RU2798647C1 - Downhole pumping unit for pipeless well operation - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention can be used for operation of production wells with a downhole pumping unit by lifting products along the production string, including high-viscosity products. The unit includes cylinder 2 with receiving valve 3, plunger 4 with discharge valve 5 connected to pump rod string 6 connected from above with a rod connected to the ground drive, a hollow shank with packer 8, a bypass device in the form of a side channel that opens when plunger 4 moves down. Cylinder 2 is equipped with an upper plug-in nipple that tightly interacts with upper locking support 9 of the liner fixed in mechanical packer 8. The length of plunger 4 is not less than the stroke of the ground drive. The side channel is made in cylinder 2 for permanent overlap by plunger 4 from the inside when plunger 4 moves between the upper and lower dead points during the operation of the ground drive. Cylinder 2 is made with extension 12 from the bottom to allow plunger 4 to descend below the dead centre with the opening of the side channel after the ground drive stops.

EFFECT: simplifying the design of the unit.

1 cl, 2 dwg

Description

The proposal relates to the oil industry and can be used for the operation of production wells with a downhole pumping unit with lifting products along the production string, including high-viscosity products, as well as in small diameter wells.

Known standard rod downhole pumping unit, consisting of a drive, a string of sucker rods, a downhole pump, auxiliary equipment (filters, gas and sand anchors), tubing strings. During the operation of a downhole pump, driven through a string of sucker rods, the liquid rises through the tubing string to the wellhead, from where it enters the collection system (A.G. Molchanov, V.L. Chicherov. "Oilfield machines and mechanisms" Textbook for technical schools. 2nd edition, revised and additional M., "Nedra", 1983, pp. 34-37).

The disadvantage of the installation is a large metal consumption due to the use of the tubing string, an increase in the duration of underground repairs, complications due to an increase in the amplitude of loads on the rod string during the production of high-viscosity products, especially in wells of small diameter (production strings with a diameter of 102 and 114 mm).

Known downhole pumping unit with a casing pump (Oil production by deep rod pumps. Scheller-Bleckmann GMBH, Ternitz, Austria, 1988, p. 24). The downhole pumping unit comprises a downhole pump with a fastening unit, a pump rod string with centralizers and an anchor packer installed in the well casing. The rod pump is lowered into the well on a string of sucker rods, and at a given depth, the attachment unit is fixed in the anchor packer. When the pump is operating, the well production is lifted along the casing string.

Disadvantages of a downhole pumping unit:

- the impossibility of killing the well during the repair involves the use of the installation only in wells with reservoir pressure below hydrostatic, which narrows the scope of the installation;

- low filling ratio of the rod pump, since all the gas coming from the reservoir along with the liquid enters the pump, accumulating in the space under the packer.

Known downhole pumping unit for the operation of production wells, including a rod pump containing a cylinder, a suction valve, a plunger with a discharge valve attached to the pump rod string with centralizers, a mount and an anchor packer. The downhole pumping unit is additionally equipped with a centralizer installed in the upper part of the rod pump cylinder and a bypass device located between the inlet valve and the attachment unit, while the plunger discharge valve is made controllable (RF patent No. 33180, publ. 10.10.2003).

The disadvantages of the installation are:

- design complexity due to the use of non-standard equipment (centrator in the upper part of the cylinder, bypass device, controlled pressure valve), which reduces the reliability of the installation;

- low reliability of the installation when killing the well due to the need to supply the killing fluid to the well at a pressure higher than the calculated allowable pressure on the formations. By overpressurizing a well there is a risk of high pressure fluid being injected into underlying or overlying formations, especially in older wells where the production string is susceptible to corrosion due to contact of the produced fluid;

- accumulation of free gas in the liner below the suction valve, which impairs the performance and reduces the performance of the pump.

Known downhole pumping unit for lifting products along the production string of a well, containing a cylinder, a suction valve, a plunger with a controlled discharge valve attached to a string of sucker rods with centralizers, a hollow shank consisting of an upper and lower parts, with an additional bypass device, a self-sealing packer , stop and side holes (patent RU No. 2361115, publ. 10.07.2009).

The disadvantages of the installation are:

- complexity of the design due to the use of non-standard equipment (controlled pressure valve, bypass device), which reduces the reliability of the installation;

- low reliability and durability of the self-compacting packer under the action of rocking forces that occur during the operation of the pump;

- the need to use an additional bypass device to lift the assembly without discharging the well fluid due to the pistoning of the sleeve packer, which, if the bypass hole fails under the action of swinging forces arising from the operation of the pump, will lead to complications, an increase in the duration of the repair, pollution of the surrounding area;

- high accident rate of the installation due to the descent of the layout, consisting of a large number of non-standard elements in one trip;

- the impossibility of replacing the pump without lifting the entire assembly of equipment;

- complication of the pump design due to the use of a controlled discharge valve for pumping liquid together with gas, which increases its cost and reduces reliability;

- stop of the liner on the bottomhole, in case of a deep sump, the metal consumption of the liner increases, while the probability of sprinkling the liner with rock removed from the reservoir during operation is high, which will lead to accidents during dismantling.

Known pumping unit for pipeless well operation, containing a cylinder, a receiving valve, a plunger with a controlled discharge valve attached to a string of sucker rods with centralizers, a hollow liner with a self-sealing packer, stop and side holes (patent RU No. 131819, publ. 27.08.2013) . From above, the cylinder is connected to a branch pipe of a larger diameter and length, provided with a narrowing in the upper part, a centralizer and side holes, and from below, the cylinder is connected to a cylinder of a smaller diameter, with a plunger placed in it, equipped with a receiving valve. The plungers are interconnected by a rod. From above, the self-sealing packer is connected to a cylinder of smaller diameter, and from below it is connected to a hollow liner, an additional packer is installed between the self-sealing packer and the hollow liner.

The disadvantages of the installation are:

- design complexity due to the use of non-standard equipment (controlled pressure valve, compound cylinders and plungers, additional packer), which reduces the reliability of the installation;

- low reliability and durability of the self-compacting packer under the action of rocking forces that occur during the operation of the pump;

- the risk of lifting the assembly with the outflow of the well fluid due to the pistoning of the sleeve packer, which will lead to complications, an increase in the duration of the repair, pollution of the surrounding area;

- high accident rate of the installation due to the descent of the layout, consisting of a large number of non-standard elements in one round-trip operation;

- the impossibility of replacing pumps without lifting the entire assembly of equipment;

- complication of the pump design due to the use of a controlled discharge valve for pumping liquid together with gas, which increases its cost and reduces reliability;

- complication of the pump design due to a change in the design of the plunger and cylinder, the use of an additional packer, which increases the complexity of manufacturing and the accident rate of the installation.

The closest in technical essence is a downhole pumping unit for pipeless well operation, including a rod pump containing a cylinder, an inlet valve, a plunger with a controlled discharge valve attached to a pump rod string with centralizers connected to a polished rod, a hollow shank with a stop, a packer and a bypass device containing a cylinder with side channels and a hollow piston (patent RU No. 99832, publ. 27.11.2011). The downhole pumping unit is equipped with additional centralizers installed in the upper part of the rod pump cylinder and on the hollow shank, as well as an emphasis-centrator, made with the maximum allowable diameter, installed at the lower end of the hollow shank. The polished rod is longer than the total length of the possible axial movement of the plunger in the pump cylinder and the hollow piston in the bypass cylinder. In this case, the receiving valve is made wide-bore.

The disadvantages of this setup are:

- design complexity due to the use of non-standard equipment (bypass device and additional bypass device, stop-centralizer, controlled discharge valve, wide-bore intake valve, centralizers in the upper part of the cylinder), which reduces the reliability of the installation in a small diameter well;

- a narrow scope of the installation, which limits its use for wells with a high gas factor, since the accumulated free gas in the liner reduces the efficiency and reduces the performance of the pump;

- low reliability and durability of the self-compacting packer under the action of rocking forces that occur during the operation of the pump;

- the need to use an additional bypass device to prevent the outflow of the well fluid when lifting the equipment due to the pistoning of the sleeve packer, which, if the bypass hole fails under the action of the swinging forces that occur during the operation of the pump, will lead to complications, an increase in the duration of the repair, pollution of the surrounding area;

- high accident rate of the installation due to the descent of the assembly, consisting of a large number of non-standard elements, in one trip;

- the impossibility of replacing the pump without lifting the entire equipment layout.

The technical result is to simplify the design of a downhole pumping unit for lifting products, including high-viscosity products with a high content of free gas, along the production string in small-diameter wells, providing the possibility of killing the well (by pushing into the formation in the event of abnormally high formation pressure and the impossibility of reducing the formation pressure). pressure according to the development conditions), preventing the influence of free gas on the pump intake and preventing complications when lowering and docking the pump.

The technical result is achieved by a downhole pumping unit for pipeless well operation, containing a cylinder with a suction valve, a plunger with a discharge valve attached to a pump rod string with centralizers, connected from above to a polished rod connected to a surface drive, a hollow liner with a packer, a bypass device in in the form of a side channel that opens when the plunger moves down.

According to the invention, the cylinder is equipped with an upper plug-in nipple that tightly interacts with the upper locking support of the liner fixed in a mechanical packer, the plunger is made with a length not less than the stroke of the ground drive, the side channel is made in the cylinder with the possibility of constant overlapping by the plunger from the inside when the plunger moves between the upper and lower dead points during the operation of the ground drive, the cylinder is made with an extension from the bottom to allow the plunger to descend below the dead center with the opening of the side channel after the stop of the ground drive.

In FIG. 1 shows a general view of the installation during operation.

In FIG. 2 shows the installation during gas shutdown or bleed.

Downhole pumping unit 1 (Figs. 1 and 2) for pipeless operation of a well contains a cylinder 2 with a receiving valve 3, a plunger 4 with an injection valve 5 attached to a string of sucker rods 6 with centralizers 7 connected from above with a polished rod connected to a ground drive, a hollow shank with a packer 8. Cylinder 2 is equipped with an upper plug-in nipple that tightly interacts with the upper locking support 9 of the shank. The plug-in rod pump is placed in the tubing 10. An opening 11 is made on the side surface of the cylinder, which acts as a bypass device in the form of a side channel that opens when the pump plunger moves down to the bottom dead center.

Plunger 4 is made with a length not less than the stroke of the ground drive. The side channel is made in the cylinder with the possibility of permanent overlapping by the plunger from the inside when the plunger moves between the upper and lower dead points during operation of the ground drive. The cylinder is made elongated at the bottom with an extension 12 for the possibility of lowering the plunger below the dead center with the opening of the side channel after the stop of the ground drive.

Downhole pumping unit for pipeless well operation operates as follows.

After the anchor packer is lowered and set in the production string 13 above the productive formation 14, the rod pump is lowered on the pump rod string 6 until the attachment point is fixed in the anchor packer, while the above-packer and under-packer spaces are separated.

Then the deep-pumping unit is put into operation. The drive (not shown in the diagram) transmits reciprocating motion to the plunger 4 through the pump rod string 6. The produced product from the formation 14 enters the pump intake, then into the above-packer space, to the wellhead and collection line. Centralizers 7 prevent wear of rods 6 and production string 13.

The mechanical packer allows separating the above-packer and under-packer space, while its advantage is the exclusion of the effect of pistoning and outflow of liquid when lifting equipment, which occurs when using a sleeve packer, which requires the use of special complex bypass devices in the above analogues. Docking the pump to the packer ensures the lifting of production along the production string, including high-viscosity products, as well as in small diameter wells.

The accumulation of gas in the liner is controlled by a dynamometer chart (form "gas effect"). When fixing the accumulation of gas in the liner, the well is stopped and the plunger 4 is lowered to the lowest position to open the hole 11 and release free gas from the under-packer space to the over-packer space (Fig. 2). During operation, gas gradually accumulates in the under-packer space, reducing the filling and pumping efficiency, which entails oil losses. When the hole is opened, the gas is bled into the space above the packer, which, after refitting the plunger and putting the unit into operation, makes it possible to ensure the necessary withdrawal of liquid and oil and eliminate the need for complex and unreliable controlled valves. The hole 11 is made, for example, with a diameter of 10 mm in the middle of the cylinder 2.

To ensure the possibility of killing the well, it is necessary to stop the well and lower the plunger to its lowest position with communication of the above-packer and under-packer spaces (Fig. 2), which will allow the well to be killed, including even in the event of a breakage of the rods (in this case, the plunger itself will be in bottom position).

Thus, the proposed downhole pumping unit, with a significant simplification of the design, makes it possible to lift the well production along the production string of small diameter, to kill the well, preventing the effect of free gas on the pump intake and complications when lowering and docking the pump due to the possibility of lowering the pump of a separate lowering lifting operation, as well as to exclude the outflow of liquid when lifting the equipment due to the exclusion of the effect of pistoning. The unit allows expanding the arsenal of tools for pipeless operation of a small diameter well, providing lifting of high-viscosity products with a high content of free gas.

Claims (1)

Downhole pumping unit for pipeless operation of a well, comprising a cylinder with a suction valve, a plunger with a discharge valve connected to a pump rod string with centralizers, connected from above to a polished rod connected to a surface drive, a hollow liner with a packer, a bypass device in the form of a side channel that opens when the plunger moves down, characterized in that the cylinder is equipped with an upper plug-in nipple that hermetically interacts with the upper locking support of the liner fixed in a mechanical packer, the plunger is made with a length of at least the stroke of the ground drive, the side channel is made in the cylinder with the possibility of permanent overlapping by the plunger from the inside when the plunger moves between the upper and lower dead points during the operation of the ground drive, the cylinder is made with an extension from the bottom to allow the plunger to descend below the dead center with the opening of the side channel after the ground drive stops working.

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