Neutral blocking remover for oil-gas well and preparation method of neutral blocking remover

Abstract

The invention discloses a neutral blocking remover for an oil-gas well and a preparation method of the neutral blocking remover, and belongs to the technical field of blocking removers. The preparation method comprises the following steps: dissolving a nonionic surfactant in water, adding a biological enzyme blocking remover and a metal chelating agent, uniformly mixing, heating, adding a dispersant, an emulsifier and a water wetting agent, and uniformly mixing to obtain the neutral blocking remover for the oil and gas well. The biological enzyme blocking remover in the formula can efficiently decompose stubborn blockages such as oil stains, organic scales and the like, so that the structures of the blockages are loose, and the metal chelating agent is further combined with metal scale ions in the blockages, so that the neutral blocking remover has a very good removal effect on multi-component complex scales. The cleaning agent is suitable for cleaning multi-component complex dirt in oil and gas wells.

Description

Technical Field

[0001] This invention belongs to the field of unblocking agent technology, and relates to an unblocking agent for oil and gas wells, specifically a neutral unblocking agent for oil and gas wells and its preparation method. Background Technology

[0002] Against the backdrop of ever-increasing energy demand, the importance of oilfield production and efficiency is becoming increasingly prominent. However, with the continuous advancement of oilfield exploitation, well blockage has gradually become one of the main factors restricting efficient oilfield production. Well blockage not only reduces oil and gas production and increases production costs, but also poses hidden dangers and serious impacts on the stable and safe production of oilfields. For example, in carbonate oilfields, due to the high concentration and low solubility product of calcium, barium, and magnesium ions, water lock, wellbore scaling, and tubing corrosion often occur. As production progresses, irreversible inorganic scale products, mainly composed of calcium, barium, and magnesium ions, are gradually generated, leading to reservoir blockage, reservoir damage, and reduced production capacity. Over time, the amount of injected water, organic matter, or other chemical reagents gradually decreases, while the injection pressure continues to rise, resulting in a gradual decrease in crude oil production and irreversible damage to the oilfield reservoir.

[0003] Currently, unclogging technologies mainly include physical and chemical methods. Chemical unclogging is more commonly used, utilizing the chemical properties of agents to degrade and dissolve components such as oil, polymers, and inorganic substances in the blockage, thus achieving the purpose of unclogging. The key to chemical unclogging technology is the unclogging agent. Chemical unclogging technology is highly targeted; it is essential to clearly identify the composition, location, and extent of the scale buildup before selecting the type and dosage of the unclogging agent.

[0004] Neutral unblocking agents utilize their active groups to react with asphalt and polymer scale in oilfield formations. They have the ability to dissolve scale at low concentrations, and the reaction is mild. They avoid the pipe blockage caused by large-scale scale shedding during traditional acid washing, and they also avoid the corrosive damage to equipment materials caused by acid washing. However, current neutral unblocking agents are not very effective, especially against complex, multi-component scale containing oil, polymers, and inorganic substances, and cannot effectively remove it. Summary of the Invention

[0005] The purpose of this invention is to provide a neutral unblocking agent for oil and gas wells and its preparation method, so as to solve the problem that current neutral unblocking agents have poor removal effect on complex multi-component fouling.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A neutral unblocking agent for oil and gas wells, the raw materials for which it is made include nonionic surfactants, bio-enzyme unblocking agents, metal chelating agents, dispersants, emulsifiers, water wetting agents and water.

[0007] As a limitation, by weight percentage, the nonionic surfactant is 0.3%-1%, the bio-enzyme deblocking agent is 0.03%-0.1%, the metal chelating agent is 4%-6.5%, the dispersant is 1%-1.7%, the emulsifier is 0.2%-0.8%, the water wetting agent is 1.5%-2.5%, and the balance is water.

[0008] As a further limitation, the nonionic surfactant includes laurylamine polyoxyethylene ether, octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, glycerol ester or sorbitol ester. The bio-enzyme unblocking agent includes SJY-03 or SJY-04.

[0009] Among them, the bio-enzyme unblocking agents SJY-03 and SJY-04 were purchased from Tianjin Shengjunyu Biotechnology Group Co., Ltd., with product numbers SJY-03 and SJY-04. These bio-enzyme unblocking agents can dissolve and disperse inorganic and organic matter in blockages, including calcium carbonate, calcium sulfate, waxes, asphaltenes, etc., especially oil stains and organic fouling, thereby restoring the permeability of oil wells.

[0010] Nonionic surfactants can emulsify, disperse, and wet, improving the overall fluidity of neutral unblocking agents. They can carry highly bioactive enzymes and metal chelating agents deep into rocks and blocked pore throats, making the unblocking effect of neutral unblocking agents more thorough.

[0011] Due to varying actual oil and gas well development and production conditions, it is necessary to select bio-enzyme unblocking agents that can adapt to these conditions. This means that the active enzymes and bacteria within these agents must maintain a certain level of activity in the oil and gas well. Many types of bio-enzyme unblocking agents are suitable for oil and gas wells; this invention selects two: SJY-03 and SJY-04. To ensure the activity of the bio-enzyme unblocking agent and to achieve better formulation, anionic or cationic surfactants are preferred because they exhibit a certain pH level and readily react with the ions in the bio-enzyme unblocking agent through charge adsorption, thus consuming the enzymes. Nonionic surfactants, on the other hand, do not chemically react with the bacteria and active enzymes in the bio-enzyme unblocking agent and do not affect the enzyme's biological activity. Therefore, nonionic surfactants were chosen.

[0012] As another limitation, the metal chelating agent includes sodium ethylenediaminetetraacetate, ammonium citrate, sodium diethylenetriaminepentaacetate, or sodium ethylenediaminetetraacetate.

[0013] Among them, metal chelating agents can form stable complexes with metal scale ions, especially for divalent metal ions, achieving the effect of descaling and unclogging.

[0014] As a third limitation, the dispersant includes sodium phosphate, sodium pyrophosphate, sodium tripolyphosphate, citrate, or gluconate.

[0015] Among them, the dispersant can disperse the blockage into tiny particles, making it easier for the fluid to carry it out of the wellbore.

[0016] As a fourth limitation, the emulsifier includes anionic surfactants or chloride-free alcohol ether carboxylates; The anionic surfactant includes sodium oleate, sodium dodecyl sulfate, alkyl sulfonate, or alkyl alcohol polyoxyethylene ether sulfate.

[0017] Emulsifiers can improve the stability of neutral unblocking agent systems and prevent oil-water separation.

[0018] As a fifth limitation, the water-wetting agent includes polyacrylate or methacrylate.

[0019] Among them, water-wetting agents can improve the compatibility of neutral unblocking agents with formation water, making the oil phase easier to flow and reducing blockages caused by water-locking effects and Jamin effects.

[0020] The present invention also provides a method for preparing the above-mentioned neutral unblocking agent for oil and gas wells, which involves dissolving a nonionic surfactant in water, adding a biological enzyme unblocking agent and a metal chelating agent, mixing well, heating, adding a dispersant, an emulsifier and a water wetting agent, mixing well, and thus obtaining the neutral unblocking agent for oil and gas wells.

[0021] As a limitation, the temperature for the heating is 45-52℃.

[0022] By adopting the above technical solution, the technical progress achieved by this invention compared with the prior art is as follows: ①The present invention provides a neutral unblocking agent for oil and gas wells. The bio-enzyme unblocking agent can efficiently decompose stubborn blockages such as oil stains and organic scale, making the structure of the blockage loose. The metal chelating agent further combines with the metal scale ions therein, so that the neutral unblocking agent has a good removal effect on multi-component complex scale. ② The present invention provides a neutral unblocking agent for oil and gas wells. Because bio-enzyme unblocking agents have high biological activity, they usually only work on the surface of dirt and cannot penetrate deep into rock fissures or pore throats. Therefore, the unblocking efficiency is still low in practical applications. To address this, a non-ionic surfactant is added, which can improve the fluidity of the neutral unblocking agent and carry the bio-enzyme unblocking agent and metal chelating agent into rock fissures and pore throats to achieve deep removal of dirt. At the same time, because the bio-enzyme unblocking agent contains active ingredients such as enzymes and bacteria, it is different from acidic cleaning agents and can play a long-term role in inhibiting the formation of dirt. ③ This invention provides a neutral unblocking agent for oil and gas wells. Each component has a synergistic effect, jointly improving the scale-dissolving and unblocking ability of the neutral unblocking agent. Experimental verification shows that the scale dissolution rate is above 89%. It can replace acidizing and scale removal measures for water injection wells to increase production. It dissolves and disperses complex scale in the formation, opens up reservoirs blocked by inorganic-organic complex scale, thereby increasing the water injection volume of water injection wells or increasing the production of acidizing oil and water wells. It can also be used for scale removal and unblocking during oil well workovers, replacing hydrochloric acid. ④ The present invention provides a method for preparing a neutral unblocking agent for oil and gas wells. The preparation process is simple and suitable for industrial production applications. Detailed Implementation

[0023] The present invention will be further described in detail below through specific embodiments. It should be understood that the described embodiments are only for explaining the present invention and do not limit the present invention.

[0024] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art.

[0025] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0026] In the following examples, the bio-enzyme deblocking agents SJY-03 and SJY-04 were purchased from Tianjin Shengjunyu Biotechnology Group Co., Ltd., with trade numbers SJY-03 and SJY-04.

[0027] Example 1 This embodiment prepared a neutral unblocking agent for oil and gas wells and verified its scale dissolution rate, specifically including the following steps performed sequentially: Dissolve 0.5 wt% laurylamine polyoxyethylene ether in 91.2 wt% water and stir until homogeneous. Add 0.1 wt% of the bio-enzymatic unblocking agent SJY-04 and stir until homogeneous. Continue to add 5 wt% of tetrasodium ethylenediaminetetraacetate and stir until homogeneous. Raise the temperature to 50°C and add 1 wt% gluconate and stir until homogeneous. Continue to add 0.2 wt% sodium dodecyl sulfate and 2 wt% methacrylate and stir until completely dissolved to obtain neutral unblocking agent α1 for oil and gas wells. The pH of this neutral unblocking agent is tested to be 7.2.

[0028] Take 20g of neutral unblocking agent α1 for oil and gas wells and add it to 100g of water (concentration of 20%). Then add 10g of scale sample from a water injection well in an oilfield. Stir for 24 hours at 85℃ (reservoir temperature) and soak for 24 hours. Filter, dry the undissolved scale sample and evaporate the water. The remaining scale sample weighs 0.38g, which means that 9.62g of scale sample has been dissolved, with a scale dissolution rate of 96.2%. This neutral unblocking agent for oil and gas wells demonstrates excellent scale removal and unblocking effects and can replace acidized reservoir stimulation technology for unblocking complex scale.

[0029] Under the same conditions, after stirring for 24 hours and soaking for 42 hours, the scale dissolution rate reached 100%. It can be seen that the longer the action time, the higher the removal rate of dirt. However, considering factors such as time, soaking for 24 hours is sufficient to meet production requirements.

[0030] The neutral unblocking agent α1 for oil and gas wells was applied to descaling a certain oil well, achieving a 100% success rate in unblocking. After descaling, the daily oil production of the well increased from 0.8 tons to 4.5 tons, completely removing the complex scale blockage and restoring the reservoir oil flow channels. In addition, before descaling and unblocking, the daily water injection volume of this well was only about 4 cubic meters, which was insufficient for water injection. After descaling and unblocking, the daily water injection volume increased to 30 cubic meters, and the stable injection time reached more than 6 months. The long-term effectiveness of the descaling and unblocking measures proves that the neutral unblocking agent for oil and gas wells has good practical production application effects.

[0031] Example 2 This embodiment prepared a neutral unblocking agent for oil and gas wells and verified its scale dissolution rate, specifically including the following steps performed sequentially: Dissolve 0.3 wt% nonylphenol polyoxyethylene ether in 92.6 wt% water and stir until homogeneous. Add 0.1 wt% of bio-enzymatic unblocking agent SJY-03 and stir until homogeneous. Continue to add 4 wt% sodium ethylenediaminetetraacetate and stir until homogeneous. Raise the temperature to 45°C and add 1 wt% citrate and stir until homogeneous. Continue to add 0.5 wt% alkyl polyoxyethylene ether sulfate and 1.5 wt% polyacrylate and stir until completely dissolved to obtain neutral unblocking agent α2 for oil and gas wells. The pH of this neutral unblocking agent is tested to be 7.5.

[0032] 20g of neutral unblocking agent α2 for oil and gas wells was added to 100g of water (concentration of 20%), and then 10g of scale sample from a water injection well in an oilfield was added. The mixture was stirred for 24 hours at 80℃ (reservoir temperature), soaked for 24 hours, filtered, and the undissolved scale sample was dried and the water evaporated. The remaining scale sample weighed 1.08g, meaning that 8.92g of scale sample was dissolved, with a scale dissolution rate of 89.2%. This neutral unblocking agent for oil and gas wells demonstrated excellent scale removal and unblocking effects and can replace acidized reservoir stimulation processes for unblocking complex scale.

[0033] Example 3 This embodiment prepared a neutral unblocking agent for oil and gas wells and verified its scale dissolution rate, specifically including the following steps performed sequentially: 1.0 wt% of sorbitol ester was dissolved in 88.15 wt% water and stirred until homogeneous. 0.05 wt% of the bio-enzymatic unblocking agent SJY-04 was added and stirred until homogeneous. 6.5 wt% of diethylenetriaminepentaacetic acid pentasodium salt was then added and stirred until homogeneous. The temperature was raised to 52℃, and 1 wt% of sodium pyrophosphate was added and stirred until homogeneous. 0.8 wt% of sodium oleate and 2.5 wt% of polyacrylate were then added and stirred until completely dissolved to obtain neutral unblocking agent α3 for oil and gas wells. The pH of this neutral unblocking agent was tested to be 6.9.

[0034] Take 20g of neutral unblocking agent α2 for oil and gas wells and add it to 100g of water (concentration of 20%). Then add 10g of scale sample from a water injection well in an oilfield. Stir for 24 hours at 85℃ (reservoir temperature) and soak for 24 hours. Filter, dry the undissolved scale sample and evaporate the water. The remaining scale sample weighs 0.32g, which means that 9.68g of scale sample has been dissolved, with a scale dissolution rate of 96.8%. This neutral unblocking agent for oil and gas wells demonstrates excellent scale removal and unblocking effects and can replace acidized reservoir stimulation technology for unblocking complex scale.

[0035] Example 4 This embodiment prepared a neutral unblocking agent for oil and gas wells and verified its scale dissolution rate, specifically including the following steps performed sequentially: Dissolve 0.7 wt% octylphenol polyoxyethylene ether in 90.27 wt% water and stir until homogeneous. Add 0.03 wt% bio-enzymatic unblocking agent SJY-03 and stir until homogeneous. Continue to add 4.5 wt% ammonium citrate salt and stir until homogeneous. Raise the temperature to 50℃ and add 1.7 wt% sodium tripolyphosphate and stir until homogeneous. Continue to add 0.8 wt% sodium oleate and 2 wt% methacrylate and stir until completely dissolved to obtain neutral unblocking agent α4 for oil and gas wells. The pH of this neutral unblocking agent is tested to be 7.1.

[0036] Take 20g of neutral unblocking agent α2 for oil and gas wells and add it to 100g of water (concentration of 20%). Then add 10g of scale sample from a water injection well in an oilfield. Stir for 24 hours at 90℃ (reservoir temperature) and soak for 24 hours. Filter, dry the undissolved scale sample and evaporate the water. The remaining scale sample weighs 1.10g, which means that 8.90g of scale sample has been dissolved, and the scale dissolution rate is 89%. This neutral unblocking agent for oil and gas wells demonstrates excellent scale removal and unblocking effects and can replace acidized reservoir stimulation technology for unblocking complex scale.

Claims

1. A neutral unblocking agent for oil and gas wells, characterized in that, The raw materials used to make it include nonionic surfactants, bio-enzymatic deblocking agents, metal chelating agents, dispersants, emulsifiers, water wetting agents, and water.

2. The neutral unblocking agent for oil and gas wells according to claim 1, characterized in that, By weight percentage, the nonionic surfactant is 0.3%-1%, the bio-enzyme deblocking agent is 0.03%-0.1%, the metal chelating agent is 4%-6.5%, the dispersant is 1%-1.7%, the emulsifier is 0.2%-0.8%, the water wetting agent is 1.5%-2.5%, and the balance is water.

3. The neutral unblocking agent for oil and gas wells according to claim 2, characterized in that, The nonionic surfactants include laurylamine polyoxyethylene ether, octylphenol polyoxyethylene ether, nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, glyceryl esters, or sorbitol esters. The bio-enzyme unblocking agent includes SJY-03 or SJY-04.

4. A neutral unblocking agent for oil and gas wells according to any one of claims 1-3, characterized in that, The metal chelating agent includes sodium ethylenediaminetetraacetate, ammonium citrate, sodium diethylenetriaminepentaacetate, or sodium ethylenediaminetetraacetate.

5. A neutral unblocking agent for oil and gas wells according to any one of claims 1-3, characterized in that, The dispersant includes sodium phosphate, sodium pyrophosphate, sodium tripolyphosphate, citrate, or gluconate.

6. A neutral unblocking agent for oil and gas wells according to any one of claims 1-3, characterized in that, The emulsifier includes anionic surfactants or chloride-free alcohol ether carboxylates; The anionic surfactant includes sodium oleate, sodium dodecyl sulfate, alkyl sulfonate, or alkyl alcohol polyoxyethylene ether sulfate.

7. A neutral unblocking agent for oil and gas wells according to any one of claims 1-3, characterized in that, The water-wetting agent includes polyacrylate or methacrylate.

8. A method for preparing a neutral unblocking agent for oil and gas wells according to any one of claims 1-7, characterized in that, It is prepared by dissolving a nonionic surfactant in water, adding a bio-enzyme unblocking agent and a metal chelating agent, mixing well, heating, adding a dispersant, emulsifier, and water wetting agent, and mixing well to obtain the neutral unblocking agent for oil and gas wells.

9. A method for preparing a neutral unblocking agent for oil and gas wells according to claim 8, characterized in that, The temperature is increased to 45-52℃.