RU2618249C1 - Method of interval productive formation treatment in open horizontal bore of well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: in method of interval productive formation treatment in open horizontal bore of well diameters of open horizontal well bore at the borders of each detected interval with low permeability are determined, a pipe composition is collected consisting of a blind joint, the first hydraulic packer, the first nozzle with perforated holes, a pulsed fluid pulsator, a breakable valve, the second nozzle with perforated holes and an inner ring excerpting, the second hydraulic packer, wherein the perforated holes of the second nozzle are overlapped from within by the hollow sleeve fixed by shear element. Then the pipe compositon is descended at the bottom end of the pipe into the first from the bottom hole interval with reduced permeability so that the hydraulic packers of the pipe composition overlapped the first interval with reduced permeability from both sides of the open horizontal well bore, process fluid is pumped through the pipe string, at first two hydraulic packers are simultaneously landed and then the breakable valve is cut off, pulsed injection of 15% concentrated hydrochloric acid is carried out through the perforated holes of the first nozle into the first interval with reduced permeability. Then a displacement plug is mounted at the well mouth and its squeezing is carried out under process fluid pressure in the pipe string, wherein the displacement plug is moved along the pipe string, lands at the hollow sleeve, destroys the shear element and moves the hollow sleeve up to the stop into the inner ring excerpting, wherein the hollow sleeve is fixed in the second perforated nozzle, well withstanding to the reaction is carried out, after completion of which reaction products are removed by swabbing along the pipe string. Afterwards injection of inverted acid-oil emulsion is carried out in an accelerated mode along the pipe string through the perforated holes of the second nozzle into the first interval with reduced permeability, then well withstanding to the reaction is carried out, after which the pipe string tension is carried out upwards and both hydraulic packers of the pipe composition are released, direct flushing is carried out and reaction products are removed from the first interval with reduced permeability, afterwards the pipe string with pipe composition is extracted from the well. The abovementioned technological operations are repeated each time for the interval treatment of remaining intervals with reduced permeability, starting with the installation of the pipe composition and extraction of pipe string with pipe composition from the well.

EFFECT: increased productivity of bottomhole zone, improved reliability of the treatment method, exception of acid destructive effect on the sealing elements of the packers.

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Description

The invention relates to the oil industry and is intended for interval processing in carbonate reservoirs in order to increase the productivity of the bottom-hole zone of an open horizontal wellbore.

A known method of interval processing of the bottom-hole zone of a horizontal well (patent RU No. 2278966, IPC ЕВВ 43/27, publ. 06/27/2006, bull. No. 18), including the interval injection into the bottom-hole zone of the acid solution. In this case, the processing sequence is set from the far interval to the interval closest to the vertical wellbore. The injection is carried out through the tubing string, while processing the next interval, the end of the tubing string is moved to the processed interval. After pumping the acid solution, an aqueous emulsifier solution is pumped into each treatment interval. The injection of acid and emulsifier solutions is carried out with a flow rate of 24-35 m ³ / day and at a pressure at the mouth of the tubing string of 0.8-1.5 MPa. Then they carry out technological exposure for no more than 3 hours and perform swabbing until depression at the bottom of the well not lower than 3 MPa.

The disadvantages of this method are:

- firstly, the low efficiency of acid treatment followed by injection of the emulsifier into a reservoir of heterogeneous permeability, opened by a horizontal wellbore, since reservoir permeability is not taken into account and intervals with reduced permeability are not identified by geophysical studies;

- secondly, the low quality of the horizontal wellbore processing due to the lack of hermetic cutoff of the treated intervals, therefore, the wellbore treatment occurs only in the near-wellbore zone of the formation, opened by a horizontal well without penetrating deep into the formation;

- thirdly, the high costs of chemical reagents (acid and emulsifiers) and their irrational use.

The closest in technical essence is the method of interval processing of the reservoir through an open horizontal wellbore (patent RU No. 2247832, IPC ЕВВ 43/27, publ. March 10, 2005, bull. No. 7), including the descent into the well of a pipe string with packers and a valve at the end of the column, pumping acid through the pipe string, the packers blocking the formation processing interval and injecting acid under pressure. The porosity, permeability and oil saturation of the near-trunk zone, along which intervals with reduced permeability are established, and the degree of cavernousness at their ends and the diameter of the trunk, are determined along the entire length of the passage of an open horizontal trunk through the reservoir by means of geophysical studies. Before lowering it into the well, a pipe assembly is introduced into the lower part of the pipe string with hydraulic packers controlled through the pipe string at both ends of the assembly and with a radial through calibrated channel in the assembly pipe, and an annular seat is installed under the shut-off ball as a valve at the end of the pipe assembly. The pipe string with the pipe assembly is lowered into the horizontal wellbore until the bottom; when unpacked packers, the horizontal wellbore is flushed. Following this, acid is pumped through the pipe string into the well in a volume equal to the volume of the first treatment interval. After that, a shut-off ball is dropped into the pipe string, the first interval from the bottom of the open hole of the horizontal well with reduced permeability is sealed from both ends. Acid is poured into the reservoir and the well is left for reaction. Then both packers are unpacked, the reaction products are removed from the wellbore by backwashing and at the same time the shut-off ball is lifted to the surface of the well, after which the pipe string with the pipe assembly is moved in the opposite direction from the bottom to the zone of the second interval from the bottom to the processing interval with a reduced permeability. Then, as in the processing of the first interval, starting with the operation of washing the wellbore with unpackaged packers and ending with the operation of removing reaction products with the lifting of the shut-off ball on the surface of the well, similar operations are performed in the above sequence. At the same time, the transfer of the pipe string with the pipe arrangement from one interval with reduced permeability to another for processing is also carried out by lifting the pipe string with the pipe assembly, and the packers are packaged at both ends of the interval of the horizontal wellbore with reduced permeability to be processed and the acid is crushed into the formation at the same time.

The disadvantages of this method are:

- firstly, the low efficiency of processing intervals with low permeability in carbonate reservoirs opened by an open horizontal wellbore, since the acid treatment of these intervals occurs only in the near-wellbore zone of a formation opened by a horizontal well without penetrating deep into the productive formation, while processing well zones of the formation presents certain difficulties due to the inability to deliver hydrochloric acid into the depth of the formation. As a result of the high rate of acid reaction in the carbonate component of the formation, water is released in the bottomhole zone, which is pushed into the depth of the formation by another portion of acid;

- secondly, the low reliability of the implementation of the method, due to the fact that the processing of intervals with reduced permeability is performed in one round trip operation of a pipe string with a pipe assembly into an open horizontal wellbore without removing it after processing each interval with a reduced permeability, so there is a high probability of loss tightness of one or both hydraulic packers and failure in the operation of technological equipment. In addition, there is a high likelihood of an leaky seating of the locking ball in the horizontal bore, while the length of the intervals with reduced permeability is different, so it is necessary to select the length of the pipe assembly along the length of the maximum interval with reduced permeability, and this, in turn, will cause inefficient injection of acid into other intervals with reduced permeability;

- thirdly, the destructive effect of acid on the sealing elements of the packers during their packing, since the packing of the packers at both ends of the pipe assembly and the crushing of acid into the formation are performed simultaneously, therefore, the sealing elements of the packers after they are removed from the well become unusable for reuse, those. are elements of one-time use, which leads to a rise in the cost of implementing the method.

The technical objectives of the invention are to increase the efficiency and reliability of the interval processing of the productive formation in an open horizontal wellbore, as well as the elimination of the destructive effect of acid on the sealing elements of the packers during their packaging.

The stated technical problems are solved by the method of interval processing of the reservoir in an open horizontal wellbore, including geophysical studies with the determination of porosity, permeability and oil saturation of the near-wellbore zone, the identification of intervals with reduced permeability, the determination of the degree of cavernosity at their boundaries and the diameter of the wellbore along the entire length of the open hole horizontal trunk in the reservoir, installation on the lower end of the pipe string pipe assemblies and with hydraulic packers controlled through the pipe string at both ends, lowering the pipe string into the well with the pipe assembly in the first interval from the bottom of the open horizontal wellbore with reduced permeability and blocking the packers on both sides of the processing interval with low permeability and injecting acid into the string pipes through the pipe assembly into the formation, holding the well for the reaction, unpacking both packers, flushing and removing reaction products from the wellbore, subsequent treatments slots open horizontal wellbore with low permeability in a direction from the bottom to the mouth, the extraction pipe with pipe joint arrangement of the well.

What is new is that the diameters of an open horizontal wellbore are determined at the boundaries of each identified interval with reduced permeability, a pipe assembly is assembled, consisting of a plug, a first hydraulic packer, a first pipe with perforated holes, a pulsed fluid pulsator, a destructible valve, and a second pipe with perforated holes and an inner ring sample, the second hydraulic packer, and the perforated holes of the second pipe are blocked from the inside by a hollow w with a shear fixed by a shear element, then the pipe assembly at the lower end of the pipe string is lowered into the first interval with reduced permeability from the bottom of the bottom so that the hydraulic pipe packers on both sides of the open horizontal wellbore overlap the first interval with reduced permeability, and the process fluid is pumped through the pipe string and first, two hydraulic packers are simultaneously planted simultaneously, and then the destructible valve is cut, the salt is pulsed 15% concentration of acid acid through the perforated openings of the first pipe in the first interval with reduced permeability, then a squeeze plug is installed at the wellhead and pushed under the influence of the process fluid pressure in the pipe string, while the squeeze plug moves along the pipe string , sits on the hollow sleeve, destroys the shear element and moves the hollow sleeve all the way into the inner ring selection, while the hollow sleeve is fixed in the second perforated nozzle, etc. the well is exposed to the reaction, at the end of which the reaction products are removed by swabbing along the pipe string, after which, in the forced mode, the reverse oil emulsion is pumped through the pipe string through the perforated holes of the second pipe into the first interval with reduced permeability, after which the well is subjected to reaction, at the end of which the pipe string is pulled up and both hydraulic packer packers are unpacked, a direct flush is performed and products are removed reaction from the first interval with reduced permeability, after which the pipe string with the pipe assembly is removed from the well, for the interval processing of the remaining intervals with reduced permeability, the above-described technological operations are repeated each time, starting with the installation of the pipe assembly and extraction of the pipe string with the pipe assembly from the well.

In FIG. 1-4 schematically and sequentially depicts the proposed method of interval processing of the reservoir in an open horizontal trunk.

The method of interval processing of the reservoir in an open horizontal wellbore is as follows.

Geophysical instruments are lowered into the open horizontal wellbore 1 (see FIG. 1) (not shown in FIGS. 1–4) and the near-barrel zone of the open horizontal wellbore 1 (see FIG. 1) is studied, determining porosity, permeability, and oil saturation layer. Intervals with reduced permeability are established, the degree of cavernousness and trunk diameters 1 at the ends of each identified interval are estimated, for example, three intervals with reduced permeability 2 ', 2ʺ, 2'ʺ are distinguished.

At the wellhead, the pipe assembly 3 is assembled (see Fig. 2), consisting of a plug 4, a first hydraulic packer 5, a first pipe 6 with perforated holes 7, a pulsed fluid pulsator 8, a destructible valve 9, and a second pipe 10 with perforated holes 11 and the inner ring sample 12 and the second hydraulic packer 13. The perforated holes 11 of the second pipe 10 are internally closed by a hollow sleeve 14 fixed by a shear element 15. The diameters of the perforated holes 7 and 11 of the first pipe 6 and second of the pipe 10, respectively, are equal, for example, 8 mm and 15 mm, which ensures the injection of chemicals through them and the free passage of reaction products during swabbing and washing during the implementation of the method.

Destructible valve 9, for example, is made in the form of a rubber membrane, tearing at a pressure of 9.0 MPa.

As a pulsed fluid pulsator 8, any known device for pulsed fluid injection into a formation described in patent RU No. 2241825, IPC ЕВВ 43/18, publ. December 10, 2004, bull. Number 34.

As hydraulic packers 5 and 13, inflatable packers are used, for example, Kazan Kvart Rubber Products Plant, the Republic of Tatarstan, inflated under pressure in the pipe string 16 and allowing hermetically to cut off the intervals with reduced permeability 2 ', 2ʺ, 2'ʺ in the open horizontal wellbore 1.

The dimensions of the hydraulic packers 5 and 13, as well as the distance L ₁ between them as part of the pipe assembly 3 during the assembly process, are taken into account taking into account the degree of cavernosity and trunk diameters at the ends of the interval L ₁ with reduced permeability, for example, the length of the interval L ₁ is 30 m.

The pipe assembly 3 is lowered at the lower end of the pipe string 16, for example, on a tubing string with a diameter of 73 mm in the first interval 2 ′ (see FIGS. 1 and 2) of length L ₁ with reduced permeability so that the hydraulic packers 5 and 13 pipe layout 3 on both sides of the open horizontal wellbore 1 overlapped the interval with low permeability.

Using a pumping unit (not shown in Fig. 1-4), for example, a cementing unit ЦА-320, process fluid, for example, waste water with a density of ρ = 1100 kg / m ³ , is pumped through a pipe string 16 (see Fig. 2) create pressure in the pipe string 16, while the hydraulic packers 5 and 13 are simultaneously simultaneously seated first, for example, under a pressure of 6.0 MPa, then the pressure in the pipe string 16 is continued to increase and when the pressure in the pipe string 16 is 9.0 MPa, destructible valve 9 is cut off, i.e. the rubber membrane is torn.

Next, a hydrochloric acid of 15% concentration is pulsedly pumped through perforated holes 7 with a diameter of 8 mm (see Fig. 3) of the first pipe 6 into the interval 2 'with reduced permeability, for example, with a flow rate of 10 m ³ / h at a pressure of 12 MPa.

As a result of pulsed injection, the near-trunk zone is cleaned and cracks expand in the near-trunk zone in the interval 2 'of the open horizontal wellbore 1 due to the reaction of hydrochloric acid with the rock of the reservoir.

In the process of implementation of the method using synthetic hydrochloric acid technical (HCl) according to GOST 857-95.

At the wellhead, a squeeze plug 17 is installed in the pipe string 16 and squeezed under pressure of the process fluid, for example, waste water with a density ρ = 1100 kg / m ³ , while the squeeze plug 17 moves along the pipe string 16, acts on the hollow sleeve 14 and destroys the shear element 15 and moves the hollow sleeve 14 all the way into the inner ring sample 12, while the hollow sleeve 14 is fixed, for example, by means of a retaining ring (not shown in FIGS. 1-4) in the second pipe 10.

Then the well is exposed to the reaction, for example, for 4 hours, at the end of which the reaction products are removed by swabbing through the pipe string 16 through perforated holes 11 (see Fig. 3) with a diameter of 15 mm of the second pipe 10 from the interval 2 'with reduced permeability at planted hydraulic packers 5 and 13. Swabbing is carried out, for example, using the PKS-5 geophysical elevator.

Then, in a forced mode with a flow rate of, for example, 70 m ³ / h, the reverse oil emulsion is pumped through the pipe string 16 (see Fig. 4) through the perforated holes 11 of the second pipe 10 into the interval 2 'with a reduced permeability of length L ₁ for the purpose of processing remote zone of an open horizontal wellbore 1.

The use of reverse oil emulsion allows you to delay the entry of acid into the reaction with the rock in the reservoir, while maintaining it in a dispersed state. This allows you to deliver the acid to its interaction with the rock in more remote areas of the reservoir, where the reaction of the reverse oil emulsion with the rock of the reservoir.

As the inverse oil acid emulsion, any known composition is used, for example, described in patent RU No. 2304711, IPC ЕВВ 43/27 “Method for preparing a reverse oil acid emulsion for processing the bottomhole zone of a well”, publ. 08/20/2007, bull. Number 23.

After that, the well is exposed to the reaction, for example, 3 hours after which the pipe string 16 is pulled upward, for example, by 10 tons, and both hydraulic packers 5 and 13 of the pipe assembly 3 are unpacked.

When pulsed injection of hydrochloric acid due to the propagation of vibrations from the point of view of the phase velocity of the propagation of vibrations and the absorption coefficient in the formation rock mass taking into account their natural frequencies (shales, limestones, sandstones, etc.), cracks expand in the near-stem zone of the formation, which allows reverse non-acidic emulsion during its subsequent injection to penetrate deep into the reservoir before interacting with the rock with minimal resistance in the near-wellbore zone.

Direct washing is performed, i.e. process fluid is pumped, for example, waste water with a density ρ = 1100 kg / m ³ through a pipe string 16 through the perforated holes of the second pipe in the interval L ₁ with reduced permeability and through the annulus (not shown in Fig. 1-4) at the wellhead. Thus, the reaction products are removed from the interval L ₁ with reduced permeability.

Next, the pipe string 16 with the pipe assembly 3 is removed from the well.

For the interval processing of the remaining intervals 2ʺ and 2'ʺ with reduced permeability, respectively, of length L ₂ and L ₃ , the above-described technological operations are repeated each time, starting with mounting the pipe assembly 3 and removing the pipe string 16 with pipe assembly 3 from the well, while the length of the pipe assembly (the distance between the hydraulic packers 5 and 13) each time is selected depending on the length L ₂ and L _3, respectively.

The efficiency of the interval treatment of the productive formation in the open horizontal wellbore is increased due to the alternate treatment of one interval, first with pulse acid treatment to clean and expand cracks in the near-wellbore zone of the open horizontal wellbore, and then deeply treat the formation by forced injection into the same interval with reduced permeability reverse oil emulsion.

The reliability of the implementation of the method is increased by extracting the layout after processing each interval with reduced permeability, conducting an audit, adjusting the length of the pipe assembly for each cut-off interval with reduced permeability.

The destructive effect of acid on the sealing elements of the packers is excluded, since they are packaged on the process fluid (waste water), which allows them to be reused after the audit of the sealing elements of the packers.

The proposed method allows you to:

- increase the efficiency and reliability of the implementation of the method;

- eliminate the destructive effect of acid on the sealing elements of the packers.

Claims (1)

A method for interval processing of a productive formation in an open horizontal wellbore, including conducting geophysical studies with the determination of porosity, permeability and oil saturation of the near-wellbore zone, identifying intervals with reduced permeability, determining the degree of cavernosity at their boundaries and the diameter of the wellbore along the entire length of an open horizontal wellbore in a productive formation, installation on the lower end of the pipe string pipe with controlled through the pipe string hydraulic packers at both ends, lowering the pipe string into the well with the pipe assembly in the first interval from the bottom of the open horizontal wellbore with reduced permeability and blocking the packer on both sides of the processing interval with reduced permeability and injecting acid through the pipe string through the pipe assembly into the formation holding the well for the reaction, unpacking both packers, flushing and removing reaction products from the wellbore, subsequent processing of open-hole intervals horizontal wellbore with reduced permeability in the direction from the bottom to the mouth, removing a pipe string with a pipe assembly from the well, characterized in that the diameters of the open horizontal wellbore at the boundaries of each identified interval with reduced permeability are determined, a pipe assembly consisting of a plug, the first a hydraulic packer, a first pipe with perforated holes, a pulsed fluid pulsator, a destructible valve, a second pipe with perforated holes with holes and an inner ring sample, a second hydraulic packer, the perforated holes of the second pipe being blocked from the inside by a hollow sleeve fixed by a shear element, then lowering the pipe assembly at the lower end of the pipe string into the first interval from the bottom of the pipe with reduced permeability so that the hydraulic pipe packers from both the sides of the open horizontal wellbore blocked the first interval with reduced permeability, the process fluid is pumped through the pipe string and after First, two hydraulic packers are simultaneously planted at the same time, and then the destructible valve is cut, 15% hydrochloric acid is pulsedly pumped through the perforated openings of the first pipe into the first interval with reduced permeability, then a cork plug is installed at the wellhead and produced squeezing under the influence of the process fluid pressure in the pipe string, while the squeezing plug moves along the pipe string, sits on the hollow sleeve, destroys the cut ohm element and moves the hollow sleeve all the way into the inner ring sample, while the hollow sleeve is fixed in the second perforated pipe, the well is exposed to the reaction, after which the reaction products are removed by swabbing along the pipe string, and then in the forced mode, the reverse oil emulsion is pumped along the pipe string through the perforated holes of the second pipe in the first interval with low permeability, then the well is exposed to the reaction, at the end of which the pipe string is pulled upward and both hydraulic packer packers are unpacked, a direct flush is performed and reaction products are removed from the first interval with reduced permeability, after which the pipe string with the pipe assembly is removed from the well, for the interval processing of the remaining intervals with reduced permeability, repeat the above technological operations, starting with the installation of the pipe assembly and extraction of the pipe string with the pipe assembly from the well.

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