oa To drill or not to drill? Piltun field update - appraisal during development

In the modern world it is very common to use geological (static) models for planning new wells. Often a range of geological static model realizations are created that represent the range of possible subsurface outcomes. A single reference case is usually selected that captures our best technical understanding of the field, based on drilling and seismic data and an underlying geological concept.

Undrilled sectors of the field inherently have higher uncertainty about subsurface outcomes, due to the limited resolution of seismic data and lateral variability away from well control.

Our subsurface models need to reflect that uncertainty and thus we rely not only on a reference case model, but reflect upon low and high case alternatives during well planning.

This paper will share our experience of planning and drilling two pilot holes supporting a planned horizontal extended reach producer well into an undrilled sector of the Piltun field. A number of conceptual geological models were developed to assess the range of possible subsurface outcomes, from conservative to optimistic. The pilot holes were designed to reduce the uncertainty range for the planned producer well. The pilot holes results confirmed one of the scenarios predicted from the conceptual model.