CN111808589B - Simulation principle and preparation method of blockage in shaft of polymer injection well of offshore oil field - Google Patents
Simulation principle and preparation method of blockage in shaft of polymer injection well of offshore oil field Download PDFInfo
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- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
- C09K8/524—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning organic depositions, e.g. paraffins or asphaltenes
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- C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
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- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
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- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/50—Compositions for plastering borehole walls, i.e. compositions for temporary consolidation of borehole walls
- C09K8/504—Compositions based on water or polar solvents
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- C09K8/52—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning
- C09K8/528—Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning inorganic depositions, e.g. sulfates or carbonates
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices, or the like
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- E21B37/00—Methods or apparatus for cleaning boreholes or wells
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- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
- C08K2003/2265—Oxides; Hydroxides of metals of iron
- C08K2003/2272—Ferric oxide (Fe2O3)
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- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/24—Acids; Salts thereof
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- C08K2003/265—Calcium, strontium or barium carbonate
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- C—CHEMISTRY; METALLURGY
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- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/24—Acids; Salts thereof
- C08K3/26—Carbonates; Bicarbonates
- C08K2003/267—Magnesium carbonate
Abstract
The invention discloses a simulation principle and a preparation method of a blockage in a shaft of a polymer injection well in an offshore oil field. The preparation method of the composite plug in the wellbore of the polymer injection well comprises the following steps: 1) Preparing a polymer mother solution by using injected water or simulated water in an offshore oilfield field; 2) Mixing the polymer mother liquor with the injected water or the simulated water, and adding calcium chloride, magnesium chloride, sodium carbonate, ferric oxide and heavy oil to obtain a composite target solution; the concentration of the polymer in the composite target liquid is the polymer injection concentration of the offshore oilfield field; 3) And placing the composite target liquid at the target oil reservoir temperature for dehydration and aging to obtain the composite target liquid. Aiming at the specific conditions of the polymer injection well, the method disclosed by the invention is utilized to simulate the corresponding composite blockage, and the blocking remover is optimized, so that the method has an important significance for improving the blocking removing effect. Therefore, the composite plug in the shaft of the polymer injection well of the offshore oil field can be used for research in a plugging removal system or a plugging removal method of the polymer injection well of the offshore oil field.
Description
Technical Field
The invention relates to a simulation principle and a preparation method of a plug in a shaft of a polymer injection well of an offshore oilfield.
Background
With the continuous development of oil fields, more and more oil fields enter a medium-high water content stage at present, and the yield is obviously reduced, so that a plurality of oil fields adopt a chemical flooding method to improve the recovery ratio. Polymer flooding is a main means for improving the recovery efficiency of crude oil and is widely applied, the Bohai sea oil field also applies a polymer flooding improvement recovery technology in large scale in 3 oil fields such as Suizhong 36-1, jinzhou 9-3, luda 10-1 and the like, and remarkable oil increasing and water reducing effects are obtained.
However, with the wide application of polymer flooding, the problems that many polymer injection wells face high injection pressure and partial wells are under-injected seriously, some wells even stop injecting, so that the yield of an effective oil well is difficult to promote, the polymer flooding effect is seriously influenced, and the efficient and rapid development of an offshore oil field cannot be realized. The blocking phenomenon of the polymer in the near wellbore area is more and more frequently mentioned, and the polymer is also more and more valued by the field engineering technicians and scientific researchers.
At present, the commonly used chemical blockage removal measures and hydraulic fracturing measures relieve the contradiction that the injection pressure is high and the injection cannot be carried out to a certain extent, but have the problems of unsatisfactory effect, short action time, poor universality and the like. The reason is that the existing research on the cause, mechanism and rule lack of systems for the blockage of the polymer injection well of the offshore oil field is caused by the fact that the offshore condition is greatly different from the land, the polymer flooding development time of the offshore oil field is obviously later than that of the land oil field, and the related research is started later. Due to the differences of the polymer injection process, the condition of the polymer-mixed sewage quality, the yield-increasing measures of polymer injection wells and the like, the blocking cause, the components of the blocking objects and the blocking mechanism of each well are greatly different in different oil fields and different platforms, and even if the forming processes and the components of the blocking objects at different positions of the same well are different, the blocking removing effect difference of the same blocking remover on the blocking objects at different wells and different positions is large. In order to effectively and thoroughly remove the blockage, the blockage of different wells and different positions needs to be simulated according to the polymer injection process of different wells, so that an experimental basis is laid for the screening of a blockage removal system and the optimization of the blockage removal process, theoretical guidance is provided, the blockage removal and injection increase effects are further improved, the effective period is prolonged, and the goal of contradiction between polymer injection layers is relieved.
The chemical flooding oilfield polymer injection well plug component comprises organic high molecular materials, rock minerals, inorganic scale precipitates, heavy components deposited in oil products and the like, and the existence state of each component in different positions near a well zone is also various. Due to different blockage causes, blockage components and existing states, blockage mechanisms at different positions of a near wellbore region present characteristics of diversification and certain regularity, and therefore, the plugs with different typical characteristics need to be simulated, and basic experimental conditions and reliable theoretical guidance are provided for developing blockage removal evaluation experiments in different modes.
Disclosure of Invention
The invention aims to provide a simulation principle and a preparation method of a plug in a shaft of a polymer injection well of an offshore oil field.
Firstly, offshore fields have the following characteristics: according to the existing material statistics, the land oil field is 5 in most 1 / 2 'or 7' casing and perforation completion, while Bohai sea oil field mostly is 7 'or 9' except few open hole completions due to special oil reservoir conditions (loose sandstone) 5 / 8 The sleeve, the perforation, the sieve tube and the gravel packing sand control completion are completed, but the sieve tube and the gravel packing sand control are provided;
the width of the screen pipe seam of the offshore oil field is mostly 0.15-0.5 mm, 20-40 mesh gravel is mostly adopted for gravel packing and sand control, and the permeability of the gravel packing layer is about 40-60 mu m 2 。
Secondly, dividing the position of the offshore oilfield polymer injection well plug: under the special well completion process condition of offshore oil fields, after the polymer solution finishes the ground preparation process, the polymer solution enters the stratum for seepage through the following links: the wellbore string is flowed first, then through a screen into the gravel pack at a high rate of seepage, the perforations filled with gravel, followed by the compacted zone and near-wellbore formation, the seepage rate gradually slowing.
By fully considering the change of factors such as near-wellbore area medium, flow velocity, flow state, pressure and the like, the main components of the polymer injection well plug are polymer, inorganic salt scale, inorganic clay mineral and oil stain through statistics of the existing plug component analysis data, and the content of the polymer in most plugs accounts for 40-70%. Therefore, the binding polymers have morphological differences and the composition of the plugs changes, so that the positions of the plugs are divided into three nodes, namely the plugs in a borehole, the plugs in a gravel packing layer and the plugs in a near wellbore zone.
The blockage in the shaft mainly comprises high-concentration polymer, inorganic salt scale and oil stain. The oxygen content in a shaft is high, most metal ions form inorganic salt scale, so the polymer exists mainly in a high-concentration polymer mode, and polymer undissolved substances, fish eyes and the like cannot stay on the wall of a well and directly enter a gravel filling layer due to the fact that polymer solution flows in the shaft in a high-speed pipe.
The blockages in the gravel packing layer of the polymer injection well mainly comprise: high-concentration polymer containing large-particle insoluble substance and fish eye, cross-linked polymer containing large-particle insoluble substance and fish eye, inorganic salt scale, and oil stain. The width of the screen pipe seam of the offshore oilfield is mostly 0.15-0.5 mm, 20-40 mesh gravel is mostly adopted for gravel packing and sand control, so large-particle insoluble substances and 'fish eyes' can be squeezed and deformed under high pressure to enter a gravel packing layer through the screen pipe, and meanwhile, the large-particle insoluble substances and the 'fish eyes' cannot enter the gravel packing layer because the throat radius of a reservoir is relatively low and stay at the place. And small particle insoluble substances and 'fish eyes' in the polymer solution can enter a near wellbore zone through extrusion deformation under the injection high pressure.
The blockages in the near-well zone of the polymer injection well mainly comprise: high-concentration polymer containing small-particle insoluble substances and fish eyes, cross-linked polymer containing small-particle insoluble substances and fish eyes, inorganic salt scale, inorganic clay mineral and oil stain. Due to the relatively low permeability and relatively small porosity in the near wellbore zone, large undissolved substances and fish eyes in the polymer cannot enter, and part of small fish eyes can be squeezed into one part due to high injection pressure. Meanwhile, due to the fact that the near wellbore zone contains a certain amount of clay, the clay is wrapped and carried in the blockage in the polymer injection process.
Analyzing the composition of the plug in the wellbore of the polymer injection well according to the kinetic process of the plug formation: high concentration polymer, inorganic salt scale, oil stain;
1) Formation of high concentration of polymer: because of long-term polymer injection, the inner wall of the shaft can gradually adsorb polymers, and after the polymers are adsorbed on the shaft wall, the polymers adsorbed on the shaft wall are slowly dehydrated due to long-term high pressure to form high-concentration polymers;
2) Formation of inorganic salt scale: because the offshore platform is lack of fresh water, the polymer preparation is directly used for producing sewage, and the sewage is completely reinjected after reaching the standard. Therefore, metal ions such as calcium, iron, magnesium and the like can be contained in the reinjection sewage, so that the blockage on the wall of the well bore contains a certain amount of inorganic calcium, magnesium and iron scale (calcium carbonate, magnesium carbonate and iron oxide);
the pipeline is corroded after long-term use, a certain amount of iron is brought in, and iron scale is formed on the wall of the well bore.
3) And (3) formation of oil stain: because the offshore platform is lack of fresh water, the polymer preparation is directly used for producing sewage, and the sewage is completely reinjected after reaching the standard. The offshore platform produced liquid treatment process is short, relatively independent, free of combined stations and high in crude oil viscosity, oil-water emulsification is serious, a certain amount of heavy oil components are contained in the reinjection water in the sewage treatment process, and the heavy oil components and the high-concentration polymer are mixed and adsorbed on a well wall.
Accordingly, the invention provides a preparation method of a composite plug in a shaft of a polymer injection well in an offshore oilfield, which comprises the following steps:
1) Preparing a polymer mother solution by using injected water or simulated water in an offshore oilfield field;
2) Mixing the polymer mother liquor with the injected water or the simulated water, and adding calcium chloride, magnesium chloride, sodium carbonate, ferric oxide and heavy oil to obtain a composite target solution; the concentration of the polymer in the composite target liquid is the polymer injection concentration of the offshore oilfield field;
3) And (3) placing the composite target liquid at a target oil reservoir temperature for dehydration and aging, dehydrating the simulated polymer at a high pressure in the shaft, reacting calcium chloride, magnesium chloride and sodium carbonate to obtain calcium carbonate and magnesium carbonate inorganic scales, thus obtaining the composite plug in the shaft of the polymer injection well, and adjusting the polymer concentration, the content of the inorganic salt scales and the content of heavy viscous oil in the composite plug through the dehydration degree.
In the preparation method, the polymer can be polyacrylamide, and the molecular weight can be 600-3500 ten thousand;
the heavy viscous oil is crude oil with the viscosity of 5000-10000 mPa & s.
In the preparation method, the concentration of the polymer is determined according to the concentration of polymer injection at the offshore oilfield site, the content of inorganic salt scale is determined according to the concentrations of calcium ions, magnesium ions and iron ions in the injection water at the offshore oilfield site, and the content of oil stain is determined according to the oil content in the injection water at the offshore oilfield site;
specifically, the concentration of the polymer in the composite plug is 10000-70000 mg/L, the mass concentration of calcium carbonate is 0-16%, the mass concentration of magnesium carbonate is 0-22%, the mass concentration of ferric oxide is 0-7%, and the mass concentration of heavy oil is 0-25%;
calcium carbonate, magnesium carbonate and iron oxide are the inorganic salt scale.
In the above preparation method, in the step 2), the concentration of the polymer in the composite target solution is 700 to 2500mg/L, that is, the concentration of polymer injection.
In the preparation method, in the step 2), the concentration of calcium ions in the composite target liquid is 0-1000 mg/L;
the concentration of magnesium ions in the composite target liquid is 0-1000 mg/L;
the concentration of iron ions in the composite target solution is 0-1.5 mg/L.
In the preparation method, in the step 2), the concentration of the heavy thick oil in the composite target liquid is 0-500 mg/L.
Specifically, the concentration of the polymer in the composite plug corresponds to the concentration of the polymer injected as shown in table 1:
TABLE 1 relationship of injection concentration to Polymer concentration in plug
Specifically, the content of calcium carbonate and magnesium carbonate in the composite plug corresponds to the concentration of calcium ions and magnesium ions in the field injection water as shown in table 2:
TABLE 2 relationship of calcium and magnesium ion concentrations in the in-situ injected water to the calcium and magnesium carbonate content in the plug
| Metal ion content/mg. L -1 | 0～200 | 200～400 | 400～600 | 600～800 | 800～1000 |
| Calcium carbonate content/% in the plug | 0～2.5 | 2.5～6.0 | 6.0～9.5 | 9.5～12.0 | 12.0～16.0 |
| Content of magnesium carbonate in plug/%) | 0～4.5 | 4.5～9.0 | 9.0～14.0 | 14.0～18.0 | 18.0～22.0 |
Specifically, the relationship between the content of iron oxide in the composite plug and the concentration of iron ions in the field injection water is shown in table 3:
TABLE 3 relationship of iron ion concentration in field injection water to iron oxide content in plug
| Metal ion content/mg. L -1 | 0～0.3 | 0.3～0.6 | 0.6～0.9 | 0.9～1.2 | 1.2～1.5 |
| Iron oxide content/% of plugs | 0～1.5 | 1.5～3.0 | 3.0～4.5 | 4.5～6.0 | 6.0～7.0 |
Specifically, the correspondence between the heavy oil content in the composite plug and the oil content of the field injection water is shown in table 4:
TABLE 4 relationship of oil content of field injection water to heavy oil content in plug
| Oil content/mg. L -1 | 0～50 | 50～100 | 100～150 | 150～300 | 300～500 |
| Heavy oil content/% of the plug | 0～3.0 | 3.0～6.0 | 6.0～9.0 | 9.0～18.0 | 18.0～25.0 |
The composite plug in the shaft of the polymer injection well of the offshore oil field can be used for research in a blockage removing system or a blockage removing method of the polymer injection well of the offshore oil field.
Detailed Description
The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.
Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
The invention provides a preparation method of a composite plug in a shaft of a polymer injection well of an offshore oilfield, which comprises the following steps:
1) Preparing a polymer mother solution by using target oil reservoir simulation water/field water, wherein the concentration of the polymer mother solution is determined according to the field preparation concentration;
2) Mixing the polymer mother liquor with calcium chloride, magnesium chloride, sodium carbonate, ferric oxide, heavy oil and prepared water to obtain composite target liquor, wherein the concentration of the polymer in the composite target liquor is determined according to the injection concentration on site;
3) Placing the composite target liquid into an oven at the oil reservoir temperature for dehydration and aging, dehydrating the simulated polymer in a shaft at high pressure, and reacting calcium chloride, magnesium chloride and sodium carbonate to obtain calcium carbonate and magnesium carbonate inorganic scales so as to obtain a composite plug in the shaft; wherein, the polymer concentration, the inorganic salt scale content and the heavy oil content in the simulated blockage are adjusted by controlling the dehydration degree.
Wherein the polymer concentration in the dehydrated simulated plugs was determined according to the injection concentration, as shown in table 1.
TABLE 1 relationship of injection concentration to polymer concentration in plug
Wherein, the content of inorganic salt scale in the plug is determined according to the concentration of calcium, magnesium and iron ions in the water injected on site. Calcium and magnesium ions with different concentrations are injected into the water, and the corresponding relation is shown in the table 2 corresponding to calcium carbonate and magnesium carbonate with different contents in the plug.
TABLE 2 relationship between the concentration of calcium and magnesium ions in the site injection water and the content of calcium and magnesium carbonate in the plug
| Content of metal ion/mg. L -1 | 0～200 | 200～400 | 400～600 | 600～800 | 800～1000 |
| Calcium carbonate content/% in the plug | 0～2.5 | 2.5～6.0 | 6.0～9.5 | 9.5～12.0 | 12.0～16.0 |
| Content of magnesium carbonate in the plug/%) | 0～4.5 | 4.5～9.0 | 9.0～14.0 | 14.0～18.0 | 18.0～22.0 |
Wherein, different iron ion content + wellbore corrosion in the injected water corresponds to different content of iron oxide, and the corresponding relationship is shown in table 3.
TABLE 3 relationship between iron ion concentration in the field injection water and iron oxide content in the plug
| Content of metal ion/mg. L -1 | 0～0.3 | 0.3～0.6 | 0.6～0.9 | 0.9～1.2 | 1.2～1.5 |
| Iron oxide content/% of plugs | 0～1.5 | 1.5～3.0 | 3.0～4.5 | 4.5～6.0 | 6.0～7.0 |
Wherein, the heavy oil content in the plug is determined according to the oil content in the injected water, the corresponding relationship of different oil contents of the injected water and the heavy oil with different contents in the plug (the heavy oil is the crude oil with the viscosity of 5000-10000 mPa.s) is shown in Table 4.
TABLE 4 relationship between oil content of field injection water and heavy oil content in plug
| Oil content/mg. L -1 | 0～50 | 50～100 | 100～150 | 150～300 | 300～500 |
| Plug heavy Thick oil content/%) | 0～3.0 | 3.0～6.0 | 6.0～9.0 | 9.0～18.0 | 18.0～25.0 |
In the following examples, 2500 million of partially hydrolyzed polyacrylamide is taken as an example of the polymer, and the target oil reservoir polymer is adopted in the practical application process.
The following examples respectively simulate and prepare composite plugs with different plug components and contents in a shaft under different polymer injection well conditions, and evaluate plugging removal effects of the obtained composite plugs.
The preparation method of the plug comprises the following steps:
1) Preparing 2500 million HPAM polymer mother liquor with the concentration of 5000mg/L by using simulated injection water under the condition of a polymer injection well; the polymer injection well conditions are shown in table 5 below:
TABLE 5 different injection water conditions and their polymer injection concentrations
2) And preparing a composite target solution according to the corresponding relationship between the concentration of polymer injected and the concentration of polymer in the plug, the content of each ion in injected water and the content of inorganic scale in the plug, and the content of oil in water injected and the content of oil stain in the plug, and according to the addition of different components in the following table 6, wherein the thickened oil is crude oil with the viscosity of 7562mPa & s.
TABLE 6 additive amounts of respective components in composite object liquid
3) And (3) putting the composite target liquid into an oven set at the target oil reservoir temperature for dehydration and aging, and dehydrating the composite target liquid to about 100.0g by mass to obtain the composite blockage in the shaft.
The mass contents of the respective components in each composite plug are shown in table 7.
The composite blockage prepared is evaluated according to the following method:
the composite plug prepared correspondingly is soaked and dissolved according to the following method: weighing a certain amount of simulated composite blockage and recording the weighed quantity as w 1 Filling into a screw thread bottle; preparing a deblocking agent Ammonium Persulfate (APS) solution with the concentration of 1%, and mixing the solution of ammonium persulfate and the simulated composite plug according to the mass ratio of 4; standing and reacting for 24 hours at the temperature of 60 ℃; testing the mass w of the simulated composite plug after reaction 2 (ii) a Calculating the dissolution rate of the plug, wherein the calculation formula is beta = (w) 1 -w 2 )/w 1 X 100% the soak dissolution rates for each simulated composite plug are shown in table 7:
TABLE 7 Mass content of each component in each composite plug and the plug removal effect
The data in table 7 show that different polymer injection wells have different injected water conditions and polymer injection concentrations, which cause different contents of each component in the blockage in the shaft and have great influence on the soaking and dissolving effects of the blocking remover, so that the corresponding composite blockage is simulated according to the specific conditions of the polymer injection wells, the blocking remover is optimized, and the method has important significance for improving the blocking removing effect.
Claims (3)
1. The preparation method of the composite plug in the shaft of the polymer injection well in the offshore oil field comprises the following steps:
1) Preparing a polymer mother solution by adopting injected water or simulated water in an offshore oilfield field;
2) Mixing the polymer mother liquor with the injected water or the simulated water, and adding calcium chloride, magnesium chloride, sodium carbonate, ferric oxide and heavy oil to obtain a composite target solution; the concentration of the polymer in the composite target liquid is the polymer injection concentration of the offshore oilfield field;
the polymer is polyacrylamide;
the heavy viscous oil is crude oil with the viscosity of 5000-10000 mPa & s;
the concentration of the polymer in the composite target liquid is 700-2500 mg/L;
the concentration of calcium ions in the composite target liquid is 0-1000mg/L;
the concentration of magnesium ions in the composite target liquid is 0 to 1000mg/;
the concentration of iron ions in the composite target liquid is 0 to 1.5mg/L;
the concentration of the heavy thickened oil in the composite target liquid is 0-500mg/L;
3) Placing the composite target liquid at a target oil reservoir temperature for dehydration and aging, and reacting calcium chloride, magnesium chloride and sodium carbonate to obtain calcium carbonate and magnesium carbonate inorganic scale, namely obtaining the composite plug in the shaft of the polymer injection well;
in the composite plug, the concentration of the polymer is 10000-70000mg/L, the mass concentration of the calcium carbonate is 0-16%, the mass concentration of the magnesium carbonate is 0-22%, the mass concentration of the iron oxide is 0-7%, and the mass concentration of the heavy oil is 0-25%;
specifically, in the composite plug, the concentration of the polymer is determined according to the concentration of polymer injection at the offshore oilfield site, and the relationship between the concentration of the polymer and the concentration of the polymer is as follows: when the concentration of polymer injection is 600 to 1000mg/L, 1000 to 1300mg/L do not include 1000mg/L, 1300 to 1600mg/L do not include 1300mg/L, 1600 to 2000mg/L do not include 1600mg/L and 2000 to 2500mg/L do not include 2000mg/L in sequence, the concentration of the polymer is 10000 to 20000mg/L, 20000 to 30000mg/L do not include 20000mg/L, 30000 to 40000mg/L do not include 30000mg/L, 40000 to 50000mg/L do not include 40000mg/L and 50000 to 70000mg/L do not include 50000mg/L in sequence;
specifically, in the composite plug, the mass concentration of the calcium carbonate is determined according to the concentration of calcium ions in the injection water at the offshore oilfield site, and the relationship between the mass concentration of the calcium carbonate and the concentration of the calcium ions in the injection water is as follows: when the concentration of calcium ions injected into water is 0 to 200mg/L, 200 to 400mg/L does not include 200mg/L, 400 to 600mg/L does not include 400mg/L, 600 to 800mg/L does not include 600mg/L and 800 to 1000mg/L does not include 800mg/L in sequence, the mass concentration of the calcium carbonate is 0 to 2.5%, 2.5 to 6.0% does not include 2.5%, 6.0 to 9.5% does not include 6.0%, 9.5 to 12.0% does not include 9.5% and 12.0 to 16.0% does not include 12.0% in sequence;
specifically, in the composite plug, the mass concentration of magnesium carbonate is determined according to the concentration of magnesium ions in the injection water at the offshore oilfield site, and the relationship between the mass concentration of magnesium carbonate and the concentration of magnesium ions in the injection water at the offshore oilfield site is as follows: when the concentration of magnesium ions in the injected water is 0-200mg/L, 200-400mg/L does not comprise 200mg/L, 400-600mg/L does not comprise 400mg/L, 600-800mg/L does not comprise 600mg/L and 800-1000mg/L does not comprise 800mg/L in sequence, the mass concentration of the magnesium carbonate is 0-4.5%, 4.5-9.0% does not comprise 4.5%, 9.0-14.0% does not comprise 9.0%, 14.0-18.0% does not comprise 14.0% and 18.0-22.0% does not comprise 18.0% in sequence;
specifically, in the composite plug, the mass concentration of the iron oxide is determined according to the concentration of iron ions in the injection water at the offshore oilfield site, and the relationship between the mass concentration of the iron oxide and the concentration of iron ions in the injection water is as follows: when the concentration of iron ions in injected water is 0 to 0.3mg/L, 0.3 to 0.6mg/L does not comprise 0.3mg/L, 0.6 to 0.9mg/L does not comprise 0.6mg/L, 0.9 to 1.2mg/L does not comprise 0.9mg/L and 1.2 to 1.5mg/L does not comprise 1.2mg/L in sequence, the mass concentration of the iron oxide is 0 to 1.5%, 1.5 to 3.0% does not comprise 1.5%, 3.0 to 4.5% does not comprise 3.0%, 4.5 to 6.0% does not comprise 4.5% and 6.0 to 7.0% does not comprise 6.0% in sequence;
specifically, in the composite plug, the mass concentration of the heavy oil is determined according to the oil content in the injection water of the offshore oilfield field, and the relationship between the mass concentration of the heavy oil and the oil content in the injection water is as follows: when the oil content in injected water is 0 to 50mg/L, 50 to 100mg/L does not include 50mg/L, 100 to 150mg/L does not include 100mg/L, 150 to 300mg/L does not include 150mg/L, and 300 to 500mg/L does not include 300mg/L in sequence, the mass concentration of the heavy thickened oil is 0 to 3.0%, 3.0 to 6.0%, 6.0 to 9.0%, 9.0 to 18.0%, 9.0 to 9.0% and 18.0 to 25.0% respectively.
2. The composite plug in the wellbore of an offshore oilfield polymer injection well prepared by the method of claim 1.
3. The application of the composite plug in the well bore of the offshore oilfield polymer injection well in the research of a plugging removal system or a plugging removal method of the offshore oilfield polymer injection well.
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| CN106526096A (en) * | 2017-01-10 | 2017-03-22 | 中海石油(中国)有限公司 | Experimental method for blockage simulation and unplugging evaluation for injection and production well of chemical flooding oilfield |
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| CN106526096A (en) * | 2017-01-10 | 2017-03-22 | 中海石油(中国)有限公司 | Experimental method for blockage simulation and unplugging evaluation for injection and production well of chemical flooding oilfield |
Non-Patent Citations (3)
| Title |
|---|
| Investigation on degradation mechanism of polymer blockages in unconsolidated sandstone reservoirs;Dong, WT;《E-POLYMERS 》;20200302;第20卷(第1期);第55-60页 * |
| 注聚合物井新型解堵增注技术研究;安坤;《中国优秀硕士学位论文全文数据库 工程科技Ⅰ辑》;20150315(第3期);B019-104 * |
| 渤海油田注聚合物井堵塞物组分分析及相互作用机理;高尚等;《油田化学》;20200625;第37卷(第02期);340-343、380 * |
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