Motiee (1991) Correlation per GPSA Data Book
Three requirements:
1. Free water present
2. Temperature below Thyd
3. Pressure above Phyd
Typical Thyd at 1000 psia:
SG 0.6: ~62°F | SG 0.7: ~66°F | SG 0.8: ~71°F
Thermodynamic:
• Methanol (10-30 wt%)
• MEG/DEG glycol injection
• Gas dehydration (<7 lb/MMscf)
Mechanical:
• Line heating/insulation
• Pressure reduction
Complete coverage of hydrate formation temperature, P-T curve prediction, and inhibition strategies.
The Motiee (1991) correlation calculates gas hydrate formation temperature as a function of pressure and gas specific gravity. It provides accuracy of ±2-3°F for typical natural gas compositions per GPSA data book validation.
Gas hydrates require three simultaneous conditions: free water present in the system, gas at or below the hydrate formation temperature, and sufficient pressure. Removing any one of these conditions prevents hydrate formation.
Hydrate prevention uses either thermodynamic methods (chemical inhibitors like methanol or MEG that depress the formation temperature) or mechanical methods (dehydration to remove free water, heating to maintain temperature above hydrate point, or insulation to reduce heat loss).
It uses the Motiee (1991) correlation to calculate natural gas hydrate formation temperature per GPSA standards.
Yes, it calculates methanol and MEG inhibitor requirements along with hydrate risk assessment per GPSA standards.
This calculator uses the Motiee (1991) correlation specifically for hydrate formation temperature, while the hydrate prediction tool uses the Hammerschmidt correlation.