CN104406907A - An oil well corrosion inhibitor dynamic diffusion corrosion monitoring device and method - Google Patents

Abstract

The invention provides a device and a method for monitoring dynamic diffusion corrosion of an oil well corrosion inhibitor. The device comprises a pressure container, a groove body, a pipeline and a water pump; preferably the device is further provided with a thermometer and a manometer. The invention also provides a dynamic diffusion corrosion monitoring method for the corrosion inhibitor of the oil well. The device and the method provided by the invention can be used for simulating the diffusion process of the corrosion inhibitor under the underground high-temperature and high-pressure environment, monitoring the corrosion rate and the corrosion inhibitor concentration change conditions at different well depths in the dynamic diffusion process of the corrosion inhibitor of the oil well, providing a basis for the research on the underground distribution condition and the diffusion rule of the corrosion inhibitor, and simultaneously contributing to the performance evaluation of the corrosion inhibitor, so that the diffusion rule and the use effect of the corrosion inhibitor under the actual working condition of an oil and gas field can be more accurately evaluated.

Description

An oil well corrosion inhibitor dynamic diffusion corrosion monitoring device and method

technical field

The invention provides an oil well corrosion inhibitor dynamic diffusion corrosion monitoring device and method, belonging to the field of corrosion monitoring.

Background technique

In the process of oil and gas extraction, due to the high flow rate and various corrosive media, downhole tools are often severely corroded, resulting in huge economic losses, so it is very important to take corresponding anti-corrosion measures for pipelines. At present, the anti-corrosion measures for oil well downhole pipe strings in my country are mainly based on the air-dropping of oil casing rings and the addition of corrosion inhibitors. A corrosion inhibitor is a substance that exists in the environmental medium in an appropriate concentration and form, and can protect the metal surface by acting on the metal surface or near the surface. Research and practice have shown that corrosion inhibitor protection technology, as a cost-effective metal corrosion control method, is especially suitable for downhole pipe string anticorrosion in oil and gas production.

In order to develop and screen high-efficiency corrosion inhibitors at home and abroad, some evaluation methods have been formed through experiments. At present, the routine indoor evaluation methods of oil well corrosion inhibitors include static corrosion coupon method, iron content measurement method and electrochemical test method. To evaluate oil well corrosion inhibitors by the above methods, generally use the produced water of oil wells to conduct corrosion experiments in indoor static state, and then obtain the corrosion inhibition rate of corrosion inhibitors. However, the actual oil well environment is a high-temperature and high-pressure environment, and the produced water flows continuously in the oil casing. This difference in the use environment makes the experimental value of the measured corrosion inhibition rate and the numerical error of the actual working condition of the oil and gas field. It is impossible to more accurately guide the delivery and application of corrosion inhibitors in the actual oil and gas production process.

Secondly, the existing experimental equipment for corrosion inhibitor evaluation cannot monitor the corrosion rate at different well depths during the diffusion process of corrosion inhibitors, nor can it test the concentration of corrosion inhibitors at different depths during the diffusion process.

In summary, there is currently a lack of experimental equipment that can simulate the diffusion process of corrosion inhibitors in the actual working conditions of oil and gas fields, and effectively test and analyze the diffusion laws of corrosion inhibitors in the oil barrel.

Contents of the invention

In order to solve the above technical problems, the object of the present invention is to provide a dynamic diffusion corrosion monitoring device for oil well corrosion inhibitors. The device can be used to simulate the diffusion process of corrosion inhibitors in downhole high temperature and high pressure environment, and monitor the corrosion rate and the concentration change of corrosion inhibitors in different well depths during the dynamic diffusion process of oil well corrosion inhibitors.

The purpose of the present invention is also to provide a method for monitoring dynamic diffusion corrosion of oil well corrosion inhibitors.

In order to achieve the above object, the present invention provides a dynamic diffusion corrosion monitoring device for oil well corrosion inhibitor, wherein the device includes a pressure vessel, a tank body, a pipeline and a water pump; Liquid port connection, monitoring port connection, feed port connection, liquid level control port connection and sampling port connection; oil well equipment and heating devices are also arranged in the pressure vessel; preferably the lower port of the oil pipe is connected to the bottom of the pressure vessel The monitoring port connection is at the same height; the tank body is connected to the liquid outlet connection, the feed port connection, and the liquid level control port connection of the pressure vessel through the pipeline through the water pump; the pressure vessel is preferably cylindrical; the Valves are provided for the liquid outlet connecting pipe, the monitoring port connecting pipe, the feed inlet connecting pipe, the liquid level control port connecting pipe and the sampling port connecting pipe; preferably the device is also provided with a thermometer and a pressure gauge, and the above-mentioned pressure vessel is used to simulate the corrosion inhibitor at high temperature and high pressure. The diffusion process in the oil cylinder is equipped with a corrosion rate monitoring port and a sampling port.

In a preferred embodiment of the present invention, the above-mentioned oil well equipment is an oil pipe, and the heating device is an electric heater.

According to the device of the present invention, the liquid outlet connecting pipes are respectively arranged at the top and the lower end of the side of the pressure vessel; the feed inlet connecting pipe is arranged at the upper end of the pressure vessel side; the monitoring port connecting pipe is arranged at the lower end of the pressure vessel side , preferably arranged below the feed port connection, and preferably 3-6, more preferably 4, of the monitoring port connection; the liquid level control port connection is arranged at the upper end of the side of the pressure vessel, preferably at the The relative positions of the mouth joints; the sampling mouth joints are arranged at the lower end of the side of the pressure vessel, preferably below the liquid level control mouth joints, and preferably there are 3-6 sampling port joints, more preferably 4;

Preferably, the pressure gauge is arranged on the liquid level control port connection.

In a preferred embodiment of the present invention, the pressure vessel is a cylindrical body, and the two sides of its upper end are respectively welded with a feed port connection pipe and a liquid level control port connection pipe. It is used to install a pressure gauge, and the pressure value inside the pressure vessel can be displayed through the pressure gauge. The liquid outlet connection set on the top of the pressure vessel is defined as the upper liquid outlet connection, and the liquid outlet connection set at the lower end of the side of the pressure vessel is defined as The lower outlet takes over;

The same monitoring port connecting pipe is provided directly below the feeding port connecting pipe, and the liquid inlet connecting pipe is provided directly below the bottom monitoring port connecting pipe; the number and spacing of the above monitoring port connecting pipes can be selected according to the needs of on-site operations. In the embodiment, the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device is equipped with 4 monitoring port connectors at equal intervals.

The same sampling port connecting pipe is provided under the liquid level control port connecting pipe, and the lower liquid outlet connecting pipe is arranged directly below the bottom sampling port connecting pipe. The number and spacing of the sampling port connecting pipes can be selected according to the needs of on-site operations. In the preferred embodiment, the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device is equidistantly provided with 4 sampling port connectors, and the monitoring port connectors and sampling port connectors are arranged at equal intervals to facilitate the recording and processing of experimental data;

The middle position of the front part of the pressure vessel is provided with a thermometer connection, and the port of the thermometer connection is provided with an internal thread, and a thermometer is installed through the threaded connection, and the thermometer is used to display the temperature value inside the cylinder;

The ports of the above-mentioned feed port connection pipe, liquid level control port connection pipe, monitoring port connection pipe, liquid inlet connection pipe, upper liquid outlet connection pipe and lower liquid outlet connection pipe are all provided with external threads, and the same valves are respectively installed through threaded connections; The valve installed on the connecting pipe of the liquid level control port is used to control the input of corrosion inhibitor and crude oil; the valve installed on the connecting pipe of the liquid level control port is used to control the liquid level in the cylinder, and at the same time release the gas in the cylinder to adjust the pressure inside the cylinder; The measuring probe of the multi-channel corrosion on-line monitor is screwed into the cylinder through the threaded hole of the valve on the monitoring port to monitor the corrosion rate; the valve installed on the liquid inlet is used to control the injection of oilfield produced water; by opening The valve installed on the lower liquid outlet can release all the liquid in the cylinder;

For the convenience of controlling sampling, in a preferred embodiment of the present invention, the port of the above-mentioned sampling port connecting pipe is provided with an internal thread, and a faucet is installed through the threaded connection, and the sampling port connecting pipe can carry out the liquid in the cylinder through the faucet installed at its end. Sampling is used to measure the concentration of the sample solution.

In a preferred embodiment of the present invention, the pipeline includes an input pipeline and an output pipeline;

The above-mentioned input pipeline includes a three-way pipe at the feeding port, a long corrosion inhibitor output pipe, a long crude oil output pipe, a short corrosion inhibitor input pipe and a short crude oil input pipe; the three-way pipe at the feeding port is connected to the valve on the feeding port connecting pipe The two sides of the feed port tee pipe are respectively connected to the corrosion inhibitor output long pipe and the crude oil output long pipe through threaded connections; the bottom ends of the corrosion inhibitor output long pipe and the crude oil output long pipe are respectively connected to the first water pump and the second water pump. The water outlet is connected; the corrosion inhibitor input short pipe and the crude oil input short pipe are respectively connected to the water inlets of the first water pump and the second water pump;

The ends of the corrosion inhibitor input short pipe and the crude oil input short pipe are provided with external threads, and are respectively connected with the corrosion inhibitor tank and the crude oil tank through the threaded holes of the corrosion inhibitor tank and the crude oil tank; The valve can respectively input the corrosion inhibitor and crude oil in the corrosion inhibitor tank and the crude oil tank into the barrel through the first water pump and the second water pump.

The above-mentioned output pipeline includes a first output pipe, a second output pipe, an upper three-way pipe, a third output pipe, a lower three-way pipe, a fourth output pipe and a fifth output pipe;

The two ends of the first output pipe are respectively communicated with the valve on the upper liquid outlet connecting pipe and the upper port of the upper tee pipe through threaded connection;

The lower port and the other port of the upper three-way pipe are respectively communicated with the third output pipe and the second output pipe through threaded connection;

The other port of the second output pipe communicates with the valve on the liquid level control port through a threaded connection;

The lower port of the third output pipe is connected with the upper port of the lower three-way pipe through threaded connection; the lower port of the lower three-way pipe is connected with the fifth output pipe through threaded connection; the other port of the lower three-way pipe is connected through threaded Connected with the fourth output pipe;

The other port of the fourth output pipe communicates with the valve on the lower liquid outlet connecting pipe through a threaded connection;

The other port of the fifth output pipe is connected with the waste liquid tank threaded hole of the waste liquid tank through a threaded connection, and the valves installed on the upper liquid outlet connection pipe, the liquid level control port connection pipe and the lower liquid outlet connection pipe are respectively opened to turn the cartridge The liquid in the body is output to the waste tank.

According to the device of the present invention, the top of the pressure vessel is provided with an openable sealing end cap; preferably, the end cap is a cylindrical structure with one end open; it is also preferred that the end cap is connected to the cylinder part of the pressure vessel through threads or bolts Sealed connection.

In a preferred embodiment of the present invention, the end cover is a cylindrical structure with one end open, the upper liquid outlet joint is provided at the center of the outer surface of the top, the oil pipe is welded at the center of the inner surface, and the inner surface is provided at the end. Thread, the end cap can be fixed on the upper end of the pressure vessel through threaded connection.

The top end of the above-mentioned pressure vessel is provided with an external thread corresponding to the internal thread at the end of the end cap, and the end cap can be fixed on the upper end of the cylindrical barrel through threaded connection.

According to the device of the present invention, the tank body includes a waste liquid tank, a crude oil tank and a corrosion inhibitor tank.

According to the device of the present invention, the crude oil tank and the corrosion inhibitor tank are respectively connected to the feed port via a water pump through a pipeline, wherein the feed port is preferably one, and the crude oil tank and the corrosion inhibitor tank are respectively passed through a pipeline, a water pump And through the three-way pipe to connect with the feed port; the waste liquid tank is respectively connected with the liquid outlet and the liquid level control port through the pipeline; wherein it is preferably connected to the two through the pipeline through two three-way pipes The outlet pipe is connected to the liquid level control port pipe.

In a preferred embodiment of the present invention, the above-mentioned waste liquid tank is used to store waste liquid, and it is located at the bottom of the side bracket of the liquid outlet connection side, and the middle part of the outer tank surface is provided with a waste liquid tank threaded hole for recycling the inside of the cylinder all liquids;

The above-mentioned crude oil tank and corrosion inhibitor tank are used to store crude oil and corrosion inhibitor respectively. They are placed parallel to the bottom of the side bracket of the liquid inlet connection. The middle part of the surface is provided with a threaded hole for a corrosion inhibitor tank. The shape and size of the above-mentioned waste liquid tank, crude oil tank and corrosion inhibitor tank can be selected according to the needs of field experiments. In the present invention, the waste liquid tank is rectangular, and the crude oil tank and corrosion inhibitor The grooves are all square grooves.

In a preferred embodiment of the present invention, the above-mentioned water pump includes a first water pump and a second water pump.

According to the device of the present invention, the oil well equipment is arranged inside the top of the pressure vessel; the heating device is arranged inside the bottom of the pressure vessel.

According to the device of the present invention, the device also includes a support for fixing the pressure vessel; preferably the support includes a square plate for fixing the pressure vessel and a pillar for supporting the square plate provided at the bottom of the square plate; preferably the The pillars are respectively arranged at the center of the bottom of the square plate and the edges of the four corners.

In a preferred embodiment of the present invention, the bracket includes a square plate and a pillar; a square plate through hole is arranged around the geometric center in the middle of the square plate, and pillars are welded at the bottom center of the square plate and the edges of the four corners. The above-mentioned square plate through holes are used to install and fix the pressure vessel, and the pillars are used to support the square plate; the shape of the square plate, the number of square plate through holes and the number of pillars can be selected according to the needs of the field operation. In the embodiment of the present invention The shape of the middle plate is square, the number of through holes of the square plate is 4, and the number of pillars is 5.

According to the device of the present invention, the middle part of the square plate is provided with a square plate through hole for fixing the pressure vessel, and the bottom of the pressure vessel is provided with a fixing hole corresponding to the square plate through hole.

According to the device of the present invention, the pressure vessel further includes a disc-shaped support, the support protrudes outward along the pressure vessel to form a protruding edge, the fixing holes are through holes, and are evenly opened on the on the edge of the support.

In a preferred embodiment of the present invention, the bottom of the pressure vessel is welded with a disc-shaped support, and its edge is surrounded by a support through hole corresponding to the square plate through hole provided on the above square plate. The pressure vessel is fixed on the support by bolt connection; the number of through holes of the support in the present invention is 4, wherein, the electric heater can be inserted into the inside of the cylinder from the threaded hole provided at the center of the bottom of the support, and through the thread The connection is mounted on a support, which is used to heat the working fluid inside the cylinder.

The above-mentioned water pumps, thermometers, pressure gauges, valves, faucets, oil pipes, and electric heaters can use related devices commonly used in the field of corrosion monitoring. According to the needs of field experiments, appropriate above-mentioned devices can be selected for dynamic diffusion corrosion monitoring of oil well corrosion inhibitors.

The present invention also provides a method for monitoring dynamic diffusion corrosion of oil well corrosion inhibitors, which is carried out by using the above-mentioned dynamic diffusion corrosion monitoring device for oil well corrosion inhibitors, and the method includes the following steps:

Close all the monitoring port connections, the liquid outlet connection on the lower side of the pressure vessel and the valves on the sampling port connection, and at the same time open the liquid inlet connection, the liquid outlet connection on the top of the pressure vessel and the liquid level control port connection. valve, and extend the measuring probe of the corrosion on-line monitor into the pressure vessel through the monitoring port connection;

Inject a certain amount of oilfield produced water from the liquid inlet connection so that the liquid level in the pressure vessel is at the port position of the oil well equipment. After the water injection is completed; close the valve on the liquid inlet connection and start heating the pressure vessel through the heating device Heating the liquid; when the thermometer shows that the temperature in the cylinder reaches the required temperature, open the feeding port connection pipe, and inject a certain amount of crude oil into the pressure vessel through the water pump. Preferably, the added crude oil does not exceed the liquid level control port connection pipe , and then inject a certain amount of corrosion inhibitor solution through the water pump;

Close all valves, and record the corrosion rate of the liquid in the pressure vessel at different depths and at different times at different times through the online corrosion monitor, preferably when multiple detection ports are installed, so as to analyze the corrosion inhibition of the corrosion inhibitor rate changes;

Open the valve on the sampling port connection pipe, sample the liquid at different depths in the pressure vessel, and test the corrosion inhibitor concentration. Preferably, when there are multiple detection port connection pipes, record the corrosion inhibitor concentration at different depths and at different times to obtain Corrosion inhibitor concentration values corresponding to different corrosion inhibition rates; control the pressure inside the pressure vessel through the liquid level control port;

After the experiment is over, open the valve on the liquid outlet connection, discharge all the liquid in the pressure vessel, and recover it to the waste liquid tank through the pipeline.

According to the method of the present invention, a certain amount of oilfield produced water is injected from the liquid inlet connection so that the liquid level in the pressure vessel is at the port position of the oil well equipment, wherein the "port position" refers to the oil pipe port submerged in oilfield produced water.

According to the method of the present invention, the addition amount of the above-mentioned corrosion inhibitor is added according to the injection ratio of simulating the actual working conditions.

According to the method of the present invention, when the thermometer shows that the temperature in the barrel reaches the required temperature, the "required temperature" depends on the formation environment to be simulated.

The oil well corrosion inhibitor dynamic diffusion corrosion monitoring device and method of the present invention can be used to simulate the diffusion process of the corrosion inhibitor under the high temperature and high pressure environment in the downhole, and monitor the corrosion rate and the concentration change of the corrosion inhibitor in different well depths during the dynamic diffusion process of the oil well corrosion inhibitor It provides a basis for the study of corrosion inhibitor distribution and diffusion law in the downhole, and at the same time contributes to the performance evaluation of corrosion inhibitors, and can more accurately evaluate the diffusion law and application effect of corrosion inhibitors in the actual working conditions of oil and gas fields. Make an evaluation.

Description of drawings

Fig. 1 is the three-dimensional schematic diagram of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 2 is the bracket schematic diagram of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 3 is the schematic diagram of the pressure vessel of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 4 is the sectional schematic diagram of the pressure vessel of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 5 is the schematic diagram of the cylinder body of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 6 is the tank schematic diagram of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 7 is the front view of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 8 is the pipeline and water pump schematic diagram of the oil well corrosion inhibitor dynamic diffusion corrosion monitoring device of embodiment 1;

Fig. 9 is the distribution change curve of corrosion inhibitor rate when corrosion inhibitor concentration is 1:3 stoste in embodiment 2;

Fig. 10 is the distribution change curve of corrosion inhibitor rate when corrosion inhibitor concentration is 750ppm in embodiment 2;

Fig. 11 is the distribution change curve of corrosion inhibitor rate when corrosion inhibitor concentration is 550ppm in embodiment 2;

Fig. 12 is the distribution change curve of corrosion inhibitor rate when corrosion inhibitor concentration is 250ppm in embodiment 2;

Fig. 13 is a distribution diagram of corrosion inhibition rates of different concentrations of corrosion inhibitors at 0.5 min in Example 2.

Explanation of main figures and symbols:

1 stand

11 square plate 12 pillar

111 square plate through hole

2 pressure vessels

21 Cylinder 22 End Cap 23 Oil Pipe 24 Electric Heater 25 Pressure Gauge 26 Thermometer 27 Valve 28 Faucet 29 Upper Liquid Outlet Connector

211 Cylinder body 212 Support 213 Feed port connection 214 Liquid level control port connection 215 Monitoring port connection 216 Sampling port connection 217 Thermometer connection 218 Liquid inlet connection 219 Lower liquid outlet connection

2121 Support through hole 2141 Pressure gauge threaded hole

3 tank

31 Waste liquid tank 32 Crude oil tank 33 Corrosion inhibitor tank

311 Threaded hole for waste liquid tank 321 Threaded hole for crude oil tank 331 Threaded hole for corrosion inhibitor tank

4 lines

41 input pipeline 42 output pipeline;

411 Feed port tee pipe 412 Corrosion inhibitor output long pipe 413 Crude oil output long pipe 414 Corrosion inhibitor input short pipe 415 Crude oil input short pipe 421 First output pipe 422 Second output pipe 423 Upper three-way pipe 424 Third output pipe 425 Fourth output tube 426 Lower tee tube 427 Fifth output tube

5 water pumps

51 first water pump 52 second water pump.

Detailed ways

In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings in the embodiments of the present invention, but this should not be construed as limiting the scope of implementation of the present invention.

Example 1

This embodiment provides an oil well corrosion inhibitor dynamic diffusion corrosion monitoring device. The device includes a pressure vessel 2, a support 1, a tank body 3, a pipeline 4 and a water pump 5. The three-dimensional schematic view and the front view of the device are shown in Figure 1 and Figure 7 respectively,

The pressure vessel 2 is located above the support 1 , the tank body 3 is located below the support 1 , and the pressure vessel 2 is connected to the tank body 3 and the water pump 5 through pipelines 4 .

The bracket 1 includes a square plate 11 and a pillar 12. The above-mentioned square plate is a square plate; four square plate through holes 111 are arranged around the geometric center in the middle of the square plate, and are welded at the center of the bottom of the square plate and the edges of the four corners. There are five pillars 12, and the schematic diagram of the support 1 is shown in FIG. 2 .

The pressure vessel 2 includes a cylinder body 21, an end cap 22, an oil pipe 23, an electric heater 24, a pressure gauge 25, a thermometer 26, a valve 27, a faucet 28 and an upper liquid outlet connecting pipe 29. The schematic diagram and cutaway diagram of the pressure vessel 2 are respectively As shown in Figure 3 and Figure 4.

The end cover 22 is a cylindrical structure with one end open, and the center of the outer surface of the top is provided with an upper liquid outlet connecting pipe 29, and the center of the inner surface is welded with an oil pipe 23, and its end is provided with an internal thread.

The cylinder body 21 is a cylindrical cylinder body 211, which includes a support 212, a liquid inlet connection pipe 218, a monitoring port connection pipe 215, a feeding port connection pipe 213, a liquid level control port connection pipe 214, a sampling port connection pipe 216, a thermometer connection pipe 217, a lower outlet pipe Port connection 219, the schematic diagram of cylinder body 211 is shown in Figure 5;

The top of the cylinder body 211 is provided with an external thread corresponding to the internal thread at the end of the end cap 22, and the end cap 22 can be fixed on the upper end of the cylinder body 211 through threaded connection;

The two sides of the upper end of the cylinder body 211 are respectively welded with a feeding port connecting pipe 213 and a liquid level control port connecting pipe 214, and the middle upper end of the liquid level controlling port connecting pipe 214 has a pressure gauge threaded hole 2141, which is connected with a pressure gauge 25 through threads;

There are four identical monitoring port connecting pipes 215 at equal intervals directly below the feeding port connecting pipe 213 of the cylinder body 211, and a liquid inlet connecting pipe 218 is provided directly below the bottom monitoring port connecting pipe 215;

There are 4 identical sampling port connecting pipes 216 at equal intervals below the liquid level control port connecting pipe 214 of the cylinder body 211, and a lower liquid outlet connecting pipe 219 is provided directly below the sampling port connecting pipe 216 at the bottom;

A thermometer connection 217 is provided at the middle of the front of the cylinder body 211;

The ports of the above-mentioned feeding port connecting pipe 213, liquid level control port connecting pipe 214, monitoring port connecting pipe 215, liquid inlet connecting pipe 218, upper liquid outlet connecting pipe 29 and lower liquid outlet connecting pipe 219 are all provided with external threads, and are respectively installed through threaded connections. There is the same valve 27; the ports of the sampling port connecting pipe 216 and the thermometer connecting pipe 217 are provided with internal threads, and a water tap 28 and a thermometer 26 are respectively installed through threaded connections;

The bottom of the cylinder body 211 is welded with a disc-shaped support 212, and its edge is provided with four support through holes 2121 corresponding to the square plate through holes 111 provided on the square plate 11 around the center of the circle. The connection fixes the pressure vessel 2 on the support 212; a threaded hole is opened in its center.

The electric heater 24 is inserted into the cylinder body 21 through a threaded hole provided at the center of the bottom of the support 212 , and is mounted on the support 212 through screw connections.

The tank body 3 includes a waste liquid tank 31, a crude oil tank 32 and a corrosion inhibitor tank 33, and the schematic diagram of the tank body 3 is shown in Figure 6;

The waste liquid tank 31 is rectangular, and it is located at the bottom of the side bracket 1 of the lower liquid outlet connecting pipe 219, and the middle part of the outer tank surface is provided with a waste liquid tank threaded hole 311;

The crude oil tank 32 and the corrosion inhibitor tank 33 are both square, and they are placed parallel to the bottom of the side bracket 1 of the liquid inlet connection pipe 218. The middle part of the crude oil tank 32 outer groove surface is provided with a crude oil tank threaded hole 321, and the corrosion inhibitor tank 33 outer groove A corrosion inhibitor tank threaded hole 331 is provided in the middle of the surface.

The water pump 5 includes a first water pump 51 and a second water pump 52. The schematic diagram of the pipeline 4 and the water pump 5 of the device is shown in FIG. 8 .

The pipeline 4 includes an input pipeline 41 and an output pipeline 42;

The input pipeline 41 comprises a feeding port tee pipe 411, a corrosion inhibitor output long pipe 412, a crude oil output long pipe 413, a corrosion inhibitor input short pipe 414 and a crude oil input short pipe 415;

The feed port tee pipe 411 is threadedly connected to the valve 27 on the feed port connection pipe 213, and both sides of the feed port tee pipe 411 are respectively connected to the corrosion inhibitor output long pipe 412 and the crude oil output long pipe 413 through threads;

The bottom ends of the corrosion inhibitor output long pipe 412 and the crude oil output long pipe 413 communicate with the water outlets of the first water pump 51 and the second water pump 52 respectively;

Corrosion inhibitor input short pipe 414 and crude oil input short pipe 415 are respectively connected to the water inlets of the first water pump 51 and the second water pump 52;

The ends of the corrosion inhibitor input short pipe 414 and the crude oil input short pipe 415 are provided with external threads, through which the corrosion inhibitor groove threaded hole 331 and the crude oil groove threaded hole 321 communicate with the corrosion inhibitor groove 33 and the crude oil groove 32 respectively;

The output pipeline 42 includes a first output pipe 421, a second output pipe 422, an upper three-way pipe 423, a third output pipe 424, a lower three-way pipe 426, a fourth output pipe 425 and a fifth output pipe 427;

The two ends of the first output pipe 421 are respectively communicated with the valve 27 on the upper liquid outlet connecting pipe 29 and the upper port of the upper three-way pipe 423 through threaded connection;

The lower port and the other port of the upper three-way pipe 423 are respectively communicated with the third output pipe 424 and the second output pipe 422 through threaded connection;

Another port of the second output pipe 422 communicates with the valve 27 on the liquid level control port connecting pipe 214 through a threaded connection;

The lower port of the third output pipe 424 is connected with the upper port of the lower three-way pipe 426 by threaded connection; the lower port of the lower three-way pipe 426 is connected with the fifth output pipe 427 by threaded connection; One port communicates with the fourth output pipe 425 through threaded connection;

The other port of the fourth output pipe 425 communicates with the valve 27 on the lower liquid outlet connecting pipe 219 through a threaded connection;

The other port of the fifth output pipe 427 communicates with the threaded hole 311 of the waste liquid tank 31 through threaded connection.

Example 2

This implementation provides a method for monitoring dynamic diffusion corrosion of oil well corrosion inhibitors, which is carried out by using the dynamic diffusion corrosion monitoring device for oil well corrosion inhibitors in Example 1. The method includes the following steps:

Close all the valves 27 on the monitoring port connecting pipe 215 and the lower liquid outlet connecting pipe 219 and the faucet 28 on the sampling port connecting pipe 216, and simultaneously open the liquid inlet connecting pipe 218, the upper liquid outlet connecting pipe 29 and the liquid level control port connecting pipe 214. Valve 27, and the measuring probe of the multi-channel corrosion on-line monitor (model CST800E, Wuhan Coster Instrument Co., Ltd.) is screwed into the cylinder 21 through the threaded hole of the valve 27 on the monitoring port connecting pipe 215;

Inject a certain amount of oilfield produced water from the liquid inlet connecting pipe 218, so that the liquid level in the barrel 21 is at the port position of the oil pipe 23, after the water injection is completed;

The chemical composition of the oilfield produced water injected above is shown in Table 1.

Table 1

Close the valve 27 on the liquid inlet connection pipe 218 and start heating the liquid in the cylinder body 21 through the electric heater 24; The second water pump 52 first injects a certain amount of crude oil into the barrel 21 so that the depth of the oil layer is at the position of the monitoring port connection pipe 215 at the uppermost end of the cylindrical barrel 211, and then injects 1L of corrosion inhibitor (HGY-1208 corrosion inhibitor, Wuhan Huakerui New Material Co., Ltd.) solution; the production rate of the corrosion inhibitor is 12.5L/min, and the concentration of the corrosion inhibitor is 1:3 stock solution, 750ppm, 550ppm and 250ppm. The time for sampling and recording the corrosion rate was set at 0.5 min, 1 min, and 2 min after perfusion. The liquid column heights corresponding to the detection ports are 0.5m, 1.0m, 1.5m and 2.0m (that is, the diffusion distance in Figure 9-12).

Close all valves 27 and faucets 28, and the corrosion inhibitor begins to diffuse in the cylinder 21. The corrosion rate of the liquid in the cylinder 21 can be recorded at different depths and at different times by a multi-channel corrosion on-line monitor. Calculate the sustained release rate to analyze the change of the corrosion inhibitor rate; the change curves of the slow release rate corresponding to different time and different depths under the four concentrations are shown in Figure 9-12.

Open the faucet on the sampling port connecting pipe 216, sample the liquid at different depths in the cylinder body 21, test the concentration of the corrosion inhibitor at different depths, and obtain the corresponding corrosion inhibitor concentration values of different corrosion inhibition rates; during the experiment, The pressure gauge 25 can display the pressure value in the cylinder body 21, open the valve 27 on the liquid level control port connection pipe 214, release the high-pressure steam in the cylinder body 21, and control the pressure inside the cylinder body 21;

After the experiment is over, open the valve 27 on the lower liquid outlet connecting pipe 219 to discharge all the liquid in the pressure vessel 2 and recycle it to the waste liquid tank 31 through the output pipeline 42 .

It can be seen from Figure 9-12 that the corrosion inhibition rate of the corrosion inhibitor basically shows a downward trend with the prolongation of the sampling time and the increase of the diffusion distance. The lower the concentration of corrosion inhibitor, the shorter the duration of its corrosion inhibition effect: under the condition of liquid production rate of 12.5L/min, when the concentration of corrosion inhibitor added is lower than 750ppm, the duration of corrosion inhibition effect is about 2min; the lower the concentration of corrosion inhibitor, the worse the diffusion effect at the longer diffusion distance, which is consistent with Fick's diffusion law. When the detection time is 0.5min, only the 0.5m detection port has a higher corrosion inhibition rate; when the detection time is 1min, the corrosion inhibition rate distribution of the four detection ports is relatively flat, indicating that the corrosion inhibitor has been fully diffused.

Among them, the distribution diagram of the corrosion inhibition rate of different concentrations of liquid injection at 0.5 minutes is shown in Figure 13. It can be seen from Figure 13 that when the concentration of the corrosion inhibitor is high, the distribution of the corrosion inhibitor is relatively gentle, indicating that the concentration gradient in the environment is relatively gentle , the diffusion in the device is relatively sufficient, and it is concluded that the high-concentration corrosion inhibitor injection liquid is conducive to the diffusion of corrosion inhibitor. Therefore, the higher the concentration of corrosion inhibitor selected during on-site filling, the better the corrosion inhibition effect.

According to the above experimental results, under the dynamic environment, when the concentration of corrosion inhibitor in the well fluid is 750ppm, the corrosion inhibition rate remains at a high level; when the concentration of corrosion inhibitor in the well fluid is lower than 150ppm, the corrosion inhibition effect is not ideal.

Example 2 is only a study of the present invention on the dynamic diffusion of corrosion inhibitors under different concentrations of corrosion inhibitors. By controlling the production fluid rate, crude oil injection volume and water content of the production fluid, the present invention can also study the influence of production fluid rate, crude oil injection volume and production fluid water content on the dynamic diffusion process of corrosion inhibitors .

Claims (10)

1. An oil well corrosion inhibitor dynamic diffusion corrosion monitoring device, wherein the device includes a pressure vessel, a tank body, a pipeline and a water pump; The outside of the pressure vessel is welded with a liquid outlet connection pipe, a monitoring port connection pipe, a feed port connection pipe, a liquid level control port connection pipe and a sampling port connection pipe connecting the inside and outside of the pressure vessel; Oil pipes and heating devices are also arranged in the pressure vessel; The tank body is respectively connected to the liquid outlet connection pipe, the feed port connection pipe and the liquid level control port connection pipe of the pressure vessel through the pipeline through the water pump; Valves are set for the liquid outlet connecting pipe, the monitoring port connecting pipe, the feed inlet connecting pipe, the liquid level control port connecting pipe and the sampling port connecting pipe; Preferably, the lower port of the oil pipe is at the same height as the monitoring port connection at the bottom of the pressure vessel; Preferably, the pressure vessel is a cylindrical barrel; Preferably, the device is also provided with a thermometer and a pressure gauge. 2. The device according to claim 1, wherein the liquid outlet connecting pipe is respectively arranged at the top and the lower end of the side of the pressure vessel; the feed inlet connecting pipe is arranged at the upper end of the pressure vessel side; the monitoring port connecting pipe It is arranged at the lower end of the side of the pressure vessel, preferably below the inlet nozzle, and preferably 3-6, more preferably 4, of the monitoring inlet nozzles; the liquid level control outlet connector is arranged at the upper end of the pressure vessel side , preferably arranged at a position opposite to the inlet nozzle; the sampling outlet nozzle is arranged at the lower end of the side of the pressure vessel, preferably below the liquid level control outlet nozzle, and preferably there are 3-6 sampling outlet nozzles, More preferably 4; Preferably, the pressure gauge is arranged on the liquid level control port connection. 3. The device according to claim 1, wherein an openable sealing end cap is provided on the top of the pressure vessel; preferably, the end cap is a cylindrical structure with one end open; it is also preferred that the end cap is connected with the The barrel part of the pressure vessel is sealed and connected. 4. The device according to claim 1, wherein the tank body comprises a waste liquid tank, a crude oil tank and a corrosion inhibitor tank. 5. The device according to claim 4, wherein, the crude oil tank and the corrosion inhibitor tank are respectively connected with the feed port connection through a pipeline via a water pump, wherein the preferred feed connection is one, and the crude oil tank and the corrosion inhibitor The tanks pass through pipelines, water pumps, and are connected to the feed port connection through a three-way pipe; the waste liquid tank is connected to the liquid outlet connection and the liquid level control port connection through pipelines; preferably through two It is respectively connected with the two liquid outlet nozzles and the liquid level control outlet nozzle through pipelines. 6. The apparatus according to claim 1, wherein the oil well equipment is arranged inside the top of the pressure vessel; the heating device is arranged inside the bottom of the pressure vessel. 7. The device according to any one of claims 1-6, wherein the device further comprises a bracket for fixing the pressure vessel; preferably the bracket includes a square plate for fixing the pressure vessel and a bottom of the square plate. A pillar for supporting the square plate; preferably, the pillars are respectively arranged at the center of the bottom of the square plate and at the edges of the four corners. 8. The device according to claim 7, wherein a square plate through hole for fixing the pressure vessel is provided in the middle of the square plate, and a fixing hole corresponding to the square plate through hole is provided at the bottom of the pressure vessel. 9. The device according to claim 8, wherein the pressure vessel further comprises a disc-shaped support, the support protrudes outward along the pressure vessel to form a protruding edge, the fixing hole is a through hole, And evenly set on the edge of the support. 10. A method for monitoring dynamic diffusion corrosion of an oil well corrosion inhibitor, which is carried out by using the dynamic diffusion corrosion monitoring device for an oil well corrosion inhibitor according to any one of claims 1-9, the method comprising the following steps: Close all the monitoring port connections, the liquid outlet connection on the lower side of the pressure vessel and the valves on the sampling port connection, and at the same time open the liquid inlet connection, the liquid outlet connection on the top of the pressure vessel and the liquid level control port connection. valve, and extend the measuring probe of the corrosion on-line monitor into the pressure vessel through the monitoring port connection; Inject a certain amount of oilfield produced water from the liquid inlet connection so that the liquid level in the pressure vessel is at the port position of the oil well equipment. After the water injection is completed; close the valve on the liquid inlet connection and start heating the pressure vessel through the heating device Heating the liquid; when the thermometer shows that the temperature in the cylinder reaches the required temperature, open the feeding port connection pipe, and inject a certain amount of crude oil into the pressure vessel through the water pump. Preferably, the added crude oil does not exceed the liquid level control port connection pipe , and then inject a certain amount of corrosion inhibitor solution through the water pump; Close all valves, and record the corrosion rate of the liquid in the pressure vessel at different depths and at different times at different times through the online corrosion monitor, preferably when multiple detection ports are installed, so as to analyze the corrosion inhibition of the corrosion inhibitor rate changes; Open the valve on the sampling port connection pipe, sample the liquid at different depths in the pressure vessel, and test the corrosion inhibitor concentration. Preferably, when there are multiple detection port connection pipes, record the corrosion inhibitor concentration at different depths and at different times to obtain Corrosion inhibitor concentration values corresponding to different corrosion inhibition rates; control the pressure inside the pressure vessel through the liquid level control port; After the experiment is over, open the valve on the liquid outlet connection, release all the liquid in the pressure vessel, and recover it to the waste liquid tank through the pipeline.