RU2667239C1 - Method for perforating well and processing bottom-hole carbonate formation zone - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil and gas production industry, to well operation, namely to methods of secondary opening and processing a bottom-hole carbonate formation zone. Method includes running into the production column (PC) of mounted on a tubing string (TS) packer and a hydromechanical piercing punch, installation of a packer in the PC with subsequent opening of the PC by feeding a working fluid into the perforator under pressure, piercing the punches of the perforations in the PC, blurring caverns by feeding the working fluid into the formed perforations of the PC through the jetting channels of the punches of the perforator. Before the running of the TS into PC, the carbonate formation is examined for inflow and the interval with a low oil inflow is determined. Fill the PC well with a viscoelastic composition from the face to the roof of the perforated carbonate formation. At the wellhead at the lower end of the TS, an assembly is collected from the bottom up, including a piercing hydromechanical perforator, a circulation valve, a mechanical packer, a swivel limiter. Run the assembly on the tubing into PC, placing the punch punches in the interval of the carbonate formation with a low inflow. Packer is placed above the top of the carbonate formation. Open the annular valve and put the packer. Piercing hydromechanical perforation is stepped stepwise with increasing pressure of the working fluid in the TS 5.0–8.0–10.0–12.0 MPa to obtain two symmetrical perforations in the PC located at an angle of 180°. At a pressure of 12 MPa, the working fluid is replaced with a 15 % aqueous solution of hydrochloric acid. Injection pressure is adjusted to 15.0 MPa. Through the jetting channels of the piercers, erosion of the caverns is made within 15 minutes. Remaining 15 % aqueous hydrochloric acid solution is poured from the tubing column through the cavities into the bottomhole zone of the carbonate formation. Pressure in the TS is reset to zero and the well is left to the technological holding. Viscoelastic composition and reaction products of a 15 % aqueous solution of hydrochloric acid with the carbonate formation rock are recovered. Through TS holes in the circulation valve and perforations of the PC wells into the bottomhole zone of the carbonate formation, pour in and extrude the solvent in the volume at a rate of 1.0 mper 1 m of the height of the carbonate layer.EFFECT: improved efficiency of erosion of caverns, improved cleaning of the bottomhole zone of the carbonate layer, and improved reliability of the method implementation are provided.1 cl, 5 dwg

Description

The invention relates to the oil and gas industry to the field of well operation, and in particular to methods for the secondary opening and processing of the bottom-hole zone of the carbonate formation.

Known methods of perforating wells using hydromechanical reusable rotary hammers, which are installed in the well on a string of tubing (tubing). They have various types and shapes of working bodies with hydraulic monitor channels and nozzles, which provide hydrodynamic erosion of caverns in the annulus of the well with high-speed jets of the working fluid described in the patents: “Device for creating perforation channels of deep penetration in oil and gas wells” (RU patent No. 2403380, IPC ЕВВ 43/114, published on November 10, 2010 in Bulletin No. 31), "Hydromechanical slotted punch (options)" (patent RU No. 2247226, IPC ЕВВ 43/112, published on 02.27.2005, in Bulletin No. 6).

Common disadvantages of the methods using these devices are:

- a decrease in the filtration properties of the formation, since when the caverns are washed out, particles of cement stone and rock — colmatant — rush deeper into the formation and clog fluid-conducting channels;

- low efficiency of erosion of caverns with a working fluid (process water), which does not allow maximizing the size of the cavity.

Also known is a method of acid treatment of a carbonate formation (patent RU No. 2535538, IPC ЕВВ 43/27, published on December 20, 2014 in bull. No. 35), including preliminary washing of the well with an organic solvent, then sequential injection of an organic solvent, a film-forming solution into the well , which is used as a 5-30% solution of fuel oil in a hydrocarbon solvent in a volume of 0.5-2.5 m ³ / m perforated thickness of the reservoir, an organic solvent buffer in an amount of 3-6 m ³ and an acid solution in an amount of 1- 5 m ³ / m apertured then and subsequent formation of tires prodavku injected into the formation fluids.

The disadvantages of this method are:

- low quality treatment of the bottom-hole formation zone (PZP), due to acid treatment through existing perforations, i.e. without additional opening of the production casing (EC) with hydromechanical piercing perforation;

- low processing efficiency of PZP, the lack of erosion of caverns before acid treatment, which does not allow processing fluid-conducting channels deep in the PZP.

The closest in technical essence and the achieved result is a method of hydromechanical perforation of wells in a depression (patent RU No. 2612702, IPC ЕВВ 43/114, publ. 03/13/2017 in bull. No. 8), in which the descent into the EC mounted on the column Tubing of the jet pump, packer and hydromechanical piercing punch. The packer is installed in the EC with the subsequent opening of the EC by feeding the working fluid into the perforator under pressure with the formation of perforation holes with perforator punches. Caverns are washed out by supplying working fluid to the formed perforations through the hydraulic monitor channels of the perforator punches. The colmatant is recovered from the PPP by creating depression with a jet pump in the under-packer space. Autopsy EC carried out in two stages. At the first stage, the formation of technological perforations without erosion of the cavities is carried out. At the second stage, the formation of perforation holes is carried out, through which caverns are washed out, at the same time depression is created by the jet pump in the under-packer space and the colmatant is extracted through technological perforation holes.

The disadvantages of this method are:

- low efficiency of erosion of caverns with a working fluid (process water), which does not allow maximizing the size of caverns;

- poor quality of cleaning the bottomhole formation zone of wells, including for wells with asphaltene-paraffin deposits (ASPO), caused by the lack of processing of the bottomhole zone after erosion of the caverns, because of this it is impossible to increase the flow of oil from the fluid-conducting channels of the formation through the caverns into the well;

- low reliability of the implementation of the method associated with the loss of tightness of the hydraulic packer during the implementation of the method;

- the duration of the implementation of the method associated with the extraction of colmatant from the BCP, since for this it is first necessary to pump out the liquid from the entire annulus (the hydraulic action packer is unpacked during pumping) using a jet pump, in connection with this the high financial costs of implementing the method.

The technical objectives of the invention are to increase the efficiency of erosion of the caverns, the quality of the cleaning of the bottomhole formation zone of the carbonate formation, as well as improving the reliability of the packer and reducing financial costs when implementing the method.

The stated technical problems are solved by the method of perforating the well and treating the bottom-hole zone of the carbonate formation, including the descent into the production string - EC mounted on the string of tubing - tubing packer and hydromechanical piercing puncher, installing the packer in the EC followed by opening the EC by applying pressure to the perforator the working fluid with piercing the perforation holes in the EC with punches, blurring the cavities by feeding the working fluid into the formed perforations EC through the hydraulic channels of the punch drills.

What is new is that before lowering the tubing string into the EC, the carbonate formation is examined for inflow and the interval with low oil inflow is determined, then the EC wells are filled with viscoelastic composition from the bottom to the top of the perforated carbonate formation, then from the bottom to the bottom of the tubing string the assembly is assembled, including a piercing hydromechanical perforator, a circulation valve, a mechanical packer, a swab limiter, the assembly is lowered onto the tubing string in the EC, while the perforator punches They are placed in the interval of the carbonate formation with a low inflow, the mechanical packer is placed over the roof of the carbonate formation, then the annular valve is opened and the mechanical packer is planted, after which piercing hydromechanical perforation is performed stepwise with increasing pressure of the working fluid in the tubing string 5.0-8.0-10 , 0-12.0 MPa to obtain two symmetrical perforation holes in the EC, located at an angle of 180 °, then at a pressure of 12 MPa, the working fluid is replaced with a 15% aqueous solution of hydrochloric acid, the injection pressure is adjusted to 15.0 MPa, through the hydromonitor channels of the perforator punches, the caverns are washed out with a 15% aqueous hydrochloric acid solution for 15 minutes, after which the residues of the 15% aqueous hydrochloric acid solution from the tubing string are pushed through the caverns into the bottom-hole zone of the carbonate formation, then discharged the pressure in the tubing string is zero and the well is left for technological shutter speed, then the viscoelastic composition and reaction products of the 15% aqueous hydrochloric acid solution with the rock of the carbonate formation are removed, for which a ball is dropped into the tubing string increase the pressure in the tubing string to open the holes in the circulation valve, then swab down to the tubing string and swab through the tubing string to extract the viscoelastic composition and reaction products of a 15% aqueous hydrochloric acid solution with the formation rock, then through the tubing string through the holes in the circulation tubing the valve and the perforations of the EC wells into the bottomhole zone of the carbonate formation are pumped and forced through the solvent in the amount of 1.0 m ³ per 1 m of the height of the carbonate formation.

In FIG. 1-5 schematically shows the proposed method.

The proposed method is implemented as follows.

The perforated carbonate formation 1 (see FIG. 1) is examined for oil inflow and the interval with low inflow is determined. For example, an open carbonate formation 1 in a well has a height of 8 m in the range of 1255-1263 m. According to the results of thermal debitometry, it was determined that in the range of 1261-1263 m the inflow (rate) of oil from the carbonate formation is lower than the average production rate of carbonate formation 1. For example, the average oil production (inflow) in the reservoir is 15 tons / day, and in the interval 1261-1263 m, oil production is 5 tons / day. Next, work is carried out to increase the oil recovery of the carbonate formation 1.

To do this, lower the technological column of pipes (not shown in Fig. 1-5) and fill EC 2 (see Fig. 1) from the bottom to the top of the carbonate formation 1 with any known viscoelastic composition 3, for example, described in patent RU No. 2620674 "Composition for isolating the annular space of wells" MPK Е21В 33/138, publ. 05/29/2017, in Bulletin No. 16. The process pipe string is removed.

Next, at the wellhead, at the lower end of the tubing string 4 (see Fig. 2), an assembly is assembled from bottom to top, including a piercing hydromechanical perforator 5 (hereinafter referred to as a perforator), a circulation valve 6, a mechanical packer 7 and a free stop 8. In this case, the condition

where d ₁ is the inner diameter of the circulation valve 6, mm;

d ₂ - inner diameter of the swab limiter 8, mm.

As a perforator 5, any known device is used, which allows to sequentially carry out punctures in EC 2 using a punch and washing out the caverns through hydraulic monitor channels made in the same punch. For example, use the device to create perforation channels in the well, described in patent RU No. 2487990, IPC EV 43/114, publ. 07/20/2013 in bull. No. 20.

As a mechanical packer 7, any known packer with a mechanical axial or radial fit is used.

The layout is lowered on the tubing string 4 to EC 2 (see FIG. 2). Punches (cutters) 9 'and 9' 'of the perforator 5 are located in the interval of the carbonate formation 1 with a low inflow of 1261-1263 m, and the mechanical packer 7 is placed above the roof of the carbonate formation 1.

An annular valve 10 is opened (see Fig. 3) and a mechanical packer 7 is planted.

An open gate valve 10 allows you to control the tightness of the mechanical packer 7 during the implementation of the method. If the packer is not sealed, the equipment is dismantled and re-launched as described above.

Then, by pumping the working fluid along the tubing string 4, piercing hydromechanical perforation is performed, i.e. an EC 2 is opened in the interval of the carbonate formation 1 with a low oil influx. As the working fluid, wastewater with a density of ρ = 1100 kg / m ^{3 is used} .

For this, for example, using a cementing unit CA-320 (not shown in Fig. 1-5), the pressure of the working fluid in the tubing string 4 and perforator 5 is first stepwise created up to 5.0 MPa with a delay of 10 seconds, then the pressure is raised to 8 , 0 MPa with a delay of 10 seconds, then raise the pressure to 10.0 MPa with a delay of 10 seconds, then raise the pressure to 12.0 MPa. Thus, two symmetrical perforations 11 'and 11' '(see FIG. 3) are obtained in EC 2 located at an angle of 180 ° relative to each other.

Then, without relieving pressure in the tubing string 4 (without removing the punches 9 'and 9''of the perforator 5 from the perforation holes 11' and 11 '' in EC 2), a 15% aqueous hydrochloric acid solution is pumped into the tubing string 4, i.e. e. replace the working fluid in the tubing string 4 with a 15% aqueous hydrochloric acid solution. The injection pressure through the tubing string 4 is brought to 15.0 MPa and through the hydraulic channels 12 'and 12''of the perforator 5 drills, caverns 13 ₁ ' and 13 ₁ '' are washed out, respectively, with a 15% aqueous hydrochloric acid solution for 15 minutes. Due to the reaction of the acid with the rock of the carbonate formation 1, the caverns 13 ₁ 'and 13 ₁ ''gradually increase in size to 13 ₂ ' and 13 ₂ ''. After that, the residues of a 15% aqueous hydrochloric acid solution from the tubing string 4 are squeezed using a process fluid, for example, waste water with a density of ρ = 1100 kg / m ³ into the bottom-hole zone of carbonate formation 1 through the 12 ”and 12 ″ hydraulic punch holes of a perforator 5 and through cavities 13 ₁ 'and 13 ₁ ''and 13 ₂ ' and 13 ₂ '', increasing the size of the caverns to 13 ₃ 'and 13 ₃ ''.

The efficiency of cavern erosion is increased by increasing the filtration properties of the carbonate formation, since a 15% aqueous hydrochloric acid solution is used, which allows one to maximize the size of eroded caverns.

The viscoelastic composition 3 located in the EC 2 of the well does not allow the 15% aqueous hydrochloric acid solution to penetrate into the existing perforation intervals 14 of the carbonate formation 1 during the erosion of the caverns 13 ', 13' ', 13' ''.

After that, the pressure in the tubing string 4 and perforator 5 is dropped to zero and the well is left for technological shutter speed, for example, for 8 hours.

Then, the viscoelastic composition and reaction products of a 15% aqueous solution of hydrochloric acid are extracted with the rock of carbonate formation 1 located under mechanical packer 7 in EC 2.

To do this, drop the ball 15 (see Fig. 4) into the tubing string 4. Since condition (1) is met: d ₁ <d ₂ , the ball 15 freely passes through the swab stop 8 and sits on the sleeve 16 of the circulation valve 6.

Using a cementing unit CA-320 (not shown in Fig. 1-5), the pressure in the tubing string 4 is increased (see Fig. 4) until the shear screw 17 is broken and holes 18 open in the circulation valve 6, for example, to 7.0 MPa As a result, the sleeve 16 of the circulation valve 6 moves down together with the ball 15 until it stops at the upper end of the perforator 5, while the holes 18 in the circulation valve 6 are opened.

Swab 19 is lowered on the geophysical cable 20 into the tubing string 4. Swabbing the tubing string 4 removes the viscoelastic composition 3 and the reaction products of a 15% aqueous hydrochloric acid solution with the rock of carbonate formation 1. For example, 15 m ^{3 of} fluid is extracted by swabbing. At the end of the swab, 4 swabs 19 are removed from the tubing string on the geophysical cable 20.

Further along the tubing string 4 through the holes 18 (see Fig. 5) in the circulation valve 6, the perforation holes 11 ', 11''and the existing perforation holes 14 EC 2 wells are pumped into the bottom-hole zone of the carbonate formation 1 and pressed through with process fluid, for example, sewage water with a density of 1100 kg / m ³ , the solvent in the amount of 1.0 m ³ per 1 m of the height of the carbonate reservoir 1.

When the height of the carbonate formation 1, equal to 8 m, is pumped and forced through the tubing string 4: 1.0 m ³ ⋅ 8 m / m = 8 m ^{3 of} solvent.

As a solvent, any known solvent is used to remove paraffin from the bottom zone of the carbonate formation, for example, MIA-prom or Intat solvent. Deposition of paraffin deposits is the main reason for the decrease in the filtration characteristics of the bottomhole formation zone of production wells, therefore, solvent treatment can improve the filtration characteristics of the bottomhole zone of production wells.

At the end of the solvent treatment of the carbonate formation 1, the mechanical packer 7 is unpacked and the layout on the tubing string 4 is removed from the EC 2 wells. The process of implementing the method is over.

The quality of cleaning the bottom-hole zone of the carbonate formation is improved, since after erosion of the caverns, the PPP is treated with solvent, both through washed-out caverns, and the existing intervals of perforation of the carbonate formation, which allows to increase the inflow (flow rate) of products from the fluid-conducting channels of the formation through caverns and perforations into the well .

The reliability of the implementation of the method increases, since the injection and delivery of a 15% aqueous solution of hydrochloric acid and solvent is carried out under the control of the tightness of the mechanical packer. A mechanical packer, unlike a hydraulic packer, is not unpacked and does not require the creation of hydraulic pressure in it to maintain tightness.

The duration of the extraction of colmatant from the bottom-hole zone of the carbonate reservoir and the viscoelastic composition is reduced, since the extraction is carried out only from the sub-packer zone of the planted mechanical packer, and not from the entire annulus, and therefore the financial cost of implementing the method is reduced.

The proposed method of perforating a well and treating a bottom-hole zone of a carbonate formation allows:

- increase the efficiency of erosion of caverns;

- to improve the quality of cleaning the bottom-hole zone of the carbonate formation;

- improve the reliability of the implementation of the method;

- reduce financial costs.

Claims (1)

A method of perforating a well and treating a bottom zone of a carbonate formation, including lowering a packer and a hydromechanical piercing puncher fixed to a string of tubing tubing into a production string (EC), installing the packer in the EC with subsequent opening of the EC by applying hydraulic fluid to the perforator piercing perforation holes in EC with punches, blurring cavities by supplying working fluid to formed perforation holes of EC through hydraulic monitor channels a perforator, characterized in that before lowering the tubing string into the EC, the carbonate formation is examined for inflow and the interval with a low oil flow is determined, then the EC wells are filled with viscoelastic composition from the bottom to the roof of the perforated carbonate formation, then at the wellhead to the lower end of the tubing string from the bottom an assembly is assembled upwards, including a piercing hydromechanical perforator, a circulation valve, a mechanical packer, a swab limiter, the assembly is lowered onto the tubing string in the EC, while the forator is placed in the interval of the carbonate formation with a low inflow, the mechanical packer is placed over the roof of the carbonate formation, then the annular valve is opened and the mechanical packer is planted, after which the hydromechanical perforation is perforated stepwise with increasing pressure of the working fluid in the tubing string 5.0-8.0- 10.0-12.0 MPa to obtain two symmetrical perforations in the EC, located at an angle of 180 °, then at a pressure of 12 MPa, the working fluid is replaced with a 15% aqueous solution of hydrochloric acid, adjusted to a pressure It is injected up to 15.0 MPa, through the hydromonitor channels of the perforator punches, the caverns are washed out with a 15% aqueous hydrochloric acid solution for 15 minutes, after which the residues of the 15% aqueous hydrochloric acid solution from the tubing string are pressed through the caverns into the bottom-hole zone of the carbonate formation then the pressure in the tubing string is reduced to zero and the well is left for technological shutter speed, then the viscoelastic composition and the reaction products of the 15% aqueous hydrochloric acid solution with the carbonate formation rock are removed, for which purpose into the tubing string, increase the pressure in the tubing string until the openings in the circulation valve open, then swab into the tubing string and lower the viscoelastic composition and reaction products of the 15% aqueous hydrochloric acid solution with the formation rock by swabbing along the tubing string, then through the tubing string through the holes in the circulation valve and the perforation holes of the EC wells are pumped into the bottomhole zone of the carbonate formation and the solvent is forced through in the amount of 1.0 m ³ per 1 m of the height of the carbonate formation.

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