RU2534284C1 - Method of oil formation treatment - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method of oil formation treatment includes running of a string with a packer to the well, setting of the packer above the oil formation and subsequent injecting and flushing through the string to the oil formation of hydrocarbon solvent and acid agent in volumes exceeding filtration resistance in the formation zone remote from the well over the same value in the bottomhole zone, process withheld and removal of waste reaction products from the treated area by depression impact on the well. Then the pipe string at the well mouth below the packer is equipped with impulse liquid pulsator. At that a valve is mounted between the packer and liquid pulsator. An ejector pump with a feedthrough accessory is mounted above the packer. The string is run in to the well so that the packer is placed above the formation. Hydrocarbon solvent is injected to the string in pulsed mode, the packer is set, and hydrocarbon solvent is flushed to the formation by process fluid under pressure not exceeding the permitted pressure to the formation. The packer is released and the well remains under exposure. Then the well is washed out and acid solution is injected to the well, the packer is set, acid solution is flushed to the formation by process fluid under pressure not exceeding the permitted pressure to the formation. The packer is released and the well remains under exposure. After exposure period the valve is actuated and impulse liquid pulsator is cut off. The packer is released, the string is run in additionally so that radial openings of the valve are opposite the formation; the feedthrough accessory is removed from the ejector pump and a blind plus is installed instead. Then the packer is set, and reaction products are extracted by process fluid injecting along the string through the ejector pump and the well is completed through its tubing-casing annulus above the packer.

EFFECT: increased efficiency of the bottomhole zone treatment, excluded damage of the well casing string.

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Description

The invention relates to the oil industry, in particular to methods for treating an oil reservoir in wells with low permeability terrigenous reservoirs.

A known method of processing the bottom-hole zone of an oil reservoir by cyclic exposure, including pumping acid into the zone of the reservoir, holding the process and extracting the spent solution by creating a depression in the well (see, for example, “Instructions for developing wells by creating controlled cyclic depressions on the formation using jet pumps: RD 39-2-130686 ". M.: Ministry of the oil industry, 1985).

The disadvantage of this method is its lack of effectiveness, since it does not provide sufficient depth and completeness of the treatment of the bottom-hole zone.

A known method of acid treatment of the bottom-hole zone of an oil reservoir (patent RU No. 2395682, IPC E21B 43/27, publ. 02/20/2010), including the injection into the reservoir of an acid system - an ester of acetic acid and an aqueous solution of hydrochloric acid, technological shutter speed up to producing acetic acid in the formation and reacting the mixture of acids with the rock of the formation, putting the well into operation, and first, the well and the bottomhole reservoir are cleaned of asphalt-resin-paraffin deposits by washing with a mutual solvent or mixture it and the ester of acetic acid, after injecting the acid system, they are forced into the reservoir, the acid system additionally containing a mutual solvent with a ratio of ester of acetic acid: mutual solvent: a solution of inhibited hydrochloric acid equal to 1: 0.5: 3.5, butyl alcohol or a by-product of the production of butyl alcohols, isolated at the stage of rectification with a boiling point in the range of 40-110 ° C, is used as a mutual solvent, and ethyl ester is ethyl ester tsetat or butyl acetate, an aqueous solution of an inhibited hydrochloric acid - 3-15% solution, the planned volume last pumped in two portions at an interval of one hour.

The disadvantages of this method are:

- firstly, the low efficiency of the formation treatment, since the increase in the permeability of the bottomhole zone of the well has a short-term effect and quickly decreases, since the reagent is not able to penetrate deep into the pores of the formation, due to the impossibility of pulse injection of both solvent and acid into the formation;

- secondly, the low quality of cleaning the bottom-hole zone of the formation from the reaction products of chemical reagents with the formation and the inability to develop the formation of the well in one round-trip pipe string;

- thirdly, a complex technological process, time-consuming and labor-intensive, associated with the injection of various types of chemical reagents in several portions, in addition, this process requires strict observance of the pumping time and stops.

The closest in technical essence and the achieved result is a method of processing the bottom-hole zone of the oil reservoir (patent RU No. 2346153, IPC E21B 43/27, publ. 02/10/2009), including the descent of the pipe string with the packer into the well, injection into the pipe string and the injection into the reservoir with the packer planted above the oil reservoir of an acid reagent containing hydrochloric and hydrofluoric acids and a surfactant through the well into the zone of the reservoir in volumes that ensure excess filtration resistances remote from the importance of the formation zone over those in its bottom-hole zone, technological exposure and removal of the spent reaction products from the treated zone by depressing the well by swabbing, the acid reagent additionally contains a corrosion inhibitor and a solvent, and fresh water or industrial water are taken as a squeezing liquid, or industrial water with the addition of a detergent, or oil, or oil with an oil-soluble demulsifier, and with a value of the conditional pick-up coefficient c Azhinov kpc least 2.5 removal of spent reaction products is carried out in a well operation mode, and at least 2.5 kpc removal of spent reaction products is carried out by force, when the CRC productivity index of at least 0.5 m ³ / day · atm forced extraction products reactions from the treated zone are stopped, and a hydrocarbon solvent is pumped into the formation before the acid reagent.

The disadvantages of this method are:

- firstly, the depressive effect on the well during the extraction of reaction products from the treated zone and development of the well are carried out by swabbing using a geophysical elevator, and this is a time-consuming and labor-intensive process. In addition, with the depressive effect of swabbing, there is a high probability of damage to the casing of the well;

- secondly, the complex technological process of implementing the method associated with the injection of various types of chemical reagents in several portions, in addition, this process requires strict observance of the pumping time and stops;

- thirdly, the low efficiency of processing the bottom-hole zone of the oil reservoir, since increasing the permeability of the bottom-hole zone of the well has a short-term effect and rapidly decreases, since the reagent is not able to penetrate deep into the pores of the formation, due to the impossibility of pulsed injection of both solvent and acids.

The technical task of the proposal is to simplify the process of implementing the method, increase the efficiency of processing the bottom-hole zone of the reservoir due to the pulsed treatment of the bottom-hole zone of the oil reservoir, as well as the depressive effect on the bottom-hole zone of the oil reservoir in a sparing mode with the exception of damage to the casing of the well.

The problem is solved by a method of treating an oil reservoir, including lowering a string of pipes with a packer into the well, planting the packer above the oil reservoir, and sequentially pumping and selling the hydrocarbon solvent and acid reagent through the tubing into the oil reservoir in volumes that exceed the filtering resistance in the zone remote from the well formation above those in its bottom-hole zone, technological exposure and removal of spent reaction products from the treated zone by depression about the impact on the well.

What is new is that at the wellhead, the pipe string below the packer is equipped with a pulsed fluid pulsator, while a valve is installed between the packer and the fluid pulser, an ejector pump with a nozzle is installed above the packer, the pipe string is lowered into the well so that the packer is located above the reservoir, a hydrocarbon solvent is pumped into the pipe string in a pulsed mode, a packer is planted, a hydrocarbon solvent is forced into the formation with a process fluid under a pressure not exceeding the permissible pressure on the formation , tear down the packer and leave the well for technological shutter speed, then wash the well and pump the acid solution into the pipe string, put the packer, push the acid solution into the reservoir with technological fluid under a pressure not exceeding the permissible pressure on the reservoir, break the packer and leave the well for technological shutter speed, at the end of the technological exposure, the valve is actuated and the pulsed pulsator of the liquid is cut off, then the packer is torn off, the pipe string is pulled in such a way that Once opposite the reservoir, a nozzle is removed from the ejector pump and a blind nozzle is installed in it, after which the packer is planted and the process fluid is pumped through the pipe string through the ejector pump, the reaction products are extracted and the well is developed in the annulus above the packer.

Figure 1-4 sequentially depicts the implementation process of the proposed method for processing an oil reservoir.

The extraction of reaction products and well development using an ejector pump, in contrast to swabbing, is a gentle way of depressing the well, since pressure reduction occurs only in the sub-packer interval, normal hydrostatic pressure is maintained along the rest of the wellbore, which completely eliminates the possibility of casing ejection or damage

The proposed method of processing an oil reservoir is implemented as follows.

The pipe string 1 (see Fig. 1), for example, a column of 73 mm tubing (tubing) at the wellhead 2 below the packer 3 is equipped with a pulse fluid pulsator 4 (of any known design), between Packer 3 and pulsed pulsator fluid 4 set the valve 5.

As packer 3, a packer of any known design is used, intended for carrying out technological operations (flushing, acid treatments, etc.) in a well (for example, manufactured by Oil and Gas Engineering - Service LLC, Neftekamsk, Republic of Bashkortostan, Russia ) a mechanical packer of the corresponding standard size of brand 2 FDA.

As a pulsed fluid pulsator 4, any known device for pulsed fluid injection into a formation described in the utility model patent RU No. 115402, IPC E21B 28/00, B 43/18, publ. in bull. No 12 on April 27, 2012

As a valve 5, for example, a sleeve 6 is used (see Figs. 1-3), equipped with a landing saddle 7 on top for a ball 8 being dropped from the wellhead into the pipe string 1 and hermetically fixed in the pipe string 1 with a shear element 9 opposite the radial holes 10 .

Above the packer 3 (see FIGS. 1 and 2), an ejector pump 11 with a nozzle 12 is installed.

As an ejector pump 11, an ejector device for studying wells of UEGIS-2 manufactured by LLC TNG-Group in Bugulma, the Republic of Tatarstan, Russia is used.

The pipe string 1 is lowered into the well 2 so that the packer 3 is located above the formation 13, and the lower end of the pulsed fluid pulsator 4 is opposite the perforation intervals 14 of the formation 13.

Next, using a pump unit with an open central valve (not shown in FIGS. 1, 2, 3, 4), a hydrocarbon solvent, for example, Nefras A-130/150, is pumped into a pipe string 1 (see figure 2) in a volume of 2 , 5 m, then packer 3 is planted (see FIG. 2) and the hydrocarbon solvent is forced into the reservoir 13 at intervals of perforation 14 with the process fluid under a pressure less than the permissible pressure on the reservoir 13.

For example, the permissible pressure on the formation is 17 MPa, then the hydrocarbon solvent is sold under a pressure of ≤17.0 MPa.

Then tear the packer 3 and carry out technological exposure to the reaction of the hydrocarbon solvent with the formation rock, for example, for 4 hours

As a hydrocarbon solvent used, for example, Nefras A-130/150 (GOST 10214-78).

At the end of the technological exposure, a direct washing of the well 2 is performed, i.e. supplying the process fluid to the pipe string 1 in one and a half volume of the well, for example, 22 m ³ .

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

The injection of a hydrocarbon solvent into the formation improves the efficiency of the subsequent acid treatment of the formation, since formation contaminants react with the acidic solution in a diluted state rather than in a solid state.

Next, any known acidic solution, for example a clay acid solution represented by mixtures of hydrochloric and hydrofluoric acids, for example a mixture of 12% HCl + 5% NH ₄ F · HF, is pumped into the pipe string 1.

They pack the packer, push it into the formation with process fluid under pressure less than the allowable pressure on the formation 13, i.e. the acid solution is pumped under a pressure of ≤17.0 MPa.

In the process of implementation of the method using synthetic hydrochloric acid technical (HCl) according to GOST 857-95. Also, ammonium fluoride acid (NH ⁴ F · HF), hydrofluoric acid according to GOST 9546-75.

After waiting for the reaction of the acid solution with the formation rocks, valve 5 is activated (see Fig. 3). To do this, drop a metal ball 8 into the pipe string 1, which sits on the seat 7 of the valve sleeve 6 of the valve 5. Then, using a pump unit, for example, cementing unit ЦА-320, hydraulic pressure is created, for example, 8 MPa in the pipe string 1 above valve 5 (see figure 3).

Under the action of the hydraulic pressure of the sleeve 6, the valve 5 moves down and opens the radial holes 10. As a result, the pulsating fluid pulsator 4 is cut off.

Then, the packer 3 is torn off, the pipe string 1 is lowered so that the radial holes 10 of the valve 5 are opposite the formation 13.

A fishing tool, for example, an inner tube, is lowered, and a nozzle 12 is removed from the ejector pump 11 by gripping it on the inner surface 15.

After that, a blind nozzle 16 is installed in the pipe string 1 (see FIG. 4), and a blind nozzle 16 is transferred to the pipe string 1 by pumping the process fluid until it fits into the ejector pump 11.

Next, the packer 3 is planted in the pipe string 1 and pumping the process fluid through the pipe string 1 through the ejector pump 11, the reaction products are extracted and the well is developed through the annulus 17 of the well 2 above the packer 3.

The use of an ejector pump for depressive effects during the extraction of reaction products and well development, in contrast to the prototype, where the depressive effects are swabbed, eliminates the occurrence of gas-air mixtures in the well, while the required bottomhole pressure is set for 2-3 minutes, which is maintained during product recovery the reaction and development of the well, which reduces the duration of the technological process of depressive effects and reduces labor costs.

The proposed method for processing an oil reservoir allows to simplify the technological process of implementing the method, to increase the efficiency of processing the bottom-hole zone of the reservoir due to pulsed processing of the bottom-hole zone of the oil reservoir. In addition, the depressive effect on the bottom-hole zone of the oil reservoir is carried out using an ejector pump, which allows the gentle reaction of acid treatment of the bottom-hole zone of the reservoir to be extracted (gently) and development of the well is carried out, as well as damage to the casing of the well can be eliminated.

Claims (1)

A method of treating an oil reservoir, including lowering a string of pipes with a packer into the well, planting the packer above the oil reservoir, and sequentially injecting and selling the hydrocarbon solvent and acid reagent in the oil reservoir in volumes that exceed the filter resistances in the formation zone remote from the well above those in its bottom-hole zone, technological exposure and removal of spent reaction products from the treated zone by depressing the well, excellent In that, at the wellhead, the pipe string below the packer is equipped with a pulsed fluid pulsator, while a valve is installed between the packer and the fluid pulser, and an ejector pump with a nozzle is installed above the packer, the pipe string is lowered into the well so that the packer is located above the reservoir, in the pipe string is pumped in a pulsed mode with a hydrocarbon solvent, a packer is planted, a hydrocarbon solvent is pushed into the formation with a process fluid under a pressure not exceeding the permissible pressure on the formation, stall the packer is removed and the well is left for technological shutter speed, then the well is washed and the acid solution is pumped into the pipe string, the packer is planted, the acid solution is pushed into the formation with technological fluid at a pressure not exceeding the permissible pressure on the formation, the packer is torn off and the well is left for technological shutter speed, at the end of the technological exposure, the valve is actuated and the pulsed pulsator of the liquid is cut off, then the packer is torn off, the pipe string is pulled so that the radial openings of the valve are located opposite the reservoir, a bore nozzle is removed from the ejector pump and a blind nozzle is installed in it, after which the packer is planted and the process fluid is pumped through the pipe string through the ejector pump, the reaction products are extracted and the well is developed through the annulus above the packer.

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