6 core and 36 cuttings samples from 4 wells in Big Lake Field were examined petrologically to assess the following microscopic traits: 1. grain size and reservoir quality of each sample; 2. morphology and origin of the pore systems; 3. rock composition, particularly that of minerals lining or filling the pores and pore throats; and 4. sensitivity of any pore lining and pore fill minerals to various common well bore fluids and to drilling and completion practices. From these data recommendations have been made concerning the optimum design for any reservoir stimulations planned for the field.