RU55050U1 - DEVICE FOR PUMPING GAS-LIQUID MIXTURES DURING TECHNOLOGICAL OPERATIONS IN WELLS - Google Patents

Abstract

A device for pumping mixtures refers to the technical means of drilling oil and gas wells intended for flushing wells. The device is made in the form of a single-screw pump with cylindrical working bodies, including a screw stator and a rotor located inside it with the number of teeth one less than the number of stator teeth. A feature of the pump acting as a compressor is the reduction in the working volume of the chambers from suction to discharge. A change in the working volume, leading to a gradual compression of the mixture, is solved by several alternative methods by changing the geometric parameters of the working bodies.

Description

The invention relates to the field of drilling oil and gas wells, namely, to technical means for flushing wells during drilling.

Known devices - booster pumps, allowing to pump gas-liquid mixtures during technological operations in wells, in particular to ensure the technology of drilling in the depression [1]. These devices are a very bulky unit - a multi-cylinder piston pump with a crank-slide mechanism and a booster attachment.

In the oil industry, as in other industries, single-screw pumps are used. The working bodies of these pumps consist of two parts: a rubberized screw stator and a metal screw rotor located inside it [2].

Between these parts helical chambers (sluices) are formed, filled with liquid. During operation, these chambers move from the suction area to the discharge area. Compared to other types of positive displacement pumps, single-screw pumps are distinguished by their simplicity of design, the absence of switchgears (valves, spools), uniformity of supply, and also low specific metal consumption.

To use single-screw pumps in gas-liquid technologies as a pump-compressor, it is necessary to reduce the volume of the chambers of the working bodies from suction to discharge.

The use of a conventional screw pump for pumping a gas-liquid mixture, as shown by experimental studies, is accompanied by a decrease in volumetric efficiency. pump and as a result of the effectiveness of its use.

The closest technical solution, selected for the prototype, is a single-screw pump according to AS No. 304353. This pump is characterized by a conical shape of the working bodies and, as a result, the volume of the chambers decreases from suction to discharge. The disadvantage of this technical solution is the complexity of the manufacture and control of the helical surfaces of the working bodies. In addition, the conical working bodies predetermine the additional load on the stator due to the partial transmission of axial hydraulic force to this part.

The objective of the present invention is to provide a device for pumping gas-liquid mixtures based on a single-screw pump and the existing manufacturing technology of its working bodies.

The device is a single-screw sectional pump with multi-step cylindrical working bodies.

The feature of the device and the principle of operation are shown in figures 1-3, and theoretical calculations.

Figure 1 presents a schematic diagram of a device, figure 2 is a longitudinal, and figure 3 is a transverse section of the working bodies of the device. Figure 4 shows a scan of the working bodies with contact lines.

As can be seen from the diagram (figure 1), the device consists of a housing 1 with a suction 2 and discharge 3 nozzles, a drive shaft 4, a bearing assembly 5 and connecting elements (flexible shafts or cardans) 6.

Working bodies consist of sequentially arranged sections. The number of sections must be at least 2. Each section consists of a stator 7 with an internal cylindrical helical surface and a cylindrical screw rotor 8 located inside it.

The connection of the rotors with each other and with the drive shaft is made using flexible shafts 6, allowing to transmit torque

torque and axial hydraulic force from rotating rotors to the bearing assembly.

The working bodies can also perform not sectional, but in the form of monolithic rotors and stators with variable geometry.

Figure 2 and 3 are the geometric parameters of the working bodies:

Z ₁ - lead (number of teeth) of the stator;

C - eccentricity (distance between the axes of the rotor and stator);

T is the pitch of the helical surface of the stator;

D is the diameter of the hollows of the helical surface of the stator. According to the theory of screw gerotor hydraulic machines, the pump displacement is a function of the following parameters

and is expressed as

where S is the living section area,

The load capacity of the pump-compressor is limited by the number of contact (sealing) lines separating the high and low pressure areas, which are shown in figure 4.

On the example of a pump with the number of stator teeth Z ₁ = 4, a scan of these lines is shown in a pair of “rotor-stator” having a length of two steps of the stator.

For a multi-step working body, the number of contact lines is determined by the formula

where L is the length of the working bodies of each section.

The inventive device operates as follows.

The device drive (not shown in the diagram) may be electric or another type. The torque from it through the drive shaft 4 and flexible shafts 6 is transmitted to the rotor group 8.

When the rotor 8 rotates, the chambers between the rotor and the stator 7 progressively move from input to output. In this case, a gas-liquid mixture with a certain volumetric gas content through the suction pipe 2 is sucked into the chambers of the first section and then pumped into the second section.

To compress the mixture, each subsequent section has a smaller working volume than the previous one. After the passage of all sections, the compressed mixture through the discharge pipe 3 is supplied to the consumer.

The task of changing the working volume of the sections, leading to a gradual compression of the mixture (with an increase in its density), is solved by several alternative design methods:

1. By changing the pitch of the helical surfaces of the working bodies of the sections with a constant number of teeth Z ₁ and eccentricity e:

T ₁ <T ₂ ; T ₂ <T ₃ ...

2. By changing the number of teeth Z ₁ with constant steps T and eccentricity e:

Z ₁ <Z ₂ ; Z ₂ <Z ₃ ...

3. A change in the eccentricity with a constant number of teeth and pitch screw surfaces

e ₂ <e ₁ ; e ₃ <e ₂ ...

4. The combination of changes in three parameters:

T, Z ₁ and e

To achieve a uniform increase in the pressure of the mixture in each section of the device, the length of the working body of each section is established from the condition of ensuring the equality of the number of contact lines λ, which are determined from the above formula (4)

Information sources

1. Turns B.C. Single screw compressor. A.S. No. 304353, 1976.

2. Baldenko D.F., Bidman M.G. and other screw pumps. M. Engineering, 1982.

3. Belei I.V., Lopatin Yu.S. and others. A method of pumping a gas-liquid mixture flushing the pump and a device for pumping. RF patent No. 714044, 1977.

4. Baldenko D.F., Baldenko F.D., Gnoev A.N. Screw downhole motors. M. Nedra, 1999.

Claims (2)

1. A device for pumping gas-liquid mixtures during technological operations in wells based on a single-screw pump, consisting of a suction and delivery nozzles, a drive shaft and sequentially arranged sections - cylindrical working bodies, each of which includes a screw stator and a screw rotor with a number of teeth located inside it one less than the number of stator teeth, and the working volume of the sections decreases from suction to discharge, characterized in that the change in the working volume of the sections bent by changing the steps of the helical surfaces of the stator and rotor while maintaining the eccentricity and the number of teeth of the working bodies, or by changing the number of teeth of the stator and rotor while maintaining the eccentricity and steps of the helical surfaces, or by changing the eccentricity of the working bodies while maintaining the number of teeth and steps of the helical surfaces of the stator and rotor, or a change in the combination of three parameters: the number of teeth, eccentricity and the steps of the helical surfaces of the stator and rotor. 2. The device according to claim 1, characterized in that the length of each section of the working bodies is established from the condition of ensuring the equality of the number of contact lines of the stator and rotor.