Research Institute of Electrical Communication, Tohoku University, Japan We present our prototype of PlanWell, a spatial augmented reality interface that facilitates collaborative field operations. PlanWell allows a central overseer (in a command and control center) and a remote explorer (an outdoor user in the field) to explore and collaborate within a geographical area. PlanWell provides the overseer with a tangible user interface (TUI) based on a 3D printout of surface geography which acts as a physical representation of the region to be explored. Augmented reality is used to dynamically overlay properties of the region as well as the presence of the remote explorer and their actions on to the 3D representation of the terrain. The overseer is able to perform the actions directly on the TUI and then the overseer's actions are presented as dynamic AR visualizations superimposed on the explorer's view in the field. Although our interface could applied to many domains, the PlanWell prototype was developed to facilitate petroleum engineering tasks such as well planning and coordination of drilling operations. Our paper describes the details of the design and implementation of the current PlanWell prototype in the context of petroleum well planning and drilling, and discusses some of the preliminary reflections of two focus group sessions with domain experts.