Research Article

Simulation of Wellbore Stability during Underbalanced Drilling Operation

Table 2

Case study input data.

Mechanical parameters

Poisson ratio ()0.2
Bulk Young’s modulus ()4.4 GPa
Maximum horizontal stress (16.8 MPa (2436 psi)
Minimum horizontal stress 14 MPa (2030 psi)
Wellbore pressure ()6.89 MPa (1000 psi)
Hydraulic parameters
Initial reservoir pressure ()11.1 MPa (1610 psi)
Fluid bulk module ()0.45 GPa
Fluid compressibility1.0 × 10−5 Pa−1
Biot’s coefficient1.0
Physical parameters
Fluid viscosity3 × 10−4 Pa⋅s
Fluid density1111 kg/m3
Matrix permeability9.869 × 10−18 m2 (0.01 md)
Porosity ()0.1
Wellbore radius0.15 m
Reservoir outer radius1000 m
Formation temperature 375 
Drilling mud temperature (330 
Thermal osmosis coefficient 1 × 10−11 m2/s K
Thermal expansion coefficient of fluid 3 × 10−4 1/K
Thermal diffusivity 1.1 × 10−6 m2/s
Thermal expansion coefficient of solid 1.8 × 10−5 1/K