RU2492320C1 - Electric centrifugal pump set for oil production and water injection - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: set comprises a centrifugal pump with a submerged electric motor, an additional lower pump section with a drive from the submerged motor, a motor hydraulic protection, a packer, a nozzle. The packer disconnects producing and water-absorbing reservoirs. The nozzle connects the lower pump section with the under-packer space and has a plunger at the lower end. The plunger tightly enters the cylinder installed in the packer. The intake of the additional pump section arranged in its upper part is connected with a flat pipe to a well space below the producing reservoir. Blades of impellers of the lower pump section are made for opposite direction of rotation. Impellers are installed on the shaft of the lower pump section in the tilted position. If a water sublayer of the producing reservoir is arranged above the oil one, a dead partition is installed in the lower part of the nozzle. Above the partition there is a hole for water arrival from the well into the nozzle. Below the partition there is a hole made for water arrival into the under-packer space from the upper part of the additional pump section via a flat pipe. In the receiving part of the additional pump section there is a centrifugal separator for separation of oil and its discharge via a side hole in the pump vessel into the well.

EFFECT: invention may be used for dual oil production and water injection in water wells.

1 cl, 4 dwg

Description

The invention relates to the oil industry and can be used for simultaneous separate oil production and water injection in waterlogged wells equipped with electric centrifugal pump units.

It is known that for the extraction of oil from the waterlogged formation and the injection of associated produced water separated in the wellbore into the underlying absorbing horizon, screw / 1 / and rod / 2 / pump installations are used. The units are twin pumps, the upper ones pumping oil with a small amount of water to the surface, and the lower ones pumping the stratified water in the wellbore into the sub-packer zone and then into the absorption layer through a pipe passing through the packer. The suction openings in oil pumping units are located above the suction openings for water. To eliminate the loads on the packer, leading to its depressurization during operation, as well as to protect the pump housings from axial loads when the packer is planted, it is known to use a sliding connector in the upper part of the pipe passing through the packer / 3 /.

The devices have the disadvantage that, to ensure separate selection of oil and water, the pump is lowered directly into the zone of the reservoir, because the distance between the oil and water inlets in the pump is small. Pumps are lowered into the reservoir zone in order to ensure that the water phase moves down after the product exits into the wellbore, and the oil up. The small distances between the receiving holes do not allow for a sufficiently complete separation of the phases.

Another reason leading to a deterioration of the separation of oil and water in the well may be the unfavorable location of water and oil layers in the context of the productive horizon, namely the upper location of the water and the lower location of the oil layers. In the productive zone of the well, there is a counterflow of fluids, in which the ablation of a part of water by an upward flow of oil or the ablation of a portion of oil by a downward flow of water is possible. Some oil entering the aquifer is unacceptable.

Closest to the alleged invention is a device for simultaneously separate oil production and injection of separated water in wells equipped with electric centrifugal pump units / 4 /. It includes an additional lower pump section located on the same shaft as the main pump, into which produced water flows through radial channels in the housing. Further, this water is pumped by the working steps of the lower section into the under-packer zone of the well from the last stage outflow through a concentric cavity formed by the inner and outer bodies, inclined radial channels and a pipe passing through the packer.

The device also has the disadvantage that the proximity of the receiving holes for water and oil in the pump. In order for the water intake to be located below the reservoir, the electric centrifugal pump must be lowered below the reservoir, which is practically difficult, and in some cases impossible.

The aim of the invention is to prevent the ingress of the oil phase into the water injected into the underlying water-absorbing layer.

This goal is achieved by the fact that in the known device, including a centrifugal pump with a submersible electric motor, an additional lower section of the pump driven by a submersible motor, hydroprotection of the engine, a packer separating the productive and water-absorbing layers, a pipe communicating the lower section of the pump with a sub-packer space and having the lower end of the plunger, hermetically entering the cylinder installed in the packer, receiving an additional section of the pump located in its upper part, communicated with a flat pipe from the well another space below the reservoir, and the blades of the impellers of the lower section of the pump are made for the opposite direction of rotation, and the impellers are placed on the shaft of the lower section of the pump in an inverted position, and in the case of an aqueous layer of the reservoir over the oil, a blind partition is installed in the lower part of the pipe above which a hole is made for water to enter from a well into a nozzle, and below is a hole for water to enter a sub-packer space from the upper part to filling section of the pump through a flat pipe, and in the receiving part of the additional section of the pump a centrifugal separator is installed to separate oil and output it through a side hole in the pump casing into the well.

Figure 1-4 shows a diagram of the proposed device. Figures 1 and 3 show the device used in the complete separation of oil and water in the borehole space. Figure 2 and 4 shows a device used for incomplete separation of phases.

An installation consisting of a main electric centrifugal pump 3, a receiving module 4, a hydroprotector 5 and 6, a submersible motor 7, an additional section 8, a pump on the shaft 9 of which inverted impellers 10 with vanes of the opposite direction of rotation. The upper part of the additional section is in communication with a flat pipe 11, the open lower end of which is located below the reservoir 12. The lower part of the additional section of the pump is connected to a pipe 13 having a passage plunger 14 at the lower end that is hermetically inserted into the cylinder 15 passing through the packer 16. Packer 16 located above the water-absorbing layer 17.

With incomplete separation of oil and water in the well (Figs. 2 and 4), the nozzle 13 has a blind partition in the lower part with holes on both sides 19 and 20, respectively, for water from the well to the nozzle 13 and forcing water into the under-packer space. The impellers 21 are made of the same design with the impellers of the main pump 3. At the reception of the additional section of the pump 8, a centrifugal separator 22 with an outlet for the oil phase is installed.

The operation of the installation is as follows.

The packer 16 is lowered into the well 1 with the cylinder 15 located in it. Next, the installation of the electric centrifugal pump is lowered together with the nozzle 13, which, entering the cylinder 15 with its passage plunger 14, divides the over-packer space of the well from the under-packer. This operation allows you to remove axial loads from the installation casing when the packer is planted, as well as vibration loads on the packer from the working installation. After the installation is launched, the watered production of the reservoir 12, entering the well, is stratified into oil and water due to the difference in their densities. The water phase, due to its higher density, occupies the lower part of the bottomhole section of the wellbore, and the oil phase, leaving the reservoir, breaks up into droplets and floats up to the receiving module 4, enters the main pump with a small amount of water and is pumped to the surface.

The main volume of water leaving the formation moves downward and enters the open intake of the flat pipe 11. Next, the aqueous phase through the pipe 11 enters the upper part of the additional section 8 of the pump and is pumped through steps 13 down to the sub-packer space and then to the formation 17. The execution of the blades of the impellers 10 in the opposite direction with respect to the impellers of the main pump 3 allows them to develop pressure with the same direction of rotation of the shaft 9 and the additional section. To prevent liquid from entering the submersible motor, hydraulic protections 5 and 6 are installed on both sides of it.

In order to avoid oil getting to the open intake of the flat pipe 11 and further into the reservoir 17, the productivity of the additional section 8 of the pump should be less than the amount of water entering the well. In this case, a small amount of the residual volume of water will enter the receiving module 4 together with the oil and the level of the oil-water section will be established directly at the receiving module 4.

The location of the receptions of the installation for oil and water at a considerable distance from each other and on both sides of the reservoir allows for separation of the formation fluids and their separate selection.

The complete separation of oil and water will occur at the upper location of the oil layer in the reservoir 12. In cases where the oil layer in the reservoir is below the water in the interval of perforation of the reservoir 12 there will be a counter movement of oil and water. At high speeds of the phases, the oil phase may be entrained in the aqueous or aqueous phases of the oil phase. The so-called “choking” of the drift flow will occur during the oncoming phase motion. The table shows the limiting values of oil and water flow rates in the perforation interval, at which “flooding” of flows obtained for a number of Ural-Volga oil fields can occur.

Qn, m ³ / day 29.8 19.6 13,2 7.59 5.26 1.85 0 Qв, m ³ / day 0 14.8 28.3 34.3 52.1 71.0 108,0

The table shows that in a column of still oil, the maximum flow rate of downward moving water is 108 m ³ / day. And, on the contrary, the limiting value of the flow rate of floating oil in a fixed column of water is 29.8 m ³ / day. The table also shows the intermediate values of the marginal flow rates moving towards oil and water.

In case of violation of the process of separation of oil and water in the well, a downward flowing water can carry away some of the oil phase that enters the aquifer 17. In these cases, the scheme shown in FIGS. 2 and 4 is applied. The downwardly moving water phase with a small amount of oil enters the inlet 19 and through the pipe 13 enters an additional section 8. After passing through a centrifugal separator 22 and the water freed from the oil by the impellers 21 will be pumped into a flat pipe 11 and through the hole 20 into the under-packer space. The oil phase separated in the separator 22 through the hole 23 will be discharged into the wellbore. In this case, the direction of the blades of the impellers 21 and the arrangement of the wheels by 9 are similar to the wheels of the main pump 3.

The technical and economic advantage of the proposed device is the reliability of utilization of the main volume of associated produced water in the well by preventing the oil phase from entering this water.

Literature

1. RF patent No. 2284410, E21B, 43/40. Downhole pumping unit for oil production and water injection into the reservoir / Fassakhov R.Kh., Badretdinov AN, Valeev A.M. Claim 05/31/2004. Publ. 09/27/2006. BI No. 27.

2. RF patent No. 106677 for a utility model. A sucker rod pumping unit for oil production and water injection into the reservoir / Valeev MD, Lishchuk AN, Gimatdinov AA et al. 04/05/2010. Publ. 07/20/2011. BI No. 20.

3. RF patent No. 74163 for utility model. Well pumping unit for simultaneous - separate oil production / Valeev A.M., Palchikov A.L., Pavlov E.G. et al. 12/06/2007. Publ. 06/20/2008. BI No. 17.

4. The decision to grant a patent for the invention according to the application No. 201113180/03 (018521) “Installation of an electric centrifugal pump for oil production and pumping associated water into the reservoir”, dated 01.08.2011. Claim 04/05/2010 / Valeev M.D., Gazarov A.G., Badretdinov A.M., Masenkin V.A.

Claims (1)

Installation of an electric centrifugal pump for oil production and water injection into the reservoir, including a centrifugal pump with a submersible electric motor, an additional lower section of the pump driven by a submersible motor, hydraulic protection of the engine, a packer that separates the productive and water-absorbing layers, a pipe that communicates the lower section of the pump with a sub-packer space and having a plunger at the lower end that is hermetically inserted into the cylinder installed in the packer, characterized in that, in order to prevent the oil phase from entering the pumped the underlying water-absorbing layer water, receiving an additional section of the pump located in its upper part, is communicated by a flat pipe with a borehole below the reservoir, and the blades of the impellers of the lower section of the pump are made for the opposite direction of rotation, and the impellers are placed on the shaft of the lower section of the pump in an inverted the position, and in the case of the location of the water layer of the reservoir over the oil in the lower part of the pipe, a blank partition is installed, above which a hole is made flow for water from the well into the nozzle, and a hole is made below for water to enter the under-packer space from the upper part of the additional pump section through a flat pipe, and a centrifugal separator is installed in the receiving part of the additional pump section to separate oil and drain it through the side hole in the housing pump into the well.

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