RU2533280C1 - Sucker-rod pump with short plunger - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: sucker-rod pump with short plunger comprises a cylinder with suction valve and travelling valve and a short plunger equipped with a set of metal rings. In the set of metal rings with diameter D the rings are pressed to each other at butt ends and piled elastically to the sealed surfaces. At the short plunger case there are circular slots with placed elastic rings. At inner surface of the metal rings there are eccentric grooves at one side intended for elastic rings and to provide shift of the metal rings in radial direction to (0.1-0.3)D. In the set in each pair the metal rings in radial plane are unfolded towards each other in eccentric position per 180°. Each pair of the metal rings in radial plane is unfolded per 90° in regard to the each next pair. Length of the ring of metal rings is not less than two diameters of the plunger. The set of metal rings is pressed in longitudinal direction by a threaded bushing with a gap of (0.05-0.1)D in regard to the short plunger case.

EFFECT: invention allows improvement in the device reliability due to improved tightness of the short plunger sealing.

3 cl, 3 dwg

Description

The invention relates to techniques for oil production, in particular to borehole sucker rod pumps, and can be used in the oil industry.

A well-known sucker-rod pump (Catalog "Well sucker-rod pumps for oil production" ZINTIKhimneftemash, M. 1988, p.22), containing a working cylinder, inside which a hollow plunger with a discharge valve is connected with a minimum clearance, connected to the column of pump rods, a cylinder receiving cone with a suction valve tightly installed in it, the housing of which is made with an outer cone, a device for lifting it, consisting of a catcher mounted on the lower end of the plunger interacting with the shank of the suction valve on the (analog).

The disadvantages of the known sucker rod pump are the design complexity and high complexity of manufacturing parts, as it requires high precision and purity of the treatment of the inner surface of the cylinder and the outer surface of the plunger, as well as hardening of these surfaces in order to increase wear resistance. The manufacture of a cylinder requires precision alloy steel tubes, as well as special expensive equipment for processing deep holes. The pump has reduced reliability due to mechanical impurities, sand particles falling into the gap between the plunger and the cylinder, which leads to rapid wear of the sealing surfaces of the plunger and cylinder, as well as to possible jamming of the plunger.

Closest to the invention is a tubular sucker rod pump with a short piston (patent RU No. 2342561, publ. 11/27/2008, CL F04B 47/00), containing a stationary cylinder with suction and discharge valves. A short piston with metal rings is installed in the cylinder with the help of a transition cylinder that protects the working surface of the piston and steel rings from damage when the piston is lowered into the pump cylinder in the tubing string. A transition cylinder is installed between the tubing string and the pump cylinder (prototype).

The disadvantage of this device is the lack of reliability due to the low tightness of the sealing rings of the short piston due to the low wear resistance of the sealing rings, which reduces the resource of the pump.

The objective of the invention is to remedy this drawback.

The technical result, due to which the task is solved, is to increase the tightness of the seal of the short piston.

This problem is solved and the technical result is achieved due to the fact that in the borehole sucker rod pump with a short piston containing a cylinder with suction and discharge valves, in which a short piston equipped with a set of metal rings is installed, the latter are pressed against each other in a set of metal rings of diameter D at the ends and elastically drawn to the sealing surfaces, moreover, annular grooves are made on the housing of the short piston, in which elastic rings are placed, and on the inner surface, metal x rings, eccentric grooves are made on one side, designed for elastic rings, providing a displacement of the metal rings in the radial direction by (0.1 ÷ 0.3) D, and in the set in each pair, the metal rings in the radial plane are turned relative to each other in an eccentricity 180 ° and each pair of metal rings in the radial plane is rotated 90 ° relative to each subsequent pair, and the length of the set of metal rings is at least two diameters of the piston, the set of metal rings is pressed in longitudinal nom direction of the threaded sleeve with a clearance (0,05-0,1) D relative to the piston housing. The total length of the set of rings can be divided in half and the parts are placed at both ends of the piston at a distance of at least three piston diameters from each other. A nanodiamond chrome coating is applied to the rubbing surfaces of metal rings.

Due to the constant contact of the inner surfaces of the grooves of the metal rings with the elastic rings, all the metal rings are elastically pressed to the surface of the cylinder due to radial displacement when the piston is installed in the cylinder, which creates a zero gap between the sealing surfaces. An increase in the number of elastic rings allows their elastic properties to be used to increase the tightness of the piston seal and compensate for wear during the operation of metal rings and the cylinder.

The installation of metal rings relative to the shoulders between the annular grooves of the piston with a gap equal to at least twice the eccentricity ensures the mobility of the metal rings in the radial direction and allows the elastic ring to be held in the groove in the longitudinal direction, which increases the tightness of the seal.

Dividing the set of rings in half and placing them at both ends of the piston at a distance of at least three piston diameters between each other eliminates the distortion of the piston and increases the tightness of the pump.

List of drawings

Figure 1 presents a diagram of a well pump with a short piston.

Figure 2 presents a cross section of a General view of the pump.

Figure 3 presents a place a in figure 2.

Device description

The well pump with a short piston contains a cylinder 1 (see Figure 1) with a suction 2 and discharge 3 valves, in which a short piston 4 with a set of metal rings 5 is installed.

In a set of metal rings 5 of diameter D, they are pressed against each other at the ends and elastically pressed to the sealing surfaces. On the body of the short piston 4, annular grooves 6 are made (see FIG. 2, FIG. 3), in which elastic round rings 7 of thickness d are placed. On the inner surface of the metal rings 5, eccentric grooves 8 with a diameter of D _{1 are made} on one side, designed for elastic rings 7, providing a displacement of the metal rings 5 in the radial direction by (0.1-0.3) D, which is approximately 0 for existing structures , 3 ÷ 0.5 mm. In the set, in each pair, the metal rings 5 in the radial plane are rotated 180 ° relative to each other in an eccentricity, and each pair of metal rings 5 in the radial plane is rotated 90 ° relative to each subsequent pair. The length of the set of metal rings 5 is at least two diameters of the short piston 4. The set of metal rings 5 is pressed in the longitudinal direction by the threaded sleeve 9 with a clearance of (0.05-0.1) D, which is approximately 0.25 ÷ 0 for existing structures, 3 mm, relative to the housing of the short piston 4.

On the rubbing surfaces of the sealing rings 5, in order to increase the wear resistance, a nanodiamond chrome coating is applied.

The total length of the set of metal rings 5 is divided in half and the parts are placed at both ends of the piston 4 at a distance of at least three piston diameters D from each other.

The device operates as follows.

After installing a short piston 4 in the cylinder 1 of the sucker rod pump, the metal rings 5 are pressed to the surface of the cylinder 1 due to the deformation of the elastic rings 7. In the places where the metal rings 5 are pressed, the gap is zero, and on the opposite side, the gap gap is equal to the slip fit tolerance. Since all pairs of metal rings 5 are tightly pressed against each other, as described above, in the set in each pair, the metal rings 5 in the radial plane are 180 ° eccentric to each other and each pair of metal rings 5 in the radial plane is rotated 90 ° relative to each subsequent pair. At the installation site of the set of metal rings 5, a complex labyrinth gap is formed, which has a large hydraulic resistance for the fluid when it passes from the high-pressure cavity in which it is located towards the low-pressure cavity. The result is sealing of the installation location of the housing of the short piston 4 relative to the cylinder 1.

The manufacture of the device does not require special equipment, and the use of unified elastic O-rings simplifies its assembly and reduces cost while increasing the resource and maintainability.

This design solution provides high tightness of the piston seal by maintaining zero clearance between the sealing surfaces during the long-term operation of the pump, accompanied by wear of the rubbing pairs, which entails an increase in the resource and reliability of the device as a whole.

The invention improves the reliability of the device by increasing the tightness of the seal of the short piston.

Claims (3)

1. A sucker rod pump with a short piston, comprising a cylinder with suction and discharge valves, in which a short piston is installed, equipped with a set of metal rings, characterized in that in the set of metal rings of diameter D the latter are pressed against each other and elastically pressed against the sealed ones surfaces, moreover, annular grooves are made on the housing of the short piston, in which elastic rings are placed, and eccentric grooves are made on the inner surface of the metal rings on one side, designated for elastic rings, providing displacement of the metal rings in the radial direction by (0.1 ÷ 0.3) D, and in the set in each pair, the metal rings in the radial plane are rotated relative to each other by 180 ° eccentricity and each pair of metal rings in of the radial plane is rotated 90 ° relative to each subsequent pair, and the length of the set of metal rings is at least two piston diameters, the set of metal rings is pressed in the longitudinal direction by a threaded sleeve with a clearance of (0.05 ÷ 0.1) D relates The body of the short piston. 2. The pump according to claim 1, characterized in that the total length of the set of rings is divided in half and the parts are placed at both ends of the piston at a distance of at least three diameters of the piston between them. 3. The pump according to claim 1 or 2, characterized in that a nanodiamond chrome coating is applied to the friction surfaces of the metal rings.

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