An original productivity-depth of damage zone ralationship for a sandstone well is given in the Figure. Original 100 Productivity, % k/k0.6 80 60 40 k/kF0.1 20 5 10 15 20 25 30 Depth of Damage Zone, cm If the damaged formation permeability is increased to 12 md as a result of acid treatment and formation reservoir permeability is 20 md, for which depth of damage zone 80% original productivity is obtained? A )5 om O 3 )10 cm C )15 cm D j20 cm E )25 cm