RU2638673C1 - Device for interval hydraulic fracturing of formation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device for performing interval-by-interval fracturing of the formation comprises a tubing string with a hollow cylindrical body connected to packer through a tail-piece at the bottom. A hollow bushing is mounted radially and rigidly in the hollow cylindrical body. A piston-punch is positioned inside the hollow bushing for limited radial movement, and configured as a cone narrowing outwards with a throttling L-shaped channel in the center. At that, the piston-punch is equipped with external radial groove communicating with the throttling L-shaped channel. The piston-punch is spring-loaded by a spring inside from the sleeve rigidly fixed in the end of the hollow bushing. In this case, a radial channel is made in the hollow bushing. In the initial position the radial and the throttling L-shaped channels are hermetically separated from each other, in the working position the vertical and throttling L-shaped channels are hydraulically communicated with each other by means of a radial groove connecting the hollow cylindrical body cavity with rock of production reservoir. A dynamic anchor is installed in the upper part of the hollow cylindrical body, and a subsurface gauge is installed under the packer.

EFFECT: improved performance of the device when conducting hydraulic fracturing of the formation.

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Description

The invention relates to the oil and gas industry and is intended for the interval acid fracturing.

A device for hydraulic fracturing (patent RU No. 2462589, IPC ЕВВ 43/26, publ. 09/27/2012, bull. No. 27) containing a waterjet perforator, made in the form of a housing with radial channels, in which bushings with a conical nozzle are fixed . The device is equipped with a sleeve located in the cavity of the housing with a central hole and a conical outer surface made with radial channels aligned in the working position with the radial channels of the nozzles and axially spring-loaded. The nozzles are made with an inclined end in contact with the conical surface of the sleeve. The nozzles are mounted for radial movement and spring loaded in the radial direction. The sleeve, located in the cavity of the body, is made with a saddle under the throttle valve. The valve seat is made with inclined grooves that connect the supravalvular cavity to the subvalvular cavity in the working position.

The disadvantages of the device are:

- firstly, the low efficiency of the device due to the fact that the inclined grooves of the sleeve have an estimated throughput, when exceeded during the hydraulic fracturing process, the fluid flow “locks” above the valve and the radial channels of the conical nozzles and the sleeve are disconnected under the dump valve (ball), which leads to a sharp increase in pressure in the device and, as a consequence, the impossibility of further hydraulic fracturing;

- secondly, limited functionality associated with the fact that it is impossible to perform interval hydraulic fracturing in a horizontal well due to the use of a dump valve, which does not provide a tight fit on the device seat in a horizontal wellbore;

- thirdly, additional costs for the operation of the device due to the preparation of a water-sand mixture for cutting holes in the casing of the well (it is necessary to use quartz sand), as well as the costs of special equipment (sand mixing unit);

- fourthly, the duration of the process of the device, since the cutting of the casing of the well occurs under the influence of a jet of hydroabrasive fluid;

- fifthly, the inability to control the pressure of the injection of hydraulic fracturing fluid directly in the interval of hydraulic fracturing.

The closest in technical essence and the achieved result is a device for interval hydraulic fracturing (patent RU No. 2123106, IPC ЕВВ 43/26, 43/114, publ. 10.12.1998), containing a tubing string (tubing), hollow a cylindrical body with nozzles and a sleeve located in the cavity of the hollow cylindrical body, with a through axial channel, a seat under the valve ball and seals, while the sleeve is made with a shank protruding outside the body and connected from below to the packer, while the body and sleeve are connected betweenoboj keyed for rotation with rotation of the packer tubing.

The disadvantages of this device are:

- firstly, the low efficiency of the device when creating a hydraulic fracture, since the nozzles of the device through which hydraulic fracturing fluid is supplied under pressure are located in the wellbore, and not in the formation rock, when creating a fracture, therefore, part of the energy of the hydraulic fracturing jet is lost before interaction with formation rock. In addition, the device does not have a fixation in the wellbore during hydraulic fracturing, which leads to dispersion of the jet in the wellbore during both sandblasting and hydraulic fracturing;

- secondly, limited functionality associated with the fact that it is impossible to perform interval hydraulic fracturing in a horizontal well due to the use of a dump valve, which does not provide a tight fit on the device seat in a horizontal wellbore;

- thirdly, additional material and financial costs for the operation of the device due to the preparation of a water-sand mixture for cutting holes in the casing of the well (quartz sand must be used), as well as the cost of special equipment (sand mixing unit);

- fourthly, the duration of the process of the device, since the cutting of the hole in the casing of the well occurs under the influence of a jet of hydroabrasive fluid;

- fifthly, the inability to control the pressure of the injection of hydraulic fracturing fluid directly in the interval of hydraulic fracturing.

The technical objectives of the invention are to increase the efficiency of the device, expand the functionality, reduce additional material and financial costs for the operation of the device, reduce the duration of the device with the ability to control pressure in the interval of hydraulic fracturing.

The stated technical problems are solved by a device for interval hydraulic fracturing containing a tubing string with a hollow cylindrical body, bottom connected through a shank with a packer.

What is new is that a hollow bushing is installed radially and rigidly in the hollow cylindrical body, inside the hollow bushing with the possibility of limited radial movement to the outside there is a piston punch, made under a cone, tapering outward, with a throttling L-shaped channel in the center, and the piston punch equipped with an external radial groove in communication with the throttling L-shaped channel, the punch piston is spring-loaded inward from the cup, which is rigidly fixed at the end of the hollow sleeve, while in the hollow sleeve in the radial channel is full, and in the initial position, the radial and throttling L-shaped channels are hermetically cut off from each other, and in the working position, the vertical and throttling L-shaped channels are hydraulically connected to each other by means of a radial groove, connecting the cavity of the hollow cylindrical body with the rock of the productive collector, moreover, a dynamic anchor is installed in the upper part of the hollow cylindrical body, and a depth gauge is installed under the packer.

In FIG. 1 shows the proposed device in its original position.

In FIG. 2 shows the proposed device in the working position.

The device for interval hydraulic fracturing contains a tubing string 1 with a hollow cylindrical body 2 at the end of the tubing string 1. The hollow cylindrical body 2 is connected to the packer 4 from the bottom through the shank 3.

As a packer 4, a packer of any known design with a mechanical anchor, for example, with an axial fit, is used. A mechanical anchor is needed to secure the device from moving down.

Radially and rigidly, for example, by means of a threaded connection (shown in FIGS. 1 and 2 conventionally), a hollow sleeve 5 is installed in the hollow cylindrical body.

Inside the hollow sleeve 5 with the possibility of limited radial movement outward under the action of hydraulic pressure, there is a piston-punch 6, made under a cone, tapering outward, with a throttling L-shaped channel 7 in the center. The piston-punch 6 is equipped with an outer radial groove 8, communicating with the throttling L-shaped channel 7.

The piston-punch 6 is spring-loaded with a spring 9 inward from the cup 10, which is rigidly fixed at the end of the hollow sleeve 5, for example, screwed with a threaded connection (Fig. 1 and 2 are shown conditionally).

A radial channel 11 is made in the hollow sleeve 5. In the initial position, the radial I (see Fig. 1) and the throttling L-shaped 7 channels of the piston-punch 6 are hermetically cut off from each other.

In the working position, the vertical 11 (see Fig. 2) and the throttling L-shaped 7 channels of the piston-punch 6 are hydraulically interconnected via a radial groove 8, connecting the cavity 12 of the hollow cylindrical body 2 with the rock of the productive collector 13 (see Fig. 2 )

A dynamic anchor 14 is installed in the upper part of the hollow cylindrical body 2 (see Fig. 1). The dynamic anchor 14 consists of radial channels 15, for example, in the amount of 4 pieces, into which the dies 17 spring-loaded from the latches 16 are installed (see Fig. 1 and 2) with an external gear surface 18.

A depth gauge 19 is installed under the packer 4 to transmit information on the injection pressure of the hydraulic fracturing fluid during the interval of hydraulic fracturing at the wellhead 20. Information is transmitted to the receiver via an optical fiber cable (not shown in Figs. 1 and 2). The fiber optic cable is lowered into the well 20 together with the tubing string 1, while the fiber optic cable is mounted on the outer surface of the tubing string 1 using clamps (not shown in FIGS. 1 and 2).

The mating surfaces of the parts of the device are equipped with o-rings (not shown in FIGS. 1 and 2) in order to exclude unauthorized fluid flows.

The device operates as follows.

The proposed device is assembled at the wellhead, as shown in FIG. 1 in the initial position, in which the radial 11 and the throttling L-shaped 7 channels of the piston-punch 6 are hermetically cut off from each other.

The device is lowered into the well 20 in the lowest interval of hydraulic fracturing in a vertical well or the interval of hydraulic fracturing closest to the bottom in a horizontal well.

Packer 4 is planted with a mechanical anchor, axially moving upwards, for example, by 1.5 m and descending to fix the mechanical anchor (fig. 2 shown conditionally) on the walls of the casing 21 of the well 20.

Next, at the wellhead 20, the upper end of the tubing string 1 is tied to the pump unit (not shown in FIGS. 1 and 2) and pumping of the process fluid into the tubing string 1 is started (see FIG. 1).

The fluid, having reached the hollow cylindrical body 2 through the tubing string 1 (see Fig. 2), enters the radial channels 15 of the dynamic armature 14 and exerts hydraulic pressure on the end face of the dies 17 spring-loaded from the clamps 17. At the same time, the fluid acts on the the end face of the piston-punch 6 spring-loaded by means of springs 9 from the cup 10, screwed into the end face of the hollow sleeve 5.

As a result, the spring-loaded dies 17 move radially outward and fix the device in the casing 21 of the borehole 20 from moving the device up, and the piston-punch 6 under the influence of fluid pressure is limited to move radially outward until it interacts with the casing 21 of the borehole 20.

The pressure in the tubing string 1 and the device continue to increase, while the piston-punch 6, compressing the spring 9, pierces the hole 22 (see Fig. 2) in the casing 21 of the well 20 and occupies a working position for hydraulic fracturing, in which the radial 11 and the throttling L-shaped 7 channels of the piston-punch 6 are hydraulically interconnected via a radial groove 8, connecting the cavity 12 of the hollow cylindrical body 2 with the rock of the productive reservoir 13. Then, without interrupting the injection, an acid hydraulic fracturing is performed one hundred. For this, hydraulic fracturing fluid is injected, for example, of any known acid composition intended for acid fracturing, for example, a 20% hydrochloric acid solution at the rate of 5 m ³ per 1 m of the formation thickness.

For example, with a layer thickness of 3 m, an injection is carried out using a pump unit: 3 m ⋅ 5 m ³ / m = 15 m ^{3 of} acid composition through a tubing string 1 through a hollow cylindrical body 2 through a radial channel 11, a radial groove 8 of the piston punch 6 and through the throttling L-shaped channel 7 of the piston-punch 6 in the rock productive reservoir 13 of the reservoir.

Raise the injection pressure of the acid composition until the hydraulic fracturing pressure is reached and the calculated volume of 15 m ^{3 of the} acid composition is pumped into the formation.

In the process of hydraulic fracturing using a depth gauge 19 control the injection pressure, which allows you to quickly adjust the flow rate of the acid composition. For example, before hydraulic fracturing is achieved, the acid composition is injected at a flow rate of 2 m ³ / min, and after hydraulic fracturing is achieved, as evidenced by the pressure drop according to the readings of the depth gauge 19, the injection flow rate is increased to 4 m ³ / min.

Moreover, during the injection of the acid composition, i.e. in the process of hydraulic fracturing, the piston-punch 6, made under the cone from the outside, remains in the punched hole 22, and the throttling L-shaped channel 7 is in contact with the rock of the productive reservoir 13 behind the casing of the well 20, and not inside the well, as described in prototype. This eliminates the loss of energy of the liquid jet (acid composition) before interacting with the formation rock, which provides a deeper penetration of the acid composition into the formation during its hydraulic fracturing. In addition, the placement of the piston-punch 6 in the hole 22 of the casing of the well 20 and the fixation of the dynamic armature 14 on the walls of the casing 21 of the well 20 from moving up provide an effective injection of the entire volume of the acid composition into the formation during hydraulic fracturing.

At the end of the hydraulic fracturing, the pressure in the tubing string 1 and the hollow cylindrical body 2 is vented. As a result, due to the returning force of the spring 9, the punch piston 6 returns to its original position, and the spring-loaded dies 17 of the dynamic armature 14 are returned, as shown in FIG. one.

Further, the device is lifted into the overlying interval of hydraulic fracturing in a vertical well or moved to the next hydraulic fracturing interval from the bottom to the mouth in a horizontal well.

The functionality of the device is expanding, since it allows you to perform interval hydraulic fracturing from the bottom to the mouth in a horizontal well and from bottom to top in a vertical well without the use of a valve or throw ball.

The holes in the casing 21 of the borehole 20 punctured by a piston-punch 6, in contrast to the sandblasting perforation, reduces the cost of working with the device, namely: the preparation of sandy water for cutting holes in the casing of the well (you must use quartz sand), as well as costs on special equipment: blender, sand mixer.

Reduces the duration of the device due to the puncture of the casing string of the well, since it does not take time to cut through the casing string of the well under the action of a water jet.

The depth gauge 19 allows you to control the pressure directly in the interval and quickly adjust the flow rate of the injected hydraulic fracturing fluid, which in turn improves the quality of hydraulic fracturing.

The proposed device for conducting interval fracturing allows you to:

- increase the efficiency of the device when performing hydraulic fracturing;

- expand the functionality of the device;

- reduce the cost of working with the device;

- reduce the duration of work using the device;

- control the injection pressure in the interval of hydraulic fracturing.

Claims (1)

A device for interval hydraulic fracturing, comprising a tubing string with a hollow cylindrical body, bottom connected via a shank with a packer, characterized in that a hollow sleeve is installed radially and rigidly in the hollow cylindrical body, a piston is located inside the hollow sleeve with limited radial movement outward a punch made under the cone, tapering outward, with a throttling L-shaped channel in the center, and the punch piston is equipped with an external radial groove, with communicating with the throttling L-shaped channel, the punch piston is spring-loaded inward from the cup rigidly fixed in the end of the hollow sleeve, while the radial channel is made in the hollow sleeve, and in the initial position the radial and throttling L-shaped channels are hermetically cut off from each other, and in the working position, the vertical and throttling L-shaped channels are hydraulically interconnected via a radial groove, connecting the cavity of the hollow cylindrical body with the rock of the productive reservoir, than in the upper portion of the hollow cylindrical body is mounted a dynamic anchor, and the depth gauge is installed below the packer.

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