阅读说明：本技术 一种适用于油气井及储层用弱酸性螯合盐垢除垢剂及制备方法 (Weak-acid chelated salt scale remover suitable for oil-gas wells and reservoirs and preparation method thereof ) 是由 王力勇 刘思良 申世芳 周飞 毕妍 王巍 于 2020-06-03 设计创作，主要内容包括：本发明公开了一种适用于油气井及储层用弱酸性螯合盐垢除垢剂及制备方法,按照相应的质量百分比分别取有机酸酐、次磷酸盐、催化剂、pH调节剂、螯合剂,余量为水；将有机酸酐和次磷酸盐置于反应釜中加水溶解后加入过氧化物催化剂反应,加入pH调节剂调节产物的PH值；加入螯合剂搅拌并溶解,得适用于油气井及储层用弱酸性螯合盐垢除垢剂；该盐垢除垢剂不仅能够增加氯化钠溶解度,同时对碳酸钙及硫酸钙等水难溶性盐垢具有较强的溶解性能,适用于清除油气生产以及储气库运行过程中地层与井筒复合型盐垢,解除上述盐垢在地层与井筒类的沉积,提高油气井生产效率。(The invention discloses a weakly acidic chelated salt scale descaling agent suitable for oil-gas wells and reservoirs and a preparation method thereof, wherein organic acid anhydride, hypophosphite, a catalyst, a pH regulator, a chelating agent and the balance of water are respectively taken according to corresponding mass percentages; placing organic acid anhydride and hypophosphite in a reaction kettle, adding water for dissolving, adding a peroxide catalyst for reaction, and adding a pH regulator for regulating the pH value of a product; adding a chelating agent, stirring and dissolving to obtain a weakly acidic chelated salt scale descaling agent suitable for oil and gas wells and reservoirs; the salt scale remover can increase the solubility of sodium chloride, has strong solubility to water-insoluble salt scales such as calcium carbonate and calcium sulfate, is suitable for removing stratum and shaft composite salt scales in the processes of oil and gas production and gas storage operation, removes the deposition of the salt scales on the stratum and the shaft, and improves the production efficiency of an oil and gas well.)

1. A weakly acidic chelating salt scale remover suitable for oil-gas wells and reservoirs is characterized by comprising 15% -25% of organic acid anhydride, 15% -25% of hypophosphite, 5% -15% of catalyst, 5% -15% of pH regulator, 2% -5% of chelating agent and the balance of water by mass.

2. The weakly acidic chelated salt scale remover suitable for oil and gas wells and reservoirs as claimed in claim 1, wherein the organic anhydride comprises maleic anhydride.

3. The weakly acidic chelated salt scale remover suitable for oil and gas wells and reservoirs as claimed in claim 1, wherein the hypophosphite comprises one or two of sodium hypophosphite, potassium hypophosphite and ammonium hypophosphite.

4. The weakly acidic chelated salt scale remover suitable for oil and gas wells and reservoirs as claimed in claim 1, wherein the catalyst comprises one or two of hydrogen peroxide, sodium carbonate peroxide and urea peroxide.

5. A weakly acidic chelated salt scale remover as claimed in claim 1, wherein the pH adjuster comprises one or more of potassium hydroxide and sodium hydroxide.

6. A weakly acidic chelated salt scale remover as claimed in claim 1, wherein the chelating agent comprises one or both of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid.

7. A preparation method of a weakly acidic chelated salt scale descaling agent suitable for oil-gas wells and reservoirs is characterized by comprising the following steps:

step 1: respectively taking 15-25% of organic acid anhydride, 15-25% of hypophosphite, 5-15% of catalyst, 5-15% of pH regulator, 2-5% of chelating agent and the balance of water according to the mass percentage;

step 2: placing organic acid anhydride and hypophosphite in a reaction kettle, adding water for dissolving, then adding a peroxide catalyst, and heating to 90-95 ℃ for reaction to obtain a solution A;

and step 3: adding a pH regulator into the solution A, and regulating the pH value of the solution A to 3.4-5 to obtain a solution B;

and 4, step 4: and adding the chelating agent into the solution B, stirring and dissolving to obtain the weakly acidic chelated salt scale descaling agent suitable for oil and gas wells and reservoirs.

8. The preparation method of the weakly acidic chelated salt scale remover suitable for the oil-gas well and the reservoir as claimed in claim 7, wherein in the step 2, the organic acid anhydride and the hypophosphite are placed in a reaction kettle, added with water, heated to 50-80 ℃, stirred and dissolved.

9. The preparation method of the weakly acidic chelated salt scale remover suitable for oil-gas wells and reservoirs as claimed in claim 7, wherein the peroxide catalyst is added in the step 2, and then the mixture is stirred and reacted for 1-2 hours.

10. The method for preparing the weakly acidic chelated salt scale remover suitable for oil and gas wells and reservoirs as claimed in claim 7, wherein in the step 4, the chelating agent is added into the solution B and stirred for 0.5-1 hour until being completely dissolved.

Technical Field

The invention belongs to the technical field of oil and gas field development, and relates to a weakly acidic chelated salt scale descaling agent suitable for oil and gas wells and reservoirs and a preparation method thereof.

Background

In the production process of oil and gas fields, salt is often deposited at the positions of stratums, gravel packing layers, oil casings, oil gas nozzles, gathering and transportation pipelines and the like due to the change of conditions such as pressure, temperature and the like, and the instability of hydrothermal mechanics and chemical incompatibility. The salt deposition of the oil and gas field seriously affects the normal production of the oil and gas field, brings huge economic loss to the production of the development of the oil and gas field, the operation of a gas storage and the like, and seriously hinders the development of the oil and gas field and the operation of the gas storage. The salt scale formed by salt deposition and salt deposition of the oil and gas field is mainly sodium chloride, and a certain amount of calcium carbonate and calcium sulfate are also arranged in the oil and gas field, the adopted scale remover is mainly used for the sodium chloride in the oil and gas field at present, and the calcium carbonate and the calcium sulfate are difficult to remove, so that the water pumping period is shorter and shorter due to incomplete salt deposition in each time; the crystalline nuclei are deposited on the tube wall for a long time each time, and the tube has to be examined regularly.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a weakly acidic chelated salt scale descaling agent capable of removing calcium carbonate and calcium sulfate salt scales and suitable for oil and gas wells and reservoirs and a preparation method thereof.

The invention is realized by the following technical scheme:

a weakly acidic chelating salt scale remover suitable for oil-gas wells and reservoirs comprises, by mass, 15% -25% of organic acid anhydride, 15% -25% of hypophosphite, 5% -15% of a catalyst, 5% -15% of a pH regulator, 2% -5% of a chelating agent and the balance of water.

Further, the organic acid anhydride includes maleic anhydride.

Further, the hypophosphite comprises one or two of sodium hypophosphite, potassium hypophosphite and ammonium hypophosphite.

Further, the catalyst comprises one or two of hydrogen peroxide, sodium carbonate peroxide and carbamide peroxide

Further, the pH regulator comprises one or more of potassium hydroxide and sodium hydroxide.

Further, the chelating agent comprises one or two of polyethylene polyamine acetic acid chelating agents such as ethylenediamine tetraacetic acid and diethylenetriamine pentaacetic acid

A preparation method of a weakly acidic chelated salt scale descaling agent suitable for oil-gas wells and reservoirs comprises the following steps:

step 1: respectively taking 15-25% of organic acid anhydride, 15-25% of hypophosphite, 5-15% of catalyst, 5-15% of pH regulator, 2-5% of chelating agent and the balance of water according to the mass percentage;

step 2: placing organic acid anhydride and hypophosphite in a reaction kettle, adding water for dissolving, then adding a peroxide catalyst, and heating to 90-95 ℃ for reaction to obtain a solution A;

and step 3: adding a pH regulator into the solution A, and regulating the pH value of the solution A to 3.4-5 to obtain a solution B;

and 4, step 4: and adding the chelating agent into the solution B, stirring and dissolving to obtain the weakly acidic chelated salt scale descaling agent suitable for oil and gas wells and reservoirs.

Further, in the step 2, the organic acid anhydride and the hypophosphite are placed in a reaction kettle, added with water, heated to 50-80 ℃, stirred and dissolved.

And further, adding a peroxide catalyst in the step 2, stirring and reacting for 1-2 hours.

Further, in the step 4, a chelating agent is added into the solution B and stirred for 0.5-1 hour until the chelating agent is completely dissolved.

Compared with the prior art, the invention has the following beneficial technical effects:

the weakly acidic chelating salt scale remover suitable for oil and gas wells and reservoirs and the preparation method thereof provided by the invention have the advantages that acidic organic chelating agent components synthesized from organic acid anhydride, hypophosphite and the like have stronger solubility on calcium carbonate scales through the action of acidity and a chelating principle, and meanwhile, the organic chelating agent synthesized under an acidic condition has stronger chelating action on calcium ions, so that the calcium carbonate scale remover has stronger solubility on acid-insoluble calcium sulfate.

Drawings

FIG. 1 is a graph showing the effect of temperature and time on the descaling efficiency of a descaling agent in example 1 of the present invention;

FIG. 2 is a graph showing the influence of temperature on the scale removal rate and the scale removal efficiency of the detergent in example 2 of the present invention;

FIG. 3 is a graph showing the influence of temperature on the scale removal rate and the scale removal efficiency of the detergent in example 3 of the present invention;

FIG. 4 is a graph of displacement pressure for core scaling and scale removal as a function of time in example 3 of the present invention.

Detailed Description

Specific examples are given below.