Publications

This paper presents an approach to casing design, or, more properly, well bore design, that focuses on well control as its primary objective.The new design approach has been implemented safely in over 25 wells in East Kalimantan operations resulting in a cost saving 3f more than US $ 300,000 per well.All casing shoes are designed to withstand the anticipated pressure to which they will be subjected under well control conditions with a view to shutting in and circulating out all kicks at all depths. This differs from many models that design the well bore to allow drilling to the next casing point without breaking down the exposed casing shoe (assuming no well control problem), and then enhance the design by the inclusion of a kick tolerance, which is often arbitrary with respect to its magnitude.A computer program has been developed to facilitate the implementation of the design method by the drilling engineer. The use of this program for a development and an exploration well is demonstrated in the paper.Unocal feels that another significant benefit from the standpoint of safety and risk management has been the virtual elimination of the diverter in Unocal East Kalimantan operations, particularly in development wells. This has closed the door to the potential for the high-dollar losses experienced in the past, when kicks were diverted rather than being shut in.