RU2759718C1 - Installation for determining gas content in sample - Google Patents

Abstract

FIELD: measuring equipment.SUBSTANCE: invention relates to measuring equipment and can be used to determine gas content in a sample under laboratory conditions. The installation for determining gas content in the sample consists of a vertically oriented measuring chamber connected to a gas separator to form a closed circulation circuit between them, to which a pressure sensor is connected, and the measuring chamber is equipped with a piston that can change the position in the vertical direction inside the chamber under the control of a control unit made with the possibility of comparing the reference value for pressure and the readings of the pressure sensor, in this case, the circulation circuit is equipped with a circulation pump connected to the control unit, capable of pumping the flow of gas extracted from the sample and moved to the measuring chamber back in the direction of the gas separator, and the said separator is thermostatically controlled, and an electric heating source is connected to the measuring chamber.EFFECT: improvement in the controllability of the gas content determination process.6 cl, 3 dwg

Description

Technology area

The invention relates to measuring instruments and can be used to measure the gas content in a sample in laboratory conditions.

State of the art

Known gasometer, disclosed in the USSR AS for invention No. 121591 (priority date: 08/29/1958, publication date: 01/01/1959, IPC G01N 7/14). The known gas meter is made in the form of two cylinders with pistons, during the forward and reverse stroke of which, for three cycles, liquid is sprayed, at which the percentage of gas in the liquid is determined.

Known automatic gas meter (disclosed in the source https://amcore.ru/issledovanie-plastovyh-flyuidov-pvt/sistema-temperaturnogo-kontrolya.html). The known gas meter is equipped with an automatic pressure maintenance system, a gas mixing system and a heating system to prevent the deposition of liquid gas components on the walls of the gas meter. As separation and differential degassing experiments are carried out in the PVT cell, the fluid is transferred to a cooled trap and, after degassing, the gas is fed into the gas meter to determine its volume.

Known automatic gasometer, designed to accurately measure the volume of gas under standard conditions (disclosed in the source: https://www.vinci-technologies.com/products-explo.aspx?IDR=82291&idr2=82558&idp=82288&IDM=601171). The known gas meter consists of a calibrated stainless steel chamber, an engine driven piston, a control unit, manual inlet and outlet valves to control the gas flow. At the same time, the pressure, volume and temperature of the liquid are constantly monitored and displayed on the interactive touch panel of the control unit. In the measuring chamber, the gas flow can be set either at constant pressure or at a constant flow rate.

Known gasometer with manual control, designed to accurately measure the volume of gas at ambient temperature and atmospheric pressure (disclosed in the source: http://www.vinci-technologies.ru/node/346). The known gas meter contains a calibrated cylinder in which a gas-tight piston slides, creating a chamber with a variable volume, and causes the floating piston to move upward, a manual mechanism by which the piston is moved to accurately determine the volume of gas at a given pressure, inlet and outlet valves, while the volume , gas temperature and pressure are continuously monitored and displayed on digital readouts.

Known atmospheric gas meter Leutert MG, designed to accurately determine the volume of released gas from the formation fluid (disclosed in the source: https://profpribor.ru/shop/neftyanoe-oborudovanie/oborudovanie-dlya-issledovaniya-plastovymosx-flyuidov/gazomet -mg). The known gas meter includes a calibrated glass cylinder with a floating piston, a degassing apparatus, in which, due to a slow decrease in pressure, the dissolved gas is released from the sample, is fed from the bottom of the cylinder, due to which the piston begins to rise, while the piston position sensor using a microcontroller reads the gas volume ; instrument panel, which displays the volume, pressure and temperature of the gas. The gas temperature is determined during the transition to the gas meter and is displayed on the front panel of the instrument.

Known automatic device for determining the volume of gas "PIK-GASOMETER", designed to determine the volume of emitted gas in atmospheric conditions (disclosed in the source: http://geologika.ru/product/avtomaticheskij-pribor-dlya-opredeleniya-obema-gaza-pik -gazometr /). The known gas meter is a graduated cylinder in which gas enters and which is equipped with a movable piston with an electric drive. The pressure in the cylinder is automatically maintained at 0.1 MPa; when it is exceeded, the piston automatically moves, increasing the volume occupied by the gas. The movement of the piston is monitored by a linear sensor, the readings of which are converted into a value of the volume of the supplied gas. The gas meter is equipped with a thermal stabilization system, a mixing system and allows automated control and data collection.

A common disadvantage of the known analogs is the insufficient controllability of the measurement process. This is due to the fact that the equilibrium composition inside the circulation loop is not provided for the gas and liquid phases, or the equilibrium composition is provided in the absence of temperature or pressure control, which reduces the reproducibility of the measurement results for the sample due to changes in the mentioned conditions in the laboratory room. In this case, the lack of equilibrium between gas and liquid can lead to a decrease in the accuracy of determining the gas content, since the gas component remains partially dissolved in the liquid in the separator.

Disclosure of the essence of the invention

The technical problem underlying the present invention is to accurately determine the gas content in a sample under laboratory conditions.

The technical result achieved with the implementation of the present invention is to improve the controllability of the process for determining the gas content.

The invention discloses an installation for determining the gas content in a sample. The installation consists of a vertically oriented measuring chamber connected to a gas separator to form a closed circulation loop between them, to which a pressure sensor is connected. The measuring chamber is equipped with a piston that is capable of changing its position in the vertical direction inside the chamber under the control of a control unit configured to compare the reference value for the pressure and the readings of the pressure sensor. Unlike the prototype, the circulation loop is equipped with a circulation pump connected to the control unit, capable of injecting the gas flow separated from the sample and transferred to the measuring chamber back towards the gas separator, the said separator being thermostatted, and an electric heating source supplied to the measuring chamber.

Additional advantages and essential features of the present invention can be presented in the following particular embodiments.

In particular, the circulation circuit is provided with inlet and outlet valves.

In particular, the circulation circuit is equipped with a pycnometer.

In particular, the circulation loop is equipped with a rotameter.

In particular, the pressure sensor is represented by a digital pressure gauge.

In particular, a pressure sensor is installed near the entrance to the measurement chamber.

The controllability of the process for determining the gas content in the sample is achieved by achieving equilibrium between gas and liquid due to repeated gas circulation in the circulation loop, and accurate recording of pressure and temperature conditions during measurements.

Equilibrium composition of gas and liquid is obtained in the separator when degassing the sample. The gas separated from the sample is repeatedly moved inside the circulation loop between the measuring chamber and the separator. Gas circulation, carried out in this way, makes it possible to obtain equilibrium compositions of liquid and gas.

The fixation of temperature conditions during measurements is ensured by thermostating the separator and heating the measuring chamber. Thermostatting of the separator is necessary in order to provide a controlled temperature value at which the sample is separated into gas and liquid components. Heating of the measuring chamber is necessary to prevent the formation of condensation on the walls of the chamber, caused by the temperature difference in the chamber and in the laboratory room. In this case, the controlled pressure at which equilibrium is achieved and the gas content is determined is set on the control unit connected to the pressure sensor in the circulation circuit. Temperature and pressure control ensures reproducible measurement results for equilibrium gas and liquid compositions. In addition, it ensures that the room temperature does not influence the measurement results.

Based on the gas content value, as well as the liquid and gas compositions after measuring the gas content, mathematical models of the formation fluid (sample) are created. The value of the gas content, as well as the state of equilibrium of the composition of the liquid and gas, obtained under controlled conditions for temperature and pressure, increase the accuracy of mathematical models. In this case, the measurement results for different portions of samples obtained under the same conditions are more correct to compare with each other.

Pressure and temperature conditions can be set arbitrarily, depending on the needs of the experimenter.

Brief Description of Drawings

FIG. 1 illustrates an apparatus for measuring the volume of a gas in a sample;

FIG. 2 illustrates a measurement chamber;

FIG. 3 illustrates a hydraulic diagram of the installation.

Implementation of the invention

In accordance with FIG. 1, the installation for measuring the volume of gas in the sample consists of a wheel frame 1, inside which a vertically oriented measuring chamber 2 is installed, equipped with a piston 3 (shown in FIG. 2). The position of the piston 3 in the vertical direction inside the chamber is changed by means of a ball screw (ball screw). The ball screw 4 serves as a rod for the piston. The ball screw nut 5 is connected by a belt drive 7 to the servomotor 8. The position of the piston 3 relative to its extreme lower position is determined by an encoder built into the servomotor 8. Frame 1 has an interactive touchscreen panel connected to the control unit. The panel allows you to display the readings of digital sensors obtained during measurements.

The measuring chamber 2 is made of a cylindrical shape with a constant cross-sectional diameter, made of stainless steel. Chamber 2 is located inside the frame 1 between the guide rods 9. The rods 9 together with the plate 10 form a U-shaped structure that keeps the piston 3 from axial rotation when the rotational force is transmitted through the belt drive 7 from the servomotor 8 to the piston 3. The chamber 2 is attached to the plate 10 and the lower part is fixed with a transport bracket 11 provided in the lower part of the frame 1. An electric heat source is supplied to the chamber 2, which heats it to a predetermined temperature. The pressure sensor 12 can be installed at the bottom of the frame 1, near the entrance to the chamber 2.

The inclusion of the measuring chamber 2 in the circulation circuit is provided as follows. On the lower flange of the chamber 2, a fitting 13 is provided for injecting gas into the chamber 2. The hydraulic pipe of the previous section of the circuit is connected to the fitting 13. A fitting 14 is made in the body of the piston, to which a tube is connected, which spirals inside the chamber 2 around the rod 4. On the other end side, this tube is connected to the fitting 15, which is made in the upper part of the chamber 2. Next, the fitting 15 is connected to the hydraulic tube of the next section of the contour. When the piston 3 moves up, the space between the spiral turns is compacted. When the piston 3 inside the chamber 2 reaches the extreme upper position, the sealed tube is collected inside the cavity made in the body of the piston 3.

In accordance with FIG. 3, the circulation circuit of the installation is made hermetically sealed and closed. The circuit consists of hydraulic pipes connecting in series valve 16, separator 17 for separating the sample into liquid and gas phases, valve 18, rotameter 19, pressure sensor 12, represented by a digital manometer, measuring chamber 2, circulation pump 20 and valve 21. Valves 21 and 16 close the common section of the circuit, on which an inlet valve 22 is installed, intended for supplying a sample. In the section of the circuit between the measuring chamber and the circulation pump, an outlet valve 23 is installed, designed to connect to the circuit of the vacuum pump and remove the gas sample. Valves 16, 18, 21 and valves 22, 23 are capable of switching between open and closed states. The separator 17 is a cylindrical container. The hole for introducing the sample into the separator is made in the lower part of the container, and the outlet for discharging the sample in the direction of the measuring chamber 2 is made closer to the upper part of the container. The separator 17 is provided with a constant temperature in the container by means of a liquid or solid-state thermostat. Embodiments of the invention are possible in which the rotameter 19 and / or pycnometer are absent.

The installation is used as follows.

Before starting measurements, a vacuum is provided in the hydraulic circuit and measuring chamber 2 by means of a vacuum pump connected to the circuit by means of valve 23. A value for the pressure in the circuit is set on the control unit, which is automatically controlled during measurements. Then the inlet valve 22 is moved to the open position, and the sample, which is a formation fluid under pressure (oil or gas), enters the circuit and through the valve 16 is directed to the separator 17. In the separator 17, the fluid is separated into liquid and gas phases. At the bottom of the separator 17, liquid accumulates, and the evolved gas is discharged into the chamber 2 through the valve 18, the rotameter 19. After the end of the start of the sample, the valve 22 is closed. To circulate the gas around the loop, turn on the circulation pump 20 and open the valve 21. The gas moves counterclockwise in the loop, in the separator 17 gas is bubbled through the liquid until the liquid and gas phases reach equilibrium.

The installation is capable of operating in two modes: in equilibrium mode and in throttling mode. In the equilibrium mode, before obtaining the measurement data, the gas flow is first repeatedly circulated around the loop, passing through the separator 17. In this case, mass exchange between the separated gas and liquid takes place in the separator, and a state of equilibrium of gas and liquid is ensured. The control of the achievement of equilibrium between gas and liquid is provided by obtaining the results of measuring the volume of gas on the control unit. In the absence of fluctuations in the gas volume, after several measurement cycles, it is assumed that the state of equilibrium between gas and liquid has been achieved. In the throttling mode, the gas circulation procedure is excluded.

The gas pressure is measured by a digital pressure gauge 12 located at the entrance to the measuring chamber 2. The pressure gauge 12 transmits the measured pressure value to the control unit. If the pressure measured by the pressure gauge 12 exceeds the controlled pressure, then the control unit sends a signal to the servomotor 8 to move the piston 3 up. The servomotor 8 drives the piston 3 and raises it relative to the extreme lower position until the pressure inside the chamber 2 is equal to the controlled one. The position of the piston 3 is fixed by the encoder of the servomotor 8. If the pressure measured by the manometer 12 is less than the controlled pressure, the control unit sends a signal to the servomotor to move the piston 3 downward. The volume of the cavity provided by the change in the position of the piston 3 is equal to the volume of the gas released from the sample. The volume of the emitted gas is calculated as the product of the height by which the piston 3 is displaced relative to its extreme lower position and the cross-sectional area of the measuring chamber 2.

Claims (6)

1. An installation for determining the gas content in a sample, consisting of a vertically oriented measuring chamber connected to a gas separator with the formation of a closed circulation loop between them, to which a pressure sensor is connected, and the measuring chamber is equipped with a piston that can change its position in the vertical direction inside the chamber under control of the control unit, configured to compare the control value for the pressure and the readings of the pressure sensor, characterized in that the circulation circuit is equipped with a circulation pump connected to the control unit, capable of pumping the gas flow separated from the sample and moved into the measuring chamber back towards the gas separator , moreover, the above-mentioned separator is thermostated, and an electric heating source is supplied to the measuring chamber. 2. Installation according to claim 1, characterized in that the circulation circuit is provided with inlet and outlet valves. 3. Installation according to claim 1, characterized in that the circulation circuit is equipped with a pycnometer. 4. Installation according to claim 1, characterized in that the circulation loop is equipped with a rotameter. 5. Installation according to claim 1, characterized in that the pressure sensor is represented by a digital pressure gauge. 6. Installation according to claim 1, characterized in that the pressure sensor is installed near the entrance to the measuring chamber.

Images