RU2531228C1 - Well operation installation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in the installation comprising a flow string with a centrifugal pump run in to the production string and connected to the water line at the wellhead equipment, a separating chamber in the lower part of the well bore under an electric-centrifugal pump equipped with a sealed case, a channel for separated oil passage that communicates annular space of the well with the separating chamber, inlet ports for separated water according to the invention the case of the electric-centrifugal pump is made so that it connects hydraulically suction of the electric-centrifugal pump with an input device located in the separating chamber and consisting of the shank plugged at the lower end and divided into sections with inlet ports, at that at the level of each inlet ports the shank is equipped with a cup performing functions of the separated water input to the input device and function of hydraulic lock for oil drops, at that inlet ports are located in one row along the shank with a decreasing diameter in each subsequent section in upward direction, and the channel for oil drops passage serves as a gap between the case and production string of the well. In order to lift separated oil from the annular space to the surface the tubing string has a larger diameter and the tubing string of less diameter is placed in it and the upper part of the latter is fixed rigidly to the oil line while its lower part is inserted hermetically in the upper cylindrical chamber of the switch mounted in the tubing string of a larger diameter at the depth below dynamic fluid level in the well, at that the switch is equipped with vertical peripheral channels for teeter water passage through it and with the lower cylindrical chamber for location of the inserted jet pump consisting of a nozzle, a mixing chamber and diffuser, which output is communicated with the upper cylindrical chamber. Operating fluid to the jet pump comes from the electric-centrifugal pump and the pumped fluid from the switch side channel from the well annular space via a back-pressure valve located at the switch exterior. In order to seal the inserted jet pump in the lower cylindrical chamber its case is equipped with sealing glands and a clamp hollow cylindrical screw at the outside. The jet pump case has radial openings under entry to the mixing chamber and a circular bore at the outside. The installation ensures oil separation from water practically in any quantity of the fluid produced from water supply wells due to potential use of the device without limitation of its rational length. Use of the installation allows maintenance of injectors intake capacity due to more qualitative treatment of intake water from oil and production of additional volume of oil from water supply wells. The installation also allows economically feasible use of a wide range of highly watered oil wells with water cut of 95%-99% as water intake donors considering their territorial location in the oil deposits, where maintenance of formation pressure is required by crosswell water pumping.

EFFECT: downhole separation of oil from the extracted product and separate lifting of oil and water to the surface at crosswell water pumping aimed to maintain formation pressure.

3 cl, 3 dwg

Description

The present invention relates to the oil industry and can be used for the operation of water wells with associated oil content in the product, as well as highly water-borne oil wells used as donor wells (water wells) for cross-pumping water in order to maintain reservoir pressure.

The well-known "Installation for the operation of the well" (patent RU No. 2355625, E21B 43/14, published in Bulletin No. 28 of 10/10/208), designed to pump part of the produced water from the reservoir through the flow line into injection wells, and the other parts of water into the overlying oil reservoir. The installation comprises a packer between the layers, a tubing string with radial openings for communication with the annulus, an electric centrifugal pump equipped with an external sealing casing, a receiving part of which communicates with the under-packer formation, and a discharge part with the cavity of the tubing string.

The disadvantage of the installation is that when it is used for the operation of water wells with oil-containing products or highly flooded oil wells as donor wells, oil can enter the injection wells and the receiving reservoir, since the installation does not provide for the separation of water and oil.

The closest in essence and the achieved result is “Downhole installation for separation of oil and water” (Patent RU No. 2290505, E21B 43/14, publ. 12/27/2006), including a separation chamber with a static separator and outlet openings for oil and water . The lower part of the well bounded by a casing string and a separation cuff, which is mounted on a liner attached to a submersible electric motor of a centrifugal pump suspended in a borehole on a tubing string with a flushing and non-return valve above the pump, is used as a separation chamber. The shank is equipped with a casing in the form of a glass, which protects the separation cuff when lowering the installation into the well. The release of the cuff from the casing is carried out when the installation is moving up due to the contact of the spring loaded crackers with the inner surface of the casing wall. The shank in the upper part above the separation cuff is equipped with an outlet for water, and 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. In the lower part, the shank is equipped with a separator, which is made of external and internal concentrically arranged pipes, closed from below, with an annular space between them, divided by partitions with horizontal holes into sectors. The outer pipe in the upper part in the sectors is equipped with openings for the separated oil to enter the cuff zone and along the entire length has radial openings for fluid to exit into half of the sectors through one. The inner pipe along the entire length in the remaining sectors has radial openings for water to enter it and further into the liner, as well as to receive the pump. In this case, the total area of the outlet as well as the outlet openings is not less than the cross-sectional area of the production casing of the well.

The known device has a complex design of downhole equipment, and when lowering the installation into the well, the cuff opens spontaneously, complicating the process of lowering the equipment into the well. The tube for diverting the separated oil above the intake of the pump increases the transverse size of the installation, which limits its use. To raise the accumulated oil to the surface, an additional pumping unit and reserve water are required, and at low reservoir pressures it is completely impossible to raise the accumulated oil to the surface from the annulus due to the absorption of the formation. In addition, to flush the accumulated oil from the annulus, it is necessary to stop the electric submersible pump, which leads to a downtime of the well.

The proposed invention solves the problem of improving the reliability of downhole equipment by simplifying the design of the separation chamber and the separation unit of the installation to ensure that the accumulated oil rises to the wellhead at low reservoir pressure without stopping the operation of the water well.

The problem is solved in that in an installation for the operation of water wells, including a tubing string with an electric centrifugal pump, lowered into the production string and wellhead fittings connected to the water line, a separation chamber located in the lower part of the well bore under the electric centrifugal pump equipped with a sealing casing, a channel for the passage of separated oil, communicating the annulus of the well with a separation chamber, inlet openings for of split water, according to the invention, the sealing casing of the electric centrifugal pump is configured to hydraulically communicate the reception of the electric centrifugal pump with an input device located in the separation chamber, consisting of a shank sealed from the lower end divided into sections with inlet openings, while at the level of each inlet opening, the shank equipped with a glass that performs the functions of the inlet of the divided water into the input device and a water trap for oil drops, the inlet the holes are arranged in a row along the liner and are made with a decreasing diameter in each subsequent section upward, and the gap between the casing and the production casing of the well serves as a channel for the passage of oil droplets.

To lift the separated oil from the annulus of the well to the surface, the tubing string is made of a larger diameter and the tubing string of smaller diameter is concentrically placed in it, the upper part of which in the wellhead is rigidly connected to the oil line and the lower part is hermetically installed in the upper a cylindrical chamber of the switch mounted in a string of tubing of larger diameter at a depth below the dynamic level of the fluid in the well, the tripod is equipped with vertical peripheral channels for passing an upward flow of water through it and a lower cylindrical chamber for accommodating an insert jet pump consisting of a nozzle, a mixing chamber and a diffuser, the outlet of which is in communication with the upper cylindrical chamber, and the working fluid enters the jet pump from an electric centrifugal pump, and the pumped liquid through the side channel of the switch from the annulus of the well through a check valve located on the outside of the switch. To seal the plug-in jet pump in the lower cylindrical chamber, its casing is provided with sealing lips on the outside and fixed with a clamping hollow cylindrical screw, while the casing of the jet pump has radial openings under the inlet of the mixing chamber and a circular groove on the outside.

Figure 1 schematically shows a General view of the installation for the operation of water wells with oil-containing products; figure 2 is a switch with a plug-in jet pump in longitudinal section; figure 3 is a cross section aa in figure 2.

Installation for the operation of water wells with oil-containing products contains a suspension string of tubing (tubing) of large diameter 1 with an electric centrifugal pump 2, which are lowered into the production string of the well 3. Submersible motor (PEM) 4 and the receiving part (input module) 5 of the electric centrifugal pump 2 on the outside of the annular space 6 and the separation chamber 7 are sealed with a casing 8. In the tubing string of a larger diameter 1, the tubing string of a smaller diameter 9 is concentrically placed st tubing in the wellhead fixture 9 is fixedly connected to the oil line 10, and the lower portion (shoe) fastening lip sealingly mounted in the upper cylinder chamber 11, a switch 12 installed in a larger diameter tubing at a depth of 1 below the dynamic fluid level in the well. The switch 12 is also provided with a lower cylindrical chamber 13 for accommodating the plug-in jet pump 14 and a side channel 15 that hydraulically communicates the jet pump 14 with the annulus 6 through a check valve 16 located on the outside of the switch 12. The latter has vertical peripheral channels 17 for the passage of pumped water by an electric centrifugal pump 2 into a tubing string of a larger diameter 1. A plug-in jet pump 14 containing a nozzle 18, a mixing chamber 19 and a diffuser 20, in the lower cylindrical chamber 13 of the sealants cuffs (not marked) and fixed with a clamping screw 21 with internal flats on a turn-key basis, and under the entrance of the mixing chamber 29 has radial holes 22 with an outer circular groove 23.

A shank 24 of the input device located in the separation chamber 8 formed from the annular space enclosed between the production casing 3 and the input device housing is connected to the nozzle of the casing 8. The gap between the casing 8 and the production casing 3 provides the inlet of oil droplets and their accumulation in the upper part of the annular space 6. The shank 24, which is muffled with the lower end, is provided along the entire length along the body with one row of inlet openings 25 and cups 26 that perform the function of a water seal for oil drops. The input device consists of several sections with a decreasing diameter of the inlet openings 25 in each subsequent section in an upward direction. In the wellhead reinforcement of the well, the tubing string of large diameter 1 is tied by a flow line 27 with a valve 28 and a water supply (not indicated).

The geometric dimensions of the inlet device for the proposed installation are selected based on the expected flow rate or performance of the electric centrifugal pump 2. The length of the inlet device is selected based on the number and diameter of the inlet openings 25 to provide a portioned distribution of the produced fluid stream in such a way that the speed of the downward flow of water in each portion entering in the glass 27 of the input device, less than the rate of ascent of oil droplets in water. The number and diameter of the inlets 26 is determined as follows.

The number of holes on the shank n≥Q / q

where Q is the predicted flow rate of the water well or ESP capacity, m ³ / day (m ³ / s); q - portioned (fractional) water flow through the inlets in m ³ / day (m ³ / s) and is determined as follows:

where, U _nk - the rate of ascent of oil droplets in water, taken on average 0.015 m / s; f is the area of the annular space between the shank 16 and the glass 18, m ² ;

D is the inner diameter of the glass;

d is the outer diameter of the shank.

The average diameter of the inlets is determined by the formula for the flow of fluid through the small holes.

where µ is the flow coefficient for a round hole, with a low value of the flow rate is adopted 0.65; ΔH is the pressure difference (pressure) in the hole, under the action of which the outflow occurs.

Calculation example:

The expected flow rate of the water well is Q = 80 m ³ / day = 0,000926 m ³ / s. The inner diameter of the cup D = 73 mm = 0.073 m (pipe 3``), and the outer diameter of the shank d = 48 mm = 0.048 m (pipe 1.5 ''); ΔH is the pressure difference (pressure) in the hole taken 0.01 MPa or 1 m

The fractional flow rate of water entering each inlet through the glass will be:

q = U * π * (0.076 ² -0.048 ² ) / 4 = 0.015 * 3.14 0.003452 / 4 = 0.00004065 m ³ / s = 3.5 m ³ / day.

The number of holes N≥Q / q≥80 / 3,5 = 23 pcs.

The average hole diameter is determined by the formula (2):

The obtained values of n and d are rounded up. The total area of the inlets will be determined if it consists only of holes with a diameter of 4.5 mm.

Σf = n * πd ^{2/4 = 23 * 3.14 *} 4.5 2/4 = 366 mm ²

We distribute the location of the diameters of the holes in size and quantity into three sections:

1st section with a diameter of 5 mm in the amount of 12;

2nd section with a diameter of 4 mm in an amount of 8;

3rd section with a diameter of 3 mm in an amount of 5;

Next, we determine the total equivalent hole area of all sections:

The final number of holes is 25 pieces with a diameter / number distribution in sections: 5/12 + 4/8 + 3/5. The distance between the holes 17 is chosen 1 m, and the height of the glass 18 is taken 0.2 m. Thus, the length of the input device is 27 m.

Installation works as follows.

When the downhole equipment of the installation is lowered into the well, a plug-in jet pump 14 is pre-installed in the lower cylindrical chamber 13 of the switch 12 and fixed with a clamping screw 21. In this case, the suspension interval of the tubing string under the switch 12 is not necessary to lower the larger diameter, the standard diameter of the tubing is sufficient. The design parameters, such as the diameter of the nozzle 18 and the mixing chamber 19, as well as the distance from the nozzle to the mixing chamber are determined by calculation according to the operating mode of the jet pump based on the productivity of the produced (working) fluid and the required pressure of the working and pumped fluids.

During operation of the electric centrifugal pump 2, an upward flow of water with oil droplets coming from the formation in the annular space of the separation chamber 7 formed between the liner 24 and production casing 3 moves along the inlet device and redistributes along the inlet openings 25. The upward flow of liquid in the separation chamber 7 on the path between the glasses 26 dramatically reduces the speed due to the large cross-sectional area of the annular space, creating conditions for gravitational separation of water from the total current. Moreover, each divided portion of the downward flow of water without trapping oil droplets from the upper open part of the cup 26 and then through the inlet holes 25 enters the shank 24. The speed of each individual portion of the downward flow is less than the rate of ascent of the oil droplets in water, and the speed of the main (upward) flow, moving further along the glass 26, is quite high and ensures the removal of oil droplets, bypassing the glasses 26. This is further facilitated by the coincidence of the direction vectors of the ascent of the oil droplets and food zhayuschayasya portion ascending fluid stream. In this case, the velocity of the upward flow as it rises along the inlet device gradually decreases due to portioned water withdrawal in the previous openings, and inside the shank due to the alternating water intake, it gradually increases, therefore the diameter of the inlet openings 25 of the upper last section of the inlet device is correspondingly smaller than the lower sections. This allows you to have the speed of the downward flow of water entering the glasses 26 on the upper section of the inlet device, also lower than the rate of ascent of the oil droplets in the water, which ensures their further ascent. The produced water purified from oil passes through the liner 24 to the intake 5 of the electric centrifugal pump 2, and the oil rises through the gap between the casing 8 and the production casing 3 and then accumulates in the annulus 6 of the well.

During the operation of the installation, the produced water through the tubing string rises to the surface and in the switch 12 enters both the tubing tubing 1 of large diameter along the peripheral channels 17 and the tubing string 9 of smaller diameter through the plug-in jet pump 14. Since the valve (not marked) on the oil line 10 is closed, and the valve 28 on the flow line 27 is open, there is no movement of fluid in the jet pump 14, respectively, the check valve 16 is closed, and all produced water is pumped into the injection wells through the water line. At the same time, the process of oil accumulation in the annulus 6 of the well takes place and over time, the oil-water section falls below the switch 12. When the annulus 6 is filled with enough oil, the valve (not marked) opens on the oil line 10, and the valve 28 closes. water enters the housing of the jet pump 14 and, passing the nozzle 18, enters the mixing chamber 19 with significant kinetic energy, due to which rarefaction is created in the area opposite the radial holes 22 e, leading to the opening of the non-return valve 16. The accumulated oil with a certain pressure from the annulus 6 through the lateral channel 15 enters the radial holes 22, then into the mixing chamber 19 and is carried away by the jet of working fluid into the throat of the diffuser 20. Next, the mixed fluid flow (oil and water) with a certain pressure according to the operating characteristics of the jet pump enters the tubing string 9, and it is pumped into the oil pipeline 10. The duration of operation of the jet pump 14 depends on the amount of oil accumulated in the annulus m borehole space 6, and is determined experimentally by successive sampling fluid samples from an oil line. After the samples of liquid samples in the oil line 10 will consist mainly of water, the installation is switched to the mode of pumping water into the injection wells by opening the valve 28 and closing the valve on the oil line 10. If there is a high-performance and high-pressure electric centrifugal pump 2, it is not necessary to ensure operation jet pump to stop the injection of water, i.e. close the valves 28, because the quantity and pressure of the working fluid are sufficient for the operation of the jet pump while pumping water into the injection wells.

The proposed installation provides the implementation of the separation of oil from water with almost any amount of produced fluid from water wells due to the possibility of using an input device without limiting its rational length. The use of the installation allows preserving the injectivity of injection wells by eliminating oil from the water injected into the reservoir and extracting an additional volume of oil from water wells. The installation also allows it to be economically feasible to use as a donor well (water intake) a wide range of highly watered oil wells according to the degree of water cut of 95% -99%, taking into account their territorial and rational location in the zone of oil deposits, which require maintaining reservoir pressure by cross-pumping water.

Claims (3)

1. Installation for the operation of water wells, including a tubing string with an electric centrifugal pump, lowered into the production string of the well and in the wellhead fittings connected to the water line, a separation chamber located in the lower part of the well bore under an electric centrifugal pump equipped with a sealing casing, a channel for the passage of separated oil, communicating an annulus above the pump with a separation chamber, inlets for the receipt of divided water, distinguishing The fact that the sealing casing of the electric centrifugal pump is made with the possibility of hydraulically communicating the reception of the electric centrifugal pump with an input device located in the separation chamber, consisting of a shank plugged from the lower end divided into sections with inlet openings, while at the level of each inlet the shank is equipped with a glass performing the functions of inlet of separated water into the inlet device and a water trap for oil droplets, the inlets being arranged in one row lengthwise of the shank and formed with decreasing diameter in each successive section in an upward direction, and as a channel for the passage of oil droplets is a gap between the casing string and the production well. 2. Installation for the operation of water wells according to claim 1, characterized in that the tubing string is made of a larger diameter and concentrically placed a tubing string of smaller diameter, the upper part of which in the wellhead is rigidly connected to the oil line, and the lower part is hermetically installed in the upper cylindrical chamber of the switch installed in the column of tubing of larger diameter at a depth below the dynamic level of the liquid in the well, while the switch with is filled with vertical peripheral channels for passing an upward flow of water through it and a lower cylindrical chamber for accommodating an insertion jet pump consisting of a nozzle, a mixing chamber and a diffuser, the outlet of which is in communication with the upper cylindrical chamber, and the working fluid enters the jet pump from an electric centrifugal pump, and pumped fluid - along the side channel of the switch from the annulus of the well through a check valve located on the outside of the switch. 3. Installation for the operation of water wells according to claim 2, characterized in that the housing of the plug-in jet pump on the outside is equipped with sealing cuffs for sealing it in the lower cylindrical chamber of the switch and is fixed with a clamping hollow cylindrical screw, while the housing of the jet pump under the input of the mixing chamber has radial holes, and on the outside - a circular groove.

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