RU2506422C1 - Development method of bottom-hole zone - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil industry. Method of bottom-hole zone treatment includes running-in of pipe string with packer to perforated interval, washing of the well equipped with master and casing valves, packer seating above the formation and treatment of the well by pumping of hydrochloric acid solution through the pipe string in pulsed mode, process exposure for reaction and extraction of reaction products. Optimal intake of the formation is set before treatment of bottom-hole zone. Then the pipe string at the well mouth below packer is equipped with impulse liquid pulsator, at that a valve is mounted between the packer and liquid pulsator. The pipe string is run-in into the well so that packer is located above the formation, thereafter with open master and casing valves the well is flushed by straight ring circulation during 10-20 minutes. The casing valve is closed and process liquid is pumped into the formation under pressure that does not exceed permitted pressure to the production string during 5-10 minutes. The casing valve is closed and process liquid is drained from the well. Washing and drainage of process liquid is repeated 3-5 times. Then hydrocarbon solvent is pumped to the pipe string, the packer is seated, hydrocarbon solvent is pressed into the formation by process fluid under pressure not exceeding permitted pressure to the formation; the well is subjected to process exposure. When process exposure is completed the valve is actuated, liquid pulsator is cut off, the packer is released, the pipe string is run-in additionally so that radial openings of the valve are located opposite the formation; and then the well is washed out by process liquid at open master and casing valves by straight ring circulation during 2 hours. At that casing valve is closed partially periodically till bottom hole pressure increases per 3-5 MPa in comparison with the initial pressure value transparent liquid appears; at that permitted pressure for production string is not exceeded. Thereafter hydrochloride acid solution and acid-clay cut mud heated up to temperature of 40-50°C is pumped to the pipe string, the packer is seated, hydrochloride acid solution and acid-clay cut mud are pressed to the formation by process liquid under pressure that does not exceed permitted pressure on formation, the packer is released and the well remains under exposure, then by return ring circulation reaction products are washed out till transparent liquid appears, hereupon actual intake of the formation is defined.EFFECT: increasing efficiency of bottom-hole zone treatment due to increase of bottom-hole zone intake with simultaneous simplification of process and reduction of treatment costs and duration.5 dwg

Description

The invention relates to the oil industry and may find application in the processing of the bottom-hole zone of a well.

A known method of processing a formation (patent RU No. 2135760, IPC E21B 43/25, published in Bulletin No. 24 dated 27. 08.1999), based on the fact that the volume of the processing interval relative to the bottom of the well is preliminarily fixed, the reagent is injected in a pulsating mode: injection at a pressure of receiving the reagent perforation interval - technological exposure at atmospheric pressure, the mode is repeated when the pressure of injection of the reagent is reduced until the pressure of the working injectivity of the well is reached, the remaining volume of the reagent is pumped when installed msya pressure exposure process is carried out and recovering the reaction products and contaminants by swabbing prior to selecting liquid in excess of not less than three times the volume of the injected reagent.

The disadvantages of this method:

- firstly, increasing the permeability of the bottomhole zone of the well has a short-term effect and decreases rapidly, since the reagent is not able to penetrate deep into the pores of the reservoir due to the mudding of the bottomhole zone;

- secondly, the low efficiency of the formation treatment in a highly accumulated bottomhole zone of the well.

The closest in technical essence is the method of processing the bottom-hole zone of the well (patent RU No. 2312211, IPC E21B 43/27, published in Bulletin No. 34 of December 10, 2007), including pulsed injection of a solution of hydrochloric acid, injection of a solution of hydrochloric acid into continuous operation, technological shutter speed for reaction and extraction of reaction products by swabbing. According to the invention, pre-washing the well with oil, updating the perforation of the reservoir at the rate of at least 5 holes / m, pumping a solution of hydrochloric acid into the well in a volume of 1.5-2.0 m ³ and technological exposure in the bath mode for 1 , 5-3.5 h, then 4-6-fold pulsed injection into the reservoir of the first portion of hydrochloric acid in a volume of 1.5-3.5 m in a cycle mode is performed: 0.8-1.2 min injection at a pressure of 1 -4 MPa, holding for 4-6 minutes for reaction, complete the injection of acid volume in a constant mode, produce a 4-6-fold pulse the second injection of a solution of hydrochloric acid into the reservoir in a volume of 2.5-3.5 m in a cycle mode: 0.8-1.2 min injection at a pressure of 1-4 MPa, holding for 4-6 minutes for reaction, complete the volume injection acids in a constant mode, carry out a technological exposure of 2.5-3.5 hours for reaction, inject a third portion of a solution of hydrochloric acid into the formation at a rate of 0.4-0.5 m ^{3 /} pm in continuous mode at a pressure of 1- 4 MPa, carry out technological exposure for the response of 2.5-3.5 hours, conduct 4-6-fold pulsed injection into the reservoir of a fourth portion of the hydrochloric solution slots based 0.8-1.0 m ³ /p.m producing formation in cycle time: 6.4 min injection at a pressure of 1-4 MPa, 4-6 min to extract response download completed continuously perform the process the reaction time is 2.5-3.5 hours, a pulsed 4-6-fold pulsed oil is pumped in the cycle mode: 0.8-1.2 minutes injection, exposure 4-6 minutes, after which the reaction products are extracted by swabbing. The disadvantages of this method are:

- firstly, a complex technological process, time-consuming and labor-intensive, associated with the injection of acid in several portions, in addition, this process requires strict observance of the injection and stopping times at a certain injection pressure;

- secondly, the additional costs of flushing the well with oil, which does not allow to qualitatively clean the bottom-hole zone of the wellbore, and for updating the perforation of the productive formation at the rate of at least 5 holes / pm significantly increase the cost of implementing the method;

- thirdly, the low efficiency of the formation treatment, which consists in 4-6-fold pulsed injection of a certain volume of hydrochloric acid into the formation in cycles: 0.8-1.2 min injection at a pressure of 1-4 MPa, holding 4-6 min for response, while long-time injection cycles in a pulsed mode with subsequent even longer exposure do not allow the hydrochloric acid solution to penetrate deep into the reservoir;

- fourthly, the reaction products of the acid are removed by swabbing, which requires the involvement of a swab lift with a team of operators, and this is an additional cost for the implementation of the method.

The technical objectives of the proposal are to increase the efficiency of formation treatment by increasing the permeability of the formation before processing, as well as simplifying the process of implementing the method, reducing the cost and duration of processing the formation.

The tasks are solved by the method of processing the bottom-hole zone of the well, including the descent of the pipe string with the packer into the interval of perforation of the formation, washing the well equipped with central and annular valves, planting the packer above the formation and treating the well by pumping acid solution through the pipe string in a pulsed mode, technological shutter speed for response and the recovery of reaction products.

It is new that before processing the bottom-hole zone of the well, the optimal formation response is set, then the pipe string at the wellhead below the packer is equipped with a pulsed fluid pulsator, while a valve is installed between the packer and the fluid pulser, the pipe string is lowered into the well so that the packer is placed above the reservoir then, when the central and annular valves are open, the well is washed with the process fluid in a pulsed mode by direct circular circulation for 10-20 minutes, the annular valve is closed and the process fluid is injected into the reservoir under pressure not exceeding the permissible pressure on the production string for 5-10 minutes, the annular valve is opened and the process fluid is poured out of the well, the technological fluid is flushed and spilled, 3-5 times, then into the pipe string a hydrocarbon solvent is injected, a packer is planted, and the hydrocarbon solvent is forced into the formation in a pulsed mode with a process fluid under a pressure not exceeding the allowable pressure on the formation and left the well for technological shutter speed, at the end of the technological shutter speed, the valve is actuated and the pulsating fluid pulsator is cut off, then the packer is torn off, the pipe string is pulled so that the radial holes of the valve are opposite the formation, then the well is flushed with technological fluid when the central and annular valves open with direct circular circulation for 2 hours, while the annular valve is periodically covered until the bottomhole pressure increases by 3-5 MPa from the initial pressure, followed by opening annular valve until a clear liquid appears, but at the same time do not exceed the permissible pressure on the production string, then a hydrochloric acid solution and a clay acid solution heated to a temperature of 40-50 ° C are successively pumped into the pipe string, a packer is planted, hydrochloric acid and clay acid solutions are pumped into the formation with a liquid under pressure not exceeding the permissible pressure on the formation, the packer is torn off, the well is left for technological shutter speed, and the products are re-circulated by reverse circular circulation tion until a clear liquid, then determining the actual acceleration of the formation.

Figure 1-3 successively depicts the process of implementing the proposed method.

The proposed method of processing the formation is implemented as follows.

Before the treatment of the formation, the optimal injection rate of the formation is determined, which is determined by the geological service of the oil and gas producing enterprise empirically based on the dynamics of the injectivity of a particular well during its operation. For example, the optimal injection rate set by the geological service of an oil and gas producing enterprise by experience is 100 m ³ / day at an injection pressure of P = 10.0 MPa.

A pipe string 1 (see FIG. 1), for example a 73 mm tubing string, at the wellhead 2 below the packer 3 is equipped with a pulsed fluid pulsator 4 (of any known design), while between the packer 3 and a pulsed fluid pulsator 4 install valve 5.

As a packer 3, a packer of any known construction is used, designed to carry out acid treatments in a well, for example, a packer with a mechanical axial installation of the appropriate size of the PRO-YaM02-YAG1 brand (produced by the scientific and production company Packer (Oktyabrsky, Republic of Bashkortostan) ( M).

As a pulsed fluid pulsator 4, a device for pulsed injection of fluid into a formation described in the patent for invention RU No. 2400615, IPC E21B 28/00; publ. in bull. No. 27 dated September 27, 2010 or the patent for invention RU No. 2241825, IPC E21B 43/18, publ. in bull. No34 dated December 10, 2004

As valve 5, a disconnector is used, which is widely introduced in the wells of OAO Tatneft, described in patents RU No. 2234589, IPC E21B 33/12, publ. in bull. No. 23 dated 08/20/2004 or RU No. 2282710, IPC E21B 33/12, publ. in bull. No.24 of 08/27/2006

Due to the use of a pulsed fluid pulsator, the process is simplified and the duration of the method is reduced, and due to the use of the valve, the number of tripping operations is reduced, which reduces the cost and processing time of the bottomhole zone of the well.

The pipe string 1 is lowered into the well so that the packer 3 is located above the formation 6, and the lower end of the pulse fluid pulsator 4 is opposite the perforation intervals 6 'of the formation 6 and with the help of a pump unit 7, for example, CA-320 grade through the container 8 with the annular open 9 and central 10 valves for 10-20 minutes, for example 10 minutes, wash the well with direct circular circulation of the process fluid. 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.

Then, the annular valve 9 is closed and, with the central valve open, 10, the process fluid is pumped into the formation 6 along the pipe string 1 at a pressure not exceeding the allowable pressure on the production string for 5-10 minutes. For example, the permissible pressure on the production string is 12 MPa, then the process fluid is pumped into the formation 6 through the pipe string 1 under a pressure of 11 MPa for 5 minutes. An annular valve 9 is opened and fluid is poured out of the well.

The washing and spouting of the process fluid is repeated 3-5 times depending on the color change of the fluid at the wellhead during the spout, which is determined visually to a transparent fluid when it enters the tank. For example, repeated spout 3 times.

Next, using a pumping unit 7 with an open central valve 10, hydrocarbon solvent 1, for example, Nefras A-130/150 grade, is pumped into the pipe string 1 in a volume of 3 m ³ , then packer 3 is planted (see Fig. 2) and forced through in a pulsed mode the hydrocarbon solvent in the reservoir 6 with a process fluid under a pressure not exceeding the permissible pressure on the reservoir 6. For example, the permissible pressure on the reservoir is 15 MPa, then the hydrocarbon solvent is forced under the pressure of 14.0 MPa.

Carry out technological exposure to the reaction of a hydrocarbon solvent with the formation rock 6, for example, for 3 hours

After waiting for the technological exposure, the valve 5 is activated (see Fig. 3), for example, by dumping the metal ball 11 into the pipe string 1, creating hydraulic pressure, for example, up to 8 MPa with the valve sleeve 12 moving down and the radial holes 13 and opening cut off the pulsating fluid pulsator 4. Then tear off the packer 3, allow the pipe string 1 to pass so that the radial holes 13 of the valve 4 are opposite the formation 6.

Next, the well 2 is washed with a process fluid with open central 10 and annular 9 gate valves with direct circular circulation for 2 hours, while the annular valve 9 is periodically closed until the bottomhole pressure increases by 3-5 MPa from the initial pressure, followed by the opening of the annular valve 9 until a transparent wellhead fluid 2.

For example, with an initial circulation pressure of 6.0 MPa, the annular pressure is increased to 9.0-11.0 MPa, but does not exceed the permissible pressure on the production string, which, for example, is 12.0 MPa.

Next, in a pipe string 1 (see Fig. 4), a hydrochloric acid solution (10-15% HC1 solution) is sequentially pumped, for example in a volume of 1 m ³ , a clay acid solution heated to a temperature of 40-50 ° C, for example, in a volume of 1 , 5 m ³ , represented by mixtures of hydrochloric and hydrofluoric acids, for example, a mixture of 10-15% HCl solution + 3-5% NH4FHF solution. Packer 3 is planted and hydrochloric acid and clay acid solutions are pushed into reservoir 6 with a process fluid under pressure not exceeding the permissible pressure on reservoir 6. A hydrochloric acid solution (10-15% HCl solution) consists of 10-15% hydrochloric acid and 90-85% water, for example fresh water with a density of 1000 kg / m ³ .

For example, the permissible pressure on the formation is 15 MPa, then the sale of acid and clay acid solutions is carried out under a pressure of <15.0 MPa, for example 13 MPa.

Apply:

- technical hydrochloric acid (HCl) according to GOST 857-95;

- acid ammonium fluoride (NHjF-HF), hydrofluoric acid GOST 9546-75.

As a hydrocarbon solvent used, for example, Nefras A-130/150 (GOST 10214-78). Nefras-C 150/200 according to TU 38.40125-82 or Nefras-Ar 120/200 according to TU 38.101809-80 can also be used as a hydrocarbon solvent.

The packer 3 is torn off (see FIG. 5), the well is left for technological shutter speed and the reaction products are washed away by reverse circular circulation until a clear liquid appears, for example, for 2 hours

After that, the central valve 10 is closed and the technological fluid is injected into the formation 6 through the annulus and the actual injectivity of the formation is determined, which is, for example, 110 m ³ / day at P = 10.0 MPa, which is higher than the optimum injectivity, which is 100 m ³ / day at P = 10.0 MPa, which indicates the effective treatment of the reservoir.

An example of practical application No. 1 (see FIGS. 1-5) at well No. 30318 of NGDU Jalilneft.

The optimal reservoir injection rate set by the geological service of the oil and gas producing enterprise experimentally is 90 m ³ / day at a reservoir injection pressure of P = 11.0 MPa. Allowable pressure on the production casing R _ec = 12.0 MPa. Allowable pressure on the reservoir is R _p = 14.0 MPa.

1. Assembled the assembly (top-down) consisting of a 73 mm tubing string, a packer, a valve, a pulsed fluid pulser and lowered it into the well so that the lower end of the tubing string was opposite the treated formation and the packer was placed higher layer.

2. With open central and annular valves, the wells were flushed by fresh water injection with a density of 1000 kg / m ³ with the addition of 0.1-0.2% of a surface-active substance (surfactant) of the ML-81B type (hereinafter referred to as process fluid) by direct circular circulation through tubing string-packer-pulsed fluid pulsator-valve-annulus-capacity-pumping unit-pipe string at a pressure of P = 9-12 MPa (flow rate 5-6 l / s) for 15 minutes

3. Then the annular valve was closed, fresh water was injected into the reservoir with a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactants of the ML-81B type at a pressure of 10 MPa for 7 minutes. They opened the annular valve and poured liquid into the tank. The operations according to claim 2 and claim 3 were repeated four times, since during the fourth outflow a transparent liquid was visually observed when it entered the tank.

4. With an open central valve, a Nefras A-130/150 hydrocarbon solvent was pumped into the tubing string in a volume of 2.5 m, a packer was placed and the hydrocarbon solvent was pushed into the formation with a process fluid under a pressure of 13.0 MPa.

5. Left the well for technological exposure, ie to the reaction of the hydrocarbon solvent with the formation rock, for example, for 4 hours, then the packer was broken.

6. After the completion of technological exposure with the formation rock, a valve was actuated, which compartment pulsed fluid pulsator. They let the pipe string so that the radial openings of the valve were opposite the treated formation.

7. The well was washed by fresh water injection with a density of 1000 kg / m ³ with the addition of 0.1-0.2% of a surfactant type ML-81B (hereinafter referred to as process fluid) through circular circulation through a tubing-pulse packer fluid pulsator-valve-annulus-capacity-pumping unit -column of pipes at a pressure of P _n = 7 MPa (flow rate 5-6 l / s) for 2 hours. At the same time, the annular valve was periodically closed until the bottomhole pressure increased by 4 MPa from the initial pressure (P _n ), i.e. up to 11.0 MPa with the subsequent opening of the annular valve, but did not exceed the permissible pressure on the production string, equal to 12.0 MPa, while a clear liquid appeared, as during the initial injection.

8. Successively pumped into the pipe string 1 hydrochloric acid solution (10-15% HCl solution) in a volume of 1.5 m ³ and a clay acid solution heated to a temperature of 48 ° C in a volume of 2.5 m ³ , represented by mixtures of hydrochloric and hydrofluoric acids , for example, a mixture of 10-15% HCl solution + 3-5% NH ₄ F · HF solution. The packer was planted and hydrochloric acid and clay acid solutions were pushed into the formation with the process fluid under a pressure not exceeding the permissible pressure on the formation (P _n = 14 MPa), i.e. under a pressure of 13.0 MPa.

9. The packer 3 was torn off and the well left for technological shutter speed, after which the mouth of the well 2 was re-laced and the reaction products were washed by reverse circular circulation until a clear liquid appeared, for example, for 3 hours

10. After that, the central valve 10 was closed and the technological fluid was injected into the formation 6 through the annulus and the actual injectivity of the formation was determined after processing the bottom-hole zone of the well, which, for example, was 110 m ³ / day at P = 11.0 MPa, which is higher than the optimum injectivity, which amounted to 90 m ³ / day at P = 11.0 MPa, which indicates the effective treatment of the bottom-hole zone of the well.

The proposed method for treating the bottom-hole zone of the well improves the efficiency of processing the bottom-hole zone of the formation by increasing the permeability of the bottom-hole zone of the formation by pretreating the bottom-hole zone of the well with a solvent in a pulsating mode with short pulses, as well as the subsequent treatment of the bottom-hole zone of the well with a saline-acid solution and heated to 40- 50 ° C with a clay acid solution, washing out the products of their reaction with the formation rock without swabbing.

The process of implementing the method is also simplified and the cost and duration of the formation treatment are reduced.

Claims (1)

A method of treating a bottomhole zone of a well, including lowering a string of pipes with a packer into the interval of perforation of a formation, flushing a well equipped with central and annular valves, planting a packer above the formation, and treating the well by pumping an acid solution through the pipe string in a pulsed mode, technological shutter speed for reacting and extracting products reactions characterized in that that before processing the bottom-hole zone of the well, the optimal formation response is set, then the pipe string at the wellhead below the packer is equipped with a pulsed fluid pulsator, a valve is installed between the packer and the fluid pulser, the pipe string is lowered into the well so that the packer is placed above the formation, and then open central and annular valves, wash the well with the process fluid in a pulsed mode by direct circular circulation for 10-20 minutes, close the annular valve and inject for 5-10 min, the annular valve is opened into the reservoir of the technological fluid under pressure not exceeding the permissible pressure on the production string, and the technological fluid is poured out of the well, the technological fluid is flushed and spilled, 3-5 times, then pumped into the pipe string hydrocarbon solvent, a packer is planted and, in a pulsed mode, a hydrocarbon solvent is pressed into the formation with a process fluid under a pressure not exceeding the allowable pressure on the formation, and the well is left on the techno Logical shutter speed, at the end of the technological shutter speed, the valve is actuated and the pulsed pulsator is cut off, then the packer is torn off, the pipe string is pulled so that the radial holes of the valve are opposite the formation, then the well is flushed with the process fluid with open circular and annular valves with direct circular circulation during 2 hours, while periodically covering the annular valve until the bottomhole pressure increases by 3-5 MPa from the initial pressure, followed by opening the annular valve and until a clear liquid appears, but at the same time do not exceed the permissible pressure on the production string, then a hydrochloric acid solution and a clay acid solution heated to a temperature of 40-50 ° C are successively pumped into a pipe string, a packer is planted, hydrochloric acid and clay acid solutions are pressed into the formation with a liquid under pressure not exceeding the permissible pressure on the formation, the packer is torn off, the well is left for technological shutter speed and the reaction products are washed by reverse circular circulation until rozrachnoy fluid then determine the actual acceleration of the formation.

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