In order to protect the reservoir, to improve the drilling rate in Daqing Oilfield and accelerate the exploration speed in Xujiaweizi Area and to think about the real condition in this part, the air under-balanced drilling technique was used in the section from 2550 to 2918 m of Xushen21 well.

Through analyzing problems existing in calculation formula of natural ventilation volume required for eliminating work-shop rest heat when hot workshop is ventilated locally via workshop internal heat balance and air balance,it deduced out rational for-mula and discusses associated aspects.

The Research of Underbalance Drilling Technology Applying in Daqing Oil Field;

Application and knowledge of underbalanced drilling technology

When the sandstone gas reservoir is drilled open by the underbalanced drilling using water based mud (WBM), the underbalance pressure normally can hardly offset the imbibition capillary force of the rock, which may result in backwash imbibition.

Application of comprehensive mud logging parameters in interpretation & evaluation of the under-balanced well gas layers;