RU2794020C1 - Sleeve cementing packer - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to devices for separating layers in a well, mainly for cementing casing strings under conditions of low hydraulic fracturing gradients and in presence of zones prone to absorption in the well, as well as to prevent oil and gas shows and interlayer crossflows. The sleeve cementing packer includes a housing lowered into the well on the casing string and fixed on it by locking elements, consisting of a sealing collar with upper and lower parts. The lower part of the sealing collar is made conical, while at least six holes are made in it, evenly spaced around the circumference of the sealing collar, equipped with throttles fixed in the collar with fasteners, with the possibility of opening the throttles with an upward flow of the casing fluid and closing when the casing fluid moves in the reverse direction. The upper part of the sealing collar is made with a straight end in form of a funnel on the inside and with an outer diameter equal to the diameter of the wellbore.

EFFECT: use of the proposed sleeve cementing packer makes it possible to reliably seal the head of the liner after its cementing, to ensure its use on the head of the liner with a release device for rotation, which has circulation holes that open at a certain pressure.

2 cl, 1 dwg

Description

The invention relates to the oil and gas industry, namely to devices for separating layers in a well, mainly for cementing casing strings under conditions of low hydraulic fracturing gradients and the presence of zones prone to absorption in the well, as well as to prevent oil and gas shows and interlayer crossflows.

The use of known collar devices, including those reinforced with steel plates, is impossible due to the additional pressure required to overcome the collapse of the packer collars when the fluid moves upwards, since there is a risk of premature opening of the circulation windows and an emergency situation, leaving cement inside the liner.

A device for sleeve cementing is known (patent RU No. 51393, IPC E21V 33/13, 33/12, publ. 10.02.2006, bull. No. 4), containing a sealing cuff placed in a cone-shaped stop with rigidly made petals, and locking elements with in order to turbulize the flow, the stop petals are made obliquely relative to the central axis of the stop, and the sealing collar is installed freely in the stop with the possibility of axial upward movement during cementing, and the stop with the petals is cast, and the device is also equipped with a restrictive ring from axial movement of the sealing collar upwards.

The disadvantages of this device are:

- weak fixation of the cuff in the stop due to its free location;

- small area of contact of the sealing cuff to the rock.

Also known is a device for separating layers in a well (patent RU No. 2164288, IPC E21B 33/13, 33/12, publ. equipped with partitions, on which scrapers are placed for erasing the clay cake from the walls of the well and obtaining turbulent movement of the cement slurry.

The disadvantage of the known device is a loose fit to the walls of the wellbore, which can cause mixing of drilling and cement slurries due to leakage of the solution and reduce the strength of the cement lining and the quality of its cementing, reducing the overall reliability of the isolation of the layers.

Closest to the proposed one is a sleeve reservoir disconnector (patent RU No. 2607485, IPC E21V 33/12, publ. 10.01.2017, bull. No. 1), including a housing in the form of a casing string centralizer, the upper cylindrical part of which is elongated with an internal annular groove , in which the tail part of the cuff is installed and fixed by locking elements, made in the form of a cylinder, while the gap between the upper and lower parts of the cuff is made corrugated in the longitudinal direction with a conditional outer diameter less than the diameter of the wellbore, and in the working position its diameter is greater than or equal to the borehole diameter.

The disadvantages of this device are:

- the presence of corrugated cuffs does not fully guarantee the expansion of the cuff in working condition;

- the lower part in the form of a rigid centralizer makes it difficult to run the casing string in the narrowing intervals;

- the probability of non-opening of the cuffs due to pressing the device to the column.

The technical task is to create a reliable and tight device above the liner uncoupler, which allows the liner to be rotated during the cementing process.

The technical problem is solved by a collar cementing packer, which includes a housing lowered into the well on the casing string and fixed on it with locking elements, consisting of a sealing collar with upper and lower parts.

What is new is that the lower part of the sealing collar is made conical, while at least six holes are made in it, evenly spaced around the circumference of the sealing collar, equipped with throttles fixed in the collar with fasteners, with the possibility of opening the throttles with an upward flow of the casing fluid and closing with movement of the behind-the-casing fluid in the opposite direction, while the upper part of the sealing collar is made with a straight end in the form of a funnel on the inside and with an outer diameter equal to the diameter of the wellbore.

Also new is that the chokes are made of hard rubber or canvas.

The drawing shows a sleeve cementing packer with a partial longitudinal section.

The sleeve cementing packer includes a body (not shown in the drawing) that is lowered into the well on the casing string 1 (see the drawing), which, using two end rings 2 (see the drawing), interconnected by a rubber sleeve 3, is fixed to the casing string 1 by locking elements 4 (end rings 2 are gummed into the rubber sleeve 3). A sealing collar 5 with upper and lower parts is installed in the casing of the collar cementing packer. The lower part of the sealing collar 5 is tapered. At the same time, at least six holes 6 are made in the lower conical part, evenly spaced around the entire circumference of the sealing cuff 5. Each of at least six holes 6, in turn, is equipped with a throttle 7 fixed to the cuff with fasteners 8 (for example, bolts or rivets). In this case, the throttles 7 are made of hard rubber or tarpaulin.

Throttles 7 are made with the possibility of opening with an upward flow of the casing fluid and closing when the casing fluid moves in the opposite direction. The upper part of the sealing cuff 5 is made with a straight end in the form of a funnel on the inside and with an outer diameter equal to the diameter of the wellbore.

The sleeve cementing packer works as follows.

The sleeve cementing packer is installed on the head of the liner (not shown) directly below the release device (not shown), which allows the liner to rotate during cementing. Before lowering into the well, on the casing string 1 (see drawing), end rings 2 are fixed with the help of locking elements 4. Centralizers (not shown in the drawing) are installed above and below the collar cementing packer at a distance of 0.5-1 m, performing a protective role for by centering the casing string 1 (see the drawing) in this area relative to the uncased walls of the wellbore (or inside the previous casing string relative to the inner walls of the previous casing string), thereby protecting the sealing collar 5 of the collar cementing packer from possible destruction during the descent into the well. The sleeve cementing packer is lowered into the well on the casing string 1 to the installation site.

In the process of lowering the liner, the upward flow of drilling fluid passes through the holes 6 in the sealing collar 5 (see the drawing), opening the throttles 7. Then, using cementing units, the estimated volume of cement slurry is pumped into the annular space of the well. After filling the annulus with cement slurry and stopping the cementing process under the action of the hydrostatic pressure of the cement slurry column, the throttles 7 close, thereby closing the holes 6. At the same time, the downward movement of the cement slurry is delayed, the sealing collar 5 expands in the radial direction and is tightly pressed against the walls of the well. In this way, the effect of the hydrostatic slurry column on the bottom of the cement column below the collar packer is greatly reduced. The cement column above the collar cementing packer after cementing is tightly seated inside the sealing collar 5 of the collar cementing packer, blocking the throttle channel, and creates a dense pack of cement with the sealing collar of the device, sealing the liner head with high quality.

Thus, the use of the proposed sleeve cementing packer makes it possible to reliably seal the head of the liner after its cementing, to ensure its use on the head of the liner with a release device for rotation, which has circulation holes that open at a certain pressure.

Claims (2)

1. A sleeve cementing packer, including a housing lowered into the well on the casing string and fixed on it with locking elements, consisting of a sealing collar with upper and lower parts, characterized in that the lower part of the sealing collar is made conical, while at least six holes evenly spaced around the circumference of the sealing cuff, equipped with throttles fixed in the cuff with fasteners, with the possibility of opening the throttles with an upward flow of casing fluid and closing when the casing fluid moves in the opposite direction, while the upper part of the sealing cuff is made with a straight end in the form of a funnel from the inside and with an outer diameter equal to the diameter of the wellbore. 2. A sleeve cementing packer according to claim 1, characterized in that the throttles are made of hard rubber or tarpaulin.

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