When large areas of oil saturation remain unswept in a petroleum reservoir, profile modification is necessary to redirect injected fluids into areas of high oil saturation. Gels made from xanthan biopolymer that is produced and transported to the field site as a liquid broth have been used for profile modification in many field projects. This report discusses the use, for profile modification treatments, of xanthan biopolymer that is produced and transported in dry, solid form. The report is divided into three sections. Section I covers mixing procedures, section II covers crosslinking procedures, and section III addresses injection strategies. The effects of reactant concentrations, pH, and salinity on crosslinking were investigated. The optimal conditions for crosslinking the powdered xanthan were identified for gel injection and for in situ gelation. The optimal concentration of polymer was found to be in the 1400 to 2000 ppM range. The transition zone from solid to pourable gels occurs at about 20 ppM chromium concentration. 20 refs., 10 figs., 14 tabs.