Hidden dangers of compressed air in line sweeping of natural gas-containing oil wells

Compressed air does pose potential safety hazards in line sweeping operations of natural gas-containing oil wells, and safety regulations must be strictly followed and protective measures taken. The following is a specific analysis:

1. Main hidden dangers

1. explosion risk
   • oil-gas mixed explosion: If the pipeline is not completely evacuated or there is a leak, compressed air and residual natural gas may mix into an explosive mixture (the explosion limit is usually 5%-15%), which may easily cause explosion when encountering fire sources (such as static electricity, high-temperature equipment).
   • case warning: In an oil field, combustible gas remained in the compressor outlet pipeline and was not completely replaced during line sweeping, resulting in a physical explosion and a fire, causing many casualties.
2. personal injury
   • high-pressure shock: The compressed air pressure is usually 4-6 bar (2-3 times the pressure of a car tire). If it is blown directly to the human body, it may cause serious injuries such as eyeball blowing, eardrum rupture, and lung damage.
   • operational risk: If you don’t wear protective equipment (such as goggles, insulating gloves) or stand near the sweeping pipeline, you may be injured by leaks or splashes.
3. equipment damage
   • high-pressure puncture: Weak pipeline connections or improper pressure control may lead to high-pressure gas leakage, damage equipment or cause secondary accidents.
   • impurity clogging: Oil stains and particulate matter in compressed air may block precision instruments or wear valve seals.
4. environmental pollution
   • oil and gas leakage: If the wellhead is not closed or the downstream is not notified in place during line sweeping, oil and gas may leak into the soil or water body, causing environmental pollution.
   • noise pollution: The noise during operation of the air compressor may exceed 85 decibels, affecting the lives of surrounding residents.
5. operational risk
   • misoperation: Failure to close the production valve and vent the pressure directly connected to the line sweeping process may lead to pressure holding or oil and gas backflow.
   • inadequate training: Operators lack training and do not master emergency plans, and are prone to improper handling in emergencies.

2. Security measures

1. Preparation before operation
   • risk assessment: Analyze the composition of the pipeline medium to confirm whether it contains toxic gases such as hydrogen sulfide, and conduct gas testing if necessary.
   • process validation: Close the production and back pressure valves, vent the pressure to zero, and ensure that the downstream station switches to the line sweeping process.
2. equipment inspection
   • pipeline integrity: Check whether the sweeping pipeline is connected firmly and avoid using low pressure pipelines to connect high-pressure processes.
   • Air compressor maintenance: Regularly replace the filter elements and lubricating oil to ensure that the compressed air is dry and clean (oil content ≤0.1 mg/m³).
3. operation specifications
   • pressure control: Slowly increase the sweeping pressure to avoid exceeding the rated pressure of the pipeline (usually ≤1.5 times the working pressure).
   • personnel protection: Operators wear goggles and insulating gloves, and are strictly prohibited from standing near the wellhead or line sweeping pipeline.
4. emergency measures
   • leak response: Equipped with a combustible gas detector, immediately stop the operation and start an emergency plan if a leak is discovered.
   • fire extinguishing equipment: The work site is equipped with fire extinguishers and fire hoses to ensure quick disposal in emergencies.
5. alternative
   • Inert gas sweep: For high-risk well sections, consider using nitrogen or carbon dioxide instead of compressed air to reduce the risk of explosion.
   • automation control: Adopt intelligent control system to monitor pressure and temperature parameters in real time to avoid human misoperation.

3. Compliance requirements

• approval and filing: A special plan needs to be formulated for line sweeping operations and submitted to the safety supervision department for approval and filing.
• record retention: Fill in the “Pipeline Purge Safety Operation Plan” and “Production Operation Duty Log” to record key parameters such as pressure changes and operating time.
• regular drills: Organize emergency drills every quarter to improve operators ‘ability to respond to sudden leaks and fires.

conclusion: Compressed air sweeping requires strict risk management and control during natural gas-containing oil wells. Safety hazards can be effectively reduced through standardized operations, equipment maintenance and emergency plans. For gas wells with high content or complex working conditions, it is recommended to give priority to inert gas or professional cleaning equipment.