When underbalanced drilling or drilling easy leaky zone by using aeration fluid, the determination of fluid density and downhole fluid column pressure is very important.
利用气体型流体进行欠平衡钻井，或钻易漏地层时，流体密度及井下液柱压力的确定十分重要。
2
By drilling down to the column statistics in the table descriptor, you can discover that the six elements in the in list predicate happen to be the bottom six values in the frequency statistics.