RU2568615C1 - Reservoir cleaning and completion device - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device includes flow string run down to the well and complete with strainer on the underside and at the top it is complete with packer installed in the well above the reservoir. There is a saddle in the flow string. Swab may be installed in the flow string. There is also a gate for discharge to the flow string. The gate is made as a ball fixed rigidly to a blind rod. The strainer is made with the upper and lower rows of openings. Inside the strainer each opening of the upper and lower row is equipped with a knock-off valve breakable upon discharge of the gate to the flow string. The upper and lower rows of openings are made at distance of the reservoir height. Sludge-collecting chamber is fixed rigidly to the strainer from below. Over the packer the flow string is complete with a row of channels sealed hermetically from inside by the saddle fixed in the flow string by shear ties. Under the row of channels in the flow string there is inner circular bore, wherein shutoff split-type spring ring is installed. From the well mouth to the flow string an axially-movable plug is inserted, and the above plug may interact with the saddle, break shear ties fixing the saddle in the flow string with opening a row of channels in the flow string, it is capable of limited axial movement with the saddle downwards up to thrust of the saddle into the limiter made at the flow string lower end and fixation of the plug in result of axial movement upwards upon thrust of the saddle into the flow string limiter.

EFFECT: improved efficiency of reservoir completion due to pre-cleaning of the reservoir bottomhole zone at deep depression generation.

5 dwg

Description

The invention relates to the field of oil and gas industry and can be used for cleaning and development of the reservoir in order to increase the permeability of the bottomhole formation zone.

A device is known for developing a wellbore by swabbing (patent RU No. 2440491, IPC ЕВВ 43/25, published on January 20, 2012, bull. No. 2), including a swab, a tubing string — tubing — with a swab stroke limiter and a filter for communication with the reservoir, the packer mounted above the reservoir, the tubing string is equipped with a hollow tip at the bottom, and the filter at the top with a nozzle with an internal cylindrical cavity, and the tip is inserted into the nozzle, from which it is spring-loaded upward and configured for longitudinal limited movement, while the tip is equipped the upper and lower rows of holes inside separated by a partition and made with the possibility of communication when moving the tip down relative to the filter nozzle through the inner cylindrical cavity of the nozzle, and the upper row of holes of the tip is made with the possibility of communication with the over-packer zone when moving the tip up and fixing relative to the filter nozzle.

The disadvantages of this device:

- firstly, the complexity of the design of the device due to the large number of nodes and parts (tip, nozzle, spring, etc.);

- secondly, low reliability due to the high probability of spring breakage under the action of alternating loads perceived by the device during operation, and, as a result, failure of the device;

- thirdly, the low efficiency of well cleaning before swab development, since the device allows you to create only minor impulses of instantaneous depressions due to the fact that the lower part of the device is filled with borehole fluid to the packer, so it is impossible to effectively clean the bottomhole formation zone in the boundary zone of perforation of the formation from foreign liquid with mechanical impurities.

The closest in technical essence and the achieved result is a device for swab well development (patent RU No. 2436944, IPC ЕВВ 43/25, published on 12/20/2011, bull. No. 35), including a tubing string lowered into the well - tubing equipped with a bottom filter and a packer installed in the well above the formation, as well as a swab and a swab stroke limiter installed in the tubing string, while between the filter and the swab stroke limiter in the tubing string there is a saddle under the resetting locking element, and between the limiter m swab stroke and a saddle above the packer in the tubing string there is a knock-down valve for communicating the tubing string with the over-packer zone after resetting the shut-off element, made in the form of a ball rigidly connected to a blind stem.

The disadvantages of this device:

- firstly, the low efficiency of development of a heavily contaminated wellbore by swabbing due to the presence of foreign fluid with mechanical impurities in the boundary zone of the perforation of the formation, which does not allow to effectively develop the formation, therefore, before using this device, it is necessary to pre-clean the bottomhole formation zone to clean it from contamination what this device does not allow;

- secondly, the shut-off element, made in the form of a ball, rigidly connected to a deaf rod, does not have a fixation in the tubing string from moving up, therefore, in wells with high reservoir pressure, when the reservoir pressure (R _pl ) is equal to (0.85-1 ) hydrostatic level (N) of the wellbore fluid column in the well, i.e. P _PL = (0.85-1) · ρ · g · H, when swabbing from the over-packer zone, the borehole fluid will flow from bottom to top in the over-packer zone of the well through the shut-off element. Therefore, after unpacking the packer, the well fluid located in the overpacker zone enters the reservoir, i.e. there is a jamming of the developed well, while the bottom-hole zone of the formation is clogged, reservoir properties of the formation deteriorate and the quality of development decreases;

- thirdly, the duration of development with the use of this device, due to the fact that swabbing from the overpacker zone must be carried out until the pressure exerted by the hydrostatic level H _{2 of the} well fluid is lower than the reservoir pressure (R _pl ), while in the process swabbing occurs overflow of the wellbore fluid from the sub-packer zone to the over-packer zone through the shut-off element, therefore the device does not allow sealing the flow of the wellbore fluid from bottom to top, and at high reservoir pressure it is necessary to swab borehole fluid for a long time.

An object of the invention is to provide a device that allows to increase the efficiency of reservoir development due to preliminary cleaning of the bottom-hole zone of the reservoir by creating a deep depression on the reservoir, as well as to improve the quality of reservoir development by eliminating the return of fluid into the reservoir in wells with high reservoir pressure and reduce the duration development in wells with high reservoir pressure by eliminating the flow of borehole fluid from the reservoir into the overpacker zone of the well (bottom x) by tightly shutting off the flow in the tubing string.

The stated technical problem is solved by a device for cleaning and developing the formation, including a tubing string lowered into the well - tubing, equipped with a filter below and a packer installed in the well above the reservoir, a saddle installed in the tubing string, as well as a swab installed in the tubing string, and a locking element discharged into the tubing string, made in the form of a ball rigidly connected to a deaf rod.

New is that the filter is made in the form of the upper and lower rows of holes, while inside the filter, each hole in the upper and lower rows is equipped with a knockout valve that is destroyed after the shut-off element is discharged into the tubing string, the upper and lower rows of filter holes being made at a distance of the formation height at the same time, a sludge collection chamber is rigidly fixed from below to the filter, and above the packer the tubing string is equipped with a number of channels hermetically sealed from the inside by a saddle fixed with shear elements fixed to the tubing string, and underneath On the side of the tubing string, an internal annular groove is made, in which a snap split spring ring is installed, and a plug is installed in the tubing string from the wellhead with the possibility of axial movement downward, which can interact with the saddle and destroy shear elements that fix the saddle in the tubing string with opening a row channels in the tubing string, and joint with the saddle of limited axial movement down to the stop of the saddle in the stopper made on the lower end of the tubing string, and fixing the plug from axial movement after the top of the saddle in abutment restrictor tubing string.

In figures 1-3 schematically shows the proposed device in the process.

In FIG. 4 shows a cross-section Α-A of the filter along the bottom row of openings with whipping valves installed in them.

In FIG. 5 in an enlarged view B shows the interval of fixation of the tube relative to the tubing string with a snap split spring ring.

A device for cleaning and developing reservoir 1 (see Fig. 1) includes a tubing string, tubing 3, lowered into the well 2, equipped with a filter 4 for communication with reservoir 1, and above a packer 5 installed in the well 2 above reservoir 1, e.g. 10 m.

The device also contains a saddle 6 installed in the tubing string 3, and a swab 7 (see Fig. 2) installed in the tubing string 3 and a locking element 8 discharged into the tubing string 3 made in the form of a ball rigidly connected to a blind stem. The filter 4 (see Fig. 1) is made in the form of the upper 9 and lower 10 rows of holes, while inside the filter, each hole of the upper 9 and lower 10 rows is equipped with a relief valve 11, which are destroyed after discharge of the locking element 8 into the tubing string 3.

The upper 9 and lower 10 rows of openings of the filter 4 are made at a distance equal to the height h of the formation 1, for example 4 m. From the bottom to the filter 4, a sludge collection chamber 12 is rigidly fixed with a sleeve 13. For example, the filter 4 is made of a pipe with a diameter of 114 mm and a length 6 m. In the upper 9 and lower 10 rows, four holes (see Fig. 4) with a diameter of 25 mm are made, in each of which a knock-off valve 11 is installed (see Fig. 1), and the sludge collection chamber 12, as well as filter 4 is made of a pipe with a diameter of 114 mm and a length of 10 m

To destroy the knocking valves 11 by the locking element 8, the following relationship must be observed:

d <D ₁ <D ₂ ,

where d is the diameter of the ball of the locking element, for example 30 mm;

D ₁ - the inner diameter of the saddle 6, for example 40 mm;

D ₂ - the inner diameter of the stopper 18, for example 50 mm

The locking element 8 is made in the form of a ball, rigidly connected to a deaf stem, which ensures guaranteed destruction of all knockdown valves 11 installed in the upper 9 and lower 10 rows of holes with subsequent communication of the formation 1 with a sludge collection chamber 12.

At the wellhead 2, the inner space 14 of the tubing string 3 is indicated by a flow line with a groove capacity (not shown), and above the packer 5 (see Fig. 1), the tubing string 3 is equipped with a number of channels 15 sealed from the inside by a saddle 6 fixed to the tubing string 3 shear elements 16.

Under a number of channels 15 of the tubing string 3, an inner annular groove 17 is made, in which a snap split spring ring 18 is mounted, for example of a triangular section (see Figs. 1 and 5).

A tube 19 is installed in the tubing string 3 from the wellhead 2 with the possibility of axial downward movement (see Figs. 1 and 3), for example, made of rubber and capable of interacting with the saddle 6 and destroying the shear elements 16 fixing the saddle 6 in the string Tubing 3 with the opening of a number of channels 15 of the tubing string 3.

The stopper 19 together with the seat 6 have the possibility of limited axial movement down to the stop of the seat 6 in the stopper 20, made on the lower end of the tubing string 3, and fixing the stopper 19 for its upper end 21 from the axial movement upwards after the seat 6 rests in the stopper 20 of the tubing string 3.

The device operates as follows.

The device is mounted in the well 2, as shown in figure 1, while the packer 5 in the well 2 is planted (packaged) 10 m above the top of the formation 1.

Then, a locking element 8 with a diameter of - d (see Fig. 2) is dropped into the tubing string 3, which freely passes through the tubing string 3 through a saddle 6 with a diameter of D ₁ and a diameter limiter of 20 - D ₂ and, having reached filter 4, destroys all valves 11 (see Fig. 4) installed in the upper 9 (with Fig. 1) and lower 10 rows of holes, as a result of which the formation 1 communicates with the sludge collection chamber 12, since the packer 5 is sealed in the well 2 above the formation 1.

The result is a sharp impulse, accompanied by a sharp depression on the formation 1, while in the sludge collection chamber 12, through the openings of the upper 9 and lower 10 rows of the filter 4, impurities 22 (filtrate, sludge, etc.) are deposited, which settle in the sludge collection chamber 12, and a foreign liquid with mechanical impurities is removed from the boundary zone of perforation 23 of formation 1, while the passage section of perforation 23 of formation 1 is cleaned and restored.

The most effective development of a well occurs after cleaning the bottom-hole zone of the formation from filtrate and mechanical impurities under the influence of deep depression on the reservoir being developed, while foreign fluid with mechanical impurities that impede well development by swabbing is removed from the boundary zone of perforation of the formation.

Thus, the proposed device allows for preliminary cleaning of the bottomhole formation zone by creating a deep depression on the formation, which increases the efficiency of further development of the formation.

Then, the swab 7 is lowered into the tubing string 3 (see Fig. 2) on the rope until the swab 7 interacts with the saddle 6. Next, the process of reservoir 1 development is started by swabbing using a ground drive, for example, a swab assembly (not shown).

The fluid is sampled along the tubing string 3 (see Fig. 2) by swabbing from the under-packer zone 24 through the open holes of the upper 9 and lower 10 rows of the filter 4 until a stable production flow of the formation 1 is obtained by periodically lifting the fluid along the tubing string 3 using a swab 7, certain portions of liquid from the well 2 with a sequential stepwise decrease in the liquid level and a corresponding change in the depth of descent of the swab 7 at each subsequent stroke. The height of the raised column of liquid and, accordingly, the volume of liquid raised in one cycle, are determined by immersing the swab 7 under the liquid level in each cycle.

After receiving a stable influx of products from reservoir 1 with disconnected subpacker 24 and superpacker 25 zones, swab 7 is removed from the tubing string 3.

At the wellhead 2, plugs 19 are installed in the tubing string 3 (see FIG. 3). The plug 19 under the influence of excess pressure created by the pump unit in the inner space 14 of the tubing string 3 above the plug 19, for example, cementing unit CA-320, is pushed down the tubing string 3 down to interact with the seat 6.

At a certain pressure created in the inner space 14 of the tubing string 3 above the plug 19 by the pump unit, for example 9.0 MPa, the shear elements 16 fixing the saddle 6 in the tubing string 3 are destroyed.

As a result, the saddle 6 and the plug 19 are shifted down to the stop of the saddle 6 in the limiter 20, made on the lower end of the tubing string 3, while opening a number of 15 channels of the tubing string 3, and the snap split spring ring 18 (see Fig. 5) fixes the tube 19 from the axial movement up beyond its upper end 21 after the seat 6 rests in the limiter 20 of the tubing string 3.

Next, the swab 7 is again lowered into the tubing string 3 (see Figs. 2 and 4) and the borehole fluid of the calculated volume is drawn from the tubing string 3 by swabbing from the overpacker zone 25 and the inner space 14 of the tubing string 3.

At the end of swabbing, the estimated fluid volume is removed from the tubing string 3 swab 7, then the packer 5 is unpacked (removed) and removed together with the tubing string 3. The calculated volume of the well fluid is equal to the sum of the volume of the well fluid in the inner space 14 of the tubing string 3 above the plug 19 and nadpakery zone 25 of the well 1, for example, is 15 m

The quality of reservoir development 1 is improved due to the elimination of the return of fluid from the well into the reservoir in wells with high reservoir pressure due to the fact that the plug is hermetically fixed in the tubing string and prevents the flow of well fluid along the tubing string 3.

The device allows to reduce the development time in wells with high reservoir pressure, since time is spent only on the selection of the estimated volume of the wellbore fluid, which is achieved thanks to plug 19, which prevents overflow of the wellbore fluid from the reservoir 1 into the overpacker zone 25 of the well 2.

The proposed device allows to increase the efficiency of the development of the reservoir by pre-cleaning the bottomhole zone of the reservoir by creating a deep depression on the reservoir, as well as to improve the quality of the development of the reservoir by eliminating the return of the well into the reservoir in wells with high reservoir pressure and to reduce the duration of development in wells with high reservoir pressure by eliminating the flow of borehole fluid from the reservoir into the above-packer zone of the well (from bottom to top) by tight shutoff of the flow in the tubing string.

Claims (1)

A device for cleaning and developing the formation, including a tubing string lowered into the well - tubing, equipped with a filter below, and a packer installed in the well above the reservoir, a saddle installed in the tubing string, and a swab installed in the tubing string, and a locking element discharged into the tubing string made in the form of a ball rigidly connected to a deaf rod, characterized in that the filter is made in the form of upper and lower rows of holes, while inside the filter, each hole of the upper and lower rows is equipped with knocking valve, which is destroyed after the locking element is discharged into the tubing string, the upper and lower rows of filter openings being made at a distance of the formation height, while the sludge collection chamber is rigidly fixed from below to the filter, and the tubing string is equipped with a number of channels above the packer that are hermetically closed from the inside by a saddle fixed to the tubing string with shear elements, and under a number of tubing string channels, an internal annular groove is made in which a snap split spring ring is installed, while in the tubing string from the wellhead with with the possibility of axial downward movement, a plug is installed that can interact with the saddle, destroy shear elements fixing the saddle in the tubing string with the opening of a number of channels in the tubing string, and jointly with the saddle have limited axial displacement down to the stop of the saddle in the stopper made on the lower end of the tubing string , and fixing the plug from axial movement upwards after the seat rests against the tubing stop.

Images