... 0008 1/2"300~50060~3503,000~11,0009 7/8"400~60060~3504,000~20,00012 1/4"550~ ... ~10Φ19 Φ16 Φ133.5"~5.5"7 5/8" API Reg Formation GuideFormationIADCFormationRock TypeFormationVery soft1Ultra soft formations with low ... strengthShale, Limestone, Dolomite, Anhydrite4~6Hard,dense and abrasive formations with ultra-high compressive strengthSiltstone, Sandstone, Mudstone6~8Extremely Hard8Ultra hard and abrasive ...