RU2512222C1 - Method for bottomhole zone treatment - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to the oil industry, in particular, to treatment methods of bottomhole zone of the formation. The method includes running of flow string with packer and blade at the end to the well, the well is separated over the perforated interval of productive formation by the packer, connection of below-packer space by the flow string to well-head of the well. Before treatment of the bottomhole zone radial openings are made in lower part of the blade, below the openings a limiter is installed. Openings in initial position are sealed hermetically by a hollow sleeve capable of axial movements till it stops at the blade limiter and fixture. At the wellhead the arrangement is made consisting of the blade spring-controlled by protrusion of the flow string and the packer. The blade can move along the axis. The arrangement is run until it stops at the blade limiter into sump contamination and change in weight of flow string hanger. Circulation liquid is pumped until weight of the flow string hanger recovers; a ball is thrown to the flow string, then excessive pressure is created at the flow string and under this pressure the hollow sleeve moved down until it stops at the blade limiter. Flow string is run so that radial openings are opposite formation top, then washing of perforated intervals is done by axial movements of the flow string from the formation top till bottom with speed of 0.15 m/min; the packer is seated and treatment of the formation is made by acid.EFFECT: raised efficiency and quality of cleaning, expanded process functionality.3 dwg

Description

The invention relates to the oil industry, in particular to methods for cleaning the bottom of the formation and restore well productivity.

A known method of thermochemical cleaning of the bottom-hole zone of a well (patent RU No. 2167284 IPC E21B 43/24, E21B 43/27, published in Bulletin No. 14 of 05/20/2001), including descent of tubing with magnesium, subsequent injection of hydrochloric acid and aging in time of reagents for the reaction, while a plug made of silumin alloy is installed on the tubing, the inner space of the tubing is filled with granular magnesium, then the hydrocarbon solvent is pumped along with the emulsifier through the annular space into the borehole zone of the reservoir and left to react with asphalt eno-paraffin deposits, after which an aqueous solution of hydrochloric acid of 15% concentration is pumped into the well through the annulus and after the end of the exothermic reaction of hydrochloric acid with granular magnesium in the open annulus, sodium bisulfate of aqueous NaHS ₄ O _{2 with a} concentration of 11% is pumped into the well a solution of sodium carbonate with a concentration of 5%, separated in the tubing with a buffer, after which the tube space is opened, as a result of which there is an ejection from the well of dissolved clogging formations, about CLOSED solutions and inflow of fluid.

The disadvantages of this method are:

- firstly, a complex technological process associated with the injection into the well of various chemicals;

- secondly, low efficiency of cleaning the bottom-hole zone in wells with sand occurrences. This is due to the fact that in such wells the injected chemical reagent cannot remove into the bottom-hole zone of the formation in order to remove asphaltene-paraffin deposits due to the presence of sand, sludge, and dirt.

A known method of cleaning the perforation of the bottomhole zone of the well (patent RU No. 2456434, IPC E21B 37/00, published in Bulletin No. 20 of 07/20/2012), characterized in that they create a depressive pressure drop between the cavity of the well and the cavity of the pump-compressor pipes due to the descent into the well of tubing equipped with a sequentially located distance from the surface of the day, the hydraulic choke in the closed position, the packer and the clapper valve, the packer are seated to separate the bottomhole zone under the packer from the polo borehole above the packer, by opening the hydraulic vacuum chute, fluid is drained from the formation into the cavity of the tubing and contaminants are removed from the perforation of the bottom-hole zone, after the contaminants enter the cavity of the perforation of the cavity of the tubing, the hydraulic choke is closed, and after sedimentation is established in the area above the clapper valve, the hydraulic vacuum choke is reopened to re-clean the perforation of the bottomhole zone, and after filling the pump cavity snow-compressor pipes with liquid carry out swabbing.

The disadvantages of this method are:

- firstly, the duration of the process of cleaning the perforation of the bottomhole zone of the well with the use of a hydraulic vacuum choke, which causes large financial and material costs;

- secondly, the low efficiency of cleaning the perforation of the bottomhole zone of the well is due to the fact that the hydraulic vacuum chunk allows you to remove sand, sludge, dirt, but does not remove asphaltene-paraffin deposits in the bottomhole zone of the formation.

The closest in technical essence is the method of cleaning the well (patent RU No. 2451159, IPC E21B 37/00, publ. In Bulletin No. 14 of 05/20/2012), including the descent of the tubing string with a packer and a pen at the end into the well , disconnecting the well above the interval of perforation of the reservoir by the packer, communicating the sub-packer space of the pipe string with the wellhead, separating the space of the pipe string above the packer by a spring-loaded valve, while additionally performing message of the space of the pipe string above the spring-loaded valve with the annulus of the well, separation of the pipe string above the place of communication with the annulus of the plunger with the valve, the selection of fluid from the space of the pipe string above the plunger with the valve and from the annulus to establish the current pressure in the well, increasing the pressure in the pipe string from the wellhead, transferring pressure to to the spring-loaded valve, opening the spring-loaded valve and communicating the under-packer space with the annulus.

The disadvantages of this method are:

- firstly, a complex process of implementing the method associated with the selection of fluid from the space of the pipe string above the plunger with the valve and from the annulus to establish the current pressure in the well, followed by an increase in pressure in the pipe string from the wellhead;

- secondly, the low quality of the implementation of the method in sand-producing wells, which is associated with a possible leaky fit of a spring-loaded valve due to "clogging" with sand, sludge and dirt of the valve seat;

- thirdly, the low efficiency of cleaning the well and the bottomhole formation zone in wells with sand occurrences allows you to remove sand, sludge, dirt, but does not remove asphaltene-paraffin deposits in the bottomhole formation zone.

The objective of the invention is to simplify the process of implementing the method, as well as improving the efficiency and quality of cleaning the bottom-hole zone of the well.

The problem is solved by a method of cleaning the bottom-hole zone of the well, including lowering the string of tubing with a packer and a pen at the end, separating the well above the interval of perforation of the reservoir by the packer, communicating the sub-packer space with the pipe string with the wellhead, and cleaning the bottom-hole zone of the well.

What is new is that before cleaning the bottomhole zone of the well in the lower part of the pen, radial holes are made, below which a limiter is installed, while the radial holes in the initial position are sealed by a hollow sleeve, which has the possibility of limited axial movement to the stop in the limiter of the pen and fixation in the pen, then, at the wellhead, an assembly consisting of a bottom-up assembly is assembled: from a pen spring-loaded from the protrusion of the tubing string and a packer installed in the tubing string compressor pipes, while using a feather of a smaller diameter than the tubing string, which is placed inside the tubing string with a protruding lower part of the pen from the tubing string, the feather being able to axially move inside the tubing string when contamination of the sump and the possibility of axial movement outward under the action of the return force of the spring, the release of the assembly is performed until the stop of the pen in the contamination of the sump until the weight of the suspension of the tubing string is changed pipes, then pumping the flushing fluid until the weight of the suspension string of the tubing is restored, the operation of lowering the string of the tubing to change weight and flushing to restore weight continues until the weight recovery of the suspension of the string of tubing is stopped, then dumped into the column tubing, the ball that sits on the seat of the hollow sleeve creates excessive pressure in the tubing string, under which the hollow sleeve moves down to the stop in the pen stop, the radial holes of the pen open, the pipe string is lowered so that the radial holes of the pen are opposite the formation roof, then axial movements of the pipe string from the roof to the bottom of the formation at a speed of 0.15 m / min, rinse intervals of perforation of the formation in the volume of the well, plant a packer and perform acid treatment of the formation, for this purpose, a 15% aqueous hydrochloric acid solution is injected and sold with technological fluid in a volume of 0.5 m per 1 m the thickness of the reservoir, unpack the packer, extract the layout at the wellhead and perform technological shutter speed for the reaction, then the reaction products are extracted by swabbing.

Figure 1, 2 and 3 schematically shows the proposed method.

The proposed method is relevant for cleaning the bottom-hole zone of the well and restoring the productivity of the well formation in those cases when sand formation occurs from the formation together with the product, i.e. sand from the formation at intervals of perforation enters the wellbore. From where part of the sand along with the product is taken by the downhole pump at the wellhead, and the other part of the sand settles in the bottom, where it is compacted. As a result, the sump of the borehole decreases and sand and pollution (mud, mechanical impurities) can occur, up to overlapping intervals of perforation of the formation.

The proposed method will allow to clean the well and restore the productivity of the formation due to washing the bottom and intervals of perforation of the formation with subsequent acid treatment of the bottom-hole zone of the formation for one descent of the tool into the well.

The proposed method is as follows.

On a well having a bottom at a depth of 1150 m and a producing formation in a terrigenous reservoir in the interval 1142-1146 m, before conducting work on cleaning the bottom-hole zone of the well and restoring the productivity of the formation 1 (see Fig. 1), wells 2 in the lower part of pen 3 are performed radial holes 4, below which the limiter 5 is installed.

For example, pen 3 is made in the form of a segment of a tubing with a diameter of 60 mm with a wall thickness of 5.0 mm and a length of, for example, 1.5 m, and the stop 5 is made in the form of an inner ring narrowing of pen 3. Cut of pen 1, for example, perform at an angle to the axis equal to 35 °.

Radial holes 4 in the initial position are sealed by a hollow sleeve 6, which has the possibility of limited axial movement until it stops in the stop 5 of pen 3. For example, in pen 3, 10 holes of 8 mm are made in the same row.

Then, at the wellhead 2, an assembly 7 is assembled, consisting of a bottom-up: from a pen 3, spring-loaded by means of a spring 8 from the protrusion 8 'of the tubing string 9 and the packer 10. The packer 10 is installed as a part of the tubing string 9 with this calculation so that it is 10 meters above the formation, i.e. in the interval of 1132 m. For example, the protrusion 8 'is performed in the form of an internal annular narrowing in the pipe of the tubing string 9.

As a packer 10, a packer of any known construction is used, intended for carrying out acid treatments in a well (for example, manufactured by the scientific and production company Packer, Oktyabrsky, Republic of Bashkortostan), a packer with a mechanical axial installation of the appropriate size of the PRO-YaM02-YAG1 brand (M )

A feather of smaller diameter — d, equal to 60 mm, is used than a tubing string with a diameter D of, for example, 89 mm.

The feather 3 is placed inside the tubing string 9 with the protruding lower part of the feather 3 from the tubing string 9.

The feather 3 has the ability to axially move inside the pipe string 9 with an emphasis on sump contamination 11 and the possibility of axial movement outward under the action of the spring return force. The diameter of the spring 8 is selected empirically, providing a return movement of the pen 3 relative to the tubing string 9. For example, the spring 8 is made of spring steel, for example 65G, with a diameter of 15 mm.

For example, in this case, the weight of the tubing string is 82 kN. Launching layout 7 is done until the stop of pen 3 in pollution 11 (sand and dirt leaving the formation together with the product and settling on the bottom of 12 wells 2) of the sump, for example, in the interval 1144 (with the interval of perforation of the formation 1142-1146 m) until the change ( unloading) the weight of the suspension string of the tubing 9 to 77 kN, then pumping the flushing fluid to restore the weight of the suspension of the string of tubing 9 to a weight of 82 kN.

As a washing liquid, fresh water with a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactant type ML-81B is used.

Operations for lowering the tubing string 9 until the weight changes to 77 kN and flushing until the weight recovery is 82 kN are continued until the suspension weight recovery of the tubing string string 9 is completely stopped and the bottom face 12 is reached at a depth of 1150 m. Thus, during the cleaning process wells 1 gradually, combining the unloading of the weight of the tubing string with the restoration of its weight, the well is cleaned of sand, sludge, and mechanical impurities.

Next, the ball 13, which sits on the landing seat of the hollow sleeve 6, is dropped into the tubing string 9 (see FIG. 2).

Using a pump unit, for example, CA-320 creates an excess pressure in the string of tubing 9 equal to, for example, 10 MPa. Under the action of excessive pressure, the hollow sleeve 6 moves downward as far as the stop into the stop 5, the radial holes 4 of pen 3 are opened. After that, the tubing string 9 is lowered from the wellhead 2 so that the radial holes 4 of pen 3 are opposite the roof 14 of formation 1.

Then, by axial movements of the pipe string from the wellhead 2 from the roof 14 to the bottom 15 of the formation 1 at a speed of 0.15 m / min, the perforation intervals of the formation (1142-1146 m) are washed out from the impurities 11 in the well volume equal to 15.72 m ³ .

The bottom-hole zone cleaning of well 2 is continued and the removal of asphaltene-paraffin deposits is started. To do this, put the packer 10 (see figure 3) so that it is at a distance of 10 m above the roof 13 of the reservoir 1.

An acid treatment of the formation 1 in the well 2 is performed. For this, injection is carried out using a low-productivity pumping unit (not shown in Figs. 1, 2, 3) through the tubing string 9 (see Fig. 3) and 15% of the process fluid is pumped an aqueous solution of hydrochloric acid in a volume of 0.5 m ³ per 1 m of formation thickness 1 in the bottomhole zone of the well 2.

In this case, with a thickness of formation 1 equal to 4 m, a 10-15% aqueous hydrochloric acid solution is injected into the column in a volume equal to 2 m ³ , and it is pressed into formation 1 with a process fluid in a volume equal to 6.7 m ³ .

The injection and sale of a 15% aqueous solution of hydrochloric acid into the bottomhole zone of the well is carried out, for example, at a rate of 12-14 l / s under a pressure not exceeding the permissible pressure on the formation, for example 12.0 MPa.

As the process fluid used wastewater with a density of 1100 kg / m ³ . When implementing the method, for example, technical hydrochloric acid (HC1) is used according to GOST 857-95.

As a low-productivity pumping unit, for example, an acid treatment unit for SIN32 brand wells manufactured by Sinergiya-N LLC, providing injection parameters within 11-18 l / s at a maximum pressure of 32 MPa, is used.

Unpack the packer 10 (see FIGS. 1, 2, 3), extract the layout 7 at the wellhead 2. Perform technological shutter speed for response, for example, for 3.0 hours

The reaction products are extracted in any known manner, for example by swabbing (not shown in FIGS. 1 and 2) along the production casing of well 2 (see FIG. 3).

The proposed method for cleaning the bottom-hole zone of the well has a simple technological implementation process, since in one run the tool allows you to clean the well and acidizing the bottom-hole zone of the well, which significantly reduces financial costs, and improving the efficiency and quality of cleaning the bottom-hole zone of the well in the proposed method is achieved by sequential removal of sand, sludge, mechanical impurities from the well first, and then the acid treatment of the bottomhole formation zone.

Claims (1)

A method of cleaning the bottom-hole zone of a well, including lowering a string of tubing with a packer and a pen at the end, separating the well above the perforation interval of the reservoir with a packer, communicating the sub-packer space of the pipe string with the wellhead, cleaning the bottom of the well, characterized in that before by cleaning the bottomhole zone of the well in the lower part of the pen, radial holes are made, below which a limiter is installed, while the radial holes in the initial position are hermetically sealed they dig it out with a hollow bushing, which has the possibility of limited axial movement up to the stop in the pen limiter and fixes it in the pen; then, at the wellhead, a bottom-up assembly is assembled: from a pen spring-loaded from the protrusion of the tubing string and the packer installed in the tubing string -compressor pipes, using a feather of a smaller diameter than the tubing string, which is placed inside the tubing string with the protruding lower part of the pen from the tubing string pipes, while the pen has the possibility of axial movement inside the pipe string when it stops against sump contamination and the possibility of axial movement outward under the action of the spring return force, the assembly is released until the pen stops in the sump contamination until the suspension weight of the tubing string is changed, then pumping flushing fluid until the weight of the suspension string of the tubing is restored; operations to lower the string of tubing before changing the weight and flushing to restore weight continue until the suspension weight recovery of the tubing string suspension is completely stopped, then a ball is dropped into the tubing string that sits on the landing seat of the hollow sleeve, overpressure is created in the tubing string, under which the hollow sleeve is moved all the way down in the pen limiter, while opening the radial holes of the pen, lower the pipe string so that the radial holes of the pen are opposite the roof of the formation, then the axial movements of the column pipes from the roof to the bottom of the formation at a speed of 0.15 m / min, wash the intervals of perforation of the formation in the volume of the well, plant the packer and perform acid treatment of the formation, for this purpose, the technological fluid is injected and sold with a 15% aqueous hydrochloric acid solution in a volume of calculation of 0.5 m ³ per 1 m of the thickness of the reservoir, unpack the packer, extract the layout at the wellhead and perform technological exposure for the response, then produce the reaction products.

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