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CN-121107613-B - Composite hardening remover applicable to high-hardness water-based system and application method thereof

CN121107613BCN 121107613 BCN121107613 BCN 121107613BCN-121107613-B

Abstract

The invention provides a composite hardening remover suitable for a high-hardness water-based system and a use method thereof. The composite hardening remover is suitable for a high-hardness water-based system of oil and gas field fracturing flowback fluid, can effectively avoid the risk of calcium sulfate scaling while obviously reducing the cost of the agent, realizes deep hardening removal, and can synchronously remove dissolved oxygen, thereby solving multiple challenges such as cost, scaling, effect, system corrosion and the like in one step.

Inventors

  • ZHONG WENYI
  • REN JINGRUI

Assignees

  • 湖南鼎中环保科技有限公司

Dates

Publication Date
20260512
Application Date
20251031

Claims (7)

  1. 1. The composite hardening remover for the high-hardness water-based system of the fracturing flowback fluid of the oil and gas field is characterized by comprising, by weight, 10-40 parts of lime, 20-60 parts of sodium sulfate, 5-25 parts of sodium sulfite and 15-50 parts of sodium carbonate; in the high-hardness water-based system of the fracturing flowback fluid of the oil and gas field, the concentration of calcium ions is more than 20000 mg/L; the components of the composite hardening agent are pre-mixed into a solid powder mixture or respectively prepared into slurry or solution to be added sequentially when in use, wherein the mode of adding the composite hardening agent sequentially comprises the steps of adding lime, sodium sulfate and sodium sulfite firstly, and adding sodium carbonate finally.
  2. 2. The composite hard remover according to claim 1, wherein the weight ratio of sodium sulfate to sodium sulfite is (8:1) to (1:1).
  3. 3. The composite hardening agent according to claim 1, wherein the lime is 15-25 parts by weight, the sodium sulfate is 45-55 parts by weight, the sodium sulfite is 10-15 parts by weight, and the sodium carbonate is 15-30 parts by weight.
  4. 4. A method of using the composite hardening removal agent for the high-hardness aqueous system of the oil-gas field fracturing flowback fluid according to any one of claims 1 to 3, which is characterized by comprising the step of adding the composite hardening removal agent to the oil-gas field fracturing flowback fluid.
  5. 5. The method according to claim 4, further comprising performing a precipitation reaction under stirring, and separating the precipitate.
  6. 6. The use method of claim 4, wherein the adding amount is 50-100 g/L of water sample.
  7. 7. The method according to claim 4, wherein the sodium sulfate is added in steps, 30% -50% of the total calculated amount is added first, and the rest sodium sulfate is added after 5-30 minutes of reaction.

Description

Composite hardening remover applicable to high-hardness water-based system and application method thereof Technical Field The invention relates to the technical field of water treatment, provides a composite hardening agent suitable for a high-hardness water-based system of an oil-gas field fracturing flowback fluid and a use method thereof, and particularly relates to a composite hardening agent for treating a high-hardness and high-mineralization water-based system and a use method thereof, which are particularly suitable for an oil-gas field flowback fluid, brine refining and industrial circulating water system. Background Hydraulic fracturing technology is one of the key technologies to enhance oil and gas field recovery, but produces a significant amount of fracturing flowback fluid. The wastewater has complex components and is characterized by high hardness (mainly Ca 2+、Mg2+), high mineralization degree and high Chemical Oxygen Demand (COD) and contains various additive residues. In order to realize environmental protection requirements and water resource recycling, the fracturing flowback fluid must undergo advanced treatment, wherein hardness (softening) reduction is a vital link before recycling or standard discharge. The high-hardness water-based system, in particular to the calcium chloride type oil-gas field flowback fluid with the calcium ion concentration exceeding 20000 mg/L, is a difficult problem in the field of industrial water treatment. The prior art generally adopts a liquid alkali-sodium carbonate method for removing hardness, but has the defects of high cost of ① and high cost of sodium carbonate, and has huge medicament cost ratio when treating water with extremely high hardness. ② Corrosion risk that dissolved oxygen in the water body can cause corrosion to metal equipment, and the traditional hard remover does not have the deoxidizing function. ③ The effect is single, only the hardness can be removed, and the problem of oxygen corrosion cannot be synchronously solved. ④ And a plurality of sets of systems are adopted for distributed addition, so that the operation program and the intensity are high. Although the prior art suggests the use of sodium sulfate to partially replace sodium carbonate to reduce costs, the introduction of sulfate may increase the risk of calcium sulfate scaling, and does not provide deep hardness removal and does not address the problems of corrosion and water discoloration caused by high dissolved oxygen. Therefore, there is an urgent need for a low cost, multi-functional, efficient synergistic hard-removal technique. Disclosure of Invention Aiming at the problems in the background art, the main purpose of the invention is to provide a composite hardening removal agent suitable for a high-hardness water-based system of an oil-gas field fracturing flowback fluid and a use method thereof, which can effectively avoid the risk of calcium sulfate scaling while obviously reducing the cost of the agent, realize deep hardening removal and synchronously remove dissolved oxygen, thereby solving multiple challenges such as cost, scaling, effect, system corrosion and the like in one step. In a first aspect, the invention provides a composite hardness remover suitable for a high hardness aqueous system of an oil and gas field fracturing flowback fluid, comprising lime, sodium sulfate, sodium sulfite and sodium carbonate. In some embodiments, the composite hardening agent comprises, by weight, 10-40 parts of lime, 20-60 parts of sodium sulfate, 5-25 parts of sodium sulfite, and 15-50 parts of sodium carbonate. In some embodiments, the composite hardness-removing agent has a weight ratio of sodium sulfate to sodium sulfite of (8:1) to (1:1), which is optimally balanced with respect to cost and synergistic effects. In some embodiments, the weight ratio of sodium sulfate to sodium sulfite is any of 8:1, 7:1, 6:1, 5:1, 4:1, 3:1, 2:1, 1:1, and any two of the above values constitute a range. In some embodiments, the lime is 10-40 parts, preferably 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 30 parts, and any two of the above values constitute any one of a range. In some embodiments, the sodium sulfate is 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, and any two of the above values constitute any one of a range. In some embodiments, the sodium sulfite is in any of the ranges consisting of 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, and any two of the above. In some embodiments, the sodium carbonate is 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, and any two of the above values constitute any one of a range. The second aspect of the invention provides a use method of the composite hardening agent suitable for a high-hardness water-based system of an oil-gas field fracturing flowback fluid, which comprises the steps of adding the composite hardening agent into the oil-gas field fr