Reservoir characterization for the management of stress-sensitivity

Reservoir stress-sensitivity operates at the near-wellbore and the reservoir scale. While the near-wellbore effects have been recognized and managed for some time, awareness of the significance of the reservoir scale effects is only now developing, aided by extreme examples such as Ekofisk, HP/HT reservoirs and unconsolidated sands. Fractured reservoirs must also be considered to be stress-sensitive, with this possibly being masked in the past by high productivities and abundant reserves. It is proposed that the appropriate conceptual model for all reservoirs is that of intact blocks of rocks bounded by discontinuities (fractures and bedding-parallel), loaded by an anisotropic stress state. This model should be used to drive the collection of stress-sensitive reservoir characterization data, knowing that the new generation of coupled simulators can usefully accommodate this data set. The data set listed enables all aspects of reservoir stress-sensitivity to be examined.