RU2320861C2 - Method for borehole oil production - Google Patents

Abstract

FIELD: oil production with reservoir pressure retention and oil displacement from deposit with water.

SUBSTANCE: method involves using water, which is lifted from producing wells along with oil, for oil displacement; operating oil-producing wells with downhole pumps driven by hydraulic motors, which are activated by water injection from surface, wherein said water is produced from water-bearing reservoirs or from opened water bodies; creating and using separate water-supply low-pressure net; connecting discharge lines of water producing wells and discharge lines of injection wells to the low-pressure net; providing some injection wells with downhole pumps driven by hydraulic drives to provide controllable water injection in reservoir and water removal from reservoir; using said pumps for water taking from water-bearing horizons and for water, oil and gas transportation from oil-producing wells to treatment plant; periodically isolating hole annuity of oil producing wells from oil accumulation net; equipping land-based injection and power pumps, namely pumping stations and locking-and-regulating well devices with remote control system, which controls thereof from central control panel.

EFFECT: improved oil displacement and decreased costs of the method realization, increased efficiency of cyclic reservoir treatment, extended reservoir coverage with displacement processes and reduced produced oil and gas costs.

4 cl, 2 dwg

Description

The invention relates to the field of oil production and can be used for downhole oil production from oil deposits using reservoir pressure maintenance and water displacement from the reservoir.

There is a method of downhole oil production from an oil reservoir (reservoir), which consists in the fact that oil and gas are displaced from the reservoir to the bottom of the producing wells by injecting water into the injection wells, which is raised together with oil and gas from the producing wells, transported to treatment facilities , separated from oil and gas, mixed with water taken from aquifers or open reservoirs, cleaned, treated with chemicals and transported to cluster pumping stations that pump this water into injection wells other [Muravyov I.M. and others. Technique and technology of oil and gas production. - M .: Nedra, 1971, pp. 38-46]. The rise to the surface of oil, gas and water flowing from the oil reservoir to the bottom of production wells is carried out by means of fountain or mechanized methods, including the use of pumps driven by hydraulic motors. As the working fluid of the hydraulic motors, part of the water raised from the producing wells is used, which, in a pre-prepared state, is pumped into the hydraulic motors by power pumps. The working fluid used in hydraulic motors rises to the surface together with oil, gas and water pumped out of the oil reservoir. [Kazak A.S., Rosin I.I., Chicherov L.G. Submersible rodless pumps for oil production. - M .: Nedra, 1973, p. 174].

The water injected into the injection wells gradually occupies an increasing volume of the pore space of the formation rocks, displacing oil and gas from them towards the producing wells. The efficiency of oil production and oil recovery of oil reservoirs are reduced due to their layered heterogeneity in cases where water moves faster through highly permeable layers, reaches the bottom of production wells, causing waterlogging of wells.

One of the known methods of combating water breakthroughs in highly permeable layers is to change the direction of water filtration and alignment of the displacement front by periodically interrupting the process of pumping water into part of the injection wells. Redistribution of injected water flows is relatively slow, the magnitude and reaction rate of the hydraulic system "injection wells - oil reservoir (reservoir) - production wells" depend on the range of regulation of the injected water flow.

The practicable range of injection control in the described method of downhole oil production is in the range from zero to the maximum flow rate determined by the injectivity of the well. For stronger and faster reactions of the system, the specified range must be increased, also ensuring the maximum possible injectivity of the wells. In addition, injection wells require periodic recovery of injectivity, since it decreases over time due to the introduction of impurities in the bottomhole zone along with water that reduce the permeability of the formation rocks. This circumstance also limits the ability to effectively manage oil displacement processes.

Thus, the disadvantage of the above-described method of downhole production is the limited ability to control the process of oil displacement, which in turn leads to an increase in the cost of oil production and reduces oil recovery.

The aim of the present invention is to reduce the cost of oil production and increase oil recovery of oil deposits by creating an effective technology for the displacement of oil from deposits by water.

This goal is achieved by the fact that in the known method of downhole oil production, which consists in displacing oil and gas from a deposit to the bottom of production wells by injecting water into the reservoirs through injection wells, which is raised from the production wells together with oil and gas, transported through oil collecting pipelines to wastewater treatment plants, there they are separated from oil and gas, cleaned of impurities that reduce the permeability of the formation, and transported through low-pressure discharge pipelines to discharge pumps (pump stations), which pump this water into the reservoir, and oil, gas and water flowing into the faces of production wells are raised to the surface by pumps equipped with hydraulic motors that drive the flow of the working fluid pumped by ground power pumps, and water is used as the working fluid, extracted from aquifers or open reservoirs, and to deliver the working fluid to the power pumps, a separate low-pressure water supply network is used, to which are equipped equipped shut-off and regulating they devices flow lines of water (water-producing) wells and flow lines of injection wells.

In order to expand the range of regulation of the flow rate of injected water from positive values (injection into the oil reservoir) to negative (water withdrawal from the oil reservoir), at least part of the injection wells are equipped with pumps driven by hydraulic motors, which are lowered into the well in two rows of pipes equipped with shut-off valves -regulating devices at the wellhead and the packer at the bottom, thereby providing the technical ability to control the flow of water when it is injected into the reservoir and taken from the reservoir, using s coming from the injection pump for injection into the reservoir as a working fluid pumps hydraulic motors; and the injection wells themselves are periodically switched into operation from the injection mode to the water withdrawal mode, while all water received from the injection wells is sent to the low-pressure water supply network.

In order to increase the efficiency of controlling the oil production process, reduce the cost of arranging and operating wells for water extraction from aquifers, as well as for pumping water, oil and gas from oil wells to treatment facilities, pumps are driven by hydraulic motors, and to drive the action of the hydraulic motors of these pumps use water pumped by the same ground-based power pumps that drive the hydraulic motors of the producing wells.

For the purpose of additional impact on the reservoir, contributing to an increase in its oil recovery, the annular space of producing wells is periodically disconnected from the oil gathering network and this connection is restored again when the liquid level in the annulus decreases to a predetermined value.

In order to automate the management of oil production, surface injection and power pumps (pumping stations), as well as shut-off and control devices of wells, are equipped with remote control systems.

Figure 1 presents a diagram of the arrangement of wells and the oil field as a whole, which implements the proposed method for downhole oil production.

Figure 2 presents as an example the scheme of the cluster arrangement of the oil field, which also used the proposed method of downhole oil production.

The above schemes contain the following elements:

1 - treatment facilities;

2 - discharge water conduits of low pressure;

3 - storage tank of water injected into the reservoirs;

4 - discharge pump (pump station);

5 - discharge high-pressure water line;

6 - locking regulating device;

7 - injection well;

8 - a string of pipes of the first row;

9 - packer;

10 - oil reservoir;

11 - pump;

12 - hydraulic motor;

13 - a pipe string of the second row;

14 - oil producing well;

15 - removal of the annulus;

16 - oil gathering pipeline network;

17 - high-pressure power conduit;

18 - power pump (pump station);

19 - water supply well;

20 - water-containing formation;

21 - water supply low pressure network;

22 - storage tank of the water supply network;

23 - pumping unit for pumping oil, gas and water from oil wells to treatment facilities.

Oil production is as follows.

Prepared for injection into oil reservoirs (purified and brought to the required standard in chemical composition), water from treatment plants 1 through low pressure discharge water ducts 2 enters the storage tanks for injection water 3 and is received by injection pumps (pumping stations) 4. Next, by injection pumps high-pressure water conduits 5, equipped with shut-off and regulating devices 6, this water enters injection wells 7, which can be used in two modes: for pumping water into the reservoir and for water withdrawals from the reservoir. During the operation of injection wells in the injection mode, the flow rate of injected water is taken as a positive value, and the reservoir pressure in the injection zone rises to a maximum. When a well is put into a water withdrawal mode, the flow rate of the injected water assumes a negative value, and the reservoir pressure in the injection zone rapidly decreases to a minimum. These fluctuations in reservoir pressure, which can be produced with high amplitude, increase the response of the hydrodynamic system, cause the redistribution of flows, significantly increase the time before water breaks into production wells and increase oil recovery. In addition, during the operation of injection wells in the selection mode, clogging substances are removed from the bottom-hole zone of the formation and restoration of injectivity of the wells.

Injection wells equipped according to the standard scheme (without a downhole pump, as an example, see the well located in Fig. 1 on the left) contain a single-row pipe string 8 equipped with shut-off and control devices 6 and a packer 9 at the bottom. In the injection mode, the shut-off and control device 6 with which this well is connected to the network 21 is closed, and the shut-off and control device 6 with which it is connected to the water conduit 5 is open. When this well operates in the selection mode, the shut-off and control device of the water conduit 5 is closed, and the shut-off and control device of the network 21 is open. Moreover, the selection of water from the well into the network 21 occurs due to gushing and continues until the pressure at the bottom of the injection well is equal to the reservoir pressure in the reservoir.

Injection wells equipped with pumps driven by hydraulic motors (in FIG. 1, the second well on the left) contain a two-row pipe string. The column of pipes of the first row 8 is connected to the hydraulic motor 12 (in the well), and at the top through the shut-off and regulating device 6 it is connected to the discharge high-pressure water conduit 5. The column of pipes of the second row 13 is connected with the bottom of the well and the intake of the pump, and at the top it is connected through the shut-off and regulating a device 6 to a high pressure injection conduit 5. A packer 9 disconnects the bottomhole zone of the wellbore from its main part and protects the casing of the well from high pressure. The annular space of the main part of the trunk below is communicated with the pump 11 and hydraulic motor 12, and above is connected via a shut-off and control device 6 to the water supply low-pressure network 21. Water is injected into the well through a pipe string of the second row 13, while the shut-off-control device 6, which connects the column 13 to the high pressure discharge conduit 5, is open, and the shut-off and control device 6, which connects the pipe string of the first row 8 to the high pressure discharge conduit 5, is closed. The locking and regulating device 6, which connects the annulus of the well with the water supply low pressure network 21, is also closed.

When water is taken from the injection well, the high pressure injection water pipe 5 is cut off by the shut-off and control device 6 from the pipe string of the second row 13 and connected to the pipe string of the first row 8, through which the water flow enters the hydraulic motor 12, driving the pump 11. Pumped out by the pump 11 water from the bottomhole zone of the well enters through the discharge of the pump 11 into the annulus of the well above the packer 9 and, together with the water spent in the hydraulic motor 12, rises to the surface, where it enters through an open shut-off and separating apparatus 6 in low-pressure water-supply network 21.

The oil displaced from reservoir 10, along with associated water and gas, enters the bottom of the producing well 14, from where it is pumped to the surface by pump 11. The hydraulic motor 12, which drives the pump 11, receives energy from the flow of the working fluid entering the hydraulic motor 12 through the pipe string of the first row 8 from the power pump (pump station) 18. The pipe string of the first row 8 is equipped with a shut-off and control device 6, which allows you to control the flow of working fluid injected into the well, including completely cutting it off. The spent working fluid, along with oil, gas and water pumped out of the formation, rises to the surface through a pipe string of the second row 13, enters the oil gathering pipeline network 16 and is transported to treatment plants 1.

In the same oil gathering network 16 through the outlet 15, equipped with a locking-regulating device 6, gas is removed from the annulus, which is separated at the intake of the pump 11 and rises up. If the shut-off and control device is closed, the pop-up gas will push the liquid level in the annulus down. Moreover, due to the difference in the density of gas and liquid, the pressure in the annulus at the wellhead will begin to increase compared to the pressure in the oil gathering network 16.

The opening of the locking and regulating device 6 will cause the gas to flow into the oil network 15 under the influence of a differential pressure, and the pressure at the bottom will decrease for a while. The dynamic level in the well will again occupy the position corresponding to the current production rate of the well. Thus, the periodic cutting off of the annular space of an oil well from the oil network allows creating pressure fluctuations at the bottom and exerting a cyclic effect on the formation, which contributes to an increase in oil recovery.

As the working fluid for driving the hydraulic motor 12, water is used, which is pumped by the power pump 18 from the water supply low pressure network 21. The sources of water entering the water supply low pressure network 21 can be: open reservoirs (not shown in FIG. 1), water-containing formation 20 and injection wells 7 during periods when they are operating in the mode of water withdrawal.

For the selection of water from the water-containing formation 20, water supply wells 19 are used, equipped with a pump 11 driven by a hydraulic motor 12. The energy for driving the hydraulic motor of the water supply wells 19, as well as the hydraulic motor of the producing wells 14, is received from power pumps (pumping stations) 18.

In cases of a large length of the oil gathering network 16, when the treatment facilities are located at a considerable distance from the production wells, it becomes necessary to use linear pumping units 23, which are driven by a hydraulic motor 12, which transmit additional energy to the oil, gas and water transported to the treatment facilities . To drive the hydraulic motor 12 of the pump unit 23 also uses the working fluid from the water supply low pressure network and power pumps (pumping stations) 18.

In comparison with analogues and prototype, the invention provides a number of advantages, including:

1. The periodic switching of injection wells from the injection mode to the water withdrawal mode, as well as the high controllability of the flow rate of injected water to the injection wells and the extraction of oil, gas and water from production wells, significantly increase the efficiency of oil displacement and oil recovery processes.

2. Using as a working fluid hydraulic motors of water taken from injection and water supply wells, reduces the cost of lifting the fluid from the producing wells and reduces the cost of oil production.

3. The use of the same type of pumps driven by hydraulic motors, the same type of ground power and pressure pumps (pumping stations), as well as the same type of shut-off and control devices equipped with remote control and monitoring systems, creates favorable opportunities for highly automated production processes, as well as to increase the reliability of the complex of technological equipment and the efficiency of oil production in general. Operation of the proposed technological system can be carried out with a minimum number of staff, as well as in conditions of difficult access to fishing facilities.

Claims (4)

1. The method of downhole oil production, which consists in displacing oil and gas from the reservoir to the bottom of the producing wells by injecting water into the injection wells, which is raised from the oil production wells together with oil and gas, transported through the oil gathering pipeline network to treatment facilities, there they are separated from oil and gas, cleaned from components that reduce the permeability of the formation rocks, and transported through low pressure discharge pipelines to injection pumps - pumping stations that pump this water into the formation, and oil, gas, and water that bites down the faces of oil wells are raised to the surface by pumps driven by hydraulic motors, which, in turn, are driven by the flow of the working fluid pumped by ground power pumps, characterized in that the water produced is used as the working fluid from aquifers or open reservoirs, and to deliver this water to power pumps create and use a separate water supply low-pressure network, to which flow lines of water producing wells are connected n, as well as flow lines of injection wells that are equipped with shut-off and control devices, and injection wells themselves, at least some of them, are equipped with pumps driven by hydraulic motors, which are lowered into the well on two rows of pipes equipped with shut-off and control devices at the wellhead and a packer at the bottom, providing technical feasibility for both controlled injection of water into the formation, and controlled selection of water from the formation using water from injection pumps for injection into the reservoir, and during oil production, injection wells are periodically switched from the injection mode to the water withdrawal modes, while all water withdrawn from the injection wells is sent to the water supply low pressure network. 2. The method of downhole oil production according to claim 1, characterized in that for the extraction of water from aquifers, as well as for transporting water, oil and gas from oil wells to treatment facilities, use pumps driven by hydraulic motors, and to drive the action of hydraulic motors uses water pumped by the same power pumps - pumping stations that drive the hydraulic motors of oil wells. 3. The method of downhole oil production according to claim 1, characterized in that in the process of oil production flowing into the bottom of an oil well, periodically cut off the annulus of the oil well from the oil gathering network, and when the liquid level in the annulus decreases to a certain point, again restore the annulus communication with the oil recovery network. 4. The method of downhole oil production according to claim 1, characterized in that each surface injection and power pump - pumping station, as well as each locking and regulating device of the wells are equipped with a remote control system from a central console.

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