RU2713820C1 - Oil and water inflow selector in horizontal wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry and can be used on new horizontal wells and on reconstructed wells by cutting off lateral shaft with horizontal end. Oil and water inflow selector comprises a cylindrical housing with a row of through filtration orifices, a thick-wall bushing with an eccentric through passage channel. Sleeve comprises at least one radial cylindrical chamber with lockable circulation hole for shut-off ball. Ball is made with density lower than density of water, but higher than oil density.

EFFECT: prevention of penetration of underlying formation water into well cavity.

1 cl, 3 dwg

Description

The invention relates to the oil industry and may find application in new horizontal wells and in reconstructed wells by means of sidetracking with a horizontal end.

The main objective of the invention is to introduce a technology that reduces the cost of production of each ton of oil due to energy saving and reduce capital costs for field infrastructure and equipment. The result is supposed to be achieved by eliminating the penetration of underlying formation water into the well cavity. Thus, only anhydrous oil is expected to be raised to the surface.

The main node in this technology is the selector of fluid flow into the cavity of a horizontal well, which allows only oil to pass through but automatically closes when water is drawn up.

Placing several such selectors in the horizontal part of the trunk in different parts of the liner string, separated by annular swell packers, will allow the well to be operated only from those areas where there is no water in the inflow. In the same areas where the wellbore will be below the oil-water contact (WOC), or, after some time, it will be lower than the WOC, and also in the areas against which cones of water breakthrough will form, the selectors will block the flow. Moreover, in the second case, when the "water cone" dissolves under the action of gravity, the selector can again automatically open to the influx of clean oil in this area (see Fig. 1 and Fig. 2)

Known devices for regulating and controlling the flow of fluid in horizontal wells. They work on the principle of the difference in viscosities and densities of water and oil. Consequently, in these environments there will be different values of hydraulic resistance during the movement of liquids, as well as flow rates.

For example, the AICV automatic well valve device of the InflowControlAS company is known. The principle of its operation is based on the difference in the viscosity of water and oil. When oil approaches the valve, it opens. When water begins to approach the well, it closes due to its lower viscosity. The device is self-regulating; communication with the surface by special control equipment is not required. (Antonenko D.A. et al., Oil industry. 2007 No. 11, pp. 84-87). The disadvantage of this device is the complexity of the settings and the lack of reliability of proper operation. In addition, the device can only limit the flow of water.

A device for controlling the flow of formation fluid during the operation of a horizontal well is known (patent RU 166287 U1). His work is based on the principle of the spool, i.e. regulation (closing, opening) depending on flow rates. (published on November 20, 2016). The disadvantage of this device is the small size of the spring piston mechanism, the possible hit and the influence of small particles on the reliability of proper operation. The device can only limit the flow of water.

Closest to the invention in terms of technical nature, the result achieved is the Halliburton OilSelector ™ inflow control system, which the author selected as the prototype. The selector uses the principle of neutral buoyancy of balls in water. Balls are placed in the annular space. During the flow of pure oil to the selector, the balls float freely. As soon as the water is pulled, the balls overlap the circulation holes made around the circumference of the selector housing. The fluid influx thus does not enter the well cavity. (easywell@halliburton.com). The disadvantage of this device is the limited amount of annular space due to small gaps. For example, even with a slight eccentricity of the body relative to the walls of the wellbore, some of the holes cannot be blocked by floating balls. The diameters of the balls are also limited in size. The possibility of their loss in the trunk, or their concentration in a pile, is not ruled out.

The task is achieved by the fact that the developed oil and water selector in horizontal wells (NVGS selector) will reliably automatically control the inflow from the annulus into the cavity of the well, freely letting oil through and shutting down immediately when pulling formation water.

The presented intake manifold selector NVGS (Fig. 3) is made in the form of a pipe, which is included in the composition of the shank 1. It consists of a housing 2 with many through filtration holes 3 of small cross-section. A thick-walled sleeve 4 is placed inside the housing, having an outer diameter at the ends corresponding to the inner diameter of the housing 2. The axial line of the main circulation channel 5 of the sleeve 4 does not coincide with the axial line of the sleeve itself so that the smallest wall thickness of the sleeve is at least 2 mm. And the largest wall thickness (opposite the smallest) would be at least 30 mm. The diameter of the passage channel 5 of the sleeve 4 is performed at least 40 mm, for the possibility of passing through the selector, during repair work on the well, a flexible tubing. In the thickened part of the sleeve 4, radial cylindrical chambers 6 (at least one) are placed, under the locking balls 7 with a neutral bulk density, in magnitude lower than the density of water, but higher than the density of oil (≈0.9 ÷ 0.95 g / cm3 ) The dimensions of the balls 7 correspond to free movement in the chamber 6, with the possibility of locking their circulation holes 8 with balls 7. The sleeve 4 in its central part has a reduced outer diameter for the formation of a flow cavity 9. At the ends of the sleeve, radial and mechanical seals 10 are made, including including, plain bearing function.

The principle of operation of the selector is as follows. After drilling a horizontal wellbore, a non-cemented liner 1 is assembled. The liner selector (at least one) is included in the liner layout. After lowering the shank 1 to the design depth, i.e. after the selector hits the horizontal part of the barrel, the selector sleeve 4 automatically, according to the law of gravity, as a “vanka-vstanka”, will certainly and finally take the position of the thickened part down, and the circulation holes 8, respectively, from above. Moreover, as long as the environment in the chambers 6 of the sleeve 4 is water, the balls 7 will clog the holes 8 in the chambers 6. Gradually and inevitably, the oil from the reservoir (while the oil-and-gas complex is below the selector level) will be pulled under the balls and flow around them , and enter the well. Then, in the calculated mode of gentle depression, a continuous flow of anhydrous oil into the well is organized. And, subsequently, when water again appears in the fluid inflow, the selector will automatically close, disconnecting this section of the wellbore from production.

A brief description of the drawings.

In FIG. Figure 1 shows a section of the horizontal part of a well cased by a non-cemented liner made of continuous casing pipes, in which (up to several tens) oil and gas inflow selectors are mounted at certain intervals, for example, every two liner casing pipes, at their junction. At the same time, in another joint of the casing pipes, a swellable casing packer (pipe) is mounted. The shank is equipped with a shoe and suspension of the shank with a packer. It is impossible to maintain a wellbore while drilling for objective reasons, it is impossible to maintain perfectly even and horizontal, nevertheless, they try to place it below the top of the productive formation, but above the estimated VOC line.

In FIG. 2 shows a section through the horizontal part of the well shown in FIG. 1, during the operation of the well, taking into account the development of reserves, and a corresponding decrease in the level of oil and gas, and the possible formation of cones of breakthrough of water inflows is shown. In FIG. 3 shows the inflow selector of the NVHS. It is performed in the form of a branch pipe with a diameter (90 ÷ 150 mm), length from 0.5 to 2 meters. The selector consists of a housing 2 with many through filtration holes 3 of small cross-section. A thick-walled sleeve 4 is placed inside the housing, having an outer diameter at the ends corresponding to the internal diameter of the housing 2. The axial line of the main circulation channel 5 of the sleeve 4 does not coincide with the axial line of the sleeve itself so that the smallest thickness of the sleeve wall is at least 2 mm. And the largest wall thickness (opposite the smallest) would be at least 30 mm. The diameter of the passage channel 5 of the sleeve 4 is performed at least 40 mm, for the possibility of passing through the selector, during repair work on the well, a flexible tubing. In the thickened part of the sleeve 4, radial cylindrical chambers 6 (at least one) are placed, under the locking balls 7 with a neutral bulk density, in magnitude lower than the density of water, but higher than the density of oil (≈0.9 ÷ 0.95 g / cm3 ) The dimensions of the balls 7 correspond to free movement in the chamber 6, with the possibility of locking their circulation holes 8 with balls 7. The sleeve 4 in its central part has a reduced outer diameter for the formation of a flow cavity 9. At the ends of the sleeve 4 are placed radial and mechanical seals 10, performing including plain bearing function.

Claims (1)

A selector of oil and water inflow in horizontal wells, included in the liner string, characterized in that there are a number of through-hole filter holes in its cylindrical body, and a thick-walled sleeve with an axially eccentric passage channel is placed in the inner cavity of the shaft, and in the thickened part of the sleeve, at least one radial cylindrical chamber with a lockable circulation hole for the locking ball with a density of magnitude lower than the density of water, but greater than the density of oil, which will be emeschatsya only vertically in the chamber under the action of gravitational forces.

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