower outer test ring, the middle outer test ring, the upper outer test ring and the outer isolation ring are the same as the outer diameter of the oil pipe short circuit.

[0020] Preferably, the sizes of the lower inner test ring, the middle inner test ring, the upper inner test ring and the inner isolation ring are the same, and the inner diameters of the lower inner test ring, the middle inner test ring, the upper inner ring and the inner isolation ring are the same as the inner diameter of the oil pipe short circuit.

[0021] Preferably, the top of the upper outer layer test ring is reduced in diameter to form an upper outer layer step portion, and the bottom of the lower outer layer test ring is reduced in diameter to form a lower outer layer step portion;

[0022] The top of the upper inner layer test ring is expanded to form an upper inner layer step portion, and the bottom of the lower inner layer test ring is expanded to form a lower inner layer step portion.

[0023] Preferably, the upper part of the oil pipe short-circuit body is provided with two limiting grooves, including an upper outer limiting groove and an upper inner limiting groove, wherein the upper outer limiting groove is used to fix the upper outer test ring, and the upper inner limiting groove is used to fix the upper inner test ring;

[0024] Two limiting grooves are arranged at the lower part of the oil pipe short-circuit body, including a lower outer limiting groove and a lower inner limiting groove, wherein the lower outer limiting groove is used to fix the lower outer test ring, and the lower inner limiting groove is used to fix the lower inner test ring.

[0025] Preferably, the upper outer layer step portion on the upper outer layer test ring is embedded in the upper outer layer limiting groove, and an outer layer sealing ring is sleeved on the upper outer layer step portion to seal and connect the upper outer layer test ring with the outer wall of the oil pipe short-circuit body;

[0026] The lower outer layer step portion on the lower outer layer test ring is embedded in the lower outer layer limiting groove, and an outer layer sealing ring is sleeved on the lower outer layer step portion to seal and connect the lower outer layer test ring with the outer wall of the oil pipe short-circuit body;

[0027] The upper inner layer step portion on the upper inner layer test ring is embedded in the upper inner layer limiting groove, and an inner layer sealing ring is sleeved on the upper inner layer step portion to seal and connect the upper inner layer test ring with the outer wall of the oil pipe short-circuit body;

[0028] The lower inner layer step portion on the lower inner layer test ring is embedded in the lower inner layer limiting groove, and an inner layer sealing ring is sleeved on the lower inner layer step portion to seal and connect the lower inner layer test ring with the outer wall of the oil pipe short-circuit body.

[0029] Preferably, the corrosion hanging plate bracket is configured as a strip corrosion hanging plate bracket or a ring corrosion hanging plate bracket.

[0030] Preferably, the corrosion coupon bracket is configured as a strip-shaped corrosion coupon bracket, and the length of the strip-shaped corrosion coupon bracket is greater than the circumference of the dosing tail pipe;

[0031] The strip-shaped corrosion hanging piece bracket is provided with a plurality of corrosion hanging piece fixing holes, and the corrosion hanging pieces are hung on the corrosion hanging piece fixing holes through fixing ropes;

[0032] Bolt holes are arranged at both ends of the strip corrosion hanging plate bracket, and fixing bolts are inserted into the bolt holes at both ends of the strip corrosion hanging plate bracket in sequence and fastened by fixing nuts to fix the strip corrosion hanging plate bracket on the dosing tail pipe.

[0033] Preferably, the corrosion coupon bracket is configured as an annular corrosion coupon bracket, and the inner diameter of the annular corrosion coupon bracket is the same as the outer diameter of the dosing tail pipe;

[0034] The annular corrosion hanging plate bracket comprises an upper semi-annular corrosion hanging plate bracket and a lower semi-annular corrosion hanging plate bracket;

[0035] The ends of the upper semi-annular corrosion coupon bracket and the lower semi-annular corrosion coupon bracket are both provided with positioning grooves, and the magnetic sheet is fixed in the positioning grooves. The magnetic sheet arranged at the end of the upper semi-annular corrosion coupon bracket has opposite polarity to the magnetic sheet arranged at the end of the lower semi-annular corrosion coupon bracket.

[0036] The upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are both provided with a plurality of corrosion hanger fixing holes, the axial direction of the corrosion hanger fixing holes is parallel to the axial direction of the dosing tail pipe, and the corrosion hangers are suspended on the corrosion hanger fixing holes by fixing ropes;

[0037] The outer walls of the ends of the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are both provided with connecting frames, and bolt holes are provided on the connecting frames. The fixing bolts pass through the bolt holes on the upper semi-annular corrosion hanger bracket connecting frame and the lower semi-annular corrosion hanger bracket connecting frame in turn and are fastened by fixing nuts to fix the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket in connection.

[0038] Preferably, the fixing rope is made of non-conductive material, and the fixing bolt and the fixing nut are both made of non-metallic material.

[0039] A method for monitoring corrosion and scaling of an oil casing with a sucker rod, using the device for monitoring corrosion and scaling of an oil casing with a sucker rod as described above, specifically comprises the following steps:

[0040] Step 1: Analyze the components of the produced water of the monitored well, comprehensively consider the influence of the water production, gas production, temperature, pressure and flow rate of the monitored well on the scaling of the wellbore, and infer the temperature, pressure, scaling ion concentration and scaling trend at different depths of the wellbore of the monitored well;

[0041] Step 2: Based on the indoor corrosion simulation experiment, combined with the temperature, pressure, CO2 content, produced water composition and pH value at different depths of the wellbore, the weight loss experiment, electrochemical experiment and corrosion product characterization method are used to simulate the corrosion and scaling conditions inside the wellbore at different depths in the laboratory, determine the laws of corrosion and scaling at different well depths, and determine the installation position of the corrosion hanging plate of the well to be monitored based on the corrosion laws and structural laws obtained, combined with the main controlling factors of corrosion, scaling trend, location of the downhole pump, and dynamic and static liquid level positions, and determine whether it is necessary to install a corrosion hanging plate bracket based on whether there is a dosing tail pipe;

[0042] Step 3, according to the corrosion coupon installation position determined in step 2, a tubing short-circuit is installed at a specified depth position of the tubing, and the outer annular corrosion coupon on the tubing short-circuit is used to monitor the corrosion condition of the inner side of the casing and the outer side of the tubing. At the same time, the inner annular corrosion coupon on the tubing short-circuit is used to monitor the corrosion condition of the inner side of the tubing, and the corrosion condition of the inner side of the tubing and the casing at different depth positions is monitored in real time;

[0043] Step 4, if it is determined in step 2 that there is a dosing tail pipe, a corrosion coupon bracket with a corrosion coupon suspended thereon is installed on the dosing tail pipe, and the corrosion coupon bracket with the corrosion coupon suspended thereon is used to monitor the corrosion condition of the casing at the bottom of the well; if it is determined in step 2 that there is no dosing tail pipe, there is no need to install a corrosion coupon bracket with a corrosion coupon suspended thereon.

[0044] Preferably, the temperature calculation formula at different depths in the well to be monitored is:

[0045] T (H) = T (0) + Gt×H (1)

[0046] Where, H is the well depth in meters; T (H) is the fluid temperature at the well depth H, in °C, T (0) is the fluid temperature at the wellhead, in °C; Gt is the fluid temperature gradient, in °C / m;

[0047] The pressure calculation formula at different depths in the well to be monitored is:

[0048] P(H) =P (0) +Gp×H (2)

[0049] Where P (H) is the pressure at the well depth H, in MPa, P (0) is the pressure at the wellhead, in MPa; Gp is ​​the fluid pressure gradient, in MPa / m;

[0050] The calculation formula for pH values ​​at different depths in the well to be monitored is:

[0051] pH (H) =pH (0) +ΔpH (3)

[0052] in,

[0053] ΔpH=4.05×10 -3 [T (H) -T (0) ]+4.58×10 -7 -3.07×10 -5 [P (H) -P (0) ] (4)

[0055] Where, pH (H) is the pH value at the well depth H, pH (0) is the pH value at the wellhead, ΔpH is the change in pH value;

[0056] According to the composition analysis results of the produced water of the monitored well, combined with the daily water production and daily oil production of the monitored well, the scaling index at the specified depth of the monitored well is calculated; if the scaling index I s When it is greater than 0, it means that there is a scaling trend at the specified depth of the well to be monitored. If the scaling index I s When it does not exceed 0, it means that there will be no scaling at the specified depth of the well to be monitored;

[0057] The scaling index calculation formula at the specified depth of the well to be monitored is shown in formula (5):

[0058]

[0059] in, and The calculation formula is,

[0060]

[0061]

[0062] In the formula, Is is the scaling index at the specified depth of the well to be monitored; [X m+ ] is the ionic activity of the m-valent cation X, in mol / L, [Y n- ] is the ionic activity of the n-valent anion Y, in mol / L; P is the pressure value at the specified depth of the well to be monitored, in MPa; is the CO2 content in the gas phase, is the fugacity coefficient of CO2; T is the temperature at the specified depth of the well to be monitored, in °F; p is the absolute pressure, in psi; μ is the ionic strength, in mol / L; a0, a1, a2, a3, a4, and a5 are all calculation coefficients of the scaling index at the specified depth of the well to be monitored; b0 and b1 are Calculation coefficient of ; is the content of CO2 in the mixed system of gas, oil and brine; BWPD is the daily water production of the well to be monitored, in bbl; BOPD is the daily oil production of the well to be monitored, in bbl; MMscf is the daily gas production of the well to be monitored under standard conditions, in MMft 3 , the standard temperature under the standard conditions is set to 273.15K, and the standard pressure is set to 101.325kPa; c0 and c1 are both calculation parameters for the CO2 content in the gas phase; a and b are both scaling index calculation indices. When the well to be monitored contains CaCO3, the scaling index calculation indices a=2 and b=1, and when the well to be monitored contains CaSO4, the scaling index calculation indices a=1 and b=0;

[0063] The ionic strength calculation formula is:

[0064]

[0065]

[0066] in,

[0067]

[0068]

[0069] Where i is the serial number of the ion in the well to be monitored, N is the total number of ion types in the well to be monitored; m i is the ion concentration of the i-th ion in the well to be monitored, in mol / L; Z i is the valence state of the i-th ion in the well to be monitored, γ iis the ionic activity coefficient of the i-th ion; A and B are the ionic strength calculation coefficients; R is the ideal gas constant, which is 8.3143 J / (mol·K); F is the Faraday constant, which is 96484.6 C / mol; e0 is the charge of the electron, which is 1.602×10 -19 C; ε is the dielectric constant, ε=ε0ε r , ε0 is the vacuum dielectric constant, which is 80, ε r is the relative dielectric constant, which is 8.854×10 -12 F / m;

[0070] The calculation formula for the ion activity of cations and anions in the well to be monitored is:

[0071]

[0072]

[0073] In the formula, is the ion concentration of m-valent cation X, in mol / L, is the ionic activity coefficient of the m-valent cation X; is the ion concentration of n-valent anion Y, in mol / L, is the ionic activity coefficient of the n-valent anion Y.

[0074] The beneficial effects of the present invention are:

[0075] The present invention provides a device and method for monitoring corrosion and scaling of oil casing with sucker rods. By identifying the key monitoring parts of the wells to be monitored, an oil pipe short-circuit with a double-layer annular corrosion hanger is arranged on the oil pipe at the key monitoring part, and a corrosion hanger bracket is arranged on the dosing tail pipe to suspend the corrosion hanger. Under the premise of not affecting the normal operation of the sucker rod in the oil pipe and the normal production of the oil pipe, the corrosion and scaling conditions of the oil pipe and casing at any depth and the bottom of the well are monitored, especially the corrosion and scaling conditions of the key parts in the oil and gas wells are monitored, which effectively solves the problems of arranging the monitoring points of corrosion and scaling in the oil pipe and casing and not disrupting the normal production and operation of the oil and gas wells during the monitoring process. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 The present invention is a schematic structural diagram of an oil pipe short circuit in a device capable of monitoring corrosion and scaling of an oil casing with a sucker rod.

[0077] Figure 2 It is a schematic diagram of the structure of the upper outer test ring of the outer annular corrosion hanging piece of the present invention.

[0078] Figure 3 It is a schematic structural diagram of the lower outer test ring of the outer annular corrosion hanging piece of the present invention.

[0079] Figure 4 It is a schematic diagram of the structure of the upper inner layer test ring of the inner layer annular corrosion hanging piece of the present invention.

[0080] Figure 5 It is a schematic structural diagram of the lower inner layer test ring of the inner layer annular corrosion hanging piece of the present invention.

[0081] Figure 6 The present invention is a schematic structural diagram of a strip corrosion hanging plate support in a device capable of monitoring corrosion and scaling of oil casing with a sucker rod.

[0082] Figure 7 The present invention is a schematic structural diagram of an annular corrosion hanging plate support in a device capable of monitoring corrosion and scaling of oil casing with a sucker rod.

[0083] Figure 8 The present invention is a flow chart of the method for monitoring corrosion and scaling of oil casing with a sucker rod.

[0084] In the figure, 1, the outer wall of the tubing short-circuit body, 2, the inner wall of the tubing short-circuit body, 3, the outer sealing ring, 4, the inner sealing ring, 5, the reinforcing rib, 6, the lower outer test ring, 7, the outer isolation ring, 8, the middle outer test ring, 9, the upper outer test ring, 10, the lower inner test ring, 11, the inner isolation ring, 12, the middle inner test ring, 13, the upper inner test ring, 14, the upper inner limiting groove, 15, the lower inner limiting groove, 16, the dosing tail pipe, 17, the strip corrosion hanging piece bracket, 18, the corrosion hanging piece fixing hole, 19, the fixing bolt, 20, the fixing nut, 21, the annular corrosion hanging piece bracket, 22, the magnetic sheet, 23, the connecting frame. DETAILED DESCRIPTION

[0085] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0086] Example 1

[0087] The present invention proposes a device for monitoring corrosion and scaling of oil casing with sucker rods, comprising an oil pipe short-circuit arranged on the oil pipe and a corrosion hanger bracket arranged on the dosing tail pipe 16, wherein a double-layer annular corrosion hanger is arranged on the oil pipe short-circuit, and a corrosion hanger is fixed on the corrosion hanger bracket made of non-metallic material, which is used to monitor the corrosion conditions of the oil pipe and casing at different depths of the monitored well.

[0088] The oil pipe short circuit is as follows Figure 1As shown, it includes an oil pipe short-connection body, an upper end portion of the oil pipe short-connection and a lower end portion of the oil pipe short-connection. The size of the oil pipe short-connection is the same as the size of the oil pipe, that is, the outer diameter of the oil pipe short-connection is the same as the outer diameter of the oil pipe, the inner diameter of the oil pipe short-connection is the same as the inner diameter of the oil pipe, and the upper end portion and the lower end portion of the oil pipe short-connection are both threadedly connected to the oil pipe.

[0089] The oil pipe short-circuit body is a circular tubular structure with two ends open. The upper end of the oil pipe short-circuit is arranged at the top of the oil pipe short-circuit body and is integrally formed with the oil pipe short-circuit body. The lower end of the oil pipe short-circuit is arranged at the bottom of the oil pipe short-circuit body and is threadedly connected with the oil pipe short-circuit body.

[0090] A circular ring-shaped reinforcing rib 5 is arranged inside the tubing short-circuit body, and a double-layer annular corrosion hanger is arranged on the tubing short-circuit body. The double-layer annular corrosion hanger includes an outer annular corrosion hanger and an inner annular corrosion hanger. The outer annular corrosion hanger is arranged on the outer wall 1 of the tubing short-circuit body to monitor the corrosion conditions inside the casing and outside the tubing, and the inner annular corrosion hanger is arranged on the inner wall 2 of the tubing short-circuit body to monitor the corrosion conditions inside the tubing.

[0091] The outer annular corrosion hanging piece includes a lower outer test ring 6, a middle outer test ring 8 and an upper outer test ring 9. The lower outer test ring, the middle outer test ring and the upper outer test ring are sequentially sleeved on the outer wall of the tubing short-circuit body in order from bottom to top. The middle outer test ring is set as an annular corrosion hanging piece. An outer isolation ring 7 is arranged between the lower outer test ring and the middle outer test ring and between the middle outer test ring and the upper outer test ring. The upper outer test ring and the lower outer test ring are sealed with the outer wall of the tubing short-circuit body through an outer sealing ring 3, which effectively avoids the crevice corrosion caused by the fluid in the casing annulus gathering in the gap between the outer annular corrosion hanging piece and the tubing short-circuit.

[0092] The inner annular corrosion hanging piece comprises a lower inner test ring 10, a middle inner test ring 12 and an upper inner test ring 13. The lower inner test ring, the middle inner test ring and the upper inner test ring are arranged on the inner wall of the tubing short-circuit body in order from bottom to top. The middle inner test ring is arranged as an annular corrosion hanging piece. An inner isolation ring 11 is arranged between the lower inner test ring and the middle inner test ring and between the middle inner test ring and the upper inner test ring. The upper inner test ring and the lower inner test ring are sealed with the inner wall of the tubing short-circuit body through an inner sealing ring 4, which effectively avoids crevice corrosion caused by the accumulation of oil field produced water in the gap between the inner annular corrosion hanging piece and the tubing short-circuit.

[0093] In this embodiment, the sizes of the lower outer test ring, the middle outer test ring, the upper outer test ring and the outer isolation ring are the same, and the inner diameters of the lower outer test ring, the middle outer test ring, the upper outer test ring and the outer isolation ring are the same as the outer diameter of the oil pipe short connection, so that the outer annular corrosion hanging piece is nested in the outer wall of the oil pipe short connection and is tightly attached to the outer wall of the oil pipe short connection, and there is no gap between the outer annular corrosion hanging piece and the outer wall of the oil pipe short connection; the sizes of the lower inner test ring, the middle inner test ring, the upper inner test ring and the inner isolation ring are the same, and the inner diameters of the lower inner test ring, the middle inner test ring, the upper inner ring and the inner isolation ring are the same as the inner diameter of the oil pipe short connection, so that the inner annular corrosion hanging piece is nested in the inner wall of the oil pipe short connection and is tightly attached to the inner wall of the oil pipe short connection, and there is no gap between the inner annular corrosion hanging piece and the inner wall of the oil pipe short connection.

[0094] At the same time, in order to ensure that the double-layer annular corrosion hanging piece is in close contact with the wall of the oil pipe short-circuit, the top of the upper outer test ring is reduced in diameter to form an upper outer step portion, such as Figure 2 As shown, the bottom of the lower outer test ring is reduced in diameter to form a lower outer step portion, such as Figure 3 As shown; the top of the upper inner layer test ring is expanded to form an upper inner layer step portion, such as Figure 4 As shown, the bottom of the lower inner layer test ring is expanded to form a lower inner layer step portion, such as Figure 5 shown.

[0095] At the same time, the upper part of the oil pipe short-circuit body is provided with two limiting grooves, including an upper outer limiting groove and an upper inner limiting groove 14, and the lower part of the oil pipe short-circuit body is provided with two limiting grooves, including a lower outer limiting groove and a lower inner limiting groove 15, wherein the upper outer limiting groove is used to fix the upper outer test ring, the upper inner limiting groove is used to fix the upper inner test ring, the lower outer limiting groove is used to fix the lower outer test ring, and the lower inner limiting groove is used to fix the lower inner test ring.

[0096] The upper outer layer step portion on the upper outer layer test ring is embedded in the upper outer layer limiting groove, and an outer layer sealing ring is sleeved on the upper outer layer step portion to seal and connect the upper outer layer test ring with the outer wall of the oil pipe short-circuit body.

[0097] The lower outer layer step portion on the lower outer layer test ring is embedded in the lower outer layer limiting groove, and an outer layer sealing ring is sleeved on the lower outer layer step portion to seal and connect the lower outer layer test ring with the outer wall of the oil pipe short-circuit body.

[0098] The upper inner layer step portion on the upper inner layer test ring is embedded in the upper inner layer limiting groove, and an inner layer sealing ring is sleeved on the upper inner layer step portion to seal and connect the upper inner layer test ring with the outer wall of the oil pipe short-circuit body.

[0099] The lower inner layer step portion on the lower inner layer test ring is embedded in the lower inner layer limiting groove, and an inner layer sealing ring is sleeved on the lower inner layer step portion to seal and connect the lower inner layer test ring with the outer wall of the oil pipe short-circuit body.

[0100] It can be seen that the device for monitoring corrosion and scaling of oil casing with sucker rods proposed in this embodiment is adopted. By setting a double-layer annular corrosion hanger on the oil pipe short-circuit, the double-layer annular corrosion hanger can be used to monitor the corrosion conditions on both sides of the oil pipe and the inside of the casing at a specified depth after the oil pipe is lowered. In conjunction with the corrosion hanger bracket set on the dosing tail pipe, the corrosion hanger is suspended by the corrosion hanger bracket to monitor the corrosion conditions of the casing at the bottom of the well, and the monitoring of corrosion and scaling of the oil casing is achieved without affecting the wall of the normal operation of the sucker rod.

[0101] Example 2

[0102] The present invention proposes a device for monitoring corrosion and scaling of oil casing with sucker rods, comprising an oil pipe short-circuit arranged between oil pipes and a corrosion hanger bracket arranged on a dosing tail pipe, wherein a double-layer annular corrosion hanger is arranged on the oil pipe short-circuit, and a corrosion hanger is fixed on the corrosion hanger bracket, which is used to monitor the corrosion conditions of the oil pipe and casing at different depths of the monitored well.

[0103] The configuration of the oil pipe short circuit in this embodiment is exactly the same as that in the embodiment 1, except that the corrosion coupon bracket in this embodiment is configured as a strip-shaped corrosion coupon bracket made of non-metallic material, such as Figure 6 shown.

[0104] In this embodiment, the strip corrosion hanger 17 support is arranged on the dosing tail pipe 16. In order to better wind and fix the strip corrosion hanger on the dosing tail pipe, the length of the strip corrosion hanger support is set to be greater than the circumference of the dosing tail pipe.

[0105] The strip-shaped corrosion hanger bracket is provided with a plurality of corrosion hanger fixing holes 18, and the corrosion hanger is hung on the corrosion hanger fixing holes by fixing ropes. The fixing ropes are made of non-conductive material to avoid galvanic corrosion between the fixing ropes and the dosing tail pipe.

[0106] The strip corrosion hanger bracket is fixed to the dosing tail pipe by bolts. Bolt holes are provided at both ends of the strip corrosion hanger bracket. The fixing bolts 19 are inserted into the bolt holes at both ends of the strip corrosion hanger bracket in turn and are fastened by the fixing nuts 20 to fix the strip corrosion hanger bracket to the dosing tail pipe. In this embodiment, the fixing bolts and the fixing nuts are made of ceramic materials, thereby avoiding galvanic corrosion between the strip corrosion hanger fixing device and the dosing tail pipe.

[0107] It can be seen that the device for monitoring corrosion and scaling of oil casing with sucker rods proposed in this embodiment is adopted. By setting a double-layer annular corrosion hanger on the oil pipe short-circuit, and cooperating with the corrosion hanger suspended by the strip corrosion hanger bracket fixed on the dosing tail pipe, the corrosion and scaling of the oil casing at different depths in the wellbore can be monitored without affecting the wall of the normal operation of the sucker rod.

[0108] Example 3

[0109] The present invention proposes a device for monitoring corrosion and scaling of oil casing with sucker rods, comprising an oil pipe short-circuit arranged on the oil pipe and a corrosion hanger bracket arranged on the dosing tail pipe, wherein a double-layer annular corrosion hanger is arranged on the oil pipe short-circuit, and a corrosion hanger is fixed on the corrosion hanger bracket, which is used to monitor the corrosion conditions of the oil pipe and casing at different depths of the monitored well.

[0110] The configuration of the oil pipe short circuit in this embodiment is exactly the same as that in the embodiment 1, except that the corrosion coupon bracket in this embodiment is configured as an annular corrosion coupon bracket made of non-metallic material, such as Figure 7 shown.

[0111] In this embodiment, the annular corrosion coupon bracket 21 is sleeved on the dosing tail pipe 16, the inner wall of the annular corrosion coupon bracket is in close contact with the outer wall of the dosing tail pipe, and the inner diameter of the annular corrosion coupon bracket is the same as the outer diameter of the dosing tail pipe.

[0112] The annular corrosion hanger bracket comprises an upper semi-annular corrosion hanger bracket and a lower semi-annular corrosion hanger bracket. The ends of the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are both provided with positioning grooves for fixing magnetic sheets. The magnetic sheet 22 is fixed in the positioning groove. At the same time, the magnetic sheet arranged at the end of the upper semi-annular corrosion hanger bracket has opposite polarity to the magnetic sheet arranged at the end of the lower semi-annular corrosion hanger bracket. Thus, after the two corresponding ends of the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are tightly fitted by magnetic force, the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are bolted together, so that the annular corrosion hanger bracket is fixed on the dosing tail pipe, and the inner wall of the annular corrosion hanger is tightly fitted to the outer wall of the dosing tail pipe.

[0113] The upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are both provided with a plurality of corrosion hanger fixing holes 18, the axial direction of the corrosion hanger fixing holes is parallel to the axial direction of the dosing tail pipe, and the corrosion hangers are suspended on the corrosion hanger fixing holes by fixing ropes, and the fixing ropes are made of non-conductive materials, thereby avoiding galvanic corrosion between the fixing ropes and the dosing tail pipe.

[0114] The outer walls of the ends of the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are both provided with connecting frames 23, and bolt holes are provided on the connecting frames. The fixing bolts 19 pass through the bolt holes on the upper semi-annular corrosion hanger bracket connecting frame and the lower semi-annular corrosion hanger bracket connecting frame in turn and are fastened by the fixing nuts 20 to fix the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket in connection. In order to avoid galvanic corrosion between the annular corrosion hanger bracket fixing device and the dosing tail pipe, the fixing bolts and the fixing nuts in this embodiment are both made of ceramic material.

[0115] It can be seen that the device for monitoring corrosion and scaling of oil casing with sucker rods proposed in this embodiment is adopted. By setting a double-layer annular corrosion hanger on the oil pipe short-circuit, and cooperating with the corrosion hanger suspended by the annular corrosion hanger bracket fixed on the dosing tail pipe, the corrosion and scaling of the oil casing at different depths in the wellbore can be monitored without affecting the wall of the normal operation of the sucker rod.

[0116] Example 4

[0117] The present invention proposes a method for monitoring corrosion and scaling of an oil casing with a sucker rod, using a device for monitoring corrosion and scaling of an oil casing with a sucker rod as described in any one of embodiments 1 to 3, such as Figure 8 As shown, the specific steps include:

[0118] Step 1: Analyze the composition of the produced water of the monitored well, comprehensively analyze the influence of the water production, gas production, temperature, pressure, and flow rate of the monitored well on wellbore scaling, and reversely infer the temperature, pressure, scaling ion concentration and scaling trend at different depths of the wellbore of the monitored well.

[0119] in,

[0120] The temperature calculation formula at different depths in the well to be monitored is:

[0121] T (H) = T (0) + Gt×H (1)

[0122] Where, H is the well depth in meters; T (H) is the fluid temperature at the well depth H, in °C, T (0) is the fluid temperature at the wellhead, in °C; Gt is the fluid temperature gradient, in °C / m.

[0123] The pressure calculation formula at different depths in the well to be monitored is:

[0124] P (H) = P (0) + Gp×H (2)

[0125] Where P(H) is the pressure at the well depth H, in MPa, P (0) is the pressure at the wellhead, in MPa; Gp is ​​the fluid pressure gradient, in MPa / m.

[0126] The calculation formula for pH values ​​at different depths in the well to be monitored is:

[0127] pH (H) = pH (0) + ΔpH (3)

[0128] in,

[0129] ΔpH=4.05×10 -3 [T (H) -T (0) ]+4.58×10 -7 -3.07×10 -5 [P (H) -P (0) ] (4)

[0131] Where, pH (H) is the pH value at the well depth H, pH (0) is the pH value at the wellhead, and ΔpH is the change in pH value.

[0132] According to the composition analysis results of the produced water of the monitored well, combined with the daily water production and daily oil production of the monitored well, the scaling index at the specified depth of the monitored well is calculated; if the scaling index I s When it is greater than 0, it means that there is a scaling trend at the specified depth of the well to be monitored. If the scaling index I s When it does not exceed 0, it means that there will be no scaling at the specified depth of the well to be monitored.

[0133] The scaling index calculation formula at the specified depth of the well to be monitored is shown in formula (5):

[0134]

[0135] in, and The calculation formula is,

[0136]

[0137]

[0138] In the formula, I s is the scaling index at the specified depth of the well to be monitored; [X m+ ] is the ionic activity of the m-valent cation X, in mol / L, [Yn- ] is the ionic activity of the n-valent anion Y, in mol / L; P is the pressure value at the specified depth of the well to be monitored, in MPa; is the CO2 content in the gas phase, is the fugacity coefficient of CO2; T is the temperature at the specified depth of the well to be monitored, in °F; p is the absolute pressure, in psi; μ is the ionic strength, in mol / L; a0, a1, a2, a3, a4, and a5 are all calculation coefficients of the scaling index at the specified depth of the well to be monitored; b0 and b1 are Calculation coefficient of ; is the content of CO2 in the mixed system of gas, oil and brine; BWPD is the daily water production of the well to be monitored, in bbl; BOPD is the daily oil production of the well to be monitored, in bbl; MMscf is the daily gas production of the well to be monitored under standard conditions, in MMft 3 The standard temperature under the standard conditions is set to 273.15K and the standard pressure is set to 101.325kPa; c0 and c1 are both calculation parameters of CO2 content in the gas phase; a and b are scaling index calculation indices. When the well to be monitored contains CaCO3, the scaling index calculation indices a=2 and b=1. When the well to be monitored contains CaSO4, the scaling index calculation indices a=1 and b=0.

[0139] The ionic strength calculation formula is:

[0140]

[0141]

[0142] in,

[0143]

[0144]

[0145] Where i is the serial number of the ion in the well to be monitored, N is the total number of ion types in the well to be monitored; m i is the ion concentration of the i-th ion in the well to be monitored, in mol / L; Z i is the valence state of the i-th ion in the well to be monitored, γ i is the ionic activity coefficient of the i-th ion; A and B are the ionic strength calculation coefficients; R is the ideal gas constant, which is 8.3143 J / (mol·K); F is the Faraday constant, which is 96484.6 C / mol; e0 is the charge of the electron, which is 1.602×10 -19 C; ε is the dielectric constant, ε=ε0ε r , ε0 is the vacuum dielectric constant, which is 80, εr is the relative dielectric constant, which is 8.854×10 -12 F / m.

[0146] The calculation formula for the ion activity of the cations and anions in the well to be monitored is:

[0147]

[0148]

[0149] In the formula, is the ion concentration of m-valent cation X, in mol / L, is the ionic activity coefficient of the m-valent cation X; is the ion concentration of n-valent anion Y, in mol / L, is the ionic activity coefficient of the n-valent anion Y.

[0150] Furthermore, the cation in the well to be monitored is Ca 2+ 、Anion is CO3 2- For example, the scaling index calculation formula at the specified depth of the monitoring well is:

[0151]

[0152] in,

[0153] Ca in the well to be monitored 2+ The ion activity is:

[0154]

[0155] In the formula, [Ca 2+ ] is the cation Ca 2+ The ion activity of The cation Ca 2+ The ion concentration is in mol / L; The cation Ca 2+ The ion activity coefficient.

[0156] CO3 in the well to be monitored 2- The ion activity is:

[0157]

[0158] In the formula, [CO3 2- ] is an anion CO3 2- The ion activity of Anion CO3 2- The ion concentration is in mol / L; Anion CO3 2-The ion activity coefficient.

[0159] Furthermore, the cation in the well to be monitored is Ca 2+ 、Anion is SO4 2- For example, the scaling index calculation formula at the specified depth of the monitoring well is:

[0160] I s =lg([Ca 2+ ][SO4 2- ])+2.52+9.98×10 -3 T+0.97×10 -6 T 2 -3.07×10 -5 p-1.09μ 0.5 +0.50μ-3.3×10 -3 μ 0.5 T (17)

[0162] in,

[0163] SO4 in the well to be monitored 2- The ion activity is:

[0164]

[0165] In the formula, [SO4 2- ] is anion SO4 2- The ion activity of For anion SO4 2- The ion concentration is in mol / L; For anion SO4 2- The ion activity coefficient.

[0166] Step 2, based on indoor corrosion simulation experiments, combined with the temperature, pressure, CO2 content, produced water composition and pH value at different depths of the wellbore, using weight loss experiments, electrochemical experiments, and corrosion product characterization methods, the corrosion and scaling conditions inside the wellbore at different depths are simulated in the laboratory, and the corrosion and scaling laws at different well depths are determined. According to the corrosion laws and structural laws obtained, combined with the main controlling factors of corrosion, scaling trends, the location of the downhole pump, and the dynamic and static liquid level positions, the corrosion hanging plate installation position of the well to be monitored is determined, and according to whether there is a dosing tail pipe, it is determined whether a corrosion hanging plate bracket needs to be installed.

[0167] Step 3, according to the corrosion hanger installation position determined in step 2, install the oil pipe short circuit at the specified depth position of the oil pipe, use the outer annular corrosion hanger on the oil pipe short circuit to monitor the corrosion condition of the inner side of the casing and the outer side of the oil pipe, and at the same time, use the inner annular corrosion hanger on the oil pipe short circuit to monitor the corrosion condition of the inner side of the oil pipe, and monitor the corrosion condition of the inner side of the oil pipe and casing at different depths in real time.

[0168] Step 4, if it is determined in step 2 that there is a dosing tail pipe, a corrosion coupon bracket with a corrosion coupon suspended thereon is installed on the dosing tail pipe, and the corrosion coupon bracket with the corrosion coupon suspended thereon is used to monitor the corrosion condition of the casing at the bottom of the well; if it is determined in step 2 that there is no dosing tail pipe, there is no need to install a corrosion coupon bracket with a corrosion coupon suspended thereon.

[0169] Example 5

[0170] This embodiment takes a production well as an example, and uses the production well as a well to be monitored to determine the corrosion monitoring position of the production well.

[0171] In this embodiment, the production well is a production well after CO2 injection, the maximum depth of the oil pipe is 2300 meters, the pump depth is 2200 meters, the dynamic (static) liquid level of the wellbore is 2100 meters, and the salinity of the produced water is about 6000 mg / L. Indoor simulation experiments show that scaling occurs at a depth of 1400 meters in the oil pipe.

[0172] The method for monitoring corrosion and scaling of oil casing with sucker rod proposed in the present invention is used to finally determine the monitoring position of the corrosion hanging piece in the production well. When setting the monitoring position, the following positions are mainly considered:

[0173] 1. The pump suction port is generally the point with the highest flow velocity in the wellbore. A corrosion hanging piece is installed under the pump or at the dosing tail pipe.

[0174] 2. The environment between the three phases of oil, gas and water is complex at the dynamic (static) liquid surface of the wellbore;

[0175] 3. The well depth is 1400m, and corrosion and scaling are serious;

[0176] 4. The well is 700m deep, with low pressure and temperature, and relatively mild corrosion.

[0177] Since the dynamic (static) liquid level of the wellbore and the location of the pump are about 100 meters apart in depth, the temperature difference is very small. There is no need to hang plates at both the dynamic (static) liquid level of the wellbore and the location of the pump at the same time. You only need to choose one of them to set the corrosion plate.

[0178] At the same time, this embodiment sets a corrosion hanging plate bracket in combination with the specific structure of the production well. If the production well is provided with a dosing tail pipe, a corrosion hanging plate bracket with a corrosion hanging plate is set on the dosing tail pipe and at the dynamic (static) liquid level. If the production well is not provided with a dosing tail pipe, a corrosion hanging plate is set under the pump or at the dynamic (static) liquid level.

[0179] Example 6

[0180] This embodiment is based on a device and method for monitoring corrosion and scaling of oil casing with sucker rods proposed by the present invention, and specifically describes a method for monitoring corrosion and scaling in oil casing by installing a strip corrosion hanger bracket on the dosing tail pipe.

[0181] Before on-site installation, each corrosion hanging piece is degreased and weighed. In this embodiment, the material of the corrosion hanging piece is the same as the material of the casing.

[0182] When the strip corrosion hanger bracket is installed on site, the two ends of the strip corrosion hanger bracket are fixed on the dosing tail pipe through fixing nuts and fixing bolts, so that the strip corrosion hanger bracket is tightly attached to the dosing tail pipe, and the corrosion hanger is hung on the corrosion hanger fixing hole of the strip corrosion hanger bracket through the fixing god.

[0183] The strip corrosion hanger bracket on the dosing tail pipe is installed to the corresponding position underground along with the oil pipe of the production well. After a period of time, the oil pipe and the dosing tail pipe are taken out, and the weight loss experiment combined with microscopic analysis is used to understand the corrosion and scaling of the casing at the depth of the corrosion hanger. The corrosion and scaling conditions in the oil casing before and after the addition of corrosion inhibitors and other additives are compared to evaluate the on-site application effect of corrosion inhibitors and other additives.

[0184] Example 7

[0185] This embodiment is based on a device and method for monitoring corrosion and scaling of oil casing with sucker rods proposed by the present invention, and specifically describes a method for monitoring corrosion and scaling in oil casing by installing an annular corrosion hanging plate bracket on the dosing tail pipe.

[0186] Before on-site installation, each corrosion hanging piece is degreased and weighed. In this embodiment, the material of the corrosion hanging piece is the same as the material of the casing.

[0187] When the annular corrosion hanger bracket is installed on site, first, the annular corrosion hanger bracket is put on the outside of the dosing tail pipe, and the ends of the upper and lower annular corrosion hanger brackets are attracted and closed by the magnetic force of the magnetic sheet, and then the fixing bolts are passed through the bolt holes on the upper and lower annular corrosion hanger bracket connecting frames in turn and fastened by fixing nuts to fix the upper and lower annular corrosion hanger brackets. At the same time, the corrosion hanger is hung on the corrosion hanger fixing hole of the annular corrosion hanger bracket by using a fixing rope.

[0188] The annular corrosion hanger bracket on the dosing tail pipe is installed to the corresponding position underground along with the oil pipe of the production well. After a period of time, the oil pipe and the dosing tail pipe are taken out, and the weight loss experiment combined with microscopic analysis is used to understand the corrosion and scaling of the casing at the depth of the corrosion hanger. The corrosion and scaling conditions in the oil casing before and after the addition of corrosion inhibitors and other additives are compared to evaluate the on-site application effect of corrosion inhibitors and other additives.

[0189] Example 8

[0190] This embodiment is based on a device and method for monitoring corrosion and scaling of oil casing with sucker rods proposed by the present invention, and specifically describes a method for installing oil pipe short circuits at different depths in a production well to monitor corrosion and scaling in the oil casing.

[0191] Before on-site installation, each corrosion coupon is degreased and weighed. When the tubing and casing are made of the same material, only the outer annular corrosion coupon can be used, but when the tubing and casing are made of different materials, both the outer annular corrosion coupon and the inner annular corrosion coupon need to be used to monitor the corrosion of the inner wall of the casing and the outer wall of the tubing respectively.

[0192] When installing the oil pipe short-circuit on site, first embed the inner sealing ring in the upper inner limiting groove, so that the upper inner step of the upper inner test ring is embedded in the upper inner limiting groove, and then install the inner isolation ring, the middle inner test ring, the inner isolation ring and the lower inner test ring in the oil pipe short-circuit in sequence, and embed the lower inner step of the lower inner test ring in the lower inner limiting groove and seal it with the inner sealing ring, and rotate the lower end of the oil pipe short-circuit to thread the lower end of the oil pipe short-circuit with the oil pipe short-circuit body into one.

[0193] When installing the outer corrosion hanging piece, embed the upper outer step on the upper outer test ring into the upper outer limiting groove, and use the outer sealing ring to seal the upper outer test ring and the outer wall of the oil pipe short-circuit body. Then install the outer isolation ring, the middle outer test ring, the outer isolation ring and the lower outer test ring in sequence, and embed the lower outer step on the lower outer test ring into the lower outer limiting groove. Then use the outer sealing ring to seal the lower outer test ring and the outer wall of the oil pipe short-circuit body to complete the installation of the outer annular corrosion hanging piece.

[0194] A method for monitoring corrosion and scaling of oil casing with a sucker rod proposed in the present invention is used to determine the setting position of the corrosion hanging piece, install a tubing short-circuit at a corresponding depth position of the tubing, and connect the two ends of the tubing short-circuit with the tubing thread. After completing the installation of the tubing short-circuit at the monitoring position, the tubing short-circuit is lowered into the wellbore along with the tubing. After a period of time, the tubing short-circuit is taken out, and a weight loss experiment combined with a microscopic analysis is used to understand the corrosion and scaling conditions of the tubing and casing at different depths.

[0195] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0196] In the present invention, the directions or positional relationships indicated by terms such as "upper", "lower", "bottom", "top", etc. are based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention. They do not specifically refer to any part or element in the present invention and cannot be understood as limitations on the present invention.

[0197] In the present invention, terms such as "connected" and "connection" should be understood in a broad sense, indicating that the connection can be fixed, integral or detachable; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meaning of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0198] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A device for monitoring corrosion and scaling of oil casing with sucker rods, characterized in that: It includes an oil pipe short-circuit arranged on the oil pipe and a corrosion hanging piece bracket arranged on the dosing tail pipe; The oil pipe short connection includes an oil pipe short connection body, an oil pipe short connection upper end portion and an oil pipe short connection lower end portion; The tubing short-circuit body is a circular tubular structure with two ends open. The upper end of the tubing short-circuit is arranged at the top of the tubing short-circuit body and is integrally formed with the tubing short-circuit body. The lower end of the tubing short-circuit is arranged at the bottom of the tubing short-circuit body and is threadedly connected with the tubing short-circuit body. The tubing short-circuit body is provided with a double-layer annular corrosion hanging plate, which includes an outer annular corrosion hanging plate and an inner annular corrosion hanging plate. The outer annular corrosion hanging plate is provided on the outer wall of the tubing short-circuit body to monitor the corrosion conditions inside the casing and outside the tubing, and the inner annular corrosion hanging plate is provided on the inner wall of the tubing short-circuit body to monitor the corrosion conditions inside the tubing. The outer annular corrosion hanging piece includes a lower outer test ring, a middle outer test ring and an upper outer test ring. The lower outer test ring, the middle outer test ring and the upper outer test ring are sequentially sleeved on the outer wall of the tubing short-circuit body in order from bottom to top. The middle outer test ring is set as an annular corrosion hanging piece. An outer isolation ring is set between the lower outer test ring and the middle outer test ring and between the middle outer test ring and the upper outer test ring. The upper outer test ring and the lower outer test ring are both sealed with the outer wall of the tubing short-circuit body through an outer sealing ring. The inner annular corrosion hanging piece includes a lower inner test ring, a middle inner test ring and an upper inner test ring, which are arranged on the inner wall of the tubing short-circuit body in order from bottom to top, the middle inner test ring is arranged as an annular corrosion hanging piece, inner isolation rings are arranged between the lower inner test ring and the middle inner test ring and between the middle inner test ring and the upper inner test ring, and the upper inner test ring and the lower inner test ring are sealed with the inner wall of the tubing short-circuit body through inner sealing rings; The corrosion hanging piece bracket is made of non-metallic material and is arranged on the dosing tail pipe. The corrosion hanging piece is fixed on the corrosion hanging piece bracket.

2. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1 is characterized in that: The two ends of the oil pipe short connection are connected with the oil pipe threads.

3. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1 is characterized in that: The outer diameter of the oil pipe short connection is the same as the outer diameter of the oil pipe, and the inner diameter of the oil pipe short connection is the same as the inner diameter of the oil pipe.

4. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1 is characterized in that: The oil pipe short-circuit body is provided with reinforcing ribs inside.

5. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 4 is characterized in that: The reinforcing rib is in a circular ring shape.

6. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1, characterized in that: The outer isolation ring and the inner isolation ring are both made of non-metallic materials.

7. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1, characterized in that: The sizes of the lower outer test ring, the middle outer test ring, the upper outer test ring and the outer isolation ring are the same, and the inner diameters of the lower outer test ring, the middle outer test ring, the upper outer test ring and the outer isolation ring are the same as the outer diameter of the oil pipe short circuit.

8. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1, characterized in that: The sizes of the lower inner test ring, the middle inner test ring, the upper inner test ring and the inner isolation ring are the same, and the inner diameters of the lower inner test ring, the middle inner test ring, the upper inner ring and the inner isolation ring are the same as the inner diameter of the oil pipe short circuit.

9. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1, characterized in that: The top of the upper outer test ring is reduced in diameter to form an upper outer step portion, and the bottom of the lower outer test ring is reduced in diameter to form a lower outer step portion; The top of the upper inner layer test ring is expanded to form an upper inner layer step portion, and the bottom of the lower inner layer test ring is expanded to form a lower inner layer step portion.

10. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 9, characterized in that: The upper part of the oil pipe short-circuit body is provided with two limiting grooves, including an upper outer limiting groove and an upper inner limiting groove, wherein the upper outer limiting groove is used to fix the upper outer test ring, and the upper inner limiting groove is used to fix the upper inner test ring; Two limiting grooves are arranged at the lower part of the oil pipe short-circuit body, including a lower outer limiting groove and a lower inner limiting groove, wherein the lower outer limiting groove is used to fix the lower outer test ring, and the lower inner limiting groove is used to fix the lower inner test ring.

11. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 10, characterized in that: The upper outer layer step portion on the upper outer layer test ring is embedded in the upper outer layer limiting groove, and an outer layer sealing ring is sleeved on the upper outer layer step portion to seal and connect the upper outer layer test ring with the outer wall of the oil pipe short-circuit body; The lower outer layer step portion on the lower outer layer test ring is embedded in the lower outer layer limiting groove, and an outer layer sealing ring is sleeved on the lower outer layer step portion to seal and connect the lower outer layer test ring with the outer wall of the oil pipe short-circuit body; The upper inner layer step portion on the upper inner layer test ring is embedded in the upper inner layer limiting groove, and an inner layer sealing ring is sleeved on the upper inner layer step portion to seal and connect the upper inner layer test ring with the outer wall of the oil pipe short-circuit body; The lower inner layer step portion on the lower inner layer test ring is embedded in the lower inner layer limiting groove, and an inner layer sealing ring is sleeved on the lower inner layer step portion to seal and connect the lower inner layer test ring with the outer wall of the oil pipe short-circuit body.

12. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 1, characterized in that: The corrosion hanging plate bracket is configured as a strip corrosion hanging plate bracket or a ring corrosion hanging plate bracket.

13. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 12, characterized in that: The corrosion coupon bracket is configured as a strip-shaped corrosion coupon bracket, and the length of the strip-shaped corrosion coupon bracket is greater than the circumference of the dosing tail pipe; The strip-shaped corrosion hanging piece bracket is provided with a plurality of corrosion hanging piece fixing holes, and the corrosion hanging pieces are hung on the corrosion hanging piece fixing holes through fixing ropes; Bolt holes are arranged at both ends of the strip corrosion hanging plate bracket, and fixing bolts are inserted into the bolt holes at both ends of the strip corrosion hanging plate bracket in sequence and fastened by fixing nuts to fix the strip corrosion hanging plate bracket on the dosing tail pipe.

14. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 12, characterized in that: The corrosion coupon bracket is configured as an annular corrosion coupon bracket, and the inner diameter of the annular corrosion coupon bracket is the same as the outer diameter of the dosing tail pipe; The annular corrosion hanging plate bracket comprises an upper semi-annular corrosion hanging plate bracket and a lower semi-annular corrosion hanging plate bracket; The ends of the upper semi-annular corrosion coupon bracket and the lower semi-annular corrosion coupon bracket are both provided with positioning grooves, and the magnetic sheet is fixed in the positioning grooves. The magnetic sheet arranged at the end of the upper semi-annular corrosion coupon bracket has opposite polarity to the magnetic sheet arranged at the end of the lower semi-annular corrosion coupon bracket. The upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are both provided with a plurality of corrosion hanger fixing holes, the axial direction of the corrosion hanger fixing holes is parallel to the axial direction of the dosing tail pipe, and the corrosion hangers are suspended on the corrosion hanger fixing holes by fixing ropes; The outer walls of the ends of the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket are both provided with connecting frames, and bolt holes are provided on the connecting frames. The fixing bolts pass through the bolt holes on the upper semi-annular corrosion hanger bracket connecting frame and the lower semi-annular corrosion hanger bracket connecting frame in turn and are fastened by fixing nuts to fix the upper semi-annular corrosion hanger bracket and the lower semi-annular corrosion hanger bracket in connection.

15. The device for monitoring corrosion and scaling of oil casing with sucker rod according to claim 13 or 14, characterized in that: The fixing rope is made of non-conductive material, and the fixing bolt and the fixing nut are both made of non-metallic material.

16. A method for monitoring corrosion and scaling of oil casing with sucker rods, characterized in that: The device for monitoring corrosion and scaling of oil casing with sucker rod according to any one of claims 1 to 15 specifically comprises the following steps: Step 1: Analyze the components of the produced water of the monitored well, comprehensively consider the influence of the water production, gas production, temperature, pressure and flow rate of the monitored well on the scaling of the wellbore, and infer the temperature, pressure, scaling ion concentration and scaling trend at different depths of the wellbore of the monitored well; Step 2: Based on the indoor corrosion simulation experiment, combined with the temperature, pressure, CO2 content, produced water composition and pH value at different depths of the wellbore, the weight loss experiment, electrochemical experiment and corrosion product characterization method are used to simulate the corrosion and scaling conditions inside the wellbore at different depths in the laboratory, determine the laws of corrosion and scaling at different well depths, and determine the installation position of the corrosion hanging plate of the well to be monitored based on the corrosion laws and structural laws obtained, combined with the main controlling factors of corrosion, scaling trend, location of the downhole pump, and dynamic and static liquid level positions, and determine whether it is necessary to install a corrosion hanging plate bracket based on whether there is a dosing tail pipe; Step 3, according to the corrosion coupon installation position determined in step 2, a tubing short-circuit is installed at a specified depth position of the tubing, and the outer annular corrosion coupon on the tubing short-circuit is used to monitor the corrosion condition of the inner side of the casing and the outer side of the tubing. At the same time, the inner annular corrosion coupon on the tubing short-circuit is used to monitor the corrosion condition of the inner side of the tubing, and the corrosion condition of the inner side of the tubing and the casing at different depth positions is monitored in real time; Step 4, if it is determined in step 2 that there is a dosing tail pipe, a corrosion coupon bracket with a corrosion coupon suspended thereon is installed on the dosing tail pipe, and the corrosion coupon bracket with the corrosion coupon suspended thereon is used to monitor the corrosion condition of the casing at the bottom of the well; if it is determined in step 2 that there is no dosing tail pipe, there is no need to install a corrosion coupon bracket with a corrosion coupon suspended thereon.

17. The method for monitoring corrosion and scaling of oil casing with sucker rod according to claim 16, characterized in that: The temperature calculation formula at different depths in the well to be monitored is: T (H) = T (0) + Gt×H (1) Where, H is the well depth in meters; T (H) is the fluid temperature at the well depth H, in °C, T (0) is the fluid temperature at the wellhead, in °C; Gt is the fluid temperature gradient, in °C / m; The pressure calculation formula at different depths in the well to be monitored is: P (H) = P (0) + Gp×H (2) Where P (H) is the pressure at the well depth H, in MPa, P (0) is the pressure at the wellhead, in MPa; Gp is ​​the fluid pressure gradient, in MPa / m; The calculation formula for pH values ​​at different depths in the well to be monitored is: pH (H) = pH (0) + ΔpH (3) in, ΔpH=4.05×10 -3 [T (H) -T (0) ]+4.58×10 -7 -3.07×10 -5 [P (H) -P (0) ] (4) Where pH (H) is the pH value at the well depth H, pH (0) is the pH value at the wellhead, ΔpH is the change in pH value; According to the composition analysis results of the produced water of the monitored well, combined with the daily water production and daily oil production of the monitored well, the scaling index at the specified depth of the monitored well is calculated; if the scaling index I s When it is greater than 0, it means that there is a scaling trend at the specified depth of the well to be monitored. If the scaling index I s When it does not exceed 0, it means that there will be no scaling at the specified depth of the well to be monitored; The scaling index calculation formula at the specified depth of the well to be monitored is shown in formula (5): in, and The calculation formula is, In the formula, I s is the scaling index at the specified depth of the well to be monitored; [X m+ ] is the ionic activity of the m-valent cation X, in mol / L, [Y n- ] is the ionic activity of the n-valent anion Y, in mol / L; P is the pressure value at the specified depth of the well to be monitored, in MPa; is the CO2 content in the gas phase, is the fugacity coefficient of CO2; T is the temperature at the specified depth of the well to be monitored, in °F; p is the absolute pressure, in psi; μ is the ionic strength, in mol / L; a0, a1, a2, a3, a4, and a5 are all calculation coefficients of the scaling index at the specified depth of the well to be monitored; b0 and b1 are Calculation coefficient of ; is the content of CO2 in the mixed system of gas, oil and brine; BWPD is the daily water production of the well to be monitored, in bbl; BOPD is the daily oil production of the well to be monitored, in bbl; MMscf is the daily gas production of the well to be monitored under standard conditions, in MMft 3 , the standard temperature under the standard conditions is set to 273.15K, and the standard pressure is set to 101.325kPa; c0 and c1 are both calculation parameters for the CO2 content in the gas phase; a and b are both scaling index calculation indices. When the well to be monitored contains CaCO3, the scaling index calculation indices a=2 and b=1, and when the well to be monitored contains CaSO4, the scaling index calculation indices a=1 and b=0; The ionic strength calculation formula is: in, Where i is the serial number of the ion in the well to be monitored, N is the total number of ion types in the well to be monitored; m i is the ion concentration of the i-th ion in the well to be monitored, in mol / L; Z i is the valence state of the i-th ion in the well to be monitored, γ i is the ionic activity coefficient of the i-th ion; A and B are the ionic strength calculation coefficients; R is the ideal gas constant, which is 8.3143 J / (mol·K); F is the Faraday constant, which is 96484.6 C / mol; e0 is the charge of the electron, which is 1.602×10 -19 C; ε is the dielectric constant, ε=ε0ε r , ε0 is the vacuum dielectric constant, which is 80, ε r is the relative dielectric constant, which is 8.854×10 -12 F / m; The calculation formula for the ion activity of cations and anions in the well to be monitored is: In the formula, is the ion concentration of m-valent cation X, in mol / L, is the ionic activity coefficient of the m-valent cation X; is the ion concentration of n-valent anion Y, in mol / L, is the ionic activity coefficient of the n-valent anion Y.

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