Liquid Loading

What is Gas Well Liquid Loading?

Gas well liquid loading refers to the accumulation of fluids within the tubing of a gas well. This phenomenon occurs when the gas flow rate becomes insufficient to overcome the force of gravity, leading to a buildup of liquids that can impede or halt production.

When Does Gas Well Liquid Loading Begin?

Liquid loading in gas wells begins when the gas flow rate is insufficient to overcome gravity. The critical point is reached when the gas flow rate and gravity forces are equal, resulting in the onset of liquid accumulation within the well.

Consequences of Liquid Loading

• Cessation of Production: Once the hydrostatic head equals the reservoir pressure, gas production stops.
• Production Decline: Reduced gas output can lead to significant drops in overall production rates.
• Potential Formation Damage: Flow and pressure surges may cause damage to the reservoir.
• Corrosion Risks: Stagnant liquids can lead to corrosion of tubing and other well components.
• Increased Operational Costs: Artificial lifting methods become necessary, adding to the budget.

Sources of Liquids in the Well

Origin of Liquid Loading

1. Formation Water:
   • Enters through perforations.
   • Typically saline, potentially causing salt scaling when saturated.
2. Water of Condensation:
   • Fresh water determined by reservoir pressure and temperature.
3. Gas Condensate:
   • Heavier hydrocarbons drop out due to reductions in pressure and temperature.

Symptoms of Liquid Loading

• Accumulation Below Critical Velocity: Liquid buildup in the well if gas velocity drops below the critical threshold.
• Sharp Drops in Cumulative Production Curve: Sudden decreases in production rates.
• Liquid Slugs at Flowlines & Surface Facilities: Visible liquid surges in the production system.
• Drop in Wellhead Temperature: Reduction in temperature due to liquid influx.
• Declining Water Production or Condensate-Gas Ratio: Changes in fluid composition at the surface.
• Changes in Flowing Pressure Gradient: Variations in pressure profiles during production.
• Intermittent Production: Unsteady gas output with periods of low or no production.
• Slow or Incomplete Pressure Buildup: Delays in pressure stabilization after shut-ins.

Deliquification Methods

To address liquid loading, various deliquification methods can be employed:

• Flaring the Well: Burning off excess gas to reduce pressure and liquid accumulation.
• Wellhead Compression: Compressing gas at the wellhead to enhance gas flow and reduce liquid buildup.
• Gas Lift:
  • Injecting gas into the tubing to lift liquids to the surface.
• Velocity String:
  • Increasing gas velocity to carry liquids upward.
• Foam Lift:
  • Introducing foam to reduce liquid density and facilitate gas flow.
• Plunger Lift:
  • Using a plunger to mechanically remove liquids from the well.

Liquid Loading Estimation