RU2491418C1 - Method to develop multizone oil reservoir - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes downhole pumping of water from an underlying water-bearing bed into an overlying payout bed along an injection well and oil withdrawal from the payout bed via a producing well, which is hydrodynamically connected to the injection well. In accordance with the invention, a device is installed in the interval of the producing bed of the producing well for downhole separation of oil and water with the possibility to lift oil to the surface and discharge of water into the nearest underlying water-bearing bed and/or abandoned oil bed in the cut. Downhole pumping of water in the injection well from the underlying water-bearing bed and/or abandoned oil bed into the producing bed is carried out with the help of a pump, efficiency of which is accepted as not more than the intake of the producing bed, the injection well head is sealed, and the pump is put into operation. As water head reduces at the pump inlet in the injection well below a certain value, the pump is stopped, and the device for downhole separation of oil and water in the producing wall is put in operation. As water head increases at the pump inlet in the injection well above a certain value, the pump is put in operation, and the device for downhole separation of oil and water in the producing wall is stopped. If hydrodynamic connection between producing and injection wells deteriorates, operating equipment is withdrawn, hydraulic rupture of the producing and/or water-bearing beds is done. Afterwards operating equipment is again lowered, and development of the multizone oil reservoir is continued.

EFFECT: increased efficiency of method.

1 dwg

Description

The invention relates to the oil industry and may find application in the development of a multilayer oil reservoir.

A known method of developing an oil or gas (gas condensate) reservoir with the maintenance of reservoir pressure, including producing and injection wells, a pumping station, high pressure water pipe (Reference book on oil production. / Under the editorship of Dr. of Technical Sciences Sh.K. Gimatudinova. - M., Nedra. - 1974. - S.109-118). The reservoir is communicated through production wells with surface oil and gas gathering communications, and through injection wells and high-pressure water pipelines - with a pumping station. Water is supplied to the pumping station either from natural reservoirs, or from specially drilled water wells, or commercial produced water along with the oil is used along with the oil (after it is separated from the oil), and special water treatment is required.

The disadvantages of this method are:

- the need to build a pumping station and high pressure water supply;

- the need for a water source, its preparation, means of supplying water to the pumping station;

- additional energy costs, the cost of maintaining the system associated with the injection into the reservoir of water.

Also known is a method of developing an oil reservoir with maintaining reservoir pressure through the use of natural energy of formation waters (A.P. Opalev, Maintaining reservoir pressure using the natural energy of pressurized water. - M.: Nedra, 1965. - pp. 65-70). The essence of the method is that in one well two layers - water-saturated and oil-saturated - are connected by perforation of the casing in the interval of both layers. As a result of the flow of water from the water-saturated reservoir into the oil-saturated reservoir, an increase in reservoir pressure is provided.

The disadvantage of this method is that from the well in which the inter-reservoir water flow is carried out, the possibility of oil production during the period when the water flow occurs is excluded. In addition, this method does not allow you to adjust the flow rate of bypassed water.

Also known is a method of injecting fluid into a formation (patent RU No. 2211314, IPC 8 E21B 43/20, published on 08.27.2003), including drilling an injection well, opening a productive and aquifer, lowering a pipe string, installing an interstratal packer, injecting fluid into the reservoir. A double pipe string is lowered into the injection well. An additional packer is installed above the exposed formations. The lower end of one of the pipes is installed in the interval of the aquifer. Connect this pipe to the storage tank at the wellhead for water or reagents to increase oil recovery. Equipped with a deep pump for supplying water from an aquifer to a storage tank. The lower end of the other pipe is installed in the interval of the oil reservoir. Connect this pipe to the storage tank. Equipped with a control panel and a discharge pump for pumping water or reagents from the storage tank. Injection into the reservoir is carried out in a constant, or cyclic, or pulsed mode under control from the control panel.

The known method is very metal-intensive, since a double string of pipes is lowered into the well, in addition, for its application it requires the presence of a storage tank at the wellhead, the piping of the well and pumps, which complicates the method, this method also does not allow to separate (separate) the products in the producing well into oil and water, and discharge the separated water into the aquifer, which causes high costs for raising high-water production and its subsequent separation into oil and water on the surface.

The closest in technical essence is the method of developing a multilayer oil reservoir (patent RU No. 23033125, IPC 8 E21B 43/20, published July 20, 2007), including downhole pumping of water from a underlying aquifer into an overlying productive reservoir through injection wells and selection oil from the reservoir through the production wells, while downhole pumping of water is performed on a natural basis due to the energy of the aquifer, in the reservoir in the area of injection wells performing the intra-well other pumping of water, by intensifying the selection through production wells, reduce reservoir pressure, while the selection through production wells is performed in a cyclic mode, providing a change in the direction of fluid flow in the reservoir, for which alternate the intensity of oil extraction from production wells located opposite each other so that one pair of opposing wells works with a maximum production rate, while the other pair of wells during this period works with a 50% production rate of the maximum production rate the flow of time until the dynamic level of oil decreases below the permissible level at its constant selection, then the well regime is changed to the opposite.

The disadvantages of the method are:

- firstly, the limited possibilities of implementing the method, since it is feasible only in natural mode due to the energy of the aquifer, which is very rare in the late stage of development of an oil reservoir, and it must be borne in mind that in the process of developing a multilayer reservoir there is a decrease in energy (reservoir pressure ) aquifer, as a result of which the flow of water into the reservoir stops, which leads to the inability to implement the method;

- secondly, the high cost of raising the watered product and its subsequent separation into oil and water on the surface, since this method does not allow to separate (separate) the product directly in the producing well for oil and water, and to discharge the separated water into the underlying section well formation;

- thirdly, with the deterioration of the hydrodynamic parameters of the reservoirs (decreased injectivity, a drop in reservoir pressure) between the producing and injection wells, the duration of the method is sharply reduced;

- fourthly, the low efficiency of displacing products from the reservoir, since water of a different horizon is used as the displacing agent.

The objective of the invention is to reduce the cost of raising products from a producing well due to downhole separation of products with water discharge into the underlying formation with the possibility of forced flow of water from the aquifer to the reservoir regardless of the energy (reservoir pressure) of the aquifer, as well as increasing the duration of the method for due to the possibility of restoring the hydrodynamic parameters of the layers between the producing and injection wells during the implementation of the method and increasing the efficiency the fact of the displacement of products from the reservoir through the use as a displacing agent of separated water from the same reservoir.

A method for developing a multilayer oil reservoir, including downhole pumping of water from an underlying aquifer into an overlying reservoir by injection well and oil extraction from the reservoir through a production well that is hydrodynamically coupled to the injection well.

New is the fact that in the interval of the productive formation of the producing well, a device is installed for downhole separation of oil and water with the possibility of lifting oil to the surface and discharging water to the nearest underlying aquifer and / or oil-produced formation, and downhole pumping of water in the injection well from the underlying aquifer and / or the produced oil reservoir into the reservoir it is carried out using a pump that ensures the development of the reservoir, the mouth of the injection well is started and the pump is put into operation, while when the pressure of the water at the intake of the pump in the injection well decreases below a certain value, the pump is stopped, and the device for downhole separation of oil and water in the production well is put into operation, when the pressure of the water is exceeded at the pump intake in the injection well above a certain pressure value, the pump is turned on, and the device for downhole separation of oil and water in the producing well is stopped, while the The production equipment is removed from the dynamic connection between the producing and injection wells, hydraulic fracturing of the productive and / or aquifer is performed, after which the production equipment is again lowered and the development of a multilayer oil reservoir is continued.

The figure shows a diagram of the implementation of the method.

On a multilayer oil reservoir, production 1 and injection 2 wells are constructed with the opening of productive 3 and aquifer 4 layers and with corresponding perforation intervals 3 'and 4' in production well 1 and perforation intervals 3 ″ and 4 ″ in injection well 2.

A pipe string 5 is lowered into the production well 1 with a packer 6 and a device for downhole separation of oil and water 7 with the possibility of lifting oil to the surface and water discharge installed above the packer 6. A device for downhole separation of oil and water 7 is placed in the perforation interval 3 'of the productive formation 3 of the production well 1. Packer 6 allows hermetic separation of the annular spaces 8 and 9 in the production well 1.

As a device for downhole separation of oil and water 7 with the ability to raise oil to the surface and discharge water, any known borehole device can be used to divide the production of a producing well into oil and water, for example, a borehole separator (patent RU No. 2291291, IPC 8 E21B 43 / 38, published on January 10, 2007, or a downhole installation for separating oil and water (patent RU No. 2290505, IPC 8 E21B 43/38, published on December 31, 2006).

A device for downhole oil separation 7 is designed to separate structurally drop oil from produced products and provides oil separation from water in the reservoir pressure maintenance system during cross-hole pumping of water, while oil separated from water rises to the surface by an electric centrifugal pump (not shown in Fig.) , and water is discharged into the nearest underlying aquifer and / or reservoir 4 produced by oil (see Fig.).

A pipe string 10 is lowered into the injection well 2, equipped at the lower end with a suction valve 10 ', and above the packer 11, as well as a pump 12 mounted above the packer 11. In addition, the pipe string 10 opposite the perforation interval 3 "of the productive formation of the injection well 2 is equipped with radial holes 13. The packer 11 allows you to tightly separate the annular space 14 and 15 in the injection well 2.

As the pump 12, for example, an electric submersible pump is used, which ensures the development of the productive formation 3. For example, when the injectivity of the formation is 250 m ³ / day. they use an electric submersible pump 12 of the UETSNB5A-250-800 brand with a capacity of 250 m ³ / day. and a pressure of 800 m sufficient to develop a productive formation 3.

At the intake of pump 12, a fluid pressure sensor 16 is installed, connected to a control panel located at the mouth (not shown in FIG.) Of injection well 2 (see FIG.).

Before starting the installation into operation, the mouth of the injection well 2 is sealed. The electric submersible pump 12 is launched into operation. The electric submersible pump 12 begins to pump fluid from the annulus 15 below the packer 11, that is, from the zone of the lower aquifer and / or oil-produced formation 4, through the pipe string 10 through the opening suction valve 11, the fluid pressure sensor 16, through the radial holes 13 pipe string 10 water enters the annular space 15 above the packer 11, from where, at intervals of perforation 3 ″, it is squeezed into the upper producing formation 3 of injection well 2, by which the product is displaced to the perforation intervals and 3 'of the production well 1.

Liquid injection from the lower aquifer and / or oil-produced reservoir 4 of the injection well 2 into the upper reservoir 3 continues until the fluid runs out in the annulus 15 below the packer 11. This occurs if the capacity of the electric submersible pump 12 exceeds the inflow (flow rate) of fluid into the annular space 15 from the lower aquifer and / or oil-produced formation 4 through perforation intervals 4 "into the annular space 14 below the packer 11.

Since the device for downhole separation of oil and water 7 is turned off, that is, there is no discharge of water into the annular space 9 of the producing well 1 and, accordingly, the movement of water from the annular space 9 of the producing well 1 through the perforation intervals 4 'along the lower aquifer and / or produced by oil to the formation 4 and water exit through the perforation intervals 4 ″ into the annulus 15 of the injection well 2, then the liquid level decreases in the annulus 15 and in the pipe string 10. At a certain point nt, when the level drops below a certain value, for example, below 50 meters, the flow of liquid (water) through the fluid pressure sensor 16 stops, which responds to this and gives a signal to the control panel (not shown in Fig.), which turns off the electric submersible pump 12 (see Fig.) and includes a device for downhole separation of oil and water 7.

When you turn off the electric submersible pump 12, the suction valve 10 'closes and eliminates the return of fluid from the upper reservoir 2.

A device for downhole separation of oil and water 7 separates the products of the productive formation 3 into oil and water, while pumping oil to the surface along the pipe string 5 of the producing well 1, and discharges water into the nearest lower aquifer and / or oil produced formation 4, while the electric submersible pump 12 remains off while filling the annular space 15 with liquid from the lower aquifer and / or oil-produced formation 4 into which water (produced water is productive 3), separated in the device for downhole separation of oil and water 7 along the pipe string, will enter the annular space 9 below the packer 6, and from there it will be pushed into the lower aquifer and / or oil-produced formation 4 through the intervals of perforation 4 ′ at intervals of perforation 4 ″ enters the annulus 15, which is filled with water (produced water) from the aquifer and / or reservoir 4 produced from oil.

In the process of filling the annular space 15, the liquid through the suction valve 10 'begins to flow from bottom to top into the pipe string 10. When the liquid level rises before receiving the electric submersible pump 12 and reaches a certain pressure value, for example 500 meters, the pressure sensor 16 sends a signal to turn on the electric submersible pump 12 and turning off the device for downhole separation of oil and water 7. The process is then repeated as described above, i.e. begins the pumping of water by an electric submersible pump 12 from the lower aquifer and / or oil-produced formation 4 into the upper producing formation 3 of the injection well 2.

With a decrease in the injectivity of the productive formation 3 and / or a decrease in the injectivity of the aquifer and / or oil-produced formation 4, production equipment is removed and hydraulic fracturing of the productive and / or aquifer and / or oil-produced formation 4 is carried out in production 1 and injection 2 wells, at appropriate intervals of perforation 3 ′ and 3 ″ in the reservoir 3 and intervals of perforation 4 ′ and 4 ″ of the aquifer and / or oil reservoir 4. Hydraulic fracturing is carried out by any method, for example, by the method of hydraulic fracturing in a well (patent RU No. 2358100, IPC 8 E21B 43/26, published in Bulletin No. 16 of 06/10/2009) or by the method of hydraulic fracturing (RF patent No. 2122633, IPC 8 E21B 43/27, publ. 1998).

After that, production equipment is again lowered into production 1 and injection 2 wells (as shown in figure 2) and the development of a multilayer oil reservoir is continued, as described above.

The proposed method of developing a multilayer oil reservoir allows to reduce the cost of raising the product and its subsequent separation due to the separation of oil and water in the interval of perforation of the reservoir of the producing well in the interval of the reservoir by subsequent lifting of oil to the surface and discharge of water into the nearest lower aquifer and / or produced oil reservoir, and the presence of a pump in the injection well allows you to forcibly pump water from the lower reservoir to the upper reservoir, regardless of energy and (reservoir pressure) of the reservoir

The ability to carry out hydraulic fracturing during the implementation of the method allows to increase the duration of the method due to the possibility of restoring the hydrodynamic parameters of the formations (reservoir pressure, injectivity). In addition, the efficiency of displacing products from the reservoir by 10-15% increases due to the use of separated water from the same reservoir as the displacing agent due to the same mineralization.

Claims (1)

A method for developing an oil reservoir, including downhole pumping of water from an underlying aquifer into an overlying reservoir through an injection well and taking oil from a reservoir through a production well hydrodynamically coupled to an injection well, characterized in that an apparatus for installing a downhole is installed in the interval of a producing reservoir of a producing well separation of oil and water with the possibility of lifting oil to the surface and discharging water into the nearest underlying section the informative reservoir and / or the oil-produced reservoir, and the downhole pumping of water in the injection well from the underlying aquifer and / or the produced oil reservoir into the reservoir is carried out using a pump that ensures the development of the reservoir, seal the mouth of the injection well and put the pump into operation, at the same time, when the pressure of the water at the intake of the pump in the injection well decreases below a certain value, the pump is stopped, and the device for downhole separation of oil and The wells in the production well are put into operation, when the water pressure at the pump inlet in the injection well exceeds a certain pressure value, the pump is put into operation, and the device for downhole separation of oil and water in the production well is stopped, and if the hydrodynamic connection between the production and injection worsens wells extract production equipment, produce a hydraulic fracture of the productive and / or aquifer, and then release production equipment again continue the development of multilayer oil reservoir.

Images