Cathodic protection anticorrosion device for inner wall of casing under oil well liquid level

Abstract

The present application belongs to the technical field of oil and gas field corrosion prevention, and particularly relates to a kind of oil well liquid level down casing inner wall cathodic protection corrosion preventer, including upper joint, heat dissipation cylinder, current collector shell, auxiliary anode shell and lower joint, the inner wall of heat dissipation cylinder is provided with heat source, constant current control module and generated electric quantity accumulation module, the auxiliary anode shell of current collector shell lower end, the current collector shell is provided with insulating support, the insulating support fixes current collector contact arm, the current collector contact arm is connected with the output end of constant current control module, the auxiliary anode shell is provided with auxiliary anode alloy, the auxiliary anode alloy is sleeved with auxiliary anode electrode, the upper end of auxiliary anode electrode is connected with insulating support, auxiliary anode electrode is connected with generated electric quantity accumulation module through alloy wire.The present application is installed under tubing pump, and the cathodic protection current is compensated to oil well casing through constant current control module, which plays a protective role in preventing corrosion of casing inner wall, can effectively prolong the oil-water well life, reduce oil well casing failure and material damage.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field corrosion prevention, and particularly relates to a kind of oil well liquid surface under casing inner wall cathodic protection corrosion preventer. BACKGROUND

[0002] Corrosion in oil and gas exploitation is a very serious phenomenon affecting oil and water well production and wellbore in the process of oilfield development. Oil casing corrosion is divided into casing outer wall corrosion and casing inner wall corrosion. Casing inner wall corrosion mainly concentrates below the liquid surface of the oil well. Above the liquid surface is gas, and the electrochemical corrosion of the inner wall is small. The liquid surface below the suction inlet of the oil pump contains less water, so the electrochemical corrosion of the inner wall of the oil well casing mainly concentrates below the suction inlet of the oil pump. At present, in order to slow down the corrosion of the inner wall of the casing, oilfields use continuous addition of corrosion inhibitor, installation of downhole sacrificial anode and other technical methods. These technologies play a certain role in the corrosion prevention of the inner wall of the casing, but also have some problems. Continuous addition of corrosion inhibitor has high cost. Corrosion inhibitor flows from the annulus of the oil well to the suction inlet of the pump. The section below the suction inlet of the pump is not protected. The amount of bracelet-shaped anode material used in the installation of downhole sacrificial anode is generally 2-4 Kg. The amount of material is small, the effective period is short, and the connection between the sacrificial anode and the pipe body becomes poor after the consumption of the sacrificial anode, which cannot provide ideal protection potential, and the application effect is not good. SUMMARY

[0003] The purpose of the present application is to overcome the shortcomings of the prior art. The present application provides a kind of installation in oil pipe pump, which uses electrochemical corrosion prevention principle, compensates cathodic protection current to oil well casing through constant current control module, effectively protects the inner wall of the casing and prevents corrosion. The auxiliary anode alloy has large weight and good protection effect. The hanger device can monitor the corrosion rate of the casing. The power accumulation module can test the protection current and voltage and record the reduction of effective power output by the casing protection. The oil well casing failure and material damage are monitored.

[0004] The technical solution of the present application is as follows:

[0005] The oil well liquid level downhole casing inner wall cathodic protection anticorrosion device comprises an upper joint, a heat dissipation cylinder, a current collector shell, an auxiliary anode shell and a lower joint; the lower part of the heat dissipation cylinder is provided with a liquid inlet hole, and the inner wall of the heat dissipation cylinder is provided with a heat source, a temperature-resistant battery pack, a constant current control module and an electric quantity generation and accumulation module; the upper end of the current collector shell is connected with the heat dissipation cylinder, and the lower end of the current collector shell is connected with the auxiliary anode shell; an insulating support is arranged in the current collector shell, the current collector arm is fixed on the insulating support, the contact points of the current collector arm are connected with the inner wall of the casing through the holes in the current collector shell, and the current collector arm is connected with the output end of the constant current control module; the auxiliary anode shell is provided with a communication hole, and the auxiliary anode shell is provided with an auxiliary anode alloy; the auxiliary anode alloy is sleeved with an auxiliary anode electrode, the upper end of the auxiliary anode electrode is connected with the insulating support, and the auxiliary anode electrode is connected with the electric quantity generation and accumulation module through an alloy lead; the upper end of the lower joint is connected with the auxiliary anode shell, and the lower joint can be connected with a lower oil pipe.

[0006] The lower end of the upper joint is connected with a hanger ring base pipe, the lower end of the hanger ring base pipe is connected with the heat dissipation cylinder, and the outer wall of the hanger ring base pipe is provided with four corrosion test rings, two of which are casing connection rings connected with the inner wall of the casing through elastic contact pieces, and the other two are casing non-connection rings.

[0007] The auxiliary anode shell is a steel shell, and the auxiliary anode alloy adopts an aluminum-zinc-indium-tin-titanium high-efficiency alloy formula.

[0008] Specifically, the three current collector arms are distributed at an angle of 120 degrees.

[0009] The electric quantity generation and accumulation module can monitor the generated current, open circuit potential, power and generated electric quantity, and store the accumulated generated electric quantity in a chip, which can be read through a mobile phone APP after being taken out.

[0010] The corrosion test ring is made of a material matched with the casing material.

[0011] The working principle of the present application is that the auxiliary anode alloy arranged in the auxiliary anode shell is a high-activity alloy material, which forms a protection potential of-1.08V in the well fluid, generates a protection current, enters the constant current control module through the alloy lead through the electric quantity generation and accumulation module, the output end of the constant current control module is connected with the current collector arm, the current collector arm conducts the protection current to the inner wall of the casing through three contact points distributed at an angle of 120 degrees, the inner wall of the casing obtains electrons, the corrosion potential decreases in the negative direction, and the cathodic protection of the inner wall of the casing is realized.

[0012] The beneficial effects of the present application are: the present application is installed below the tubing pump, which can effectively prolong the well life of oil-water wells, reduce casing failure and material damage of oil wells; the auxiliary anode alloy has a large weight, and the weight of a single auxiliary anode alloy can reach 24 Kg, which meets the protection of the casing 500 m below the liquid level of the oil well, and has a long effective period; the auxiliary anode alloy is installed inside the auxiliary anode shell, which avoids the liquid scouring to cause the auxiliary anode alloy to consume reactive power and inefficient reaction, so that all the electric energy converted by the electrochemistry is supplemented to the protection body; the auxiliary anode alloy deposits in the tubing tail pipe cavity and does not pollute the wellbore; the auxiliary anode alloy is made by casting with the auxiliary anode electrode, and will not fall off and cause the downhole string to be stuck due to the expansion of the deposit; the electric quantity accumulation module can test the total electric quantity provided by the auxiliary anode alloy protection, read the data through the APP software after being pulled out, check the protection electric quantity and the auxiliary anode alloy consumption, and help to identify whether the anticorrosion device can continue to be used in the well. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 is a structural schematic diagram of the present application.

[0014] 1 upper joint 2 elastic contact 3 hanger base pipe 4 casing connection ring 5 casing non-connection ring 6 heat dissipation cylinder 7 heat source 8 battery pack 9 constant current control module 10 electric quantity accumulation module 11 liquid inlet hole 12 alloy wire 13 current combiner 14 insulation support 15 auxiliary anode electrode 16 auxiliary anode alloy 17 communication hole 18 auxiliary anode shell 19 lower joint. DETAILED DESCRIPTION

[0015] The oil well casing inner wall cathodic protection device below the liquid level comprises an upper joint 1, the upper end of the upper joint 1 is connectable with a tubing pump, the lower end of the upper joint 1 is connected with a hanger base pipe 3, the lower end of the hanger base pipe 3 is connected with a heat dissipation cylinder 6, and the outer wall of the hanger base pipe 3 is provided with four corrosion test rings, two of which are casing connection rings 4 connected with the inner wall of the casing through elastic contacts 2, and the other two are casing non-connection rings 5. The casing corrosion monitoring hanger is a device matched with the oil well casing inner wall cathodic protection device below the liquid level for testing the corrosion rate of the oil well and comparing the cathodic protection effect. The corrosion test rings of the casing corrosion monitoring hanger are made of materials matched with the tubing material, which can compare the corrosion degree and corrosion rate of casings with the same material in the well. The casing non-connection ring 5 tests the corrosion rate of the steel in a natural state, and the casing connection ring 4 is connected with the inner wall of the casing, so that when the inner wall of the casing is protected, the test ring is also in a protected state. By comparing the corrosion rates of the two sets of rings, the effect of the cathodic protection in the well can be checked.

[0016] The heat sink 6 has a liquid inlet hole 11 at the bottom. The inner wall of the heat sink 6 is equipped with a heat power supply 7, a heat-resistant battery pack 8, a constant current control module 9, and a power generation accumulation module 10. The output terminal of the power generation accumulation module 10 is electrically connected to the input terminal of the constant current control module 9. During the process of replenishing electrons through the constant current control module 9, the power generation accumulation module 10 will measure and collect the voltage, current, power, and power generation of the protection. The total power generation and power generation are accumulated and the data is stored in the module. After the cathodic protection corrosion inhibitor on the inner wall of the casing is removed below the oil well fluid level, the total power generation and power generation can be read through a mobile APP to provide data to determine the effectiveness of the casing inner wall protection, assess the consumption of auxiliary anodes, and determine whether it can still be used in the well.

[0017] The upper end of the manifold 13 housing is connected to the heat sink 6, and the lower end of the manifold 13 housing is connected to the auxiliary anode housing 18. An insulating bracket 14 is installed inside the manifold 13 housing, and the insulating bracket 14 fixes three manifold 13 contact arms. The three manifold 13 contact arms are distributed at 120°. The contact points of the manifold 13 contact arms pass through the holes of the manifold 13 housing and are connected to the inner wall of the casing. The manifold 13 contact arms are connected to the output terminal of the constant current control module 9. The 120° orientation of the manifold 13 contact arms as flow guides the current, which satisfies the protection potential transmission in the deep well deviation state, so that the protection current transmission is stable and effective.

[0018] The auxiliary anode housing 18 is a steel housing with a connecting hole 17. An auxiliary anode alloy 16 is installed inside the auxiliary anode housing 18. The auxiliary anode alloy 16 adopts an aluminum-zinc-indium-tin-titanium high-efficiency alloy formula. An auxiliary anode electrode 15 is cast inside the auxiliary anode alloy 16. The upper end of the auxiliary anode electrode 15 is connected to the insulating support 14. The auxiliary anode alloy 16 will not fall off and will not get stuck in the downhole tubing due to sediment expansion. The auxiliary anode electrode 15 is connected to the power generation accumulation module 10 through the alloy wire 12. The upper end of the lower connector 19 is connected to the auxiliary anode housing 18 and can be connected to the lower tubing.

[0019] The auxiliary anode alloy 16 forms a protective potential of -1.08V in the well fluid. The auxiliary anode alloy 16 generates a protective current, which enters the constant current control module 9 through the alloy wire 12. The output terminal of the constant current control module 9 is connected to the contact arm of the manifold 13. The contact arm of the manifold 13 conducts the protective current to the inner wall of the casing through three contacts distributed at 120°. The inner wall of the casing receives electrons, and the corrosion potential decreases in the negative direction, thereby achieving cathodic protection of the inner wall of the casing.

[0020] The auxiliary anode alloy 16 adopts an aluminum-zinc-indium-tin-titanium high-efficiency alloy formula, has high-efficiency electrochemical corrosion prevention, and improves the electrochemical efficiency by 10%; it is particularly suitable for corrosion prevention of the inner wall of the oil well casing in the case of serious pitting corrosion; the auxiliary anode alloy 16 is arranged in the auxiliary anode shell 18, the weight of the auxiliary anode alloy 16 is not limited, the weight of a single auxiliary anode alloy 16 can reach 24 Kg, and the protection of the casing 500 m below the liquid level of the oil well is met; meanwhile, the effective period is long, the auxiliary anode alloy 16 is prevented from being caused by liquid scouring to have no-power consumption and ineffective reaction, the electric quantity of electrochemical conversion is fully supplemented to the protection body; the auxiliary anode alloy 16 consumption is deposited in the tail pipe cavity of the oil pipe, and the wellbore is not polluted.

[0021] It should be noted finally that the above examples are only used to illustrate the technical solutions of the present application rather than limiting them; although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application claimed.

Claims

1. A cathodic protection corrosion inhibitor for the inner wall of the casing below the oil well fluid level, characterized in that, It includes an upper connector (1), a hanging ring base tube (3), a sleeve connecting ring (4), an elastic contact plate (2), a heat sink (6), a junction box (13) housing, an auxiliary anode housing (18), and a lower connector (19); The lower end of the upper connector (1) is connected to the base tube (3) of the hanging ring device, and the lower end of the base tube (3) of the hanging ring device is connected to the heat sink (6). Four corrosion test rings are provided on the outer wall of the base tube (3), two of which are sleeve connection rings (4), and the sleeve connection rings (4) are connected to the inner wall of the sleeve through the elastic contact piece (2). The other two corrosion test rings are sleeve non-connection rings (5). The heat sink (6) has an inlet hole (11) at the bottom. The inner wall of the heat sink (6) is equipped with a heat power supply (7), a heat-resistant battery pack (8), a constant current control module (9) and a power generation accumulation module (10). The power generation accumulation module (10) can monitor the generated current, open circuit potential, power and generated power, and store the accumulated generated power in the chip. After being retrieved, the generated power can be read through a mobile phone APP. The upper end of the junction box (13) is connected to the heat sink (6), and the lower end of the junction box (13) is connected to the auxiliary anode housing (18). An insulating bracket (14) is provided inside the junction box (13). The insulating bracket (14) fixes the junction box (13) contact arm. The contact point of the junction box (13) contact arm passes through the hole of the junction box (13) housing and is connected to the inner wall of the sleeve. The junction box (13) contact arm is connected to the output terminal of the constant current control module (9). The auxiliary anode housing (18) has a connecting hole (17), and an auxiliary anode alloy (16) is provided inside the auxiliary anode housing (18). An auxiliary anode electrode (15) is sleeved inside the auxiliary anode alloy (16). The upper end of the auxiliary anode electrode (15) is connected to the insulating support (14). The auxiliary anode electrode (15) is connected to the power generation accumulation module (10) through an alloy wire (12). The upper end of the lower connector (19) is connected to the auxiliary anode housing (18), and the lower connector (19) can be connected to the lower oil pipe.

2. The cathodic protection corrosion inhibitor for the inner wall of the casing below the fluid level in oil wells according to claim 1, characterized in that, The auxiliary anode housing (18) is made of steel, and the auxiliary anode alloy (16) adopts an aluminum-zinc-indium-tin-titanium high-efficiency alloy formula.

3. The cathodic protection corrosion inhibitor for the inner wall of the casing below the fluid level in oil wells according to claim 1, characterized in that, The three junction (13) contacts are distributed at 120°.

4. The cathodic protection corrosion inhibitor for the inner wall of the casing below the fluid level in oil wells according to claim 1, characterized in that, The corrosion test ring is made of a material that matches the material of the sleeve.

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