Patent ID: 8186433

Claim:
A method of gravel packing an interval in a wellbore comprising: drilling a wellbore into a subterranean formation to create an interval in the formation; introducing a pipe into the wellbore adjacent the interval thereby forming an annulus between the pipe and a wellbore wall; introducing a first gravel pack carrier fluid into a first section of the annulus, where the first gravel pack carrier fluid comprises: water having a first salt concentration; at least one viscoelastic surfactant (VES) in an amount effective to increase the viscosity of the water; at least one internal breaker; at least one fluid loss control agent; and gravel; and introducing a second gravel pack carrier fluid into a second section of the annulus adjacent the first section of the annulus, where the second gravel pack carrier fluid is identical to the first gravel pack carrier fluid except that it has a second salt concentration different from the first salt concentration.