A REVIEW OF ZECHSTEIN DRILLING ISSUES

A number of issues can arise when drilling through Zechstein formation s that have a bearing on the health and safety of personnel, as well a s on the time to complete operations and final well costs. Operational problems present some intrinsic hazard or safety risk. Additionally, the procedures applied to alleviate these problems also present a safe ty risk, as they are usually nonroutine and unfamiliar, thus increasin g the likelihood of errors. In this paper, the operational issues, the ir causative mechanisms, and alleviation procedures are introduced and categorized. Decision analysis is applied to each of the operational issues, for both the well planning stage and for the drillsite, which relates the well responses to the causative mechanism and, therefore, to the selection of the most appropriate alleviation procedure.