RU2512216C1 - Treatment method of bottomhole zone - Google Patents

Abstract

FIELD: oil and gas industry.SUBSTANCE: invention relates to oil industry. Treatment method of bottomhole zone includes running tubing string to the interval of stratum perforation, pulsed pumping of 10-15% water solution of hydrochloric acid through the tubing string, process holdout within 3 hours for the purpose of reacting and extracting of reaction products. Before running the tubing string is equipped bottom-up with device for pulsed fluid pumping, breakable valve, tube with perforated holes and sleeve inside and packer. In running process tube with perforated holes is installed 2 meters below the lower interval of stratum perforation. Hydrocarbon solvent is pumped through the tubing string in continuous mode with unseated packer; then process holdout is maintained. In process holdout process fluid is pumped in volume of 0.5 mto the tubing string and annular space alternately in 4 cycles each 20 minutes; thereafter hydrocarbon solution and reaction products are washed by backwash from the well. Then the tubing string is elevated so that the device for pulsed fluid pumping is set opposite bottom of the stratum; the packer is seated, sleeve is moved down relative to the tube with perforated holes, and holes of the perforated tube are sealed by sleeve fixing in regard to the tube with perforated holes; the tubing string is filled with process fluid and by created excessive pressure the breakable valve is cut thus allowing fluid communication in the piping string and stratum through the device for pulse fluid pumping. Then through the tubing string pumping ad squeezing of 10-15% water solution of hydrochloric acid is made in pulsed mode in volume based on calculation of 0.8 mper 1 m of stratum thickness with gradual flow rise of 10-15% water solution of hydrochloric acid pumping from 0.5 m/h up to 0.8 m/h; process holdout is maintained within 3 hours and reaction products are extracted by swabbing.EFFECT: increasing efficiency of stratum treatment due to preliminary cleaning and washing of bottomhole zone by hydrocarbon solvent with further treatment by hydrochloric acid solution in pulsed mode with short pulses and flow increase thus allowing yield increase at further development of stratum, simplifying production process, reducing costs and duration of stratum treatment.1 ex, 2 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 acid treatment of the formation (patent RU No. 2442888, IPC E21 B 43/27, publ. 02/20/2012 in bull. No. 5), including the allocation in the processed formation zones of different permeability, pumping a portion of the hydrochloric acid solution into the zone of higher permeability, the subsequent delivery to the same zone of a viscous liquid based on oil with a portion of a solution of hydrochloric acid with a surfactant - surfactant, the sale of a solution of hydrochloric acid with a surfactant with a well fluid in a cyclic mode into the zone of lower permeability and the removal of the reacted hydrochloric acid you are from the well in the last cycle, while the concentration of the hydrochloric acid solution at each stage of its application is reduced.

The disadvantages of this method are:

- firstly, the low efficiency of the formation treatment with a solution of hydrochloric acid in a highly accumulated bottom-hole zone of the well, without preliminary treatment of the bottom-hole zone;

- secondly, the increase in the permeability of the bottomhole zone of the well occurs only in the zones of the formation with high permeability and has a short-term effect, which decreases rapidly, since the reagent is not able to penetrate deep into the pores of the formation due to the mudding of the bottomhole zone.

The method of acid treatment of the bottomhole formation zone (patent RU No. 2451176, IPC E21 B 43/27, published on 05/20/2012 in bull. No. 12), including the descent of the pipe string into the interval of perforation of the formation, injection in two cycles of 10-15% an aqueous solution of hydrochloric acid using squeezing fluid, containing each pulse injection of the solution at a pressure of 1-4 MPa, injection of this solution at constant pressure, technological exposure for 2.5-3.5 hours for reaction and recovery of reaction products with subsequent cleaning of the well flushing fluid, with the impulse waistband injection solution is performed up to 5 minutes. with stops for 6-10 min., and the injection at constant pressure is carried out in portions of 2-4 m ³ with a holding time between portions of 2-4 hours, and the injection of portions of the solution is stopped when the injection pressure exceeds 3 MPa, and the acidic pump is injected between the injection cycles a composition containing a 24-26% solution of hydrochloric acid in oil, with a volume of 1-4 m ³ under pressure up to 7 MPa, oil is used as squeezing and flushing liquids, and the extraction of reaction products.

The disadvantages of this method are:

- firstly, there are additional costs associated with the use of oil for flushing and selling hydrochloric acid into the well, which does not allow qualitatively cleaning the bottom-hole zone of the well formation, which significantly increases the cost of implementing the method;

- secondly, a complex process, time-consuming and labor-intensive, associated with the injection of acid in several portions, in addition, it is very demanding in the implementation of the process, requiring strict observance of the injection and shutdown times at a certain injection pressure;

- thirdly, the low efficiency of the formation treatment, since in the highly accumulated bottom-hole zone, short-time injection cycles of a hydrochloric acid solution with long exposure do not allow the hydrochloric acid solution to penetrate deep into the formation.

The objective of the invention is to increase the efficiency of the formation treatment with a solution of hydrochloric acid due to pre-treatment of the bottomhole zone of the well, followed by injection of an aqueous solution of hydrochloric acid in a pulsed mode with short pulses with an increase in the volume of injection, as well as simplification of the process of implementing the method, reducing the cost and processing time layer.

The problem is solved by the method of processing the formation in the well, including the descent of the pipe string into the interval of perforation of the formation, the pulsed injection of a 10-15% aqueous hydrochloric acid solution through the pipe string, technological shutter speed for 3.0 hours for reaction and extraction of reaction products.

New is that before lowering into the well, the pipe string is equipped from the bottom up with a device for pulsed fluid injection, a destructible valve, perforated nozzle with a sleeve with a sleeve inside and a packer, while lowering the pipe string, the perforated nozzle is installed 2 m below the lower interval of formation perforation, hydrocarbon solvent is injected through the pipe string in a continuous mode with the packer not planted and the well is left for technological shutter speed, while in the process exposure in 4 cycles every 20 minutes. alternately 0.5 m ^{3 of} process fluid is pumped into the pipe string and the annulus of the well, after which the hydrocarbon solvent and reaction products are washed back by washing in the volume of the well, then the pipe string is lifted so that the device for pulsed fluid injection is located opposite the bottom of the formation, the packer is planted, the sleeve is moved down relative to the perforated nozzle and the holes of the perforated nozzle are sealed by the sleeve with its fixation relative to the per formed by openings of the nozzle, fill the pipe string with the process fluid, cut off the destructible valve by creating excess pressure, and hydraulically communicate the pipe string through the device for pulsed fluid injection with the formation, then 10-15% are pumped and pumped through the pipe string in the pulse mode - aqueous solution of hydrochloric acid in a volume of 0.8 m ³ per 1 m of formation thickness with a gradual increase in the injection flow rate of a 10-15% aqueous hydrochloric acid solution from 0.5 m ³ / h to 0.8 m ³ / h you The technological endurance for the reaction of 3.0 hours is increased and the reaction products are extracted by swabbing.

Figure 1 schematically shows a method of processing a formation in a well during the cleaning and washing of the bottom-hole zone of the well

Figure 2 schematically shows a method of treating a formation in a well in a pulsed (pulsating) mode of injecting a solution of hydrochloric acid into the formation.

SUMMARY OF THE INVENTION

Well productivity is largely determined by the permeability of the bottom-hole zone. Existing methods of hydrochloric acid treatments of the bottomhole zone of the well, especially carbonate formations, are ineffective or temporary. The essence of the method consists in cleaning and washing the bottom-hole zone of the well formation with the aim of increasing the injectivity of the formation during subsequent injection into the formation of a solution of hydrochloric acid, pressed into the pore microcrack space of carbonate rocks in a pulsating mode with a short pulse time (1-2 s). This allows you to most fully and high quality to restore or increase the permeability of the bottomhole zone of the well due to the treatment coverage of the formation in depth and power. As a result, the efficiency of the method increases, resulting in increased productivity of the well, the duration and cost of implementing the method are reduced in comparison with the prototype.

Concrete example

The bottom-hole zone of an oil well is processed at a depth of 1270 m and a diameter of 168 × 9 mm. The reservoir is perforated at depths from 1255 to 1261 m. The bottomhole reservoir is carbonate, pore-fractured. The well was decommissioned at a current flow rate of 1 m ³ / day.

Before the treatment of the formation, its injectivity is set, which must be achieved after processing the bottom-hole zone of the well and which is determined by the technological service of the repair enterprise empirically based on the dynamics of changes in the injectivity of this well during its operation. For example, the required injection rate set by the technological service of the repair enterprise is 80 m ³ / day at an injection pressure of P = 12.0 MPa.

Before the descent into the well 1 (see Fig. 1), the pipe string 2 with the packer 3 in the perforation interval 4 of the formation 5, the lower end of the pipe string 2 is sequentially equipped from bottom to top with the following arrangement: a pulse injection device 6, a destructible valve 7, for example, made in in the form of a membrane and perforated nozzle 8 with a sleeve 9 inside, and above the packer 3.

Next, a pipe string 2 with the above arrangement is lowered into the well 1.

During the descent of the pipe string 2, the perforated holes of the pipe 8 are installed 2 m below the lower perforation interval 4 of the formation 5 in order to effectively rinse the hydrocarbon solvent during the implementation of the proposed method, and the packer 3 is placed 5 m above the formation 5, for example, in the range of 1250 m

As a packer 3, a packer of any known construction is used, designed to carry out acid treatments in a well (for example, manufactured by the scientific and production company “Packer” in Oktyabrsky, the Republic of Bashkortostan), a packer with a mechanical axial installation of the corresponding standard size of the PRO-YaJ-142 brand.

As a pulsating fluid pulsator 4 can be used a device for pulsed injection of fluid into the reservoir, described in the patent for invention RU No. 2241825, IPC E21 B 43/18, publ. in bull. No34 dated December 10, 2004

Through the pipe string 2 in continuous mode with the packer 3 not planted from the wellhead, a hydrocarbon solvent, for example, in a volume of 2.0 m ^{3, is} pumped using a pump unit, for example, TsA-320. Using a process fluid, with an open annular valve (not shown), the hydrocarbon solvent is brought to formation 5 (see Fig. 1), i.e. establish a bath of hydrocarbon solvent opposite the perforation interval 4 of the formation 5. Carry out technological exposure in the bath mode for reaction for 4 hours, while there is a slow penetration of the hydrocarbon solvent into the bottom zone of the formation 5 and the dissolution of the clogging compounds and rock particles.

Nefras-S 150/200 according to TU 38.40125-82 or Nefras-Ar 120/200 according to TU 38.101809-80 can be used as a hydrocarbon solvent.

Fresh water with a density of 1000 kg / m ³ with the addition of 1% surfactant type ML-81B is used as a process fluid, which improves the washing properties of the process fluid.

In the process of technological exposure from the wellhead using a pump unit, for example, CA-320, in 4 cycles every 20 minutes alternately, 0.5 m ^{3 of} process fluid is pumped into the pipe string 2 and the annular space 10 of the well 1 into the bottomhole zone of the formation 5 to dissolve the clogging compounds and rock particles in it, i.e. rinse the hydrocarbon solution, while from the bottom zone of the formation 5 into the wellbore 1, the mudding compounds and rock particles dissolved in the hydrocarbon solvent are washed out of the bottom zone of the formation 5. The destructible valve 7 is made in the form of a membrane, for example of rubber material, and hydraulically disconnects the device for pulsed fluid injection from a hydrocarbon rinse layout.

Then, hydrocarbon solution and reaction products are washed back from well 1, i.e. the supply of process fluid in the annular space 10 and the rise of the pipe string 2 in the volume of the well 1, equal to 22.43 m ³ .

Raise the pipe string 2 (see figure 2) so that the device for the pulse injection of fluid 6 is placed opposite the bottom of the formation 5. This is done in order to increase the efficiency of the pulse effect on the bottomhole zone of the well throughout the perforation interval 4 of the formation 5. Then, the packer is planted 3 in the well 1. After that, a whipping tool is lowered into the pipe string 2 for cutting the destructible valve 7, for example, a load made in the form of two tubing 60 mm in diameter with an external protrusion interacting with the sleeve th 9 on a geophysical cable (not shown). Next, the load is unloaded with an external protrusion onto the sleeve 9, the shear screw 11 is destroyed and the sleeve 9 is moved relative to the perforated nozzle 8. As a result, the sleeve 9 seals the holes of the perforated nozzle 8 from the inside and is fixed with a retaining ring (not shown) relative to the pipe string 2 (see figure 2).

The pipe string 2 is filled with process fluid using a pump unit, for example, CA-320, and an overpressure is created in the pipe string, for example, equal to 9.0 MPa, and the destructible valve 7 is cut off. As a result, the pipe string 2 is hydraulically communicated through the pulse pump 6 with layer 5.

Then, through the pipe string 2 through the device for pulsed injection of fluid 6 in a pulsed mode from the wellhead using a pumping unit, for example, ЦА-320, 10-15% aqueous hydrochloric acid is pumped in the amount of 1 m ³ per 1 m of the formation thickness 5, therefore, at a formation thickness of 6 m, the injection volume of the hydrochloric acid solution is taken to be 5 m ³ .

The injection of this volume of hydrochloric acid solution into the reservoir 5 is carried out with a gradual increase in the flow rate of the acid solution from 0.5 m ³ / h to 0.8 m ³ / h.

Technical hydrochloric acid (HCl) is used according to GOST 857-95.

The reaction products and pollutants are removed by swabbing along the pipe string 2 when the packer 3 is planted, if the pulse injection device 6 is equipped with a check valve (not shown), or the reaction products and pollutants are extracted by swabbing along the production string after removing the pipe string 2 (see Fig. 2) with the layout.

Re-determine the injectivity of the formation 5 after processing the bottom-hole zone of the well. For example, the injectivity set by the technological service of the repair enterprise is 100 m ³ / day at an injection pressure of P = 12.0 MPa, which is higher than the required injectivity of 80 m ³ / day at an injection pressure of P = 12.0 MPa. This indicates the effectiveness of processing the bottom-hole zone of the well. If the required injection rate of 80 m ³ / day is not achieved at an injection pressure of P = 12.0 MPa, the above operations, from the descent of the pipe string to the extraction of the reaction products by swabbing, are repeated.

The application of the proposed method allows to increase the efficiency of the formation treatment by pre-cleaning and washing the bottom-hole zone of the well with a hydrocarbon solvent, followed by treatment with a hydrochloric acid solution in a pulsed mode with short pulses with an increase in volume, which, with subsequent development of the formation, will increase the productivity of the formation. In addition, the simplification of the process allows to reduce the cost and duration of the formation and to avoid additional costs for the implementation of the method.

Claims (1)

A method of treating a bottomhole zone of a well, including lowering a pipe string into the perforation interval of a formation, pulse pumping a 10-15% aqueous hydrochloric acid solution through a pipe string, holding for 3.0 hours for reaction and recovering reaction products, characterized in that before lowering into the well, the pipe string from bottom to top is equipped with a device for pulsed fluid injection, a destructible valve, perforated nozzle with a sleeve with a sleeve inside and a packer, while lowering the pipe string, the perforated hole With the holes, the nozzle is installed 2 meters below the lower interval of the formation perforation, hydrocarbon solvent is injected through the pipe string in continuous mode when the packer is not planted, and the well is left for technological shutter speed, while in the process of technological shuttering for 4 cycles every 20 minutes. alternately 0.5 m ^{3 of} process fluid is pumped into the pipe string and the annulus of the well, after which the hydrocarbon solvent and reaction products are washed back by washing in the volume of the well, then the pipe string is lifted so that the device for pulsed fluid injection is located opposite the bottom of the formation, the packer is planted, the sleeve is moved down relative to the perforated nozzle and the holes of the perforated nozzle are sealed by the sleeve with its fixation relative to the per formed by openings of the nozzle, fill the pipe string with process fluid and create an overpressure to cut off the valve being destroyed and hydraulically communicate the pipe string through a device for pulsed fluid injection with the formation, then 10-15% aqueous fluid is pumped and pumped through the pipe string in a pulsed mode hydrochloric acid solution in the amount of 0.8 m ³ per 1 m of the thickness of the reservoir with a gradual increase in the injection rate of a 10-15% aqueous hydrochloric acid solution from 0.5 m ³ / h to 0.8 m ³ / h The technological endurance for the reaction for 3.0 hours is carried out and the reaction products are recovered by swabbing.

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