Influence of Gas Solubility on Zero Gas Flow Characteristics in MPD Operation

In this paper the authors have put forward the concept of annular zero gas flow and developed the residual gas model, considering the parameters of gas solubility, slippage, and the oil-based drilling fluid volume coefficient [1-3]. The calculation results show that in the process of continuous gas influx at the bottom of the well, the phenomenon of annular zero gas flow can be defined in terms of gas solubility [4-6]. The increase in the back pressure, the decrease in the gas invasion rate, and the decrease in the oil-based ratio can cause an increase in the length of the annular zero gas flow well section. When the back pressure increases from 0.1 to 4.0 MPa, the length of the annular zero gas flow section increases from 1000 to 2700 m. If the zero gas flow is not taken into consideration, the maximum error of the annular void ratio is 21.22% [7-10]. When the CO 2 , gas invades the bottom of the well, the oil-based ratio increases from 0.1 to 5, the length of the annular zero gas flow section increases from 1500 to 2250 m, and the maximum error of the annular void ratio is 26.57%.