In order to verify the robustness of our results, we tested two permeability profiles with permeability variations of [+ or -]1 order of magnitude with respect to the used values.
Possible reasons of this discrepancy are (1) the different assumed configurations used to model the ground displacements (here a 3D one is assumed, with respect to the 2D from previous work), (2) the different permeability profiles, and (3) the fact that we exclude the possibility of poroelastic induced afterslip.
In a following study, van Kruijsdijk and Cox  developed a method for identifying the permeability profiles along the well trajectory of a horizontal well considering the variable underbalance and the more complex outer boundary conditions of a horizontal well.
A paper by Kneissl  presented a method of simultaneously deriving reservoir pore pressure and permeability profiles in real time during underbalanced drilling by introducing fluctuations in the bottom hole pressure during drilling.
In this paper, the reservoir pore pressure and permeability profiles are the main reservoir properties needed to be characterized.
At first we will propose a new methodology to acquire reservoir pore pressure and then discuss how to extract the reservoir permeability profiles during drilling.
Permeability Profiles. To determine the reservoir permeability, we make the simplifying assumption that the permeability is constant in specified zones of the well.
To facilitate the precise calculation and estimate permeability profiles in time, a computer procedure was used in this paper.
The methodology presented in this paper has been used to identify the reservoir pore pressure and permeability profiles of approximately 10 wells during underbalanced drilling in China.
The estimated and actual permeability profiles are indicated in Figure 14 and show a good agreement in magnitude on the whole.