RU2321772C1 - Oil-well sucker-rod pump - Google Patents

Abstract

FIELD: oil producing industry.

SUBSTANCE: invention is designed for producing high viscosity oils. Proposed sucker-rod pump has fixed cylinder, movable cylinder and fixed plunger. Fixed cylinder is connected with tubing string. Delivery valve is installed in upper part of movable cylinder. Housing of delivery valve is connected with rod on which centralizer and automatic coupler are mounted to connect rod with tubing string. Fixed hollow plunger is arranged inside movable cylinder. Said plunger is connected in lower part with hollow intake branch pipe whose inner diameter is equal to inner diameter of plunger, and outer diameter is smaller than outer diameter of plunger. Intake hollow branch pipe and fixed cylinder are interconnected in lower part by means of discharge valve housing, thus forming ring discharge chamber. Discharge valve periodically communicates discharge chamber with annulus. Suction valve is installed in upper part of hollow plunger, being arranged coaxially with delivery valve.

EFFECT: provision of effective operation of pump owing to increased capacity and enlarged range of use.

2 dwg

Description

The invention relates to the oil industry, in particular to technology for the production of high viscosity oil.

A well-known sucker-rod pump for pumping highly viscous oil (AS USSR No. 1588910 dated 10/19/1987, ЕВВ 47/02), comprising a fixed shortened cylinder lowered on tubing, a movable cylinder and a fixed plunger, mounted in a movable cylinder associated with a string of pump rods. The fixed plunger and the fixed cylinder are interconnected by locking the lock in the castle support installed in the lower part of the tubing string above the fixed shortened cylinder. The suction and discharge valves are located at the bottom of the pump, respectively, in the movable cylinder and the stationary plunger. The fixed shortened cylinder is equipped with an additional suction valve and forms an additional working pair with the main movable cylinder.

A disadvantage of the known design is the limitation of the range of use of the pump, namely: the hydraulic weighting of the bottom of the rod string, according to the pump diagram described in the description, is not enough to compensate for the hydrodynamic resistance of the fluid both in the tubing string and in the valve couples, even with an increased cross section for highly viscous production oil, such as permacarbonic oil of the Usinsky oil field with a viscosity in reservoir conditions of 680-780 MPa · s. With such a viscosity of the produced oil, the hydrodynamic resistance in the suction valve of the movable cylinder and in the tubing string increases, which leads to the suspension of the rod string and, as a result, the rod string breaks.

The closest in technical essence, adopted by the authors for the prototype, is a borehole sucker rod pump (patent of the Russian Federation 1588024 dated 03/25/1983, ЕВВ 47/02), containing a stationary cylinder connected to a string of tubing, a plunger, a rod connected to a string of pump rods, a discharge chamber periodically communicating through a discharge valve with an annulus, a receiving chamber, a suction and discharge valves. The rod string is prevented from hanging during the down stroke due to the force acting on the pump plunger and directed downward by lowering the pressure in the discharge chamber below the pressure at the pump inlet.

The disadvantage of this design is the decrease in pump performance by reducing the useful volume of the receiving chamber by the volume of the plunger rod located in the receiving chamber. In addition, the range of use of the pump is narrowed. In wells complicated by the removal of solids, high gas content of the well fluid, or in wells with low reservoir pressure and high water cut, the use of a suction filter, gas separator or liner, respectively, leads to a significant increase in the outer diameter of the pump, complicating the design and installation and dismantling work at the well as the suction valve is located on the side. This limits its use in wells with the most common production casing diameter (less than 168 mm).

The present invention is to increase the efficiency of the pump by increasing its productivity and expanding the range of use of the pump.

The task is achieved by the design of the pump. The downhole sucker rod pump comprises a fixed cylinder, a movable cylinder and a fixed plunger, while the fixed cylinder is connected to the tubing string. A discharge valve is installed in the upper part of the movable cylinder, the body of which is connected to the stem. A centralizer and an automatic coupler are mounted on the rod with the ability to connect the rod to the rod string. Inside the movable cylinder, a fixed hollow plunger is installed, connected at the bottom with a hollow receiving pipe made with an inner diameter equal to the inner diameter of the plunger and an outer diameter smaller than the outer diameter of the plunger. The receiving hollow pipe and the stationary cylinder in the lower part are interconnected by means of a discharge valve housing and form an annular discharge chamber. The discharge valve periodically provides communication between the discharge chamber and the annulus. A suction valve is installed at the top of the hollow plunger.

Salient features of the claimed invention are:

- the pump is equipped with an additional movable cylinder installed between the stationary cylinder and the plunger;

- the plunger is made hollow and stationary;

- the plunger is connected in the lower part with a receiving hollow nozzle made with an inner diameter equal to the inner diameter of the plunger and an outer diameter smaller than the outer diameter of the plunger with the formation of an annular discharge chamber in which the discharge valve is installed between the stationary cylinder and the receiving hollow nozzle;

- the body of the discharge valve is connected to a fixed cylinder and a receiving hollow nozzle of the plunger;

- a suction valve is installed in the upper part of the plunger;

- a discharge valve is installed in the upper part of the movable cylinder;

- the body of the discharge valve is connected to the stem;

- a centralizer and an automatic coupler are mounted on the rod with the possibility of connecting the rod to the string of pump rods.

The specified set of essential features ensures the achievement of the task. The design of the pump allows you to increase the volume of the working receiving chamber and, as a result, to increase the productivity of the pump. The inventive design also allows you to significantly expand the range of use of the pump. When changing the viscosity of the produced oil, the pump design allows for the same diameter of the plunger and cylinders, only by changing the outer diameter of the inlet pipe (using a replacement pipe), change the volume of the discharge chamber and, as a result, change the vacuum pressure in it, which will lead to a change in the magnitude of the force directed downward. Thus, depending on the viscosity of the produced fluid, it is possible to change the magnitude of the downward force to compensate for the hang of the rod string during the movement of the movable cylinder downward and, as a result, to change the load on the rocker head of the rocking machine, that is, the design allows wider use of the pump depending on the viscosity of the produced fluid. In addition, the design of the pump allows, if necessary, to change its supply in the direction of decreasing, without worsening the filling conditions of the receiving chamber due to the possibility of ensuring minimal dead space in both the receiving and discharge chambers. The pump design also makes it possible to use it in wells with complicated conditions: in the presence of mechanical impurities, high gas content or in wells with low reservoir pressure and high water cut, a suction filter, a gas separator of serial production or a liner can be used without increasing the diameter of the pump and, as a result, use the pump in wells with the most common diameters of production casing (140-168 mm). Thus, the range of use of the inventive pump is much wider than that of the prototype.

The claimed combination of essential features is not known to us from the prior art. The invention can be manufactured in the factory and used in the production of highly viscous oil.

The essence of the proposed technical solution is illustrated by diagrams. Figure 1 shows a longitudinal section of a borehole sucker rod pump at the lowermost position of the movable cylinder. Figure 2 presents a longitudinal section of a borehole sucker rod pump with the highest position of the movable cylinder.

The downhole sucker rod pump contains a fixed cylinder 1, connected in the upper part to the tubing (tubing) 2. Inside the fixed cylinder 1 is mounted a movable cylinder 3, in the upper part of which is placed a pressure valve 4, the housing of which is connected to the stem 5. On the rod 5 mounted centralizer 6, and above it - automatic coupler 7. The rod is made with the possibility of connection using automatic coupler 7 with a column of rods 8. Inside the movable cylinder 3 has a fixed hollow plunger 9 connected in the lower part a receiving hollow pipe 10 formed with an inner diameter equal to the inner diameter of the plunger, and an outer diameter smaller than the outer diameter of the plunger, wherein between the stationary cylinder 1 and the receiving pipe 10 is formed an annular discharge chamber 11. The receiving hollow tube may be removable. Depending on the outer diameter of the inlet pipe 10, the volume of the annular discharge chamber 11 is selected. The height of the discharge chamber is equal to or less than the length of the hollow inlet pipe 10. The inlet pipe 10 and the stationary cylinder 1 are connected in the lower part to the body of the discharge valve 12. In the upper part of the stationary plunger 9 a suction valve 13 is installed. The cavity of the movable cylinder between the suction valve 13 and the discharge valve 4 forms a receiving chamber 14. The suction and discharge valves are aligned, which allows lzovat valve pair "saddle-ball" with an enlarged flow area, without increasing the diameter of the pump.

The pump is mounted and lowered into the well in the following sequence.

- The hollow plunger 9 with a suction valve 13 is connected in the lower part with a receiving hollow pipe 10 to which the body of the discharge valve 12 is attached.

- The assembled plunger is inserted into the movable cylinder 3.

- The assembly of the movable cylinder 3 and the stationary plunger 9 is inserted into the stationary cylinder 1, which is connected to the body of the discharge valve 12. In this case, the free space between the stationary cylinder 1 and the receiving hollow pipe 10 forms a discharge chamber 11.

- The housing of the discharge valve 4 connected to the movable cylinder 3 is connected to the rod 5, at the end of which an automatic coupler 7 and a centralizer 6 are mounted.

- The assembled pump with a fixed cylinder 1, a prefabricated plunger and a movable cylinder 3 is connected to the tubing string 2 and lowered to a predetermined depth.

- Lower the rod string 8 with the centralizer to connect to the rod 5 of the pump using the coupler 7.

- Select the length of the rod column 8 using shortened rods to ensure minimal dead space in the receiving and discharge chambers.

The pump is as follows.

The ground drive is a rocking machine, by means of a rod column 8, it moves the reciprocating cylinder 3 with the discharge valve 4 installed in it in the upper part. When the movable cylinder 3 moves upward (suction cycle), the pressure in the superplunger zone decreases and under the pressure of the liquid column in the annulus, the suction valve 13 opens and the supraplunger zone — the receiving chamber 14 — is filled with well fluid. In the discharge chamber 11, which is formed by the free space between the stationary cylinder 1 and the receiving hollow pipe 10, the pressure decreases from the pressure at the pump inlet at the lowermost position of the movable cylinder 3 (lower dead center - N.M.T.) to the vacuum pressure corresponding to the thermodynamic environmental conditions in the discharge chamber of the pump at the extreme upper position of the movable cylinder 3 (top dead center - V.M.T.). The rarefaction pressure is determined by the stroke length of the movable cylinder 3, the magnitude of the "dead" space in the discharge chamber and the magnitude of the leakage into the discharge chamber 11.

When the movable cylinder 3 moves down, the gas-liquid mixture in the supra-plunger zone - the receiving chamber 14 is compressed to a pressure equal to the pressure on the pump discharge in the tubing string 2, the injection valve 4 is opened and the borehole fluid coming from the annulus into the plunger zone is pumped into the tubing string 2. At the same time, the suction valve 13 is closed. The pressure in the discharge chamber 11 varies from the vacuum pressure at the position of the movable cylinder in V.M.T., to the pressure at the intake of the pump when the position of the movable plunger in N.M.T. Leaks of liquid that entered the discharge chamber during the movement of the movable cylinder 4 upward are squeezed into the annulus by the movable cylinder as it moves downward through the discharge valve 12. The cycle then repeats.

Well killing, as well as flushing of the pump, is carried out according to the technology adopted for serial sucker rod pumps.

When dismantling the pump, the movable cylinder is lifted on the rods, and then on the tubing string, the assembly of the stationary cylinder with the plunger is lifted, while the fluid from the tubing will drain through the discharge valve 12 into the well.

The proposed well sucker-rod pump can be used in the wells of the permocarbon deposits of the Usinsky oil field with an oil viscosity of 680-780 MPa · s in reservoir conditions.

Thus, the design of the pump allows you to increase its efficiency by increasing productivity, as well as expanding the range of its use, namely: the pump can be used in the production of highly viscous oil with complicated operating conditions for wells, and also provides the ability to change the load on the head of the balancer of the machine - rocking due to changes in tensile force acting on the rod string.

Claims (1)

A downhole sucker rod pump comprising a stationary cylinder connected to a tubing string, a plunger, a rod connected to a tubing string, a discharge chamber periodically communicating via a discharge valve with an annulus, a receiving chamber, a suction and discharge valve, characterized in that the pump is equipped with an additional movable cylinder installed between the stationary cylinder and the plunger, while the plunger is made hollow and connected at the bottom with a receiving hollow pipe made with with an inner diameter equal to the inner diameter of the plunger and an outer diameter smaller than the outer diameter of the plunger, with the formation of an annular discharge chamber between the stationary cylinder and the receiving hollow nozzle, in which a discharge valve is installed, the body of which is connected to the stationary cylinder and the receiving hollow nozzle of the plunger, a suction valve is installed on the upper part of the plunger, and a discharge valve is placed in the upper part of the movable cylinder, the body of which is connected to the rod on which the center is mounted Torr and a coupler device connectable with the stem of sucker rods string.

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