Effects of Different Factors on Methane Hydrate Formation Using a Visual Wellbore Simulator

Area of Science:

• Geosciences
• Chemical Engineering
• Petroleum Engineering

Background:

• Wellbore hydrate formation and decomposition are influenced by salinity, temperature, pressure, and gas-liquid ratios.
• Inhibitors are crucial in drilling fluids to prevent wellbore blockages caused by hydrates.

Purpose of the Study:

• To investigate the impact of various factors on hydrate formation, inhibition, and decomposition within a wellbore simulator.
• To analyze the effects of water type, pressure, inhibitor concentration, and gas-liquid ratios on methane hydrate formation.

Main Methods:

• Utilized a visual wellbore simulator to study methane hydrate (MH) formation, inhibition, and decomposition.
• Verified the accuracy of the experimental device before conducting tests.

Main Results:

• Salinity (10% NaCl brine) significantly reduced MH formation compared to freshwater, indicated by a smaller pressure drop (1.24 MPa vs. 6.73 MPa).
• Kinetic inhibitor GID3 showed effectiveness, but excess concentrations (1.0-2.0 wt%) reduced its inhibitory effect.
• Increased pressure and gas-liquid ratios (GLR) enhanced methane absorption by hydrates, though inhibitors complicated this relationship.
• Specific decomposition solutions were found to accelerate MH decomposition, mitigating wellbore blockages.

Conclusions:

• Salinity acts as a thermodynamic inhibitor, reducing dissolved gas and MH formation.
• Kinetic inhibitor effectiveness is dosage-dependent, with excess amounts being counterproductive.
• Pressure and GLR influence methane uptake, but inhibitor presence complicates dissolution.
• Optimized decomposition strategies are vital for managing wellbore hydrate issues in exploitation.