CN115785931A - Chelating blocking remover system for removing inorganic scale of gas well and blocking removing method - Google Patents
Chelating blocking remover system for removing inorganic scale of gas well and blocking removing method Download PDFInfo
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Abstract
The invention discloses a chelate blockage removing agent system and a blockage removing method for removing inorganic scale of a gas well, wherein the chelate blockage removing agent system consists of three sets of working solutions, namely hydrochloric acid working solution, earth acid working solution and chelating agent working solution, wherein the components of the hydrochloric acid working solution comprise 15-20% of HC l, 2-4% of corrosion inhibitor, 0.5-2% of iron ion stabilizer, 1-2% of clay stabilizer, 0.1-0.5% of cleanup additive and the balance of water by mass percentage; the components of the earth acid working solution are 8-13% of HC l, 3% of HF, 2-4% of corrosion inhibitor, 0.5-2% of iron ion stabilizer, 1-2% of clay stabilizer, 0.1-0.5% of cleanup additive and the balance of water by mass fraction; the chelating agent working solution comprises 10-20% of chelating agent and 0.5-1% of dispersing agent by mass; the blockage removing method comprises the following steps: (1) injecting a hydrochloric acid working solution into a gas well shaft; (2) injecting an earth acid working solution into the shaft; (3) injecting a chelating agent working solution into the well bore; (4) And (4) returning the injected chelating blocking remover system to the ground to finish the whole construction process.
Description
Technical Field
The invention relates to a chelating blocking remover system for removing inorganic scale of a gas well and a blocking removing method, belonging to the technical field of oil and gas field development.
Background
The sulfates or carbonates of barium, strontium, magnesium and calcium are common inorganic scales in natural gas wells, stratum brine with high mineralization can generate rock salt aggregation due to changes of conditions such as temperature, pressure and the like, and meanwhile, various indissolvable iron compounds such as ferrous carbonate, ferric oxide, ferric sulfide and the like can be generated due to the existence of carbon dioxide, hydrogen sulfide and dissolved oxygen, and the generation of the inorganic scales has great harm to the development of oil and gas fields.
The existing descaling methods comprise chemical descaling, coiled tubing hydraulic jet descaling, coiled tubing mechanical descaling and the like. Wherein, the chemical descaling has the advantages of high blockage removing efficiency, wide range, low labor intensity and the like; the hydraulic jet descaling of the continuous oil pipe is greatly influenced by the size of a shaft, and the application range is limited; the mechanical descaling operation of the continuous oil pipe has high difficulty, high cost and high risk, the shaft cannot smoothly rotate, the descaling and blockage removing quality is poor, and the mechanical descaling operation can only be used for gas wells which are not suitable for acid pickling and cannot be descaled by acid; in contrast, the advantages of chemical descaling are more obvious.
The published 'a scale remover formula for an oil field downhole string' (with the application number of CN 202111380778.6) discloses a scale remover formula which comprises the following components in parts by weight: 2 parts of aminocarboxylate chelating agent, 2 parts of HAC (acetic acid), 1 part of high-efficiency penetrating agent, 3 parts of surfactant, 1 part of corrosion inhibitor, 15 parts of sodium dodecyl sulfonate, 2 parts of citric acid, 3 parts of disodium salt, 7 parts of polyacrylic acid, 4 parts of metal complexing agent and 3 parts of polypropyleneethanol. The patent application No. CN202111359512.3 discloses a scale-inhibiting and descaling agent, which comprises the following components: AMPS terpolymer, bis 1, 6-hexamethylene triamine pentamethylene phosphonic acid, pyrophosphoric acid, carbon nano tubes, 2-vinyl pyridine, N' -methylene bisacrylamide, sodium hexametaphosphate and water; the AMPS terpolymer, the bis-1, 6-hexamethylene triamine pentamethylene phosphonic acid and the sodium hexametaphosphate are adopted, so that the composite scale inhibitor has the effects of inhibiting and dispersing the scales such as carbonate, silicate, sulfate, calcium phosphate, zinc scale, iron oxide and the like, has high scale inhibition performance, is suitable for each component under the high-temperature condition to play a better synergistic effect, and can be used when a boiler runs; in the presence of N, N' -methylene bisacrylamide, pyrophosphoric acid, carbon nano tubes and vinyl pyridine are polymerized to prepare the composite adsorption compound with high scale inhibition and scale removal performance. "sandstone acidification scale remover and its preparation method" (application number CN 202011221006.3) disclose a scale remover and its preparation method, this scale remover is by monomer A and monomer B copolymerized polymer of 1; the weight average molecular weight of the polymer is 1000-1300 g/mol, and the molecular weight distribution coefficient is 1.1-1.2; the descaling agent for sandstone acidification is a polymer containing sulfonic groups, can be directly added into the prepared acidification working solution for use, can effectively remove calcium and magnesium ions in the acidification process, and does not influence the reaction or interaction between the acidification working solution and acid-erodible minerals or acid-soluble substances.
The invention aims to provide a chelating deblocking agent system aiming at the coexistence of inorganic scales such as sulfate, carbonate, metal oxide and the like.
Disclosure of Invention
Aiming at the problems of the background technology, the invention provides a chelating blocking remover system and a blocking remover method for removing inorganic scale of a gas well, which are used for efficiently removing the inorganic scale of the gas well shaft in the coexistence of sulfate, carbonate and metal oxide.
The invention provides a chelating deblocking agent system for removing inorganic scale of a gas well, which consists of three sets of working solutions, namely hydrochloric acid working solution, earth acid working solution and chelating agent working solution,
preferably, the hydrochloric acid working solution is used for dissolving carbonate components in inorganic scale; the earth acid working solution is used for dissolving away clay and silicate substances in inorganic scale; the chelating agent working solution is used for dissolving sulfate inorganic scale which is difficult to dissolve in acid in the inorganic scale.
Preferably, the components of the hydrochloric acid working solution are 15-20% of HCl, 2-4% of corrosion inhibitor, 0.5-2% of iron ion stabilizer, 1-2% of clay stabilizer, 0.1-0.5% of cleanup additive and the balance of water by mass fraction; the components of the earth acid working solution are 8-12% of HCl, 3% of HF, 2-4% of corrosion inhibitor, 0.5-2% of iron ion stabilizer, 1-2% of clay stabilizer, 0.1-0.5% of cleanup additive and the balance of water by mass fraction; the chelating agent working solution comprises 10-20% of chelating agent and 0.5-1% of dispersing agent by mass.
Preferably, the chelating agent is one or more of DTPA, EDTA, GLDA.
Preferably, the corrosion inhibitor is one of nitrite, arsenite, aldehyde corrosion inhibitor and imidazole corrosion inhibitor.
Preferably, the iron ion stabilizer is one of acetic acid, citric acid and lactic acid.
Preferably, the clay stabilizer is one or more of sodium chloride, potassium chloride, ammonium chloride and trimethyl allyl ammonium chloride.
Preferably, the cleanup additive is one of polyacrylamide and guar gum.
Preferably, the dispersant is one of sodium polyacrylate, sodium dodecyl sulfate and sodium hexametaphosphate.
The invention discloses a gas well inorganic scale blockage removing method, which uses the chelating blockage remover system for removing the gas well inorganic scale, and comprises the following steps:
s1, injecting a hydrochloric acid working solution into a gas well shaft;
s2, injecting the soil acid working solution into the shaft to fully erode the clay and silicate substances in the inorganic scale;
s3, injecting a chelating agent working solution into the shaft to fully erode sulfate inorganic scale which is difficult to dissolve in acid in the inorganic scale;
drawings
FIG. 1 is a flow chart of a plugging removal method for removing inorganic scale of a gas well.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The present invention will be described in detail below with reference to several examples.
Example 1
Firstly, preparing a chelating blocking remover system:
(1) Preparing hydrochloric acid working solution with the volume 1.2 times that of a shaft according to the volume of the shaft, wherein the formula comprises 20% of HCl, 3% of arsenite, 1% of citric acid, 1.5% of potassium chloride, 0.2% of polyacrylamide and the balance of water by mass percentage;
(2) Preparing a soil acid working solution with the volume 1.2 times that of a shaft according to the volume of the shaft, wherein the formula comprises 12% of HCl, 3% of HF, 3% of arsenite, 1% of citric acid, 1.5% of potassium chloride, 0.2% of polyacrylamide and the balance of water in percentage by mass;
(3) According to the volume of a shaft, chelating agent working solution with the volume 1.2 times that of the shaft is prepared, and the formula comprises EDTA (ethylene diamine tetraacetic acid) with the mass fraction of 20% and sodium dodecyl sulfate with the mass fraction of 1%.
It should be noted that the final effect of the formula of the earth acid working solution with HCl mass fraction of 12% to 13% is not much in the first embodiment, and therefore, redundant description is not necessary.
During field construction, the blockage removing method comprises the following steps:
(1) Injecting a hydrochloric acid working solution into a gas well shaft to ensure that the hydrochloric acid working solution is filled in the whole shaft space with inorganic scale distribution, and closing the well for 5 hours so as to fully erode carbonate components in the inorganic scale;
(2) Injecting an earth acid working solution into the shaft to ensure that the whole shaft space with inorganic scale is filled with the earth acid working solution, partially injecting the hydrochloric acid working solution in the step (1) into an oil gas reservoir, or returning the hydrochloric acid working solution to the ground through the shaft annulus or an oil pipe, closing the well for 5 hours, and fully dissolving clay and silicate substances in the inorganic scale by the earth acid working solution to be injected;
(3) Injecting a chelating agent working solution into the shaft to ensure that the chelating agent working solution is filled in the whole shaft space with inorganic scale distribution, wherein the soil acid working solution injected in the step (2) partially enters an oil gas reservoir and can also be returned to the ground through the shaft annulus or an oil pipe, closing the well for 5 hours, and fully dissolving and corroding the sulfate inorganic scale which is difficult to dissolve in acid in the inorganic scale by the chelating agent working solution to be injected;
(4) And (4) returning the injected chelate blocking remover system to the ground to finish the whole construction process.
Example 2
Firstly, preparing a chelating blocking remover system:
(1) Preparing a hydrochloric acid working solution with the volume 1.2 times that of a shaft according to the volume of the shaft, wherein the formula comprises 15% of HCl, 4% of arsenite, 2% of citric acid, 1.5% of potassium chloride, 0.2% of polyacrylamide and the balance of water by mass percentage;
(2) Preparing a soil acid working solution with the volume 1.2 times that of a shaft according to the volume of the shaft, wherein the formula comprises 8% of HCl, 3% of HF, 4% of arsenite, 2% of citric acid, 1.5% of potassium chloride, 0.2% of polyacrylamide and the balance of water by mass percentage;
(3) According to the volume of the shaft, chelating agent working solution with the volume 1.2 times that of the shaft is prepared, and the formula comprises EDTA with the mass fraction of 10% and sodium dodecyl sulfate with the mass fraction of 1%.
It should be noted that, in the above two embodiments, the content of HF in the earth acid working fluid may be in the range of 3% to 5% by mass, which can achieve the efficient blockage removal effect.
During the field construction, the blockage removing method comprises the following steps:
(1) Injecting a hydrochloric acid working solution into a well bore of the gas well, filling the whole well bore space with inorganic scale distribution with the hydrochloric acid working solution, and closing the well for 7 hours so as to fully erode carbonate components in the inorganic scale;
(2) Injecting an earth acid working solution into the shaft to ensure that the whole shaft space with inorganic scale is filled with the earth acid working solution, allowing part of the hydrochloric acid working solution injected in the step (1) to enter an oil gas reservoir, or returning the hydrochloric acid working solution to the ground through the shaft annulus or an oil pipe, closing the well for 7 hours, and fully dissolving and corroding clay and silicate substances in the inorganic scale by the earth acid working solution to be injected;
(3) Injecting a chelating agent working solution into the shaft to enable the chelating agent working solution to fill the whole shaft space with inorganic scale distribution, enabling part of the soil acid working solution injected in the step (2) to enter an oil and gas reservoir and also to be discharged back to the ground through the shaft annulus or an oil pipe, closing the well for 7 hours, and fully dissolving and eroding sulfate inorganic scale which is difficult to dissolve in acid in the inorganic scale by the chelating agent working solution to be injected;
(4) And (4) returning the injected chelating blocking remover system to the ground to finish the whole construction process.
The method for removing the inorganic scale of the gas well mainly comprises three steps of injecting hydrochloric acid working solution into a gas well shaft to inject the hydrochloric acid working solution into the gas well shaft; injecting a soil acid working solution into the shaft to fully erode clay and silicate substances in the inorganic scale; by injecting chelating agent working solution into the well bore, sulfate inorganic scale which is difficult to dissolve in acid in the inorganic scale is fully corroded.
And (3) performance testing:
the solubility was evaluated by taking the chelate blocking remover prepared in example 1 as an example.
The evaluation method comprises the following steps: (1) Taking a filter, drying the filter paper, cooling the filter paper in a dryer, and weighing the mass of the filter paper; weighing about 5g of dirty sample, and placing the dirty sample in a beaker; (3) Preparing 50mL of a chelating blocking remover, slowly adding the chelating blocking remover into a beaker containing a dirt sample, and then putting the beaker into a water bath at 90 ℃; (4) Preparing a filtering device, laying filter paper, fully reacting, filtering, drying, weighing, and recording the weight of the scale sample after corrosion; (5) Calculating the corrosion rate of the chelating blocking remover to the scale sample by using a weight loss method according to the following formula:
erosion rate (%) = (weight of scale sample before erosion (g) -weight of scale sample after erosion (g))/(weight of scale sample before erosion (g)) × 100%.
According to the above evaluation method, the corrosion rate of the chelating deblocking agent of example 1 on the scale sample was tested, and the corrosion rate of HCl (concentration 20%), HCl (concentration 12%) + HF (concentration 3%), EDTA (concentration 10%) on the scale sample under the same conditions was tested for comparison, three groups of experiments were tested, and the final corrosion rate was averaged over the three groups, and the test results are shown in table 1.
TABLE 1 Corrosion Rate under different conditions
| Liquid name | HCl | HCl+HF | EDTA | Chelating blocking remover |
| Rate of corrosion | 45.81％ | 51.16％ | 8.1％ | 95.38％ |
From the test results in table 1, the main component of the scale sample is carbonate inorganic scale, most of the carbonate rock inorganic scale can be dissolved by using HCl, HCl and HF, and the corrosion rates are 45.81% and 51.16%; when EDTA is used, because the dispersion effect is poor, the contact area of the EDTA and the scale sample is limited, the corrosion rate is only 8.1 percent, and the EDTA mainly chelates metal ions to ensure that the metal ions in the scale sample are dissolved in the solution; when the chelating deblocking agent provided by the invention is used for carrying out corrosion experiments, HCl and HF can dissolve most of carbonate, metal oxide, clay and silicate inorganic scales, the EDTA dispersion effect is good, the contact area of the chelating deblocking agent and a scale sample is large, the reaction is sufficient, the corrosion rate can reach 95.38%, and the effect is unexpectedly good.
The chelating blocking remover system-gas well inorganic scale corrosion effect test results are as follows:
TABLE 2 chelating deblocking agent System-gas well inorganic Scale Corrosion Effect Table
The field use effect is as follows:
example 1 was applied to a gas well in Sichuan. The gas well formation water contains a large amount of scale-forming cations Ca 2+ 、Mg 2+ And Ba 2+ Scaling phenomena are easy to occur, and scaling products block a shaft; the inorganic components of the plug are mainly ferrous sulfide, ferrous carbonate, calcium carbonate, magnesium carbonate, barium sulfate, calcium sulfate, strontium sulfate, silicon dioxide and the like; before inorganic scale of a shaft is removed, the oil pressure and the casing pressure of the well are both lower than 5MPa, and the gas production is almost 0 before the inorganic scale of the shaft is removed; the chelating deblocking agent system and the deblocking method of the embodiment 1 are adopted to remove inorganic scale in a shaft, the oil pressure and the casing pressure are increased to about 10MPa after deblocking, and the gas production is about 30 multiplied by 10 4 m 3 D, unblocking effectIs good.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A chelate blocking remover system for removing inorganic scale of a gas well is characterized in that: the chelating deblocking agent system consists of three sets of working solutions, namely hydrochloric acid working solution, earth acid working solution and chelating agent working solution.
2. The chelating deblocking agent system for removing inorganic scale from gas wells as defined in claim 1, wherein: the hydrochloric acid working solution is used for dissolving carbonate components in inorganic scale; the earth acid working solution is used for dissolving away clay and silicate substances in inorganic scale; the chelating agent working solution is used for dissolving sulfate inorganic scale which is difficult to dissolve in acid in the inorganic scale.
3. The chelating deblocking agent system for removing inorganic scale of gas wells as claimed in claim 1, wherein the hydrochloric acid working solution comprises 15-20% by mass of HCl, 2-4% by mass of corrosion inhibitor, 0.5-2% by mass of iron ion stabilizer, 1-2% by mass of clay stabilizer, 0.1-0.5% by mass of cleanup additive, and the balance of water; the components of the earth acid working solution comprise 8-13% of HCl, 3-5% of HF, 2-4% of corrosion inhibitor, 0.5-2% of iron ion stabilizer, 1-2% of clay stabilizer, 0.1-0.5% of cleanup additive and the balance of water by mass percentage; the chelating agent working solution comprises 10-20% by mass of a chelating agent and 0.5-1% by mass of a dispersing agent.
4. The chelating deblocking agent system for removing inorganic scale from gas wells as recited in claim 2, wherein the chelating agent is one or more of DTPA, EDTA, GLDA.
5. The chelating deblocking agent system for removing inorganic scale from gas wells as defined in claim 2, wherein said corrosion inhibitor is one of nitrite, arsenite, aldehyde corrosion inhibitors, and imidazole corrosion inhibitors.
6. The chelating deblocking agent system for removing inorganic scale from gas wells as recited in claim 2, wherein the iron ion stabilizer is one of acetic acid, citric acid and lactic acid.
7. A chelating deblocking agent system for removing inorganic scale from gas wells as defined in claim 2, wherein said clay stabilizer is one or more of sodium chloride, potassium chloride, ammonium chloride, and trimethyl allyl ammonium chloride.
8. The chelating deblocking agent system for removing inorganic scale from gas wells according to any one of claims 2 to 6, wherein the cleanup additive is one of polyacrylamide and guar gum.
9. The chelating deblocking agent system for removing inorganic scale from gas wells as recited in claim 7, wherein the dispersant is one of sodium polyacrylate, sodium dodecyl sulfate, and sodium hexametaphosphate.
10. An inorganic scale blockage removing method for a gas well is characterized by comprising the following steps: the use of the chelating deblocking agent system of any one of claims 1 to 8 for the removal of gas well scale comprising:
s1, injecting a hydrochloric acid working solution into a gas well shaft;
s2, injecting the soil acid working solution into the shaft to fully erode the clay and silicate substances in the inorganic scale;
and S3, injecting a chelating agent working solution into the shaft to fully erode sulfate inorganic scale which is difficult to dissolve in acid in the inorganic scale.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108278098A (en) * | 2018-01-05 | 2018-07-13 | 中国石油天然气股份有限公司 | A kind of gas field pit shaft method for removing blockage |
| CN114854384A (en) * | 2021-02-03 | 2022-08-05 | 中国石油天然气股份有限公司 | Blocking remover system and blocking removing method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108278098A (en) * | 2018-01-05 | 2018-07-13 | 中国石油天然气股份有限公司 | A kind of gas field pit shaft method for removing blockage |
| CN114854384A (en) * | 2021-02-03 | 2022-08-05 | 中国石油天然气股份有限公司 | Blocking remover system and blocking removing method |
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