Abstract: The physics mechanics properties and mineral composition properties of the drilling strata rock are foundational data that carries out the fast and scientific drilling, but the influence of mineral composition to drillability hasn't been get the value. This paper put forward according to strata rock scraps datas of well logging as research object, carried on rather overall mineral composition identify and analysis to the plastic mudstone, fine sandstone and conglomerate. The results indicated that, the mineral composition t of rock in the oil-field area is mainly quartz, clay, plagioclase, calcite and orthoclase.The mineral composition contents of clay and plagioclase decline; But the quartz content increases with the increasing of well depth. The drillability value of mudstone has the trend of decline with the increment of clay content, but increase with quartz content. The drillability value of sandstone has the trend of decline with the increment of clay content, but increase with quartz content. The drillability value of conglomerate has the trend of decline with the increment of clay and quartz contents.

Key words: strata rock, mineral composition, identify and analysis, drillability, penetration rate