Yesterday, the paper SPE-214962-MS “Analysis Of The Sources Of Uncertainty In Geopressure Estimation While Drilling” has been presented at the SPE Annual Technical Conference in San Antonio, TX, USA. It was the next last presentation in the last session of the conference. There was nevertheless, all things considered, a relatively good attendance: about 50 persons. There were 3 questions after the presentation:
Q: Can the shown simulations handle cuttings bed?
A: the shown simulations were just illustrations of the importance of several factors that influence uncertainty. I don’t want to go in the details of the simulations themselves.
Q: How this process differ from a standard one?
A: Usually, uncertainty is not handled at all except for wellbore position. Even if it is handled for one discipline, it is never passed to the other disciplines involved in the workflow. We wanted to highlight that there is no shame in talking about uncertainty and that this is actually an important aspect of cross-disciplinary work.
Q: It was time that uncertainty was addressed by our industry beside the domain of wellbore position. What would you say is the most dominant effect on geo-pressure uncertainty?
A: that depends very much on the context of the case. Drilling ERD wells on Sakhalin is probably dominated by the wellbore position uncertainty as this will influence where you will cross different formation layers. On the contrary, if you drill a deep vertical well, wellbore position uncertainty has probably a much lower impact than other causes of uncertainty, such as the uncertainty on the PVT of the mud. The purpose of the paper was to list several sources of uncertainties, even though the list is probably not complete, and to define a framework on how to propagate them.