Risk Assessment of Annular Pressure Caused by Tubing Leakage in Offshore Gas Wells with High CO₂

Table 1

Calculated parameters.

Parameters	Numerical value	Parameters	Numerical value
Ground temperature gradient	0.02°C/m	Stratigraphic density	2.35 g/cm^3
Production layer temperature	150°C	Stratigraphic thermal diffusion coefficient	m^2/s
Production layer pressure	115 MPa	Thermal conductivity of strata	5.1 W/(m-°C)
Circumferential liquid density	1.2 g/cm^3	Oil pipe roughness	m
Thermal conductivity of annular liquid	0.62 W/(m-°C)	Isobaric expansion coefficient of annular liquid	0.00013°C^-1
Isothermal compression coefficient of annular liquid	0.00040 MPa^-1	Thermal conductivity of gases	0.025 W/(m-°C)
Specific heat capacity of produced gas	2310 J/(kg-°C)	Relative density of produced gas	0.75
Daily gas production capacity	40 × 10^4 m^3/d	Output gas viscosity	Pa-s
Adiabatic index of gas	1.29	Gas constants	8.3414
Cement sheath thermal conductivity	0.52 W/(m-°C)	Casing thermal conductivity	50.5 W/(m-°C)
Stratigraphic specific heat capacity	890 J/(kg-°C)	Leak point depth	3000 m
Space step	1 m	Time step	20 s