RU2526058C1 - Device for acid-hydraulic fracturing of formation - Google Patents

Abstract

FIELD: oil-and-gas industry.SUBSTANCE: proposed device comprises case with radial channels accommodating sleeves with conical nozzles arranged to display radially and spring-loaded in radial direction, sleeve with conical outer surface arranged inside the case and fitted with central hole with seat from discharge valve composed by ball. Split cone of the case is arranged under said sleeve. Note here that conical nozzles are rigidly connected with said split cone composed by sectors surrounding the case inner surface along the perimeter. The number of split cone sectors corresponds to that of conical nozzles. Split cone has inner conical surface facing said outer conical surface of the sleeve. Inner circular groove is made in said case. Split cone and conical nozzles can expand split cone radially and to arrange it in said inner circular groove at the sleeve axial displacement downward against inner thrust. The latter is made at the case bottom end under action of overpressure above the valve and communication of valve pot with conical nozzles. Valve ball passing the fluid from bottom to top is provided with rod rigidly secured to said ball and equipped with parachute.EFFECT: higher efficiency and reliability.2 dwg

Description

The invention relates to the oil and gas industry and is intended for acid fracturing in open wellbores.

A device for hydraulic fracturing (patent of Germany No. 2402757, IPC EV 43/25, publ. In 1978), comprising a housing with radial channels in which bushings with a conical nozzle are fixed.

The disadvantage of this device is the low efficiency associated with the inability to change the distance between the ends of the nozzles and the treated formation.

A device for hydraulic fracturing (copyright certificate SU No. 1029673, IPC ЕВВ 43/263, publ. 05/10/1999) is also known, comprising a housing with a cap with a rod and a reflector forming a combustion chamber in which a powder charge with an igniter and a sealing are placed element.

The disadvantages of this device are the low reliability and the need for strict safety measures to avoid injuries to staff.

It is also known a device for hydraulic fracturing (patent RU No. 2412346, IPC ЕВВ 43/26, publ. 02.20.2011, Bull. No. 5), containing a geophysical cable, a transportation means connected to a hydraulic fracturing means, the transportation means being made in in the form of a hydraulic propeller connected by a common shaft with a drive and a high-voltage generator, located inside a sealed enclosure, installed, in turn, inside the casing with the formation of an annular gap, while the high-voltage generator is made with a piezoelectric kimi plates and a common shaft with the rollers has wheels, the last of which have the ability to exert pressure on the piezoelectric plate during rotation of the common shaft of the actuator.

The disadvantages of this device are the design complexity due to the large number of nodes and parts, as well as the low efficiency of hydraulic fracturing due to the fact that hydraulic fracturing occurs due to the discharge, causing hydraulic shock in the well.

The closest in technical essence and the achieved result is a device for hydraulic fracturing (patent RU No. 2462589, IPC ЕВВ 43/26, publ. 09/27/2012, Bull. No. 27), containing a housing with radial channels in which bushings are fixed with a conical nozzle, while it is provided 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, while the nozzles are made with the inclined end in contact with the conical surface of the sleeve, while the nozzles are mounted with the possibility of radial movement and spring-loaded in the radial direction, while the sleeve placed in the cavity of the housing is made with a seat under the throttle valve, while the valve seat is made with inclined grooves connecting operating position supravalvular cavity with subvalvular cavity.

The disadvantages of this device are:

- firstly, low work efficiency due to the fact that the inclined grooves of the sleeve have an estimated throughput, when exceeded, during the process of hydraulic fracturing, a "blocking" of the fluid flow above the valve and uncoupling of the radial channels of the conical nozzles and the sleeve 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, the low reliability of the device associated with a high probability of breaking the spring under the sleeve when creating excessive pressure in the cavity of the device above the valve;

- thirdly, the inability to flush the well through the device after acid fracturing in the open wellbore;

- fourthly, the outflow of fluid displaced by a string of pipes during the descent and ascent of the device at the wellhead.

The technical objectives of the proposal are to increase the efficiency and reliability of the device with the ability to flush the well after acid fracturing and to eliminate the outflow of well fluid at the wellhead.

The tasks are solved by a device for acid hydraulic fracturing, comprising a housing with radial channels, in which bushings with conical nozzles mounted with the possibility of radial movement and spring-loaded in the radial direction are fixed, a sleeve with a conical outer surface located in the cavity of the housing and equipped with a central hole with a saddle under the throw valve, made in the form of a ball.

What is new is that in the casing a split cone is mounted on top of the sleeve, while the conical nozzles are rigidly connected to the split cone made in the form of sectors covering the inner surface of the housing along the perimeter, the number of sectors of the split cone corresponding to the number of conical nozzles, while the split cone equipped with an inner conical surface interchanged with the outer conical surface of the sleeve, the inner ring groove being made in the housing, and the split cone and conical nozzles and they have the ability to radially expand and place the split cone in the inner annular groove of the housing with the axial movement of the sleeve down to the internal stop made on the lower end of the housing under the action of overpressure over the valve and communication of the valve space with conical nozzles, while to the ball of the dump valve passing liquid from bottom to top; a rod equipped with a parachute from above is rigidly fixed.

Figure 1 schematically in longitudinal section shows the proposed device.

Figure 2 shows a section aa of the device.

The device for acid fracturing (HFGR) comprises a housing 1 (see FIG. 1) with radial channels 2, in which bushings 3 are mounted with conical nozzles 4 mounted radially outward and spring-loaded by springs 5 in the radial direction. The device also includes a sleeve 6, located in the cavity of the housing and equipped with a Central hole 7 with a seat 8 for the throttle valve, made in the form of a ball 9.

Conical nozzles 4 are rigidly connected, for example, using a threaded connection 10 with a split cone 11 (see figure 2), made in the form of sectors 11 ', 11 ″ ... 11 ⁿ , covering the inner surface of the housing 1 around the perimeter.

The number of sectors 11 ', 11 ″ ... 11 ^{n of the} split cone 11 corresponds to the number of conical nozzles 4. For example, for three conical nozzles 4, a split cone 11 is made up of three sectors 11', 11 ″, 11 ‴, covering the inner surface of the housing 1 by perimeter with an angle of 120 ° each.

The split cone 11 (see Fig. 1) is equipped with an inner conical surface 12 interchanged with the outer conical surface 13 of the sleeve 6.

An inner annular groove 14 is made in the housing 1, and the split cone 11 and the conical nozzles 4 have the possibility of radial expansion with the placement of the split cone 11 in the inner annular groove 14 of the housing 1 with axial movement of the sleeve 6 down to the inner stop 15 made on the lower end of the housing 1 under the action of excess pressure and communication nadklapannogo space 16 with conical nozzles 4. To the ball 9 of the throttle valve, passing liquid from the bottom up, the rod 17 is rigidly fixed from above, equipped with a parachute 18 from above. arashyut 18 made of a rubber material, e.g., thickness of 5 mm and a diameter d of 15-20 mm smaller than the internal diameter D of the housing 1.

A device for acid fracturing works as follows.

The device, as shown in figure 1, at the end of the pipe string (not shown in figures 1 and 2) is lowered into the open hole well. During the descent, the borehole fluid from the bottom up through the central hole 7 (see Fig. 1) of the sleeve 6 enters the pipe string above the device, which eliminates its spout at the wellhead.

After reaching the interval of the open borehole, where it is necessary to make a crack, a waste valve is thrown into the pipe string, which sits on the saddle 8 of the sleeve 6, after which the acid fracturing process is started with the injection of fracturing fluid through the pipe string. As a fracturing fluid, a 10-15% aqueous solution of thickened hydrochloric acid is used according to GOST 857-95.

The rupture fluid along the pipe string reaches the device and exerts pressure on the sleeve 6, since the central hole 7 of the sleeve 6 is blocked by a throttle valve. As a result, the sleeve 6 begins to move down and with its conical surface acts on the split cone 11, consisting of three sectors 11 ', 11 ″, 11 ‴ (see figure 2).

The split cone 11, consisting of three sectors 11 ′, 11 ″, 11 ‴, together with the conical nozzles 4 moves radially outward, while the split cone 11 (sectors 11 ′, 11 ″, 11 ‴) moves into the inner annular groove 14 of the housing 1 and conical nozzles 4, compressing the springs 5, move radially and extend beyond the diameter of the housing 1.

The fracture fluid passes through the conical nozzles 4, gains significant speed and has a dynamic effect on the reservoir (not shown in FIGS. 1 and 2), forming cracks in it.

In the proposed device, an increase or decrease in the volume of pumped fracture fluid, i.e. the differential pressure at the exit of the nozzle does not affect the operability of the device, while it is sufficient to create an excess pressure of 1.5-2.0 MPa in the device above the valve to move the sleeve down and to communicate the valve space with the formation through conical nozzles. In addition, the design of the proposed device does not "lock" the fluid flow and there is no need to combine the radial holes of the sleeve and the conical nozzle for the operation of the device, as indicated in the prototype, therefore, its work efficiency is increased.

After stopping the flow of the fracture fluid, the conical nozzles 4 under the action of the force of the springs 5 return to their original position.

At the end of the hydraulic fracturing, backwash the wells, i.e. flushing fluid is pumped into the annulus of the well with the removal of reaction products through the devices from the bottom up and along the pipe string at the wellhead, while the fluid with the reaction products enters the device and flows from the undervalve space 19 into the overvalve space 16, with the discharge valve due to the parachute 18 it is washed out by a stream of liquid from the bottom up from the device along the pipe string at the wellhead (not shown in FIGS. 1 and 2), and the liquid with the reaction products through the central hole 7 (see FIG. 1) of the sleeve 6 of the lift maetsya up the pipe string and the wellhead misses in channel capacity (in Figures 1 and 2 are not shown).

After backwashing, the device can be transferred to another interval of the open hole for hydraulic fracturing in another interval of the well or can be freely raised to the surface. In the process of lifting a device with a pipe string, the borehole fluid does not pour out at the wellhead, since the waste valve is washed from the device along the pipe string.

The proposed device for acid fracturing can increase the efficiency and reliability, as well as flushing the well after acid fracturing and eliminates the outflow of well fluid at the wellhead.

Claims (1)

A device for acid fracturing, comprising a housing with radial channels in which bushings with conical nozzles mounted for radial movement and spring-loaded in a radial direction are fixed, a sleeve with a conical outer surface located in the cavity of the housing and equipped with a central hole with a saddle for the throttle valve made in the form of a ball, characterized in that in the housing a split cone is located under the sleeve, while the conical nozzles are rigidly connected to the split cone made in the form of sectors covering the inner surface of the housing along the perimeter, and the number of sectors of the split cone corresponds to the number of conical nozzles, while the split cone is equipped with an internal conical surface interchanged with the outer conical surface of the sleeve, the inner ring groove being made in the housing, and the split cone and conical nozzles have the possibility of radial expansion and placement of the split cone in the inner annular groove of the housing during axial movement Sleeve down to an inner abutment provided on the lower end of the housing under the action of excess pressure on the valve and messages supravalvular space with conical nozzles, the junk to the ball valve, the liquid permeable bottom up, top rigidly fixed rod, equipped with top parachute.

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