RU2314412C1 - Method and device for oil well treatment - Google Patents

Abstract

FIELD: equipment for liquid inhibitor injection into annulus of oil well cluster with the use of pumping plant to prevent salt or paraffin deposit development or corrosion damage.

SUBSTANCE: method involves linking injection line of well treatment device to annulus of well; supplying inhibitor under pressure with the use of plunger pump from vessel into annulus via injection pipeline connected with plunger pump outlet; controlling inhibitor flow rate. Device is mounted on cross-country vehicle, which moves between wells of one or several oil field well cluster for serial treatment thereof. During each well treatment pressure in annulus is previously reduced and threshold pressure level is set in signaling manometer installed in injection line. Two or more inhibitor types are serially supplied along with provision of predetermined amount of each inhibitor delivery in reaction zone through produced liquid under gravity. Injection line pressure is controlled. After termination of each inhibitor type supply injection line is cleaned with flushing liquid. Oil well treatment device comprises plunger pump, which may perform metered inhibitor supply in well annulus from vessel communicated with plunger pump inlet through sucking line, injection line connected to plunger pump outlet and provided with check valve, as well as inhibitor flow rate control means. Device also has at least one additional vessel connected with plunger pump inlet through suction line, vessel with flushing liquid and signaling manometer.

EFFECT: increased number of wells to be treated in unit time, possibility of necessary amount of inhibitor to be injected, prevention of inhibitor forcing in reservoir, possibility to supply several inhibitor types in single operation and decreased inhibitor consumption.

4 cl, 2 dwg

Description

The method and device according to the proposed group of inventions relate to a technique intended for supplying liquid inhibitors by means of a pump unit to the annular space of an oil well cluster to prevent scaling, paraffin deposition and corrosion.

An oil well cluster is understood to mean a special site of artificial origin, a section of the field’s territory with wellheads located on it remote from each other at a distance of at least five meters, or single wells remote from each other at a distance of at least 50 m. The number of wells in the cluster determined by the field development project.

The method and device according to the proposed group of inventions can be used in oil production using electric centrifugal pump installations, sucker rod pumps, other methods with the presence of circulation between the tubing and the annulus of an oil well, and the oil well should not gush through the annulus.

The following methods and devices are known for supplying reagents to a well by means of metering units.

From the patent of the Russian Federation No. 2167272 (IPC ЕВВ 37/06, published January 27, 2001), a method for feeding an inhibitor into a well is known. The method includes connecting the injection line of the device for treating wells to the annulus of the well, supplying under pressure with a pump a predetermined amount of inhibitor into the annulus of the well. The known method allows the processing of pipes with a corrosion inhibitor.

However, this method does not provide the ability to treat wells with several inhibitors of various types and purposes, in particular corrosion inhibitors, scale inhibitors, paraffin inhibitors and antihydrate inhibitors, and this method does not allow the supply of various inhibitors to pipeline sections and other oil equipment.

A known method for the preparation and supply of a water-soluble corrosion inhibitor reagent (RF patent No. 2172389, IPC ЕВВ 37/06, published on 08/20/2001).

The method includes loading the reagent into the container and dosing it into the annulus of the well.

This method also does not allow sequential treatment of the well by inhibitors for various purposes in one operation of connecting to the annulus.

Known wellhead block supply of a chemical reagent according to the patent of the Russian Federation No. 42059, IPC ЕВВ 43/00, ЕВВ 37/06, which was published on November 20, 2004. The device includes a metering pump connected to the tank, as well as a pressure gauge and means for controlling the flow of the inhibitor, made in the form of a level sensor.

This device does not allow the supply of several inhibitors to the well in a single operation. In addition, it does not provide for a piping flushing system. This device is stationary.

Known dosage installation according to the patent of Russian Federation No. 2238393, IPC ЕВВ 37/06, which was published on January 20, 2004.

The dosing unit contains a container for the inhibitor, a metering pump connected to it via a pipeline, an additional container for the inhibitor, means for controlling the flow of the inhibitor, made in the form of a level sensor. An electric contact pressure gauge and a non-return valve are installed on the pipeline connecting the inhibitor tank and the metering pump.

The known installation does not allow you to track the pressure level of the inhibitor. When used, the inhibitor moves in the annulus under high pressure. As a result, the inhibitor can be crushed into the reservoir, which leads to clogging of the perforation zone and to spontaneous killing of the oil well, that is, the cessation of its flowing.

The closest analogue of the claimed method is a method of processing oil wells, disclosed in US patent US No. 4375833 (published on 03/08/1983, IPC ЕВВ 43/12). The method includes connecting the injection line of the device for processing the wells to the annulus of the well, supplying the inhibitor from the reservoir under pressure using the plunger pump through the injection line connected to the outlet of the plunger pump into the annulus of the well, controlling the flow of the inhibitor.

The method provides the ability to automatically close the discharge line and open the discharge valve with recirculation of the inhibitor using the pump back along the recirculation lines to the capacity of the inhibitor.

The disadvantage of this analogue is the impossibility of sequential treatment of the well by inhibitors of various types in one technological operation, as well as the inability to service the entire cluster of oil wells using one device.

The closest analogue of the claimed device is a device for processing wells, described in the aforementioned US patent No. 4375833. A device for treating oil wells contains a plunger pump configured to dose the inhibitor into the annulus of the well from a reservoir that is connected to the inlet of the plunger pump through the suction line of the inhibitor, a discharge line connected to the outlet of the plunger pump and equipped with a check valve, and flow control means inhibitor.

The known device also does not allow the processing of the well by several inhibitors in one technological operation.

In addition, the known device does not contain means for moving it to process several wells, and also does not contain means to prevent crushing of the inhibitor into the formation when it is fed into the annulus.

The technical result of the claimed group of inventions is:

1) Ensuring the possibility of servicing many clusters of treated wells using one device and, as a result, an increase in the number of processed wells per unit time;

2) providing the ability to supply a given number of inhibitors;

3) prevention of crushing of the inhibitor into the reservoir;

4) providing the possibility of supplying, during one operation, connecting several types of inhibitors to the annulus of the well, which makes it possible to process not only the surface of the tubing of the well, but also pumping equipment in one technological operation while reducing the time required to connect to the annulus. This makes it possible to increase the resource of oilfield equipment and ultimately reduce the cost of produced oil;

5) reduction of inhibitor costs due to accurate subsidizing of the inhibitor in accordance with the oil production rate of each particular well and its operating parameters taken separately.

The specified technical result is achieved by implementing a method for treating oil wells, which includes connecting the injection line of the device for processing wells to the annulus of the well, pressurizing the inhibitor from the tank through the injection line, connected to the outlet of the plunger pump, to the annulus of the well using a plunger pump inhibitor flow control.

According to the present invention, a device for processing wells mounted on a cross-country vehicle is moved between the wells of the bushes of one or more fields for their sequential processing, moreover, when processing each well, the pressure in the annulus is previously reduced and the pressure level is set on the signaling pressure gauge mounted on discharge lines, sequentially supply two or more types of inhibitors with the possibility of delivering a predetermined amount of each inhibitor to the reaction zone through the produced fluid under its own weight, while monitoring the pressure on the discharge line, after the supply of each type of inhibitor is completed, the discharge line is washed with washing liquid.

To increase the efficiency of using a patented device, referred to in the technical documentation of MBRH (mobile reagent unit), with the sequential supply of two or more types of inhibitors into the well during one operation, the inhibitor with a higher density is fed first.

The dosage of the inhibitor is calculated based on the working concentration of the inhibitor used, the flow rate of water in the produced fluid and the period between treatments according to the formula:

where D is the dosage of the inhibitor, l / day;

Q - flow rate of water in the produced fluid;

C is the working concentration of the inhibitor, g / t;

T is the period between treatments, days;

ρ is the density of the inhibitor, kg / l.

The specified technical result is also achieved when using a device for processing oil wells, containing a plunger pump, configured to dose the inhibitor into the annulus of the well from the reservoir, which is connected to the inlet of the plunger pump through the suction line, a discharge line connected to the outlet of the plunger pump and equipped check valve, a means of controlling the flow of inhibitor.

According to the present invention, the device is mounted on a cross-country vehicle configured to move bushes between one or more fields between wells and their sequential processing, while the device is equipped with at least one additional tank connected along the suction line to the inlet of the plunger pump, a tank with a flushing liquid, as well as a signaling pressure gauge mounted on the discharge line, and is configured to sequentially supply two and more types of inhibitors in the annulus, with the possibility of delivering a given amount of each inhibitor to the reaction zone through the produced fluid under its own weight.

The invention is further illustrated by a specific implementation example and the accompanying drawings, which depict the following.

Figure 1 shows a General view of a device for processing oil wells.

Figure 2 shows the hydraulic circuit of a device for processing oil wells.

Figure 1 shows an embodiment of a device for processing oil wells, in which all the blocks of the device are installed in the van of the vehicle, made with the possibility of transporting the said blocks from one well of a cluster of oil wells to another.

In this embodiment, the device consists of a vehicle (1), a plunger pump (2) installed in a vehicle van on a frame (7), a power station (3), which is a source of electricity for the plunger pump motor (2). The power station (3) is installed in the vehicle van (1) on the frame (8). The control cabinet (9) is installed in the vehicle van (1) and is designed to control the plunger pump (2). A signaling pressure gauge (12) is installed in the discharge line (6) and serves to turn off the plunger pump (2) at an overpressure of the inhibitor or at a minimum pressure, as well as in the event of a pressure drop when the discharge line ruptures. Two containers (4) are fixed on the floor of the vehicle van (1), which contain inhibitors of various purposes, for example, a corrosion inhibitor and a scale inhibitor. In the van of the vehicle (1), a tank with washing liquid (5) is also installed and fixed.

Figure 2 shows a schematic hydraulic diagram of a device for processing oil wells.

Two tanks for the inhibitor (4) and a tank for flushing fluid (5) are connected through ball valves along the suction line (16) to the inlet of the plunger pump (2). The output of the plunger pump (2) is connected via the discharge line (15) through a ball valve and a check valve (10) with a high pressure sleeve (11) for connection to the annular space of an oil well (not shown in the drawing). Between the plunger pump (2) and the check valve (10) on the discharge line (15), a signaling pressure gauge (12) is installed. Also, the outlet of the plunger pump (2) through ball valves through recirculation lines (17) is connected to tanks for inhibitors (4) and a tank for flushing fluid (5).

The means for controlling the expenditure of inhibitors are made in the form of flow meters (18) on tanks (4) and level meters (19).

The operation of the device for processing oil wells and the implementation of the patented method of processing oil wells is as follows.

Before starting work, it is necessary to install a vehicle (1) with a device for processing oil wells on a horizontal surface and provide cooling for the power plant (3). During operation of the device, the pressure in the annulus of the well should not exceed 40 atm. To check the tightness, it is necessary to pressure test the discharge line (with the annular valve closed) by filling it with flushing liquid under pressure, the value of which is one and a half times the value of the supply pressure of the inhibitor.

After checking the tightness, it is necessary to set the maximum pressure level on the signaling pressure gauge (12) installed on the discharge line (15), and connect the installation for processing oil wells to the annulus using a high-pressure hose (11). Next, determine the presence of circulation between the tube and annulus. After that, when the annular valve is closed, the ball valve K1 is opened and the calculated amount of the inhibitor having a high density is fed into the annulus. In the present embodiment, the inhibitor is a scale inhibitor.

Scale inhibitor is supplied from the corresponding tank (4) to the metering plunger pump (2) through the suction line channel (15) connecting this tank (4) to the inlet of the plunger pump (2) by suction of the inhibitor by moving the pump plunger (2).

The plunger pump (2) delivers the inhibitor through the discharge line (15), which ends with a check valve (10) connected to the high pressure sleeve (11). The non-return valve (10) prevents the reverse movement of the inhibitor in the absence of pressure in the pipeline created by the metering plunger pump (2).

From the injection line (15), the inhibitor through the high pressure sleeve (11) is fed into the annulus of the well. In this case, the ball valves K4, K5, K6 of the recirculation lines (17) must be closed.

The experiments showed that the pressure on the discharge line should be in the range of 15 to 20 atm, preferably 16 atm. Using a signaling pressure gauge (12), the inhibitor supply pressure is monitored. If the pressure of the inhibitor is exceeded, as evidenced by the pressure gauge signal (12), the discharge line (15) connecting the outlet of the plunger pump (2) and the annulus of the treated oil well is turned off by stopping the plunger pump (2). When the inhibitor pressure decreases (for example, when the discharge line is cut off), the discharge line (15) is also turned off by stopping the plunger pump (2). The flow rate of the injected scale inhibitor is controlled using a level gauge (19) and a flow meter (18).

After pumping the required (estimated) amount of scaling inhibitor into the treated oil well, the plunger pump is turned off (2).

Then switch the plunger pump (2) to the tank (5) with flushing fluid. The metering plunger pump (2) is turned on and the entire inhibitor supply line is flushed with washing liquid in a volume twice as large as the volume of the discharge lines. Next, turn off the metering plunger pump and open the recirculation line (ball valves K4, K5, K6) connecting the outlet of the plunger pump (2) and containers with inhibitors (4) and flushing fluid (5).

After washing the discharge line, another type of inhibitor is supplied — a corrosion inhibitor, etc., by repeating all of the above operations.

In other embodiments of the method and device, additional containers may be installed on the vehicle to supply other types of reagents.

After the sequential supply of inhibitors, the pressure in the discharge line (15) is reduced to the pressure in the vessels (4). The pressure drop is monitored using a pressure gauge (12). After the pressure has decreased, the injection line (15) is disconnected from the annulus of the well.

Then the vehicle moves under its own power with a device for processing wells fixed to it to the next oil well of the bush. And carry out the processing of the next oil well bush by repeating all of the above operations.

The processing time for one well is about 10-15 minutes, depending on the amount of inhibitor injected and the performance of the metering plunger pump (2).

The mobility of the patented device allows for a large number of operations per shift. The device can be moved between the wells of the bushes in the field, and depending on the remoteness of the fields, it is possible to work at several fields. High maneuverability of the vehicle allows you to work on fields with non-solid road surface.

Due to its mobility, the patented installation has the ability to process up to 25 points significantly remote from each other during one work shift. For example, in the oil field where the work is carried out, the wells are separated from each other by a distance of 2 to 40 km. Processing is carried out by impact dosage.

When using stationary installations on one well by constant dosing of the inhibitor for a month, 100 kg of one type of inhibitor is supplied. A patented device by shock dosing 4 times a month, that is, once a week, allows the injection of 25 kg of each type of inhibitor at a time. Thus, it is possible to process a large number of wells using one mobile device.

The inhibitor is prevented from being crushed into the reservoir by providing the ability to deliver a given amount of each inhibitor to the reaction zone through the produced fluid under its own weight, which is expressed in the movement of portions of inhibitors in the produced fluid solely under the influence of gravity without additional acceleration. This mode of movement is ensured through the use of a plunger pump, with the help of which a predetermined amount of inhibitor is fed into the annulus. In this case, portions of inhibitors from the injection line, the pressure of which is maintained within a given range of values and is controlled by a signaling pressure gauge, entering the annulus, flow freely in the direction of the perforation zone. With such a supply system, the inhibitor is injected into the annulus, and then by gravity flows through a column of liquid into the pump intake area, which avoids crushing the inhibitors into the reservoir.

The prevention of crushing of the inhibitor in the perforation zone is also due to the fact that the inhibitor is not supplied to the tubing, but into the annulus of the well, while the well continues to work. In this case, the inhibitor flows down the annulus and enters an ESP (electric centrifugal pump) due to the circulation between the tubing and the annulus of the oil well.

When a corrosion inhibitor is mixed with the aqueous phase of the produced fluid, the surfactants of the inhibitor are mixed, which subsequently create a protective film on the surface of the tubing.

After the scaling inhibitor arrives at the electric centrifugal pump, the inhibitor, getting into the aqueous phase, dissolves and prevents the formation of salt ions, which ultimately prevents the formation of salts on the working elements of the ESP and ensures long-term trouble-free operation of the pumps.

Thus, it is possible to supply several types of inhibitors during one operation of connecting to the annulus of the well, which makes it possible to process not only the surface of the well pipes and protect it from corrosion in one technological operation, but also to protect pumping equipment while reducing the time required to connect to annulus. This makes it possible to increase the resource of oilfield equipment and ultimately reduce the cost of oil produced.

The ability to flush the injection line after the supply of each type of inhibitor is completed allows the use of different types of inhibitors.

The dosage of the inhibitor (in liters) is calculated based on the working concentration of the inhibitor used, the flow rate of oil, liquid or water and the period between treatments. Thus, the supply of the inhibitor is carried out taking into account the actual flow rate of each well so as to ensure the required dosage level of the inhibitor for any type of well.

The ability to sequentially supply two or more types of inhibitors with the possibility of supplying a predetermined amount of each inhibitor to the annulus of one well allows you to protect downhole equipment from corrosion, from salt formation, to protect the well stock from paraffin-gum formation.

The low cost of operating the patented device for treating wells, also referred to as MBRH (mobile reagent unit) or UDRM (mobile reagent dosing unit) in technological documentation, makes it an indispensable and popular tool in the oil and gas industry.

Claims (4)

1. A method of treating oil wells, including connecting the injection line of the device for processing wells to the annulus of the well, supplying pressure of the inhibitor using the plunger pump from the reservoir through the injection line connected to the outlet of the plunger pump, into the annulus of the well, controlling the flow of the inhibitor, characterized in that the device for processing wells mounted on a high-cross-country vehicle is moved between wells of bushes of one or more x deposits for their sequential treatment, and during the treatment of each well, the pressure in the annulus is preliminarily reduced and the pressure level is set on a signaling pressure gauge installed on the injection line, two or more types of inhibitors are sequentially supplied to ensure that a given amount of each inhibitor can be delivered to the zone reaction through the produced fluid under the action of its own weight, while monitoring the pressure on discharge lines, after the supply of each type of inhibitor is completed, the discharge line is washed with washing liquid. 2. The method according to claim 1, characterized in that when sequentially feeding two or more types of inhibitors into the well during one operation, the inhibitor with a higher density is first fed. 3. The method according to claim 1, characterized in that the dosage of the inhibitor is calculated based on the working concentration of the inhibitor used, the flow rate of water in the produced fluid and the period between treatments according to the formula

where D is the dosage of the inhibitor, l / day; Q - flow rate of water in the produced fluid; C is the working concentration of the inhibitor, g / ton; T is the period between treatments, days; ρ is the density of the inhibitor, kg / l. 4. A device for treating oil wells, comprising a plunger pump configured to dose the inhibitor into the annulus of the well from a reservoir that is connected to the inlet of the plunger pump through an intake line, an injection line connected to the outlet of the plunger pump and equipped with a check valve inhibitor consumption, characterized in that it is installed on a high-cross-country vehicle, made with the possibility of moving between the wells of bushes of one or several fields and their sequential processing, while the device is equipped with at least one additional tank connected along the suction line to the inlet of the plunger pump, a tank with flushing fluid, as well as a signaling pressure gauge installed on the discharge line, and is configured to supply two and more types of inhibitors in the annulus with the possibility of delivering a given amount of each inhibitor to the reaction zone through the produced fluid under the action of m of its own weight.

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