When underbalanced drilling or drilling easy leaky zone by using aeration fluid, the determinationof 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
Single age variable stock volume growth model had low coefficient ofdetermination, but it was improved a lot by introducing site index and stand density index in reparameterization.
The important factors for laser depth-microdrilling are the sufficient power density, suitable focal length, determinationof the best image plane and refocusing etc.