RU2727849C1 - Continuous-action constant volume degasser - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil and gas industry, namely to degassing equipment, and can be used for extraction of dissolved gas from drilling fluid by continuous extraction of part of flushing liquid at constant temperature mode from flow at outlet from oil well with its further mixing until formation of gas-air mixture, intended for further transportation and component-by-component analysis. Degasser of constant volume includes peristaltic pump, degassing chamber, at that, degasser comprises sampling device made in form of cylinder perforated in lower part, in the center of which there is a rotor containing blades arranged along it along a spiral connected to a peristaltic pump, the output of which is connected to a mixer containing a mixing chamber with a mixing aperture, a spray splitter and a degassing chamber.EFFECT: high accuracy and stability of determining content of gas in gas-air mixture extracted from flushing liquid, by creating continuous flow of gas-air mixture at outlet of degasser.11 cl, 1 tbl, 4 dwg

Description

The invention relates to the oil and gas industry, namely to degassing equipment, and can be used to extract dissolved gas from the drilling fluid (when carrying out drilling operations, the fluid circulating in the well is usually called drilling mud, drilling fluid, further the term "flushing fluid" will be used, abbreviated - PZh) by continuous withdrawal of a portion of the flushing fluid at constant temperature from the flow at the outlet of the oil well, followed by mixing it until the formation of a gas-air mixture intended for further transportation and component analysis.

For the purposes of regular monitoring of the flushing liquid by the content of free gas and true density, a method has been developed for determining the concentration of free gas in carbonated solutions by the compression method, manual and automatic devices have been developed and introduced for regular monitoring (Berezhnoy A.I., Degtev N.I. Degassing of flushing solutions in drilling. - M .: Gostoptekhizdat, 1963, 164 p.; Degtev NI, Zinkevich AI Control and degassing of drilling fluids. - M .: Nedra, 1978, 152 p.). From these sources of information are known: plunger device VG-1 (SU 147364, publ. 1962, No. 10), VG-2, modernized device VM-6 (hand-held devices); automatic device for continuous measurement of free gas in drilling mud, automatic devices AKG, automatic complexes AK-1 and AK-2.

The disadvantage of the known hand-held devices is their unsuitability for the organization of continuous high-precision control of the parameters of the flushing liquid by the content of free gas.

The disadvantages of all known automatic devices for determining the content of free gas in the flushing liquid by the compression method are:

- measurement resolution with a cycle time of 3 minutes (20 measurements per hour);

- small volume of the measured sample (100 cm ³ );

- low measurement accuracy.

These disadvantages are not so significant in the general control of the parameters of the drilling fluid, but they do not allow the use of these tools in gas logging. Gas logging is a measurement method that allows you to determine the amount of hydrocarbon gases entering the mud when drilling a well. The results of gas logging make it possible to identify gas-saturated formations. For example, at a reservoir drilling rate of 60 m / h (which is typical for Western Siberia), one definition will fall on 3 m of penetration, which is completely unacceptable for gas logging.

A device for continuous determination of the volumetric gas saturation of the drilling fluid by installing 3 ^x high-precision pressure sensors on the split mouth is known (Lukyanov E.E., Strelchenko V.V. Geological and technological research of wells. - M .: Oil and Gas, 1997, 688 p. ), but, unfortunately, due to the low height of the split mouth and the small measuring base, this promising method for determining the volumetric gas saturation of a drilling fluid (LF) is not always possible.

Known device for automatic measurement of the volumetric gas content of the drilling fluid according to SU 1492239, 14.10.1987, containing a sampling and measuring chambers. When this device is operating, sampling for analysis is carried out without using a pump for supplying a solution due to the flow of drilling fluid by gravity when the receiving part is immersed under the level in the trough. The disadvantage of this device is low reliability when working with viscous drilling fluids. The reliable operation of the device is also not facilitated by the presence of a large number of mechanical elements in it. In addition, the small volume of the sample and the rather long cycle of its study seriously reduce its information value.

Known degasser drilling fluid, which contains an open bottom housing, placed in a tank with carbonated drilling fluid. An engine is mounted on the housing cover and gas outlets with fittings for connection to the gas-air line are mounted. A flange is fixed on the motor shaft, on which hollow tubes are mounted symmetrically through 120 ° around the circumference at an angle of 5 to 15 ° relative to the axis of rotation of the shaft, oriented from bottom to top, serving as a centrifugal pump. In each of the pipes, in the lower part, intake holes are formed, located in the direction of rotation of the engine, for intake of the gaseous drilling mud from the reservoir, and on top, there are outlet holes directed towards the walls of the housing for the outlet of the degassed solution. Between the housing cover and above the centrifugal pump, a perforated disk is mounted on the hollow tube fastening elements with the possibility of rotating it together with the pump. In the lower part of the body, drain windows are made for withdrawing the flowing degassed solution from the degasser (RF patent No. 185084, IPC Е21В21 / 06, published on November 21, 2018).

This device, intended for cleaning the drilling fluid from gases dissolved in it, cannot be used for continuous sampling of a certain amount of drilling fluid for the purpose of subsequent analysis of the dissolved gases contained in it. The disadvantage of the known device is the possibility of rapid contamination of the elements of the degasser due to the formation of a mud cake, which leads to a decrease in the efficiency of degassing. For the same reason, frequent service is required (flushing, cleaning the degasser).

Known degasser containing a vertical centrifugal pump equipped with a gas outlet pipe and guide vanes at the inlet of the flow of degassed liquid, and a vertical hollow cylindrical degassing tank. The gas outlet pipe and the degassing tank are in communication with the gas pumping device. The tank is connected to the pump by a feed pipe that bifurcates into two pipelines. Both lines are located inside the top of the degassing tank and are double helical. The outlet ends of the pipelines are located on opposite sides of the inner wall of the degassing tank and are made tangential to it. At the inlet of the pipelines, control valves are installed (RF patent No. 130231, IPC B01D19 / 00, publ. 20.07.2013 prototype).

The disadvantage of the known device is that it is intended for cleaning the drilling fluid from gas during drilling, i.e. is one of the elements of the flushing liquid purification system and cannot be used to extract a certain amount of gas, the required continuous analysis of the amount and composition of gas in the flushing liquid.

The technical problem to be solved by the claimed invention lies in the possibility of maximum (close to 100%) gas extraction from the drilling fluid during drilling under constant conditions in order to determine the quantitative content of gas in the gas-air mixture contained in the drilling fluid for subsequent analysis of the recovered gas.

The goal is to improve the accuracy and stability of determining the gas content in the gas-air mixture extracted from the drilling fluid during drilling.

The advantage of the claimed device in comparison with known analogues is increase and stabilization of degassing while excluding its dependence on the level of the flushing liquid and its temperature, which ensures the reliability of the device in severe climatic conditions.

The technical result, the achievement of which is ensured by the implementation of the entire claimed set of features, consists in obtaining at the outlet of the device a continuous flow of a gas-air mixture extracted from the flushing fluid, which is a source of representative samples for analyzing the gas contained in the flushing fluid during drilling, which, in turn, allows to increase the accuracy and stability of determining the gas content in the gas-air mixture extracted from the flushing liquid.

The terms used by the authors in this description have the following interpretations:

Constant conditions mean the provision of a constant volume of degassed flushing fluid per unit of time at a constant temperature.

Constant volume - the volume of the flushing liquid from which the gas contained in it is extracted, pumped over per unit of time. This constant volume per unit time (or flow) is provided by the use of a peristaltic pump. For the device according to the invention, the constant volume is 3 to 5 l / min.

Thermal stabilization - maintaining a constant temperature of the treated flushing liquid not lower than 55 °, at which the gases contained in the flushing liquid are in a gaseous state.

The technical result, the achievement of which is ensured by the implementation of the entire claimed set of features, consists in obtaining at the outlet of the device a continuous flow of a gas-air mixture extracted from the flushing fluid, which is a source of representative samples for analyzing the gas contained in the flushing fluid during drilling, which, in turn, allows to increase the accuracy and stability of determining the gas content in the gas-air mixture extracted from the flushing liquid.

To ensure the technical result, the degasser of constant volume includes a peristaltic pump, a degassing chamber, while the degasser contains a sampling device made in the form of a cylinder perforated in the lower part, in the center of which there is a rotor containing blades arranged along it in a spiral, connected to a peristaltic pump, the outlet of which is connected to a mixer containing a mixing chamber with a mixing whisk, a spray suppressor and a degassing chamber. The blades of the sampling device of the degasser are made alternately tapering and widening downward, while the outer part of the blades has a rounded shape. The perforation of the perforated sampling device is made in the form of holes with a diameter of 2.5 to 7.5 mm. The rotor of the sampling device is connected to a flexible shaft and through a docking unit with a reducer of the peristaltic pump, while the docking unit contains a friction clutch that protects the kinematic mechanism from overloads arising in the event of jamming of the rotor blades of the sampling device. The mixing rim installed in the mixing chamber is made expanding downward with the blades set at an angle of 20 to 25 degrees to the vertical, while the angle between the blades is 120 degrees. The mixing chamber has an outlet for sampling the released gas-air mixture and a connection for air intake. The degasser contains a programmable frequency converter that provides current protection and the ability to adjust the rotational speed of the peristaltic pump, and, accordingly, the flow rate of the flushing fluid, through which both motors of the degasser are connected to the network. The degasser contains two motors, one of which drives the peristaltic pump, the second motor drives the mixer rim in rotation, as well as a thermal cover. A heater is installed at the outlet of the peristaltic pump in front of the mixer inlet.

The essence of the claimed invention is illustrated by drawings, where:

FIG. 1 shows a general view of the claimed device.

FIG. 2 shows a functional diagram of the claimed device.

FIG. 3 shows a sampling device.

FIG. 4 shows a picture of the mixer.

The figures in FIG. 1-3 include the following items:

1 - sampling device,

2 - peristaltic pump,

3 - mixer,

4 - thermo cover,

5 - mixer motor,

6 - electric motor of the peristaltic pump,

7 - mixing chamber,

8 - degassing chamber,

9 - fitting for air suction,

10 - fitting for sampling the gas-air mixture,

11 - gas-air line,

12 - a whisk with blades,

13 - flexible shaft,

14 - suction hose,

15 - drain hose,

16 - chute (exit from the pancreatic well),

17 - rotor,

18 - body of the sampling device,

19 - upper bearing,

20 - blades of a spiral shape,

21 - lower bearing,

22 - outlet fitting,

23 - intake holes for RV suction.

Degasser of constant volume of continuous operation (hereinafter referred to as the degasser) (Fig. 1) includes a sampling device 1 connected to a peristaltic pump 2, the outlet of which is connected to the mixing chamber 7 of the mixer 3 connected by a gas-air line to the gas analytical unit of the geological and technological research station (GTI) ... For operation at negative ambient temperatures, the device consists of a thermal cover 4, which is put on the degasser and the suction hose and maintains a constant temperature of + 40 ° C. The degasser may contain pressure, temperature and resistivity sensors (not shown in the drawings).

The sampling device 1 is immersed in the chute 16 (outlet of the drilling fluid from the well) and creates conditions for unhindered suction of the flushing fluid by the peristaltic pump 2.

The sampling device 1 is made in the form of a cylinder, in the lower part of which there are holes, in the center there is an inner rotor 17 with blades 20 of a spiral shape (Fig. 3). The blades are made alternately tapering and widening downward, while the outer part of the blades has a rounded shape.

The spiral shape of the blades during rotation prevents the accumulation of cuttings (cuttings) in the lower part of the sampler. Depending on clockwise / counterclockwise rotation, the blades either throw cuttings up or down like a drill.

The blades, rotating, clean the intake holes 23 for suction of the flushing fluid. The intake holes have a diameter of 2.5 to 7.5 mm and are located optimally with respect to the flow of flushing fluid.

The given dimensional range of the diameters of the intake holes is optimal. If the diameter of the intake hole is less than 2.5 mm, then it will poorly pass the flushing liquid; if the diameter of the intake hole is more than 7.5 mm, then large particles of cuttings will get into the working volume of the cylinder, which can clog it.

The rotor 17 of the sampling device 1 is driven in rotation by a flexible shaft 13, which removes the torque from the gearbox of the peristaltic pump 2. The shaft has a length of 3 meters and is connected to the pump gearbox using a special docking unit (not shown in the figure).

The design of the docking unit includes a pin connecting the shaft of the reducer of the peristaltic pump 2 with the threaded end of the flexible shaft. Everything is protected by a flange fixed to the gearbox, a cover (outer shell of the flexible shaft) is attached (screwed) to the flange.

The mixer 3 includes an engine 5, a mixing chamber 7, a degassing chamber 8 located in the upper part of the mixer 3 above the mixing chamber 7.

In the mixing chamber 7, a rim 12 is installed, expanding downward (pyramidal), with three blades. There may be more blades, but their number does not enhance a positive result. The rim blades are set at an angle of 20 to 25 degrees to the vertical. The angle between them is 120 degrees. This interval is optimal for using the whisk for the specified purpose. A spray suppressor is installed on the whisk stem in the upper part (not shown in the figure). The sprinkler is round and has a larger diameter than the round window located above it and separating the volume of the degassing chamber from the mixing chamber. The sprinkler is installed with a gap, preferably at least 2 mm, below this window and prevents direct splashes from entering the degassing chamber upward. The splash guard has small blades welded on top to throw away any splashes that might get into this gap.

The degassing chamber, installed above the mixing chamber and splash bar, is 2.5 cm high and has a relatively small volume. The degassing chamber has two fittings, one of which 10 is used for sampling the gas-air mixture for analysis, and the second 9 is used for sucking in air in order to equalize the pressure in the degassing chamber. A gas-air line 11 is connected to the fitting 10 for sampling the gas-air mixture and supplying the emitted gases to the gas analyzer.

The electric motor of the peristaltic pump and the electric motor of the mixer are connected to the network through a programmable frequency converter, which provides current protection and the ability to adjust the rotational speed of the peristaltic pump, and, accordingly, the flow rate of the flushing fluid.

The claimed device operates as follows.

The sampling device 1, made in the form of a degasser perforated in the lower part of the cylinder, is immersed in the chute 16 (outlet of the drilling fluid from the well), ensuring unhindered suction of the flushing fluid by the peristaltic pump 2. Unhindered suction of the flushing fluid through the perforation holes in the lower part of the sampling device is ensured by their optimal with a size of 2.5 to 7.5 mm and the execution of blades (20) of a spiral shape (Fig. 3), which, when rotating, clean the inlet intake holes from fragments of cuttings contained in the drilling fluid, and prevent the accumulation of cuttings (cuttings) in bottom of the sampler. If the holes (perforations) in the sampling device are not cleaned, they can quickly become clogged (blocked) with pieces of cuttings and the suction of the drilling fluid becomes difficult and can be quickly completely stopped. Rotation to the rotor 17 of the sampling device 1 is transmitted by a flexible shaft 13 from the reducer of the peristaltic drift 2.

The flushing liquid is continuously supplied to the peristaltic pump 2. Pump 2 creates a flow with a constant flow rate, which enters the mixer 3 through the lower flange connection, then is mixed by the mixer at a speed of about 1500 rpm.

In the mixer, a pyramidal whisk with three blades breaks the flushing liquid and forms a gas-air mixture (a mixture of gas released from the flushing liquid and air) with a constant degassing ratio. The air-gas mixture accumulates in the degassing chamber 8. Air-gas mixture is a mixture of gas (taken for analysis) and atmospheric air. The line along which the gas-air mixture is transported further is the gas-air line 11.

Depending on the operating conditions, the degasser is equipped with a thermal cover and / or a flushing fluid heater (not shown in the figures). In offshore drilling with the use of a riser (riser), hydrocarbon gases, due to cooling of the drilling fluid when passing through the riser, can precipitate into the liquid phase. This makes it impossible to obtain representative gas analysis results. For the purpose of heating the flushing fluid after the peristaltic pump, but before entering the mixer, a flushing fluid heater (not shown in the figures) is installed, which maintains the temperature of the flushing fluid flow not lower than 55 ° C.

Under these conditions, the hydrocarbon gases contained in the washing liquid and subject to analysis are in a gaseous state, due to which they can be removed from the washing liquid and sent for analysis.

Further, the gas-air mixture is fed to the geological and technological research station (GTI), where its component-wise analysis is performed on a chromatograph. The spent flushing fluid is drained from the mixing chamber through the drain hose 15 back to the circulation system of the drilling rig.

The possibility of implementing the claimed device is illustrated by the technical characteristics of the claimed device, shown in Table 1.

Table 1

Peristaltic pump: Internal (working) hose diameter Mm sixteen Rated speed of the pump rotor rpm 35 Pump motor power kW 1.1 Rated speed of the pump motor shaft rpm 1480 Pump capacity m ³ / hour 0.1-0.3 Maximum pressure generated by the pump kgf / cm ² 12 Mixer: Mixer motor power kW 0.55 Rated speed of the mixer motor shaft rpm 1500 Nutrition IN 380 Weight (assembled), no more Kg 120 Dimensions, no more (LxWxH) Mm 750 × 500 × 700

The device can be mass-produced on existing standard equipment using standard components.

Claims (11)

1. Degasser of constant volume, including a peristaltic pump, a degassing chamber, while the degasser contains a sampling device made in the form of a cylinder perforated in the lower part, in the center of which there is a rotor containing blades arranged along it in a spiral, connected with a peristaltic pump, an outlet which is connected to a mixer containing a mixing chamber with a mixing whisk, a splash damper and a degassing chamber. 2. The degasser according to claim 1, characterized in that the blades of the sampling device are made alternately narrowing and widening downward, while the outer part of the blades has a rounded shape. 3. The degasser according to claim 1, characterized in that the perforation of the perforated sampling device is made in the form of holes with a diameter of 2.5 to 7.5 mm. 4. The degasser according to claim 1, characterized in that the rotor of the sampling device is connected to a flexible shaft and through a docking unit with a reducer of the peristaltic pump, while the docking unit contains a friction clutch that protects the kinematic mechanism from overloads arising in case of jamming of the rotor blades of the sampling device ... 5. The degasser according to claim 1, characterized in that the mixing whisk installed in the mixing chamber is made expanding downward with the blades set at an angle of 20 to 25 degrees to the vertical, while the angle between the blades is 120 degrees. 6. The degasser according to claim 1, characterized in that the mixing chamber has an outlet pipe for sampling the released gas-air mixture and a connection for air suction. 7. The degasser according to claim 1, characterized in that it contains a programmable frequency converter that provides current protection and the ability to adjust the rotational speed of the peristaltic pump (and, accordingly, the RV flow), through which both motors of the degasser are connected to the network. 8. The degasser according to claim 1, characterized in that it contains two motors, one of which drives the peristaltic pump, the second motor drives the mixer rim in rotation. 9. The degasser according to claim 1, characterized in that it contains a thermal cover. 10. The degasser according to claim 1, characterized in that a heater is installed at the outlet of the peristaltic pump. 11. The degasser according to claim 1, characterized in that a heater is installed at the mixer inlet.

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