Deep and difficult is an often-used euphemism for those petroleum objectives that are continuing to grow into an increasingly large fraction of companies’ exploration portfolios, now the easy conventionals are in their twilight years.

Based on six years of experience of such plays and prospects in the likes of Libya, Nigeria, Brazil, the Gulf of Mexico and more, the challenges may be categorised in several dimensions: capabilities for definition; operational well execution; and, the success engineering stretch (which refers to the requirement to envisage development engineering in that uncomfortable zone beyond what is currently deliverable with today’s technology).

The ability to define the deep and difficult is addressed in two ways, with the aid of example projects from Shell’s portfolio. The sub-salt seismic imaging revolution in the Gulf of Mexico of the past three years has introduced some interesting paradigm challenges regarding velocity manipulation and image integrity (consciously choosing prospects and well locations that are not on the best image). Staff competencies and the organisational behaviours required to accept such paradigm challenges are also discussed.

Operational well execution is discussed with respect to examples of well design challenges in some high cost markets and hostile borehole operating environments. It is demonstrated that ensuring objective depths are reached and gathering sufficient data in borehole evaluation programmes are frequently more difficult than planned.

It is concluded that to make the deep and difficult genuinely viable parts of your portfolio, mixing the cocktail of aspiration and stretch with equal parts of technology delivery and flawless execution needs to be in the hands of skilled bartenders.