Sand Production Mechanisms in Sandstone Gas Reservoirs during Cyclic Injection-Production with Variable Water...

Area of Science:

• Geology
• Petroleum Engineering
• Reservoir Engineering

Background:

• Depleted reservoirs used for underground gas storage often contain formation water, leading to sand production during operations.
• Existing research on sand production primarily addresses single-phase flow, neglecting the complexities of water-bearing reservoirs.

Purpose of the Study:

• To investigate the sand production mechanism in reservoir rocks under two-phase flow conditions.
• To evaluate the influence of water saturation and alternating injection-production cycles on sand production in gas storage.

Main Methods:

• Experimental measurement of critical sand production pressure difference in cores at various water saturations.
• Cyclic injection-production tests in sandstone cores to assess sand production trends.
• Comparison of results under two-phase flow with single-phase flow conditions.

Main Results:

• The critical sand production pressure difference is generally higher in water-bearing cores than in dry cores.
• Sand production exhibits a nonmonotonic trend with water saturation (0%-85%), peaking at 30% water saturation.
• The number of alternating displacement cycles affects sand production, with decelerated growth up to 30 cycles and accelerated growth thereafter.

Conclusions:

• Water saturation significantly influences sand production in gas storage reservoirs.
• Understanding these two-phase flow dynamics is crucial for optimizing gas storage operations in water-bearing sandstone formations.