Chemicals Used in Chemical Injection Pumps for Oil and Gas Extraction

Oil and gas, the lifeblood of modern industry, play a pivotal role in energy supply and economic development. To efficiently and safely extract these resources, various advanced technologies are widely employed, among which pneumatic chemical injection pump technology is a crucial component. By precisely controlling the injection of chemicals, pneumatic chemical injection pumps effectively address numerous challenges encountered during extraction, such as corrosion, scaling, and emulsification, thereby enhancing recovery rates and prolonging equipment lifespan. This article aims to provide a comprehensive overview of the primary injected chemicals and their functions in oil and gas extraction using pneumatic chemical injection pumps, serving as a reference for professionals in related fields.

Primary Injected Chemicals and Their Functions

1. Corrosion Inhibitors

• Mechanism of Action: Corrosion inhibitors form a protective film on metal surfaces, preventing corrosive substances from directly contacting the metal, thus slowing down or preventing corrosion.  
• Common Types: Amines, imidazolines, phosphate esters, etc. Amine corrosion inhibitors adsorb onto metal surfaces, forming a hydrophobic protective layer; imidazoline corrosion inhibitors exhibit excellent high-temperature resistance, suitable for high-temperature and high-pressure environments; phosphate ester corrosion inhibitors form stable protective films through reactions with metal ions.  
• Application: Widely used in pipelines, storage tanks, downhole equipment, etc., particularly in environments containing corrosive media such as hydrogen sulfide and carbon dioxide.

2. Scale Inhibitors

• Mechanism of Action: Scale inhibitors interfere with the crystallization process of scaling ions, preventing or delaying scale formation.
• Common Types: Polyacrylates, organic phosphates, and phosphonates. Polyacrylates disperse scale crystals, preventing their growth, while organic phosphates and phosphonates chelate scaling ions, prevent their aggregation.
• Applications: Commonly used in water flooding, injection wells, and pipelines to prevent the formation of scales such as calcium carbonate and barium sulfate.

3. Demulsifiers

• Mechanism of Action: Demulsifiers reduce the interfacial tension between oil and water, destabilizing emulsions and promoting oil-water separation.
• Common Types: Alcohols, phenols, and ethylene oxide derivatives. Alcohol-based demulsifiers reduce interfacial tension, promoting droplet coalescence, while phenol-based demulsifiers alter the properties of the interfacial film, destabilizing emulsions. Ethylene oxide derivatives are effective across a wide range of emulsions.
• Applications: Primarily used in crude oil dehydration and wastewater treatment.

4. Pour Point Depressants

• Mechanism of Action: Pour point depressants alter the crystallization behavior of crude oil, lowering its pour point.
• Common Types: Polymers and alkylphenols. Polymer-based depressants modify the morphology of wax crystals, preventing their aggregation, while alkylphenols lower the melting point of wax crystals, reducing the crude oil’s pour point.
• Applications: Mainly used in the transportation and storage of crude oil in low-temperature environments.

5. Biocides

• Mechanism of Action: Biocides kill or inhibit the growth of microorganisms, preventing microbial-induced corrosion and blockages.
• Common Types: Quaternary ammonium compounds, glutaraldehyde, and sodium hypochlorite. Quaternary ammonium compounds disrupt cell membranes, killing bacteria, while glutaraldehyde reacts with proteins, inhibiting bacterial growth. Sodium hypochlorite offers broad-spectrum antimicrobial activity.
• Applications: Widely used in injection wells, pipelines, and storage tanks to prevent the growth of sulfate-reducing bacteria and iron bacteria.

6. Thickeners

• Mechanism of Action: Thickeners increase the viscosity of injected fluids, improving oil displacement efficiency and enhancing oil recovery.
• Common Types: Polymers and cellulose derivatives. Polymer-based thickeners increase fluid viscosity by increasing molecular weight, while cellulose-based thickeners form a three-dimensional network structure, enhancing viscosity.
• Applications: Primarily used in polymer flooding and conformance control.

7. Surfactants

• Mechanism of Action: Surfactants reduce the interfacial tension between oil and water, improving oil mobility and enhancing recovery rates.
• Common Types: Sulfonates and alkylphenol ethoxylates. Sulfonates reduce interfacial tension, promoting oil emulsification and migration, while alkylphenol ethoxylates alter the properties of the interfacial film, enhancing oil recovery.
• Applications: Mainly used in chemical flooding and foam flooding.

8. Wax Dispersants

• Mechanism of Action: Wax dispersants dissolve or disperse wax deposits, removing wax buildup from pipelines and equipment.
• Common Types: Solvents and surfactants. Solvent-based dispersants dissolve wax deposits, while surfactant-based dispersants disperse wax, detaching it from metal surfaces.
• Applications: Primarily used in pipelines, storage tanks, and downhole tools to remove wax deposits.

9. Flow Improvers

• Mechanism of Action: Flow improvers reduce the flow resistance of liquids in pipelines, aiding in the removal of liquids from wells.
• Common Types: Surfactants and alcohols. Surfactant-based flow improvers reduce flow resistance, while alcohol-based flow improvers lower liquid viscosity.
• Applications: Mainly used in gas lift and pump-assisted oil recovery.

Chemical Selection and Application Considerations

In oil and gas extraction, the selection and application of chemicals are crucial. Improper selection or use can not only affect extraction efficiency but also cause damage to equipment, personnel, and the environment. Therefore, various factors must be comprehensively considered, and relevant regulations must be strictly followed.

1. Factors Influencing Chemical Selection

Geological Conditions:

• Temperature: Formation temperature significantly affects the stability and reaction rate of chemicals. High temperatures may cause certain chemicals to decompose or become ineffective, while low temperatures may reduce their reactivity. Therefore, chemicals effective within specific temperature ranges must be selected.
• Pressure: Formation pressure also influences chemical performance. High-pressure environments may alter the phase and solubility of chemicals, affecting their efficacy.
• Permeability: Formation permeability determines the flow capacity of fluids within the rock. High-permeability formations may require high-viscosity chemicals to enhance oil displacement efficiency, while low-permeability formations may need low-viscosity chemicals to ensure penetration into the rock.
• Formation Water Chemistry: The salinity, pH, and ionic composition of formation water can affect chemical reactions and stability. Chemicals compatible with formation water must be selected to avoid precipitation, scaling, or other adverse reactions.

Fluid Properties:

• Crude Oil Viscosity: High-viscosity crude oil requires viscosity reducers or surfactants to lower flow resistance and enhance recovery.
• Water Content: High-water-content crude oil requires demulsifiers to promote oil-water separation.
• Corrosiveness: If crude oil or formation water is corrosive, corrosion inhibitors or corrosion preventatives must be used to protect pipelines and equipment.
• Wax Content: High-wax-content crude oil requires wax dispersants or pour point depressants to prevent wax deposition and solidification.
• Sulfur Content: High-sulfur crude oil requires chemicals capable of withstanding sulfide corrosion.
• Microbial Content: Fluids containing microorganisms require biocides to inhibit microbial growth, preventing corrosion and blockages.

Equipment Materials:

• Carbon Steel: Carbon steel is prone to corrosion and thus requires corrosion inhibitors or corrosion preventatives.
• Stainless Steel: Stainless steel has better corrosion resistance but may still be susceptible to certain chemicals.
• Alloy Steel: Alloy steel offers higher corrosion resistance and strength, suitable for high-temperature and high-pressure environments.
• Polymer Materials: Polymer materials are sensitive to certain chemicals and may swell, soften, or degrade.
• Sealing Materials: Sealing materials must be compatible with the chemicals used to prevent leaks.

2. Optimization of Chemical Injection Volume and Method

Injection Volume:

• The injection volume of chemicals must be optimized based on formation conditions, fluid properties, and equipment materials.
• Excessive chemical injection may lead to waste and environmental pollution, while insufficient injection may fail to achieve the desired effect.
• Optimal injection volumes can be determined through experiments and simulation calculations.

Injection Method:

• Injection methods include continuous injection, intermittent injection, and pulse injection.
• Continuous injection is suitable for equipment requiring long-term protection, such as pipelines; intermittent injection is suitable for wells requiring periodic treatment, such as injection wells; pulse injection is suitable for wells requiring rapid blockage removal.
• The injection method must be optimized based on specific conditions.

Injection Location:

• The injection location must consider the chemical’s mechanism of action, ensuring that the chemical can fully exert its effect at the required location.

3. Safety and Environmental Regulations

Safety Regulations:

• Personal protective equipment (PPE) such as protective clothing, gloves, goggles, and respirators must be worn during operations.
• Chemical safety operating procedures must be followed to avoid skin and eye contact.
• Regular safety training and emergency drills must be conducted.

Environmental Regulations:

• Relevant environmental regulations must be adhered to, preventing chemical leaks and pollution.
• Waste chemicals and packaging materials must be properly disposed of.
• Regular environmental monitoring must be conducted to ensure compliance with environmental standards.
• Environmentally friendly chemicals should be considered.

Pneumatic chemical injection pump technology plays a vital role in oil and gas extraction. By precisely controlling the injection of chemicals, it effectively addresses numerous challenges encountered during extraction, enhancing recovery rates and extending equipment lifespan. As technology continues to advance, the application prospects for pneumatic chemical injection pumps will become even broader.