There are more than 15 sand control methods and one of thefrequently used methods is the rate control method. There aremainly two cases where the rate control method can beapplied: (1) permeability is significantly damaged around awell and the sand problem induced by erosion failure due toabnormally large drawdown can be controlled by the ratecontrol method, and (2) the stability of a sand-arch built bydisintegrated sand particles can be controlled by rate control.A series of laboratory tests were conducted in this work tomeasure the sand-arch strength using a polyaxial confiningcell. The parameters changed in these experiments were theratio of grain size to cavity diameter, grain distribution, oil-waterratio, and confining stresses. A similar experiment waspreviously conducted by the Colorado School of Mines 1 andIKU 2, however, the tests conducted by the Colorado Schoolof Mines used 20-40 mesh loose sands which are too coarsecompared with actual reservoir sands, and IKU used airinstead of liquid flow. Both of them used a certain immobilewater saturation while the saturation change from 0 to 30%significantly reveals the complex phenomena of water effectsupon sand-arch strength. The present laboratory tests selecteda large grain size to observe large mechanical arch strengthwithout capillary pressure effects and an intermediate grainsize to observe capillary pressure effects. An analyticalsolution of a spherical cavity growth due to erosion of thepost-failure zone is also developed to verify the observedphenomena in the laboratory tests.
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