Methods and apparatus for improving performance of gravel packing systems

Abstract

Improved methods and apparatus for completing wells and gravel packing an interval of a wellbore are provided. The methods include the steps of placing a perforated shroud having an internal sand screen disposed therein in the zone, and injecting particulate material into the annuli between the sand screen and the perforated shroud and the perforated shroud and the wellbore to thereby form packs of particulate material therein to prevent the migration of fines and sand with produced fluids. The perforated shroud has a flow-controlling means for restricting fluid movement between the casing/shroud and shroud/screen annuli during gravel packing. The flow-controlling means may be comprised of a material installed on a selected number of the shroud perforations which blocks or partially blocks fluid flow through the otherwise permeable wall of the perforated shroud during gravel packing. Preferably, the material is removable after the gravel has been placed, such as by melting or dissolving, to accommodate production flow during the production phase without restriction. Materials suitable for application in the improved methods include magnesium oxide/magnesium chloride/calcium carbonate mixtures, oil soluble resins, waxes, soluble polymers, etc. Other suitable materials employ other mechanisms such as temperature, oil solubility, internal breaker or flow shear stress to remove them.