RU2330936C2 - Method of lifting of fluid from well - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention concerns methods of oil lifting from wells. The method involves installation of a perforated casing pipe and oil well tubing with a reverse valve in the bottom part. The reverse valve is also installed in the casing pipe above the perforation interval with the help of a packer. Well fluid is lifted through the central hole of the oil well tubing by displacing the fluid with natural gas compressed to the necessary pressure and pumped to the hole clearance of the oil well tubing. At that, fluid level in the hole clearance should not fall to the bottom of the oil well tubing.

EFFECT: streamlining of fluid lifting from the well bottom to the surface, reduction of fluid lifting expenses and improvement of environmental situation.

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Description

The invention relates to techniques for lifting oil from wells.

Known methods of lifting oil from wells to the surface, based on the use of piston, electric centrifugal or other devices lowered to the bottom of the well (see Prince K.R. Urazakov, V.V. Andreev, V.P. Zhulaev. Oilfield equipment for cluster wells. - M.: Nedra, 1999; book edited by Sh. K. Gimatudinova. A reference book on oil production. - M.: Nedra, 1974).

The disadvantage of analogues is the presence of rather complex devices in the well, often failing, which necessitates expensive underground repairs, downtime of wells and an increase in the cost of production. The operation of deep-well pumps is significantly deteriorating due to the fact that most wells are drilled in directional direction (cluster drilling), and a large amount of mechanical impurities is removed from the productive formations along with the fluid (see book K.R. Urazakov. wells. - M .: Nedra, 1993).

There is a known gas-lift method for raising oil to the surface, in which tubing with valves installed at different depths is lowered into the well (into the casing). A gas is injected into the annulus (into the annular space between the casing and tubing) by means of compressors, which, getting into the inner cavity of the tubing, is mixed with the liquid being lifted through the inner cavity of the tubing, facilitating the liquid column due to reducing its density, and contributes to the advancement of this liquid to the surface by “pushing” it to the surface by rising gas bubbles (see the book, edited by Sh.K. Gimatudinova. Reference book on oil production. - M .: Nedra, 1974).

Significant disadvantages of the prototype are the bulkiness and complexity of the technical implementation of the surface compressor facilities, high gas consumption (low efficiency), technical and economic inappropriateness of using the compressor method of operating wells with a large percentage of produced water in the produced oil. For these reasons, the compressor method of lifting oil from the bottom of the wells to the surface is replaced by the deep-pump method, which was the case, for example, at OJSC Samotlorneftegaz.

The aim of the present invention is to simplify the method of lifting fluid from the bottom to the surface, simplifying the downhole pumping equipment, improving the environmental situation, reducing the cost of lifting fluid from the wells.

This goal is achieved by the fact that two valves are lowered into the well, one of which is fixed in the casing with the help of a packer above the roof of the oil reservoir, and the other in the lower part of the tubing. The fluid from the well is displaced to the surface through the inner cavity of the tubing pumped into the annulus by the gas produced together with the oil, and the fluid level in the annulus does not drop to the bottom of the tubing (the fluid in the annulus is used as a “fluid piston”).

The drawing shows a schematic diagram of a method of lifting liquid from the bottom to the surface and a schematic diagram of a device for its implementation. In the well equipped with a casing 1, the tubing 2 is lowered with a check valve 3 in the lower part. The non-return valve 4 is installed with the help of a packer 5 above the roof of the productive formation 6 and is designed so that the pressure raised in the annulus when the fluid is displaced to the surface does not affect the formation 6 (so that the liquid located on the bottom is not "crushed" into the formation 6). On the surface are the receiver 7, an electric motor with a compressor 8 and solenoid valves 11-15.

When gas is injected from the receiver 7 into the annulus, the valve 4 will be closed and the liquid from the annulus, opening valve 3, will flow into the internal cavity of the tubing and in the discharge line. The fluid level in the annulus should not fall to valve 3 (it should be 10-20 meters higher), which can be monitored using gauges 9 and 10, i.e. at a lower value of the liquid level in the annulus, gas from the annulus should not pass into the internal cavity of the tubing. Then the pressure in the annulus decreases (for example, using a compressor 8 is pumped into the receiver 7), the valve 3 is closed and the pressure of the column of liquid in the inner cavity of the tubing will not be transmitted to the reservoir 6. At this point, the hydrostatic the pressure of the liquid column in the annulus will be less than the reservoir pressure, valve 4 will open and fluid from the reservoir 6 will flow into the annulus, trying to rise to a static level.

After reaching the dynamic level established by the technological service (or after the established time of fluid accumulation in the annulus), the cycle of fluid displacement from the annulus is repeated.

Simple calculations show the reality of this method of lifting the liquid. On the example of a real well, we take the depth H of the descent of the tubing 1000 meters, the static level H _article 300 meters from the mouth. Assume that the well is filled with formation water with a specific gravity of 1.14 g / cm ³ (in the presence of oil, the pressure values will be less). The hydrostatic pressure of the liquid column of a fully filled tubing will be 114 kg / cm ² . If we assume that the pressure at the wellhead (necessary for “pushing” the fluid to the automated group metering unit or oil recovery park) is 10 kg / cm ² , then the pressure at the bottom of the tubing will be 124 kg / cm ² . The hydrostatic pressure of the liquid column in the annulus at the bottom of the tubing (700 meters from the bottom of the tubing) will be 79.8 kg / cm ² , for 80 kg / cm ² . In this case, when the check valve 4 is closed, at the mouth of the annulus to displace the fluid, it is necessary to create a pressure greater than 120-80 = 44 kg / cm ² . If necessary, by pushing oil to the surface along the inner cavity of the tubing, lower the level in the annulus by 100 meters (i.e., up to 400 meters from the mouth), then the pressure of the injected natural gas must be raised from 44 to 56 kg / cm ² . Accordingly, if it is necessary to lower the liquid level in the annulus by 200 meters from the static (from 300 meters), then the pressure of natural gas in the annulus should be raised to 68 kg / cm ² .

The receiver for implementing the proposed method can be made of steel pipe with a diameter of 1420 mm, used for laying main gas pipelines, the working pressure of which is 75 kg / cm ² .

An increase in the efficiency of the proposed method for raising liquid from wells can be achieved by using this method in several neighboring wells (say, wells A and B of a wellbore) if gas from the annulus of the well in which the fluid displacement cycle is completed (well A) is bypassed in the annular space of the neighboring well B, in which it is necessary to increase the pressure in the annular space for the implementation of the fluid lifting cycle. Solenoid valves have electro-valves 11-15. When gas is injected from the receiver 7 into the annulus of well A, the electrovalves 14, 15 and 12 are open. The remaining electrovalves are closed. After lowering the level in the annulus in well A to the required depth, the solenoid valve 15 closes and when the solenoid valve 14 is open, the solenoid valve 11 opens and pressure from the annulus of well A passes to the annulus of well B. After the pressure equality in the annulus of wells A and B is reached, the solenoid 14 closes, and the solenoid valve 15 opens. A further increase in pressure in the annulus of well B to the desired value is achieved by supplying gas from the receiver 7. A further decrease in pressure in the annulus of well A is achieved by connecting the annulus of well A to the suction line of compressor 8, for which the solenoid 13 opens and the solenoid 12 closes .

Thus, it is possible to connect to the receiver all the wells of one cluster by installing an additional required number of solenoid valves.

The equipment of the entire well cluster is controlled by a control station installed on the surface in a convenient location.

Thus, it is possible to lift fluid from all the wells in the cluster, having one receiver of the required volume, one electric motor with a compressor, and high-pressure connecting hoses. To increase the reliability of the well cluster, it is advisable to have a receiver and an electric motor with a compressor as backup.

The productivity of each well in the cluster can be regulated independently of the rest by the magnitude of the range of pressure changes in the annulus.

Claims (1)

The method of lifting fluid from wells equipped with a perforated casing string and tubing with a check valve in the lower part, characterized in that the check valve is also installed in the casing above the perforation interval using a packer, and the fluid from the wells is lifted by displacement through the internal the cavity of the tubing by periodic injection into their annulus of compressed natural gas to the required pressure, and the liquid level in the annulus is not lower t to the bottom of the tubing.