A completed model in either 2D or 3D is often considered finished and valid if horizon/ fault ties are complete, and when wells and volume information are attached to the model in the correct locations. Most model building software on the market stop at this stage. However, these so-called completed models may not be geologically permissible either in terms of the representation of the present structure, or, commonly, in terms of the geological evolution which is implied by the interpretation.

Midland Valley's unique strength is that we provide a complete suite of tools to check the geological, as well as geometrical, validity of the model based on known and quantifiable geological constraints. At its simplest this can involve unfolding and unfaulting the model (restoration) to check that all of the rock volume implied in the interpretation is correctly represented. In addition, the processes by which it has arrived at its current configuration can be validated for all geological time steps.

In more complex cases the sediment, erosional, compactional and isostatic history can also be accounted for in the validation process.

A model which does not restore and is not balanced cannot be a valid representation of reality. A balanced and restored model is both valid and geologically permissible and always represents a lower risk solution.

Reducing risk produces real commercial benefits

Most drilling surprises and production problems arise from an incomplete or inappropriate understanding of the geology. In most cases this is related to the structure either during reservoir deposition or to subsequent structural development. While improving data quality is always important, the key to understanding and managing geological uncertainty lies in modelling the geological process, identifying alternative interpretational strategies and comparing the outcomes of multiple scenarios. The restoration process is central to this approach and can provide a precise quantification of the uncertainty in modelling.

Midland Valley has assisted clients to reduce risk in exploration drilling through validation of the geological model and increasingly is helping clients improve drilling success in production in a variety of geological environments. This includes crestal drilling and down flank sub-thrust step outs in mature fields where lower than 50% success in drilling has been eliminated through better understanding of the updip geology.

Midland Valley continues to research and develop new fundamental approaches to risk and uncertainty modelling and is working on innovative new techniques for whole model uncertainty characterisation. This approach includes data, interpretation and algorithm uncertainties as model attributes and as well as novel visualisation techniques for communication and management of risk.