Research on optimum design technology of casing of low permeability block in ShengLi Oilfield

Based on the character of low permeability block in Shengli Oilfield, on the condition of obvious layer and safety drilling, optimum design of surface casing is researched, using 273.1 mm casing as surface casing and 346.1 mm drilling bit as primary bit, as the result, OD of surface casing decreased 19.61%, OD of drilling bit decreased 22.14%. The analysis indicates that safety factor of tension resistance increases 10.58%~10.81%, safety factor of collapse resistance increases 39.67%~39.81%, safety factor of burst resistance increase 14.29%. The application results show that, optimization design technology of 273.1 mm surface casing is successful, which can not only assure drilling safety and meet with requirement of oil recovery, but also decrease drilling cost and achieve a gain of high effective development in low permeability oilfield.