In this example a reservoir pore pressure depletion stage will be simulated in a 3D column geometry. The reservoir is underlain and overlain by shale lithologies. The reservoir is 1000 depth below the sea floor and water level is 500 m. The model is initialized following a sequence of stages:

 

1.Elastic initialization during which gravity is applied and hydrostatic conditions are imposed on the whole column

2.Nonlinear initialization stage during which stresses go back to zero, the constitutive model is changed from elastic to plastic and the stresses are re-initialised.

3.Displacement reinitialization stage

 

After initialization a depletion stage follows during which a drop of 6 MPa in reservoir pore pressure is imposed. Only mechanical field is solved with the pore pressure values being prescribed. Pore pressure at nodes for both states (initial and after depletion) is provided in separate files as nodal spatial grids. For simplicity material properties are assumed the same for all lithologies.

 

Schematic of problem definition

 

This example aims to be a reference for:

•Prescribing pore pressure values at mesh nodes

•Multi stage initialization

•Usage of restart files