RU2506421C1 - 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, packer seating in production casing with master and casing valves above the formation and 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. At the well mouth the pipe string below packer is equipped with impulse liquid pulsator, at that a valve is mounted between the packer and liquid pulsator; pipe string is run-in into the well so that packer is located above the formation; thereafter the well is flushed with process liquid at open master and casing valves by straight ring circulation in pulse mode 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 actual intake of the formation is determined at pressure that does exceed permitted pressure to the production string. If actual intake is lower than the optimal one then hydrochloride acid bath is installed in the well opposite formation interval under pressure that does not exceed permitted pressure to the production string. If actual intake is equal to the optimal one or higher then hydrocarbon solvent is pumped to the pipe string, add process liquid up to volume bigger per 0.5-1 m³ than volume of the reagent displaced from the pipe string under pressure not exceeding permitted pressure to the formation. The well is subjected to process exposure. When 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; by return ring circulation reaction products are washed out during 3-5 hours, at that fluid influx from the formation is controlled. Then casing valve is closed and by process liquid pumping to the pipe string through the valve well intake is determined under intake pressure of the formation.

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 duration.

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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 treating a formation (patent RU No. 2135760, IPC ЕВВ 43/25, published in Bulletin No. 24 of 08/27/1999), 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 pressure, carry out technological exposure and extraction of the reaction products and pollutants by swabbing to take the liquid in a volume exceeding at least three times the volume of the injected reagent.

The disadvantages of this method are:

- 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 ЕВВ 43/27, published in bulletin No. 34 of December 10, 2007), which includes pulsed injection of a solution of hydrochloric acid, injection of a solution of hydrochloric acid into continuous operation, technological shutter speed for the reaction and extraction of reaction products by swabbing, according to the invention, the wells are pre-washed with oil, updating the perforation of the reservoir at the rate of at least 5 holes / lm, injection of hydrochloric acid solution in the wells in a volume of 1.5-2.0 m ³ and the process speed to a bath mode for 1.5-3.5 hour, then is performed 4-6 times the pulse injection into the formation of the first portions of hydrochloric acid solution in a volume of 1.5 3.5 m ³ in the cycle mode: 0.8-1.2 min injection at a pressure of 1-4 MPa - holding for 4-6 minutes for reaction, complete the injection of the acid volume in a constant mode, perform a 4-6-fold pulse injection into formation of the second portion of hydrochloric acid solution in a volume of 2.5-3.5 m ³ 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 injection of the acidic volume you are in constant mode, carry out a technological exposure of 2.5-3.5 hours for the reaction, inject a third portion of hydrochloric acid solution into the reservoir at the 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 the fourth portion of the hydrochloric acid solution at the rate of 0.8-1.0 m ^{3 /} p.m of productive formation in cycle mode: 4-6 min injection at a pressure of 1-4 MPa, shutter speed 4-6 min for response, complete the injection in continuous mode, perform techno logical shutter speed for a response of 2.5-3.5 hours, a pulsed 4-6-fold pulsed oil flow is carried out in a cycle mode: 0.8-1.2 minutes injection, shutter speed 4-6 minutes, after which the reaction products are extracted by swabbing . The disadvantages of this method are:

- firstly, a complex process, time-consuming and labor-intensive, associated with the injection of acid in several portions, in addition, requiring 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 processing the bottom-hole zone of the well by increasing the permeability of the bottom-hole zone by exposure to it with acid treatment or a hydrocarbon solvent, as well as simplifying the process of implementing the method, reducing the cost and duration of the formation treatment.

The stated technical problems are solved by the method of processing the bottom-hole zone of the well, including lowering the string of pipes with a packer into the interval of perforation of the formation, flushing the well, planting the packer in the production string of the well with central and annular valves above the formation and pumping hydrochloric acid through the pipe string in a pulsed mode, technological reaction extract and reaction product recovery.

What is new is that before treatment of the bottom-hole zone of the well, the optimal formation response is set, 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 pulsed fluid pulser, the pipe string is lowered into the well so that the packer is placed above the reservoir then, with the open central and annular valves, 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 they are pumped 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 washing and spout of the process fluid is repeated 3-5 times, then determine actual injectivity of the formation at a pressure not exceeding the allowable pressure on the production string, if the actual injectivity is lower than optimal, then hydrochloric acid is installed in the well opposite the formation a different “bath” at a pressure not exceeding the permissible pressure on the production string, and if the actual injectivity is equal to or higher than optimal, then a hydrocarbon solvent is pumped into the pipe string, brought to the formation through the pipe string, the packer is planted and pressed into the formation with process fluid in a volume for 0.5-1 m ³ greater than the volume displaced reagent from the tubing at a pressure not exceeding the permissible pressure on the formation, the well is left to process exposure, after exposure technology etc. they actuate the valve and cut off the pulsating fluid pulsator, then tear off the packer, lower the pipe string so that the radial holes of the valve are opposite the formation, and the reaction products are washed out by reverse circular circulation for 3-4 hours, while the flow of fluid from the formation is controlled, then close the annular valve and pumping the process fluid through the pipe string through the valve determines the injectivity of the well under the pressure of the injectivity of the formation.

Figure 1-4 sequentially shows the process of implementing the proposed method.

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

Before processing the bottom-hole zone of the well, the optimal injectivity of the formation is set (injectivity, which corresponds to the average value of the injectivity of the well plus or minus 10%), which is determined by the geological service of the oil and gas producing enterprise empirically based on the dynamics of the injectivity for a particular well during its operation.

A pipe string 1 (see FIG. 1), for example a tubing string 73 mm (tubing), 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 design is used for acidizing the formation and injecting hydrocarbon solvents into the well (for example, a packer with a mechanical axial installation of the corresponding missile defense type, manufactured by the scientific and production company Packer, Oktyabrsky, Republic of Bashkortostan) -YAMO2-YAG1 (M)).

As a pulsed fluid pulsator 4 can be used a device for pulsed injection of fluid into the reservoir described in the patent for invention RU No. 2400615, IPC ЕВВ 28/00, publ. in bull. No. 27 dated September 27, 2010, or the patent for invention RU No. 2241825, IPC 8 ЕВВ 43/18, publ. in bull. No34 dated December 10, 2004

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

Due to the use of a pulsed fluid pulsator, the implementation of the method is simplified and its duration is reduced, and due to the use of a 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, after which the annular 9 and central 10 valves are opened and the well is washed with direct circular circulation of the process fluid with using a pump unit 7, for example, grade CA-320 through a container 8 for 10-20 minutes, for example 10 minutes 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 reservoir through the pipe string 1 at a pressure not exceeding the permissible pressure on the production string, for example 12 MPa, for 5-10 minutes, for example 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.

The actual injectivity of the formation is determined under pressure not exceeding the permissible pressure on the production string, for example, as noted above, at a pressure not exceeding 12 MPa.

If the actual injectivity is lower than optimal, then in the well opposite the interval of the formation 6, a hydrochloric acid “bath” is installed under a pressure not exceeding the allowable pressure on the production string.

For example, the actual injection rate was 40 m ³ / day at P = 12.0 MPa, and the optimal injection rate set by the geological service of the oil and gas company experimentally, for example, is 100 m ³ / day at P = 12.0 MPa, (the well worked 3 years, throttle response by years: 110; 100; 100 m ³ / day).

Therefore, a hydrochloric acid “bath” is installed under a pressure not exceeding the permissible pressure on the production casing, as noted above, 12 MPa.

To do this, with the closed annular valve 9 using the pump unit 7, hydrochloric acid is pumped into the pipe string 1 and pressed through to the formation 6 with process fluid, the pressure is raised to 6 MPa and the central valve is closed. Thus, a hydrochloric acid “bath” is installed under a pressure of 6 MPa, for example, in a volume of 1 m ³ 15% Hcl, for example, for 3-4 hours with closed annular 9 and central 10 valves, for example, 3 hours. For installing hydrochloric acid “ baths "use hydrochloric acid synthetic technical in accordance with GOST 857-95. If the actual injectivity of formation 6 is equal to or greater than the optimal injectivity, for example, 100 m ³ / day, then a hydrocarbon solvent is pumped through the pipe string 1, for example, in a volume of 3 m ³ , it is brought to formation 6 and the packer is planted (see Fig. 2 )

The solvent is pushed into the reservoir 6 with the process fluid in a volume 0.5-1 m ³ higher than the volume of the displaced reagent from the pipe string, at a pressure not exceeding the permissible pressure on the reservoir 6, for example, 14 MPa, therefore, the injection and delivery of the hydrocarbon solvent into the reservoir 6 carried out at a pressure of up to 14 MPa.

As a hydrocarbon solvent used, for example, Nefras A-130/150 (GOST 10214-78). Nefras-S 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. Leave the well for technological exposure. These technological operations can increase the permeability of the bottomhole formation zone.

After waiting for the reaction with the formation rock 6 of the hydrochloric acid “bath” or solvent, valve 5 is activated (see FIG. 3), for example, by dropping the ball 11 into the tubing string 1 (see FIG. 1), creating hydraulic pressure, for example, up to 8 MPa, with the movement of the sleeve 12 (see figure 3) of the valve 5 (see figure 2) down and the opening of the radial holes 13 (see figure 3) and cut off the pulsating fluid pulsator 4. Then tear the packer 3 (see figure 3), allow the pipe string so that the radial holes 13 of the valve 4 were opposite the formation 6, re-bind the wellhead 2 (see figure 3) for I reverse the circular circulation and reverse circular circulation wash the reaction products for 3-4 hours, for example 3 hours? and control the flow of fluid from the reservoir 6. Then again put the packer 3 (see figure 4) in the well 2, close the Central valve 10 and determine the injectivity of the reservoir 6 after processing by pumping the process fluid at a pressure of injectivity of the reservoir, for example, under pressure, equal to 10.5 MPa. Pickup is 100 m ³ / day.

An example of practical application No. 1 (see Figs. 1-4) at well No. 13057 of the NGDU Aznakaevskneft.

The well worked for 5 years, acceleration by years: 140; 130; 110; 110; 100 m ³ / day The optimal formation injectivity set by the geological service of the oil and gas production enterprise experimentally is 120 m ³ / day at a formation injectivity pressure of P = 10.0 MPa. Allowable pressure on the production casing Rmax≤12.0 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.

2. The wells were washed by fresh water injection with a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactant type ML-81B through circular circulation through the 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 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 Pmax≤12.0 MPa for 7 min. They opened the annular valve and poured liquid into the tank.

3. Repeated the operation according to claim 2 four times, since in the process of the fourth spout, a transparent liquid was visually observed when it entered the tank.

4. Determined the actual injectivity of the reservoir, which is equal to 70 m ³ / day under pressure P = 10.0 MPa, allowable pressure on the production string Rmax = 12 MPa.

5. Installed hydrochloric acid "bath" under a pressure of 6.0 MPa. To do this, with a closed annular valve using a pumping unit, hydrochloric acid was pumped in a volume of 1.5 m ³ 15% HCl into the pipe string and pressed into the reservoir with fresh water with a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactant type ML-81B, raised the pressure to 6 MPa and closed the central valve and left the hydrochloric acid “bath” to react with the formation rock for 3.5 hours with the central 10 and annular valves closed.

6. After waiting for the response of the hydrochloric acid “bath” with the formation rock, a valve is actuated by which the pulsed fluid pulsator is cut off.

7. Tore off the packer, let down the tubing string so that the radial openings of the valve were opposite the treated formation. Re-bandaged the wellhead for reverse circular circulation and reverse circular circulation washed the reaction products by injection of fresh water with a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactant type ML-81B for 4 hours until transparent liquids.

8. The packer was planted in the well, the central valve was closed, and the injectivity of the formation was determined after treatment with fresh water injection at a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactants of the ML-81B type at an injection pressure of 10.0 MPa the injectivity was 140 m ³ / day, which is higher than the optimal injectivity of the formation, which is 120 m ³ / day at P = 10.0 MPa, which indicates the effectiveness of the work on processing the bottom-hole zone of the well.

An example of practical application No. 2 (see Figs. 1-4) at well No. 12468 of NGDU Aznakaevskneft.

The well worked for 4 years, acceleration by years: 100; one hundred; 90; 90 m ³ / day The optimal formation injectivity set by the geological service of the oil and gas producing enterprise experimentally is 90 m ³ / day at a formation injectivity pressure of P = 12.0 MPa. Allowable pressure on the production casing Рmax≤14.0 MPa.

1. Assembled the assembly and lowered into the well, as in example No. 1.

2. The well was flushed with fresh water by circular circulation through the tubing string - packer - pulsed fluid pulsator - valve - annulus-capacity - pump unit - pipe string at a pressure of P = 9-12 MPa (flow rate 5-6 l / s) within 20 minutes 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% of a surface-active substance (surfactant) of the ML-81B type at a pressure of Рmax≤14.0 MPa for 10 min. They opened the annular valve and poured liquid into the tank.

3. Repeated the operation according to claim 2 three times, since in the process of the third spout, a transparent liquid was visually observed when it entered the tank.

4. Determined the actual injectivity of the formation, which is equal to 100 m ³ / day under pressure P = 12.0 MPa, not exceeding the permissible pressure on the production string Rmax = 14 MPa.

5. The formation was treated with Nefras A-130/150 hydrocarbon solvent. For this, a hydrocarbon solvent was pumped into the tubing string in a volume of 2.5 m ³ and a packer was planted, the hydrocarbon solvent was pushed into the reservoir with fresh water with a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactants of the ML-81B type in a volume of 3.5 m ³ more than the displaced volume of the reagent from the tubing string under pressure not exceeding the permissible pressure on the formation of 15 MPa.

6. After waiting for the reaction of the hydrocarbon solvent with the formation rock, a valve is actuated by which the pulsed fluid pulsator is cut off.

7. Tore off the packer, let down the tubing string so that the radial openings of the valve were opposite the treated formation. The wellhead was re-laced for reverse circular circulation and washed with fresh water with a density of 1000 kg / m ³ with the addition of 0.1-0.2% ML-81B type surfactant by reverse injection with the reaction products for 3.5 hours to a clear liquid.

8. The packer was planted in the well, the central valve was closed, and the injectivity of the formation was determined by fresh water injection with a density of 1000 kg / m ³ with the addition of 0.1-0.2% surfactants of the ML-81B type with an injection pressure of 12.0 MPa at this injectivity was 100 m ³ / day, which is higher than the optimal injectivity of the formation, which is 9.0 m ³ / day at P = 12.0 MPa, which indicates the effectiveness of the work on processing the bottom-hole zone of the well.

The proposed method for treating the bottom-hole zone of the well allows to increase the efficiency of processing the bottom-hole zone of the formation by increasing the permeability of the bottom-hole zone of the formation by pre-washing the wells with the subsequent installation of a hydrochloric acid “bath” or pumping the solvent into the formation in a pulsed mode with short pulses with subsequent washing out of the reaction products 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 for processing 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, planting a packer in a production string of a well with central and annular valves above the formation, and injecting hydrochloric acid solution through the pipe string in a pulsed mode, technological shutter speed for reacting and extraction of reaction products, characterized in that before processing the bottom-hole zone of the well, the optimal formation response is set, at the wellhead, the pipe string below the packer is equipped with it a pulse fluid pulsator, in which case a valve is installed between the packer and the pulsed fluid pulser, the pipe string is lowered into the well so that the packer is placed above the reservoir, and then, with the central and annular valves open, the well is washed with the process fluid in a pulsed mode by direct circular circulation for 10- 20 min, close the annular valve and inject the process fluid into the reservoir at a pressure not exceeding the allowable pressure on the production string, for 5-10 min, open the annular valve is removed and the process fluid is poured out of the well, the process fluid is flushed and poured out 3-5 times, then the actual injectivity of the formation is determined at a pressure not exceeding the allowable pressure on the production string, if the actual injectivity is lower than optimal, then in the well opposite the formation, hydrochloric acid "bath" under pressure not exceeding the permissible pressure on the production casing, and if the actual throttle response is equal to or higher than optimal, then in a hydrocarbon solvent is pumped into the pipe string, brought to the formation through the pipe string, the packer is planted and pressed into the formation with process fluid in a volume 0.5-1 m ³ higher than the volume of the displaced reagent from the pipe string, at a pressure not exceeding the permissible pressure on the formation , leave the well for technological shutter speed, at the end of 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 found s against the formation and inverse circular loop is washed out of the reaction products for 3-4 hours, while controlling the inflow of formation fluid and then closing the annular gate valve and pumping the process fluid through the pipe string through the valve hole define pickup pressurized reservoir injectivity.

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