Reservoir compaction and subsidence

In unconsolidated or poorly consolidated reservoirs, deformation associated with hydrocarbon production can lead to reservoir compaction, land surface subsidence and potentially fault reactivation. In the United States, surface subsidence has been reported in at least 37 out of 50 states affecting an area of more than 80,000km2 (Johnson, 1998). Surface subsidence can lead to major costs and a loss of social license to operate, while reservoir subsidence may result in casing shear and the loss of production.

Possible compaction magnitude and surface subsidence based on projected field depletion levels can be evaluatedThis can be done using 1D analytical methods or 3D numerical models, depending on the complexity of the geological setting.  The 1D models can be used to understand the critical parameters and evaluate the necessity of building a 3D numerical model, enabling the most suitably cost effective solution to be used.   

The 3D numerical modelling can be combined with Ikon Science's 4D seismic tools to determine the feasibility of 4D seismic for optimal field management of both subsidence and production.

Swarbrick et al TLE 2012 - Review of pore-pressure prediction challenges in high-temperature areas. Image shows pressure versus depth and porosity versus depth profiles illustrate the relationship between vertical effective stress, compaction and porosity change used in predicting pore pressures when the origin of excess pressure is disequilibrium compaction (undrained shale mudrocks).