Shared Earth Models – Making them Become Reality

Integration of subsurface information into a fully consistent set of simulation models is still a very desirable but hardly achieved goal. Subsurface simulations serve very different needs such as predicting fluid flow, mechanical simulations of borehole stability and structural reconstruction, and consequently have very different requirements while properties in these models are often related. A Shared Earth Model is here interpreted as a holistic subsurface model that communicates subsurface geometry, properties and property contrast in a suitable fashion to the various simulation models. We will show that only those static models are suited as Shared Earth Models that properly represent stratiform contrast as well as contrast at discontinuities. For optimum representation the mechanism used for discontinuities must work equally well at different scales of model resolution. The requirement of scale-independent sampling of stratiform and fault-parallel property contrasts is fully addressed by faulted orthogonal grids (e.g. the so-called Jewel grid). The strength and flexibility of faulted orthogonal grids has been tested on a wide range of examples covering exploration to well-scales and prove that modelling technology has advanced to a stage where full-subsurface Shared Earth Models become reality.