RU2291291C1 - Well separator - Google Patents

Abstract

FIELD: oil industry, possible use in system for maintaining bed pressure during inter-well transit of water for separating structurally condensed oil from extracted product of water well transferred from former oil extractive category due to water-flooding of productive bed.

SUBSTANCE: device includes separating chamber and outlet aperture for water below separating chamber. As separating chamber device uses lower section of well limited by casing string and separating collar, which is mounted on tail, connected to immersed electric motor of electric centrifugal pump, suspended in well on tubing column. Tail in lower section below separating collar is provided with limiter, and in upper section above separating collar - with outlet aperture for water. As outlet aperture for oil, draining pipe is used with windows and branch pipes for connecting space below separating collar and space above the intake of electric centrifugal pump. On the tail below separating collar a cover is positioned with possible vertical movement along the tail in form of a barrel with guides for which it is possible to contact tail limiter and also walls of internal surface of casing string of well using spring-loaded dentils.

EFFECT: separation of small oil volumes from large water volumes.

2 dwg

Description

The present invention relates to the oil industry and may find application in a system for maintaining reservoir pressure during cross-well pumping to separate structurally drop oil from produced products from a water well that has moved from the former oil production category due to flooding of the reservoir.

Known borehole sand separator, comprising a housing consisting of sections placed one above the other, sub, connecting sections, a channel for supplying fluid to the separator, tubes for downward flow and fishing chambers. In the separator sections are connected in series. Sub are made with longitudinal channels for the upward flow and transverse channels. These channels in the lower two-sided sub are connected with the annulus between the casing of the well and the casing of the separator, and in the intermediate sub with longitudinal channels below the sub. In the fishing chambers, the cross-sectional space for the upward flow is made larger than the cross-section for the downward flow (RF patent No. 2191261, class E 21 B 43/38, publ. 20.10.2002).

The known separator provides increased reliability and service life of the well pump due to the separation of sand. However, the separator does not provide high-quality separation of oil from water

Closest to the proposed invention in technical essence is a unit for separating well fluid, including a separation chamber, in which a static separator is located for separating water from oil, including an inlet for receiving well fluid from the inlet section of the well below the separation chamber, an outlet for oil-rich a component opening into a well section above the separation chamber, and an outlet for a water-rich component opening in the downhole section of the well under the separation chamber, and the height of the separation chamber is greater than the thickness of the dispersion layer that forms in it under normal operating conditions (application for invention of the Russian Federation No. 2003103440/03, class E 21 B 43/38, publ. 20.07.2004 - prototype).

The known device provides the separation of oil and water at sufficiently large ratios of oil and water in the composition of the reservoir fluid and does not allow the separation of small volumes of oil from large volumes of water.

The proposed invention solves the problem of separating small volumes of oil from large volumes of water.

The problem is solved in that the borehole separator, including a separation chamber, an oil outlet above the separation chamber and a water outlet below the separation chamber, according to the invention, uses the lower part of the well bounded by a casing and a separation sleeve installed on the liner as a separation chamber attached to a submersible motor of an electric centrifugal pump suspended in a borehole on a tubing string, a shank in the lower part The beneath the separation cuff is equipped with a limiter, and in the upper part above the separation cuff, there is an outlet for water, while a drain pipe with windows and nozzles is used as an oil outlet for communicating the space under the separation cuff and the space above the reception of the electric centrifugal pump, on the shank below the dividing cuff is placed a casing in the form of a glass with the possibility of vertical movement along the shank, and the casing has guides made in the form of couplings with the possibility of contact with the liner limiter, and with the inner surface of the casing wall using its external spring-loaded crackers.

Figure 1 presents the claimed downhole separator; figure 2 is a longitudinal section of the connecting sleeve of the casing-glass.

The separator contains a shank 1 with a separating sleeve 2 and a limiter 3, connected to the bottom of the submersible motor 4 of the electric centrifugal pump 5 with a drain - check valve 6 mounted on the tubing string 7. Shank 1 has a channel 8 communicating it above the separating sleeve 2 the inner cavity with the intake of the electric centrifugal pump 5, and below the dividing sleeve 2 on the outside, the shank 1 is equipped with a casing in the form of a glass (casing-glass) 9 with guides 10, with the possibility of about moving along the liner 1. In the inner cavity, the liner 1 has a discharge tube 11 with windows 12 for passing the oil accumulated under the sleeve 2 above the intake of the electric centrifugal pump 5 through the nozzles 13. The assembled downhole equipment is lowered into the casing 14 of the well 15, the annular space of which is at the mouth tied with oil pipe 16, and the flow line is connected to the water supply 17. The casing-cup 9, concentrically located in the casing 14, is fixed on the shank 1 with a shear pin 18 (see figure 2). On the coupling 19 of the casing-glass 9, assembled from short thin-walled pipes, lateral spring-loaded crackers 20 are placed, made upward and in contact with the casing 14.

Downhole separator operates as follows.

When the electric centrifugal pump 5 is lowered in a layout with a downhole separator into the well, the cuff 2 is located in the casing 9, the lower end of the shank 1 rests against the bottom of the casing 9, which is fixed with a shear pin 18 on the shank 1, and spring loaded crackers 20 of the coupling 19, in contact with the wall of the casing 14, slide down.

Upon reaching the required depth, the tubing string 7 is lifted to the length of one pipe. In this case, due to the contact of the side spring-loaded crackers 20, made upward and placed on the couplings 19 of the casing-cup 9, with the inner surface of the casing 14, the casing-cup 9, cutting the pin 18, moves down to the stop 3 and releases the elastic separation cuff 2, which in the open state overlaps the annular space of the casing 14 below the submersible motor 4. In this case, the cuff 2 does not suffer from pressure drop, since the pressure above and below it is practically equally.

During the operation of the electric centrifugal pump 5, an upward flow of water with oil drops passing in the gap between the casing-cup 9 and the casing 14, due to the narrowing of the annular space, will acquire an increased speed of movement, which leads to an increase in the number of mutual collisions of oil drops with each other, contributing to merging and enlargement of oil droplets, as well as their sticking with gas bubbles, causing an increase in the speed of their ascent in water. Since oil has the properties of surface-active substances, the capture of its drop is accompanied by the spreading of oil particles (rise) under the influence of surface forces on the surface of a gas bubble. Further, the upward flow, having fallen into the annular zone under the separation cuff 2, will drastically reduce the speed, and oil droplets accumulate under the separation cuff due to the ascent rate and the gas flotation lift 2. Separation of the oil and gas bubble from water occurs due to the fact that the water flow rate directed in the casing-glass 9 down to the shoe of the shank 1, less than the rate of ascent of oil droplets with gas in water. The produced water purified from oil through the casing-cup 9 enters the liner 1 and then passes through the channel 8 to the intake of the pump 5, and the oil and gas through the windows 12 and the pipe 13 is discharged above the intake of the pump and then accumulates in the annular space of the well 15. In the process In operation, the produced water from the donor well (water intake) is pumped into the injection wells through the flow and water lines. At the same time, the process of accumulation of oil occurs in the annulus 15 of the well 15 and the oil-water section eventually approaches the intake of the pump 5.

When filling the annulus of the well from the dynamic fluid level to the drain - check valve 6, the installation is turned off. The annulus filling time with oil is calculated or determined experimentally. When this drain - check valve 6 opens (using the well-known downhole valve device according to the patent of the Russian Federation No. 2150575), and the tube space communicates with the annular. Next, the secant valve is opened on the oil pipeline 16 and oil from the annulus is displaced into the oil pipeline by the reverse flow of water from the water pipe 17 through the tubing 7, or due to the outflow of water from injection wells (the pressure in the water pipe is usually an order of magnitude higher than in the oil pipe), or by direct flushing with a pump unit. If the injection wells-acceptors of this donor well have unused water pipes from the well pumping well, they can also be used to create a reverse flow of water into the donor well. From the selected samples in the oil pipeline, the end of the oil displacement process is determined, after which the installation of the donor well is started and the secant valve in the oil pipeline 16 is closed.

The implementation of downhole separation of oil and water with periodic pumping of accumulated oil from the annular space of donor wells using the proposed borehole separator allows you to save the injectivity of injection wells by cleaning the injected water from oil products and to extract additional oil from water wells.

Claims (1)

A downhole separator including a separation chamber, an oil outlet above the separation chamber and a water outlet below the separation chamber, characterized in that the lower part of the well bounded by a casing and a separation sleeve mounted on a liner attached to the liner is used as the separation chamber submersible electric motor of an electric centrifugal pump suspended in a well on a tubing string, a shank in the lower part under the separation the cuff is equipped with a stopper, and in the upper part above the separation cuff - an outlet for water, while a drain pipe with windows and nozzles is used as an oil outlet for communicating the space under the separation cuff and the space above the reception of the electric centrifugal pump, on the shank below the separation cuff placed a casing in the form of a glass with the possibility of vertical movement along the shank, and the casing has guides made in the form of couplings with the possibility of contact with the liner limiter and with the inner surface of the casing wall using its external spring-loaded crackers.

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