TY - JOUR
TI - Characteristics of a non-circulating transient flow during gas invasion in the underbalanced drilling process
AU - Wei Na
AU - Meng Ying-Feng
AU - Liu An-Qi
AU - Li Hai-Tao
AU - Jiang Lin
AU - Zheng Li-Jun
AU - Fu Qiang
AU - Lv Xingcai
JN - Thermal Science
PY - 2019
VL - 23
IS - 4
SP - 2257
EP - 2264
PT - Article
AB - The wellbore flow in a liquid-based underbalanced drilling process consists  of a steady multiphase flow during normal drilling and a transient  gas-liquid flow without mud-cycling. The theory of steady multiphase flow  has been used to calculate the pressure profile of normal drilling.  Therefore, it is vital to figure out how to calculate the transient pressure  variation caused by formation fluid flow-ing into wellbore when the  mud-cycling is stopped. In this paper, a numerical simulation method and a  mathematic model are established to study the wellbore flow and to control  pressure during the underbalanced drilling process with liquid-based mud.  The results also shed a light on the hidden mechanism of this special flow.