Well-control fluids were used during a routine overbalanced workover operation in an offshore well completed in high-permeability sandstone. A fluid-loss-control pill was used to control excessive losses; however, because of the high permeability of the reservoir and the absence of sized particles in the pumped pill, a large amount of fluid was lost to the formation. A comprehensive review, accompanied by laboratory work, was conducted to identify the damaging mechanism and formulate a remedial treatment.
Polymer-based fluids are beneficial in terms of generating viscosity to clean out the wellbore during any well intervention. Improper polymer selection has led to significant formation damage in several situations. Polymers also can invade the high-permeability zones, hampering hydrocarbon flow through the zones. Bipolymers generally are removed through acidizing, which breaks down the polymer backbone. The damage caused by polymers can be minimized with proper polymer selection.
Standard remedial treatments for removing the near-wellbore polymer include injecting solvents (e.g., xylene), acids, alcohols, glycols, surfactants, or a mixture of these liquids into the well....
Formation-Damage Diagnosis Facilitates Successful Remediation in Sandstone
01 February 2016