CN112943168A - Blockage removing method for removing drilling fluid pollution of open hole well section - Google Patents
Blockage removing method for removing drilling fluid pollution of open hole well section Download PDFInfo
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- CN112943168A CN112943168A CN202110038548.5A CN202110038548A CN112943168A CN 112943168 A CN112943168 A CN 112943168A CN 202110038548 A CN202110038548 A CN 202110038548A CN 112943168 A CN112943168 A CN 112943168A
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- 239000012530 fluid Substances 0.000 title claims abstract description 52
- 238000005553 drilling Methods 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 title claims abstract description 42
- 239000007788 liquid Substances 0.000 claims abstract description 89
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims abstract description 64
- 229920002678 cellulose Polymers 0.000 claims abstract description 58
- 239000001913 cellulose Substances 0.000 claims abstract description 58
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 52
- 239000010428 baryte Substances 0.000 claims abstract description 46
- 229910052601 baryte Inorganic materials 0.000 claims abstract description 46
- 238000010276 construction Methods 0.000 claims abstract description 20
- 230000015556 catabolic process Effects 0.000 claims abstract description 18
- 238000006731 degradation reaction Methods 0.000 claims abstract description 18
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 17
- 239000001768 carboxy methyl cellulose Substances 0.000 claims abstract description 7
- 229920002134 Carboxymethyl cellulose Polymers 0.000 claims abstract description 5
- 235000010948 carboxy methyl cellulose Nutrition 0.000 claims abstract description 5
- 239000008112 carboxymethyl-cellulose Substances 0.000 claims abstract description 5
- 150000002978 peroxides Chemical class 0.000 claims abstract description 5
- 230000000593 degrading effect Effects 0.000 claims abstract 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 48
- 238000006073 displacement reaction Methods 0.000 claims description 44
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 28
- 238000005086 pumping Methods 0.000 claims description 19
- 238000002156 mixing Methods 0.000 claims description 17
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 15
- 230000015572 biosynthetic process Effects 0.000 claims description 15
- 238000003756 stirring Methods 0.000 claims description 12
- 238000004140 cleaning Methods 0.000 claims description 10
- 239000004576 sand Substances 0.000 claims description 9
- 238000004132 cross linking Methods 0.000 claims description 8
- 230000007797 corrosion Effects 0.000 claims description 7
- 238000005260 corrosion Methods 0.000 claims description 7
- ZRALSGWEFCBTJO-UHFFFAOYSA-N Guanidine Chemical compound NC(N)=N ZRALSGWEFCBTJO-UHFFFAOYSA-N 0.000 claims description 6
- 239000006004 Quartz sand Substances 0.000 claims description 6
- CHJJGSNFBQVOTG-UHFFFAOYSA-N N-methyl-guanidine Natural products CNC(N)=N CHJJGSNFBQVOTG-UHFFFAOYSA-N 0.000 claims description 3
- 230000002378 acidificating effect Effects 0.000 claims description 3
- SWSQBOPZIKWTGO-UHFFFAOYSA-N dimethylaminoamidine Natural products CN(C)C(N)=N SWSQBOPZIKWTGO-UHFFFAOYSA-N 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 2
- 244000007835 Cyamopsis tetragonoloba Species 0.000 claims 1
- 239000002245 particle Substances 0.000 abstract description 10
- 230000035699 permeability Effects 0.000 abstract description 10
- 230000000903 blocking effect Effects 0.000 abstract description 9
- 239000007787 solid Substances 0.000 abstract description 5
- 238000011084 recovery Methods 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 19
- 238000006243 chemical reaction Methods 0.000 description 9
- 238000002347 injection Methods 0.000 description 9
- 239000007924 injection Substances 0.000 description 9
- 102000004190 Enzymes Human genes 0.000 description 6
- 108090000790 Enzymes Proteins 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 229920002907 Guar gum Polymers 0.000 description 4
- 230000003203 everyday effect Effects 0.000 description 4
- 239000000665 guar gum Substances 0.000 description 4
- 229960002154 guar gum Drugs 0.000 description 4
- 235000010417 guar gum Nutrition 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 239000000047 product Substances 0.000 description 3
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 2
- 239000009096 changqing Substances 0.000 description 2
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 2
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
- E21B41/005—Waste disposal systems
- E21B41/0057—Disposal of a fluid by injection into a subterranean formation
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
- E21B41/02—Equipment or details not covered by groups E21B15/00 - E21B40/00 in situ inhibition of corrosion in boreholes or wells
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
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- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Detergent Compositions (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a plug removal method for removing drilling fluid pollution of an open hole well section, which comprises the steps of firstly preparing a cellulose plug removal liquid, changing the pH value of stratum liquid, degrading cellulose in the drilling fluid by using a cellulose degradation agent and peroxide, then removing solid particles such as barium sulfate and the like in the drilling fluid by using a barite plug removal liquid, and achieving the purpose of recovering the stratum permeability; performing fracturing construction, and filling the opened natural cracks; and (5) replacing the sand-carrying liquid in the shaft with active water to enter the stratum to finish the blockage removing process. Adding a cellulose degradation agent and peroxide to degrade carboxymethyl cellulose in the drilling fluid, then adding a barite blocking remover to remove solid particles such as barium sulfate in the drilling fluid, and realizing the recovery of stratum permeability. The method has strong operability, can effectively remove the damage of cellulose and solid particles in the drilling fluid to the stratum, and successfully solves the problem of pollution of the drilling fluid to the stratum in an open hole section.
Description
Technical Field
The invention belongs to the field of oilfield chemistry, and particularly relates to a method for removing drilling fluid pollution in an open hole section.
Background
The ultra-low permeability reservoir represented by Ansai and Jingan in Changqing oil fields enters a double-high development stage after long-term water injection development, the dominant water drive direction is gradually formed, water flooded wells are increased, and the difficulty in digging residual oil by conventional measures is high. In order to fully submerge the residual oil, develop the low-yield well and long-stop well treatment, the thought of excavating the residual oil and recovering the yield of the water-flooded well by sidetracking the old well is provided on the basis of quantitative description of the residual oil.
The low pressure and low permeability of the Changqing oil field require modification before the production of the oil well to have productivity, and the well completion mode must meet the technical requirement of reservoir modification, so the perforation well completion mode is adopted. However, for sidetrack lateral wells, because each lateral well has a large inclination and each lateral well section has a short length, casing cannot be put in, and only an open hole completion mode can be adopted, so that a large amount of drilling fluid remains in the formation. A large amount of inorganic, organic and high molecular compounds contained in the drilling fluid inevitably pollute the stratum and cause permeability reduction, so that a method for removing the drilling fluid pollution after the open hole completion of the low-permeability oil reservoir is urgently needed, the damage of the drilling fluid to the reservoir is reduced, and the permeability of the reservoir is recovered.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide a method for removing the pollution of a drilling fluid in an open hole section.
The invention is realized by the following technical scheme.
A method for removing drilling fluid pollution in an open hole well section comprises the following steps:
s1, preparing a cellulose blockage removing liquid: adding 10-14% of hydrochloric acid into 85-88% of water according to the mass ratio to obtain a hydrochloric acid solution, respectively adding 0.08-0.10% of cellulose degradation agent and 0.1-0.3% of industrial hydrogen peroxide into the hydrochloric acid solution, and mixing and stirring to obtain a cellulose unblocking liquid;
s2, injecting a cellulose blockage removing solution: squeezing the prepared cellulose blockage removing liquid into a stratum damaged by drilling fluid at a small displacement, after the blockage removing liquid is pumped, cleaning the blockage removing liquid in a shaft into the stratum by using active water, and closing the well for reacting for 6-8 hours;
s3, preparing the barite plugging removal liquid: the preparation concentration is 250L/m3The barite blockage removing liquid;
s4, injecting the barite plugging removal liquid: squeezing the prepared barite plugging removal liquid into the stratum treated in the step S2 at a small displacement, after the plugging removal liquid is pumped, cleaning the plugging removal liquid in the shaft into the stratum by using active water, and closing the well for reacting for 6-8 hours;
s5, fracturing construction: after the formation treatment is finished, injecting by a large-displacement pump to open the main fracture; carrying a propping agent by using a guanidine gum cross-linking liquid with large discharge capacity to fill the opened natural cracks;
and S6, replacing the sand-carrying liquid in the shaft with active water to enter the stratum by the construction displacement with large displacement, and completing the blockage removing process.
With respect to the above technical solutions, the present invention has a further preferable solution:
further, adjusting the pH value of the liquid system to 2-3; then respectively adding the cellulose degradation agent and the industrial hydrogen peroxide into the hydrochloric acid solution.
Further, the hydrochloric acid is 31% industrial hydrochloric acid.
Further, the cellulose degradation agent is HL-308 type biological enzyme produced by Chuzhou biological enzyme factory.
Further, 27.5% of industrial hydrogen peroxide is adopted as the hydrogen peroxide.
Further, the barite blocking remover is prepared by mixing a barite blocking remover and water according to a mass ratio of 1: 3, and stirring at high speed for 5-8 min.
Further, in the step S2, the cellulose unblocking liquid is injected in a range of 0.3 to 0.5m3Pumping at a rate of 0.3-0.5m3And pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum.
Further, in the step S4, the barite unblocking liquid is injected in a range of 0.3-0.5m3Pumping at a rate of 0.3-0.5m3And pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum.
Further, in the step S5, the guar gum cross-linking solution is adopted according to the formula of 240-620g/cm3The sand concentration of (2.0-3.0 m in terms of discharge capacity)3The sand carries 20-40 meshes of quartz sand per min.
Due to the adoption of the technical scheme, the invention has the following beneficial effects:
1) according to the method, cellulose biological enzyme and peroxide have a good degradation effect on carboxymethyl cellulose under an acidic condition, so that beta-1, 4-glycosidic bonds in a carboxymethyl cellulose structure in the drilling fluid are degraded into water-soluble micromolecular saccharides. Can basically complete the degradation of the sodium carboxymethylcellulose within 30-60 min.
2) After the well is closed for reaction for several hours, the barite blocking remover is added, and solid particles such as barium sulfate in the drilling fluid are removed through corrosion of barite blocking remover to the barium sulfate, so that the recovery of the formation permeability is realized, and the corrosion rate can reach over 64%.
3) The permeability of the damaged stratum of the well is recovered, oil is produced by about 1t every day after the well is put into operation, and the water content is stabilized at 29-40%.
4) The method has strong operability, can effectively remove the damage of cellulose and solid particles in the drilling fluid to the stratum, and successfully solves the problem of pollution of the drilling fluid to the stratum in an open hole section.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention:
FIG. 1 is a schematic diagram of a drilling fluid unblocking process;
FIG. 2 is a fracture construction curve of example 1 after treating damage of drilling fluid in an open hole interval;
FIG. 3 is a fracture construction curve of example 2 after treating damage of drilling fluid in an open hole interval;
FIG. 4 is a fracture construction curve of example 3 after treating damage to drilling fluid in an open hole interval.
Detailed Description
The present invention will now be described in detail with reference to the drawings and specific embodiments, wherein the exemplary embodiments and descriptions of the present invention are provided to explain the present invention without limiting the invention thereto.
The embodiment of the invention provides a method for removing drilling fluid pollution of an open hole well section, which comprises the following steps:
s1, preparing a cellulose blockage removing liquid: adding 10-14% of hydrochloric acid solution into 85-90% of water according to the mass ratio to obtain hydrochloric acid solution, and adjusting the pH value of a liquid system to 2-3; respectively adding 0.08-0.10% of cellulose degradation agent and 0.1-0.3% of industrial hydrogen peroxide into a hydrochloric acid solution, and mixing and stirring to obtain the cellulose unblocking liquid.
Wherein, the hydrochloric acid is 31 percent of industrial hydrochloric acid; the cellulose degradation agent is HL-308 type biological enzyme produced by Chuzhou biological enzyme factory; the industrial hydrogen peroxide is 27.5 percent of industrial hydrogen peroxide.
S2, injecting a cellulose blockage removing solution: the prepared cellulose blockage removing liquid is added by 0.3-0.5m3The displacement is squeezed into the stratum damaged by the drilling fluid at a displacement of 0.3-0.5m3Pumping active water into the well at a displacement of/min to remove the cellulose in the wellDisplacing into the formation as shown in figure 1.
After the injection of the plug removing pump is finished, the plug removing liquid in the shaft is cleaned into the stratum by active water, and the well is closed for reaction for 6-8 min.
S3, preparing the barite plugging removal liquid: the method comprises the following steps of mixing a barite blocking remover and water according to a mass ratio of 1: 3, and stirring at high speed for 5-8min to obtain the final product with concentration of 250L/m3The barite blockage removing liquid.
S4, injecting the barite plugging removal liquid: the prepared barite blockage removing liquid is added by 0.3-0.5m3A/min displacement pump is pumped into the formation treated in step S2, and then at 0.3-0.5m3Pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum; after the injection of the plug removing pump is finished, the plug removing liquid in the shaft is cleaned into the stratum by active water, and the well is closed for reaction for 6-8 min.
S5, fracturing construction: after the formation treatment is finished, injecting by a large-displacement pump to open the main fracture; in the pumping process of the fracturing fluid, 620g/cm of guar gum cross-linking fluid is adopted according to the formula of 240-3The sand concentration of (2.0-3.0 m in terms of discharge capacity)3The sand carries 20-40 mesh quartz sand at min, and fills the opened natural cracks.
S6, at a rate of 2.0 to 3.0m3And (3) replacing the sand-carrying liquid in the shaft with active water to enter the stratum by construction displacement with large displacement per minute to finish the blockage removing process.
The effect of the method of the present invention is illustrated by the example of LC45-26 wells.
Example 1
In order to solve the problem of damage to the formation caused by the drilling fluid after the open-hole completion of the multilateral well, the embodiment provides a method for relieving the damage to the formation caused by the drilling fluid, as shown in fig. 1 and 2, and the method comprises the following steps:
s1, adding 31% industrial hydrochloric acid into 87.72% water according to the mass ratio to obtain a hydrochloric acid solution, and adjusting the pH value of the liquid system to 3; respectively adding 0.08% of cellulose degradation agent and 0.2% of industrial hydrogen peroxide into a hydrochloric acid solution, and mixing and stirring to obtain the cellulose unblocking liquid:
s2, adding 25kg of the prepared cellulose unblocking liquid to 0.4m3The displacement is squeezed and pumped into the stratum damaged by the drilling fluid at a displacement of 0.3m3Pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum; after the injection of the plug removing pump is finished, cleaning the plug removing liquid in the shaft into the stratum by using active water, and closing the well for reaction for 7 hours;
s3, preparing the barite plugging removal liquid: the method comprises the following steps of mixing a barite blocking remover and water according to a mass ratio of 1: 3, and stirring at high speed for 6min to obtain the product with the concentration of 250L/m3The barite blockage removing liquid;
s4, mixing the prepared barite unblocking liquid by 0.3m3The/min displacement pump is then pumped into the formation treated in step S2 at 0.5m3And pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum. After the injection of the plug removing pump is finished, cleaning the plug removing liquid in the shaft into the stratum by using active water, and closing the well for reaction for 8 hours;
s5, fracturing construction: after the formation treatment is finished, injecting by a large-displacement pump to open the main fracture; in the pumping process of the fracturing fluid, the guar gum cross-linking fluid is adopted according to the ratio of 240g/cm3The sand concentration of (2) is 3.0m3Carrying 20-40 mesh quartz sand at min, and filling the opened natural cracks;
s6, at 3.0m3And (3) replacing the sand-carrying liquid in the shaft with active water to enter the stratum by construction displacement with large displacement per minute to finish the blockage removing process.
After the blockage removing construction is finished, cellulose, barite and other particles in the drilling fluid are effectively removed, oil is produced by an LC45-26 well every day for about 1t, the water content is stable at 29%, the effect is stable, and the corrosion rate of barite blockage removing liquid to barium sulfate can reach 65.43%. The production curve is shown in FIG. 2.
Example 2
S1, adding 10% hydrochloric acid solution into 89.87% water according to the mass ratio, and adjusting the pH value of the liquid system to 2-3; respectively adding 0.10% of cellulose degradation agent and 0.3% of industrial hydrogen peroxide into a hydrochloric acid solution, and mixing and stirring to obtain the cellulose blockage removing solution:
s2, mixing the prepared cellulose unblocking liquid by 0.3m3The displacement per minute is squeezed and pumped to the ground damaged by the drilling fluidIn a layer, then at 0.5m3Pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum; after the injection of the plug removing pump is finished, cleaning the plug removing liquid in the shaft into the stratum by using active water, and closing the well for reaction for 6 hours;
s3, preparing the barite plugging removal liquid: the method comprises the following steps of mixing a barite blocking remover and water according to a mass ratio of 1: 3, and stirring at high speed for 5min to obtain the product with concentration of 250L/m3The barite blockage removing liquid;
s4, mixing the prepared barite unblocking liquid with the thickness of 0.4m3The/min displacement pump is then pumped into the formation treated in step S2 at 0.3m3And pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum. After the injection of the plug removing pump is finished, cleaning the plug removing liquid in the shaft into the stratum by using active water, and closing the well for reaction for 7 hours;
s5, fracturing construction: after the formation treatment is finished, injecting by a large-displacement pump to open the main fracture; in the pumping process of the fracturing fluid, the guar gum cross-linking fluid is adopted according to the proportion of 500g/cm3The sand concentration of (2) is 3.0m3Carrying 20-40 mesh quartz sand at min, and filling the opened natural cracks;
s6, at 2.0m3And (3) replacing the sand-carrying liquid in the shaft with active water to enter the stratum by construction displacement with large displacement per minute to finish the blockage removing process.
After the blockage removing construction is finished, cellulose, barite and other particles in the drilling fluid are effectively removed, oil is produced by an LC45-26 well every day for about 1.4t, the water content is stable at 35%, the effect is stable, and the corrosion rate of barite blockage removing liquid to barium sulfate can reach 64.37%. The production curve is shown in FIG. 3.
Example 3
S1, adding 14% hydrochloric acid solution into 85.72% water by mass, and adjusting the pH value of a liquid system to 2-3; respectively adding 0.08% of cellulose degradation agent and 0.2% of industrial hydrogen peroxide into a hydrochloric acid solution, and mixing and stirring to obtain the cellulose unblocking liquid:
s2, mixing the prepared cellulose unblocking liquid by 0.5m3The/min displacement is squeezed and pumped into the stratum damaged by the drilling fluid and then 0.4m3Min displacement pumpingThe cellulose blockage removing liquid in the shaft is replaced into the stratum by the sex water; after the injection of the plug removing pump is finished, cleaning the plug removing liquid in the shaft into the stratum by using active water, and closing the well for reaction for 6 hours;
s3, preparing the barite plugging removal liquid: the method comprises the following steps of mixing a barite blocking remover and water according to a mass ratio of 1: 3, and stirring at high speed for 8min to obtain the product with the concentration of 250L/m3The barite blockage removing liquid;
s4, mixing the prepared barite unblocking liquid by 0.5m3The/min displacement pump is then pumped into the formation treated in step S2 at 0.4m3And pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum. After the injection of the plug removing pump is finished, cleaning the plug removing liquid in the shaft into the stratum by using active water, and closing the well for reaction for 6 hours;
s5, fracturing construction: after the formation treatment is finished, injecting by a large-displacement pump to open the main fracture; in the pumping process of the fracturing fluid, 620g/cm of guanidine gum cross-linking fluid is adopted3The sand concentration of (2) is 3.0m3Carrying 20-40 mesh quartz sand at min, and filling the opened natural cracks;
s6, at 2.5m3And (3) replacing the sand-carrying liquid in the shaft with active water to enter the stratum by construction displacement with large displacement per minute to finish the blockage removing process.
After the blockage removing construction is finished, cellulose, barite and other particles in the drilling fluid are effectively removed, about 2t of oil is produced in an LC45-26 well in the day after the production, the water content is stabilized at 40%, the effect is stable, and the corrosion rate of barite blockage removing liquid to barium sulfate can reach 66.02%. The production curve is shown in FIG. 4.
Tests show that cellulose biological enzyme and peroxide have better degradation effect on carboxymethyl cellulose under the acidic condition, and can basically complete the degradation of sodium carboxymethyl cellulose within 30-60 min; the corrosion rate of the barite plugging removal liquid to barium sulfate can reach 66%; by implementing the blockage relieving construction, the cellulose blockage relieving liquid and the barite blockage relieving liquid sequentially enter the deep part of the stratum, and particles such as cellulose and barite remained in the stratum in the drilling process are corroded, so that the permeability of the damaged stratum of the well is recovered, the oil is produced for about 1t every day after the well is put into operation, and the water content is stabilized to be about 30-40%.
After the process is implemented, the particles such as cellulose, barite and the like in the drilling fluid are effectively removed, the initial permeability of the stratum is restored again, and the well normally produces after fracturing.
The present invention is not limited to the above-mentioned embodiments, and based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some technical features without creative efforts according to the disclosed technical contents, and these substitutions and modifications are all within the protection scope of the present invention.
Claims (10)
1. A plug removal method for removing drilling fluid pollution in an open hole well section is characterized by comprising the following steps:
s1, preparing a cellulose blockage removing liquid: adding 10-14% of hydrochloric acid into 85-88% of water according to the mass ratio to obtain a hydrochloric acid solution, respectively adding 0.08-0.10% of cellulose degradation agent and 0.1-0.3% of industrial hydrogen peroxide into the hydrochloric acid solution, and mixing and stirring to obtain a cellulose unblocking liquid;
s2, injecting a cellulose blockage removing solution: squeezing the prepared cellulose blockage removing liquid into a stratum damaged by drilling fluid at a small displacement, after the blockage removing liquid is pumped, cleaning the blockage removing liquid in a shaft into the stratum by using active water, and closing the well for reacting for 6-8 hours;
s3, preparing the barite plugging removal liquid: the preparation concentration is 250L/m3The barite blockage removing liquid;
s4, injecting the barite plugging removal liquid: squeezing the prepared barite plugging removal liquid into the stratum treated in the step S2 at a small displacement, after the plugging removal liquid is pumped, cleaning the plugging removal liquid in the shaft into the stratum by using active water, and closing the well for reacting for 6-8 hours;
s5, fracturing construction: after the formation treatment is finished, injecting by a large-displacement pump to open the main fracture; carrying a propping agent by using a guanidine gum cross-linking liquid with large discharge capacity to fill the opened natural cracks;
and S6, replacing the sand-carrying liquid in the shaft with active water to enter the stratum by the construction displacement with large displacement, and completing the blockage removing process.
2. The method for removing the blockage of the drilling fluid pollution in the open hole section according to claim 1, wherein the pH value of a liquid system is adjusted to 2-3; then respectively adding the cellulose degradation agent and the industrial hydrogen peroxide into the hydrochloric acid solution.
3. The method of claim 1, wherein the hydrochloric acid is 31% industrial hydrochloric acid.
4. The method of claim 1, wherein the cellulose degradation agent is a type HL-308 bio-enzyme produced by Chuzhou bio-enzyme factory.
5. The method of claim 1, wherein the hydrogen peroxide is 27.5% industrial hydrogen peroxide.
6. The deblocking method for removing drilling fluid pollution in an open hole well section according to claim 1, wherein the barite deblocking fluid is prepared by mixing a barite deblocking agent and water according to a mass ratio of 1: 3, and stirring at high speed for 5-8 min.
7. The method for removing the drilling fluid pollution in the open hole section of the well according to the claim 1, wherein in the step S2, the cellulose removing solution is injected by 0.3-0.5m3Pumping at a rate of 0.3-0.5m3And pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum.
8. The method for removing the drilling fluid pollution in the open hole section of the well according to claim 1, wherein in the step S4, the barite plugging solution is injected by 0.3-0.5m3Pumping at a rate of 0.3-0.5m3And pumping active water at a displacement of/min, and replacing the cellulose blockage removing liquid in the shaft into the stratum.
9. The method as claimed in claim 1, wherein in step S5, the guar cross-linking fluid is used in an amount of 240-620g/cm3The sand concentration of (2.0-3.0 m in terms of discharge capacity)3The sand carries 20-40 meshes of quartz sand per min.
10. The plug removal method for removing drilling fluid pollution of the open hole section according to claim 1, wherein the cellulose degradation agent and peroxide are used for degrading the carboxymethyl cellulose within 30-60 min under an acidic condition; the water content is stable at 29-40%, and the corrosion rate of the barite plugging removal liquid to barium sulfate is more than 64%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110038548.5A CN112943168A (en) | 2021-01-12 | 2021-01-12 | Blockage removing method for removing drilling fluid pollution of open hole well section |
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| CN113887088A (en) * | 2021-11-08 | 2022-01-04 | 西南石油大学 | Method for determining dosage of blocking remover for removing reservoir barite pollution |
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