RU2788100C1 - Method for studying the hydromechanical characteristics of well filters - Google Patents

Abstract

FIELD: hydromechanical characteristics of well filters.

SUBSTANCE: method for studying hydromechanical characteristics of well filters consists in placing the filter under test in the test chamber, setting the test chamber in the required position, preparing the working fluid with specified characteristics. The necessary flow rate of the working fluid is set, the working fluid is pumped into the test chamber, the circulation of the working fluid through the filter under test is ensured. The characteristics of the working fluid are controlled and maintained at the predetermined level. The working fluid pressure at the inlet to the test chamber and at the outlet of the filter being tested is measured. The pressure of the working fluid at the inlet to the test chamber is upped to a sharp increase in discharge pressure, that is, until the filter is clogged. The difference in pressure at the inlet to the test chamber and at the outlet of the filter being tested is determined. The degree of clogging of the filter under test is evaluated by the difference in pressure at the inlet to the test chamber and at the outlet of the filter being tested. The final difference in pressure values is used to judge the efficiency of the filter being tested. The working fluid continues to be fed into the test chamber until the pressure in it increases and until the required collapse pressure is reached or until a loss of control over sand filtration is detected. Loss of control over sand filtration is assessed by a sharp drop in pressure inside the test chamber recorded on a pressure sensor.

EFFECT: increasing the reliability of the results of ongoing tests by conducting tests under conditions that are as close as possible to the actual operating conditions of well filters.

1 cl, 1 tbl, 1 dwg

Description

The invention relates to testing techniques, in particular to methods for testing downhole filters of various types of design used for the production and storage of hydrocarbons in the oil and gas industry, namely, testing downhole filters for collapse pressure.

The most promising and reliable method of sand control is the installation of downhole filters in the well. The downhole filter is one of the most important elements of the well bottomhole design, which ultimately determines the efficiency of the well throughout its entire life.

The method for studying the hydromechanical characteristics of well filters is designed to assess the nominal collapse pressure at which the filter is destroyed and the ability to retain mechanical impurities during fluid filtration on complete assemblies of anti-sand filters used in the operation of water, oil, gas and gas condensate wells occurs. In addition, the method allows you to identify methods of influence on the clogged filter in order to clean it.

Collapse pressure tests are performed to verify the nominal collapse pressure specified by the supplier/manufacturer, or to determine the collapse pressure at which the well screen breaks down and loses the ability of the well screen to retain solids. Collapse pressure tests are carried out by injecting the working fluid from the outside of the well screen.

Thus, the creation of a method for studying the hydromechanical characteristics of borehole filters on the collapse pressure will help to select the optimal design of borehole filters for reliable prevention of well sanding during long-term and stable operation under heavy load.

The closest technical solution to the proposed method is the method implemented in the bench for testing filters of downhole pumping units (RF patent No. 2687690 C1, E21B 43/08, G01M 99/00, 05/15/2019). According to a known method, filters are tested for downhole pumping units operating under conditions complicated by a high content of abrasive particles in reservoir products. The tested filter equipped with a safety valve is coaxially installed in the casing string. The cover of the casing is hermetically sealed. A breather opens in the lid, and through the valve through the pipeline, the hydraulic system of the stand is filled with the model liquid. After filling the hydraulic system of the bench with liquid, the valve is closed, the breather is plugged with a plug. Compressed air or a model liquid with a given overpressure is supplied to the casing by means of a supercharger. The amount of excess pressure in the casing is regulated by changing the tightening force of the safety valve spring and is controlled by the readings of the manometer. Thus, downhole operating conditions are simulated in the casing for a filter equipped with a safety valve.

The disadvantages of the known method are as follows. The known method does not allow to simulate the conditions typical for horizontal and directional wells. In addition, the supply of mechanical impurities to the injection pipeline does not make it possible to achieve uniformity of the model medium and control its parameters during testing, because preparation and maintenance of the homogeneity of the model medium is not provided.

The task to be solved by the present invention is the creation of such a method for studying the hydromechanical characteristics of borehole filters for collapse pressure, which makes it possible to test the collapse pressure of borehole filters under conditions typical both for vertical wells and for horizontal and directional wells.

The technical result, to which the present invention is directed, is to increase the reliability of the results of the tests carried out by carrying out tests under conditions as close as possible to the actual operating conditions of downhole filters.

The specified technical result is achieved due to the fact that in the method for studying the hydromechanical characteristics of well filters, during which the test filter is placed in the test chamber, the test chamber is installed in the required position and the working fluid with the specified characteristics is prepared, according to the invention, the necessary flow rate of the working fluid is set, working fluid into the test chamber, circulate the working fluid through the tested filter, control the characteristics of the working fluid and maintain them at a given level, then measure the pressure of the working fluid at the inlet to the test chamber and at the outlet of the tested filter, increase the pressure of the working fluid at the inlet to the test chamber to the required one and maintain the required pressure for a predetermined period of time, determine the difference in pressure values at the inlet to the test chamber and at the outlet of the tested filter, then evaluate the degree of clogging of the tested filter by the difference in pressure values at the inlet to the test chamber and at the outlet of the tested filter, then at the end of a given period of time, the final difference in pressure values at the inlet to the test chamber and at the outlet of the tested filter is fixed and the pressure of the working fluid at the inlet to the test chamber is reduced, and then the efficiency of the tested filter is judged by the final pressure difference.

In addition, the specified technical result is achieved due to the fact that in the claimed method, the test chamber can be installed in a vertical position.

Also, the specified technical result is achieved due to the fact that in the claimed method, the test chamber can be installed in a horizontal position.

Also, the specified technical result is achieved due to the fact that in the claimed method the test chamber can be installed in an inclined position.

The essence of the claimed technical solution is illustrated by a drawing, which shows a diagram of a stand for testing the hydromechanical characteristics of borehole filters for collapse, which includes:

- test chamber (1) with top and bottom covers (2, 3) at the ends;

- tested filter (4);

- pump unit (5);

- container (6) for preparing the working fluid, in the upper part of which an electric motor (7) is installed with a stirrer on the motor shaft installed in the container (6) to prevent settling of solid particles;

- container (8) with washing liquid;

- capacity (9) for waste fluid;

- pipeline (10) for supplying the working fluid;

- pipelines (11, 12, 13) for the removal of the working fluid;

- pipeline (14) for supplying the working fluid for testing the collapse pressure;

- pipelines (15, 16), respectively, supply or discharge of the working fluid, depending on the direction of the fluid flow;

- pipeline (17) for draining the waste liquid;

- pipeline (18) for supplying flushing liquid;

- pipeline (19) for supplying the working fluid;

- pipeline (33) for draining the waste liquid.

- pressure sensors (20, 21) at the ends of the test chamber;

- stop valves (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32);

In addition, pressure gauges (not indicated in the diagram) can be additionally installed as part of the stand.

The method for testing the hydromechanical characteristics of well filters to assess the nominal collapse pressure and hydraulic resistance of the filter is carried out as follows.

Before assembling the stand, all components of the stand are checked for strength and tightness. On the stand for testing the hydromechanical characteristics of downhole filters, tests can be carried out both with liquid and with liquid along with mechanical impurities in various proportions. At the same time, the pipelines adjacent to the test chamber 1 are flexible and allow it to be installed in any position (vertically, horizontally or at an angle).

Check the closure of all shut-off valves (22-30). The tested filter (4) is placed in the test chamber (1), which is tightly closed in the lower part on one side. Ensure that the test chamber (1) is closed with covers (2 and 3). Install the camera (1) in the required position (vertically, horizontally or at an angle). The required amount of liquid is poured into the container (6) for preparing the working fluid, and the required amount of flushing liquid is poured into the container (8) with the flushing fluid. The electric motor (7) is turned on and by adding the necessary components (chemical reagents and solid particles) to the container (6) for preparing the working fluid in the required proportions, the working fluid is prepared with the specified characteristics (density, viscosity, concentration of solid particles). The volume of the working fluid in this case must exceed the volume required to fill the entire system of the stand. If necessary, (for example, the container (6) remained full after previous tests), the waste liquid container (9) is drained of liquid and, if necessary, cleaned of solid particles.

Open the shut-off valves (23, 25, 26, 28, 30) on the respective pipelines (19, 14, 11, 16) and fill the system with working fluid. Then the pump unit (5) is turned on, the required flow rate of the working fluid is set, and it is pumped from the tank (6) to prepare the working fluid, first through the pipelines (19, 10) for supplying the working fluid and then through the pipeline (14) for supplying the working fluid for testing collapse pressure and the pipeline (16) for supplying the working fluid to the test chamber (1) through the bottom cover (3). The liquid begins to be filtered through the filter (4) into its inner part and exits through the top cover (2) through pipelines (15, 11, 13) for removing the working fluid and enters the container (6) for preparing the working fluid. The liquid begins to circulate in a closed cycle through the tested filter (4). Measure the pressure of the working fluid at the inlet to the test chamber and at the outlet of the tested filter. In the circulation process, the conformity of the characteristics of the working fluid in the container (6) for preparing the working fluid is monitored and, if necessary, maintained at a given level by adding the required amount of chemicals or diluting the working fluid with water. The liquid is circulated until a sharp increase in the discharge pressure, determined by the pressure sensor (20), which indicates that the filter (4) is clogged with solid particles from the working fluid (the degree of clogging is estimated from the difference in the readings of the pressure sensors (20, 21), namely, the pressure difference at the entrance to the test chamber (1) and at the exit of the tested filter (4)). At the same time, the required pressure is maintained for a predetermined period of time. At the end of the predetermined time period, the final difference in pressure values at the inlet to the test chamber and at the outlet of the tested filter is fixed and the pressure of the working fluid at the inlet to the test chamber is reduced, and the efficiency of the tested filter is judged by the final difference in pressure values. Further, the injection of liquid into the test chamber (1) is continued until the pressure increases until the required collapse pressure value, determined by the manufacturer, is reached, or until a loss of control over sand filtration is recorded (estimated by a sharp drop in the pressure value on the sensor (20) pressure). During the tests, the pressure values at the inlet to the test chamber (1) and at the outlet of the filter (4) are constantly recorded by pressure sensors (20, 21), the difference in values of which determines the pressure drop across the filter (4). At the end of the test, turn off the electric motor (7), open the shut-off valves (22 and 27) on the corresponding pipelines (18 and 17) and close the shut-off valves (30) on the pipeline (16). The pipeline (14) for supplying the working fluid for testing the collapse pressure is flushed, while the fluid enters the container (9) for the waste fluid. Then the shut-off valve (24) on the pipeline (15) is opened, the shut-off valve (25) on the pipeline (14) is closed and the pipelines (15, 11, 13) for removing the working fluid are washed, while the liquid is poured into a container (6) to prepare the working fluid. liquids. Then, the stop valves (30) on the pipeline (16) are opened, (26) are closed on the pipeline (11) and the filter (4) and the test chamber 1 are washed, while draining the waste liquid into the container (9). After that, the pumping unit (5) is turned off and all valves are closed. After that, the waste liquid from the container (9) is drained by opening the locking device (32), after which the waste liquid is recycled or disposed of.

During the tests, depending on the selected test mode (fluid flow rate, solids concentration and pressure), the main characteristics of the tested filter (4) in the test chamber (1) are evaluated:

- nominal collapse pressure;

- comparison of the maximum actual and passport pressure values at which there is no loss of the filter's ability to retain mechanical impurities during fluid filtration

- hydraulic resistance of the filter.

Based on the test results, a conclusion is made on the conformity of the hydromechanical characteristics of the tested filter declared by the manufacturer with the actual one.

After testing, open the top cover (2) (or top (2) and bottom (3)) and remove the filter (4).

If necessary, the test chamber (1) is dismantled and mounted again.

If necessary, a new filter sample is installed in the test chamber (1) and the tests are repeated.

Verification of the proposed method for the study of the hydromechanical characteristics of downhole filters on the collapse pressure was carried out as follows.

Before the study, the test sample of the well filter (4) was installed in a horizontal position and the working fluid was prepared. Then the stand was filled with working fluid to a pressure of up to 2 atmospheres. At the same time, the performance of the manometers was checked. According to the readings of pressure sensors (20, 21), the tightness of the system was recorded (pressure value equal to 2 atmospheres is maintained for 10-15 minutes). Further, by turning on the pumping unit (5), the pressure value was raised to a sharp jump, i.e. determined by the conditions of the experiment, for example, up to 120 atmospheres, which was also recorded according to the readings of the pressure sensor (20 or 21) at the entrance to the test chamber (1). The stand worked up to a sharp pressure jump for 1 hour. At the same time, with a frequency of 1 minute, pressure sensors (20,21) recorded the pressure value at the inlet to the test chamber (1), which amounted to 120 atmospheres, and at the outlet of the filter (4), the value of which corresponded to 100 atmospheres. The pressure drop across the filter was - 20 atmospheres.

To repeat the study, the conditions of the experiment can be changed. Studies were also carried out with a changed value of the pressure at the entrance to the test chamber (1), for example, from 120 atmospheres to 170 atmospheres, as a result of which a loss of control over sand filtration was obtained (estimated by a sharp decrease in pressure values at the inlet to the filter and an increase in the outlet from the filter (4), which changed from 170 to 140 atmospheres at the inlet and from 120 to 140 atm at the outlet).

The stand has a design that allows you to quickly change the angles of inclination of the test chamber (4) and test the hydromechanical characteristics of well filters. The test chamber can be installed both vertically and horizontally and in an inclined position.

Thus, there is an expansion of the functionality of the method, which consists in the possibility of testing downhole filters under conditions typical for both vertical wells and horizontal and directional wells. Testing according to the proposed method allows you to determine the efficiency of the well filter and determine the period of time and conditions and their duration under which the filter is clogged, as well as to obtain a comparison of the maximum actual and passport pressure values at which there is no loss of the filter's ability to retain mechanical impurities during fluid filtration . In other words, the implementation of the claimed method provides an increase in the reliability of the results of the tests carried out by conducting tests under conditions as close as possible to the actual operating conditions of downhole filters. Comparison of the parameters of the bench according to the prototype and the bench according to the claimed method when testing the downhole filter for collapse is shown in table 1.

Claims (1)

A method for studying the hydromechanical characteristics of well filters, which consists in placing the tested filter into the test chamber, preparing a working fluid with specified characteristics of density, viscosity and concentration of solid particles, characterized in that the flow rate of the working fluid is set, the working fluid is injected into the test chamber, and circulation of the working fluid through the tested filter, control the characteristics of the working fluid and maintain them, measure the pressure of the working fluid at the inlet to the test chamber and at the outlet of the tested filter, increase the pressure of the working fluid at the inlet to the test chamber until a sharp increase in its discharge pressure, that is, the moment clogging of the filter, determine the difference in pressure values at the inlet to the test chamber and at the outlet of the tested filter, evaluate the degree of clogging of the tested filter by the difference in pressure values at the inlet to the test chamber and at the outlet of the tested filter tra, after clogging the filter, the final difference in pressure values at the inlet to the test chamber and at the outlet of the tested filter is fixed and the pressure of the working fluid at the inlet to the test chamber is reduced, and the efficiency of the tested filter is judged by the final difference in pressure values, in addition, the working fluid continue to feed into the test chamber until the pressure in the test chamber increases until the collapse pressure reaches the value determined by the manufacturer, or until loss of control over sand filtration is detected, and the loss of control over sand filtration is evaluated by a sharp drop in value pressure inside the test chamber, fixed on the pressure sensor, while the studies are carried out when the test chamber is installed both in horizontal and in vertical and inclined positions.

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