A conventional simulator cannot explain some phenomena that occur during production such as subsidence, compaction, casing damage, wellbore stability, sand production. Most conventional reservoir simulators do not incorporate stress changes and rock deformations with changes in reservoir pressure and temperature during the course production.
A novel relationship of porosity as a function of pressure, temperature and mean total stress is developed for iterative coupling of stress and flow.
- Terzaghi (1936) : The fundamentals of geomechanics are based on the concept of effective stress formulated by Terzaghi
- Biot (1941) : Based on the concept of Terzaghi’s effective stress, Biot investigated the coupling between stress and pore pressure in a porous medium and developed a generalized three-dimensional theory of consolidation.
- Skempton (1954) : Skempton derived a relationship between the total stress and fluid pore pressure under undrained initial loading through the so-called Skempton pore pressure parameters A and B. Geerstma(1957) : Geerstma gave a better insight of the relationship among pressure, stress and volume.
- Van der Knaap (1959) : Van der Knaap extended Geertsma’s work to nonlinear elastic geomaterials.
- Nur and Byerlee (1971) proved that the effective stress law proposed by Biot is more general and physically sensible than that proposed by Terzaghi.
- Rice and Clearly (1976) solved poroelastic problems by assuming pore pressure and stress as primary variables instead of displacements as employed by Biot.
- Bulk volumes of reservoir blocks are constan throughout the simulation
- Reservoir pore volumes must be equal to the true pore volumes as computed by the geomechanics module
Strong and Weakness
(+) The new formula not only improves the accuracy of the coupling, but also reduces substantially the number of coupling iterations.