ABSTRACT A major UK JIP has recently been completed, its purpose being to identify appropriate limits within which subsea drilling operations can be performed. One of the main deliverables from the JIP has been acceptable Operating Envelopes for ‘routine’ case subsea drilling operations. This paper presents a definition of what constitutes a ‘routine’ case drilling system; typical operating envelopes are also presented. Application of this information wil I greatly reduce the requirement for case-specific analysis of subsea drilling operations; indeed, the intention is that for ‘routine’ case operations, the need for analysis will be completely eliminated. The data contained in this paper forms the basis of a forthcoming UK Institute of Petroleum Guideline publication.