Field Development Decisions in deepwater contexts are often taken with unavoidable subsurface uncertainties. The main target of the present work is the proposal of a methodology aimed at defining the best development strategy, accounting for these key reservoir uncertainties with illustration on a specific case.
The prospect under investigation is named Pollux, an undrilled potential deepwater reservoir, whose unique source of information is 3D seismic. A strong analogy with Castor, a close oil reservoir in production since 2008, is supposed, based on similar seismic character and same depositional environment. This analogy allows (1) transferring to Pollux some of the characteristics of Castor, (2) identifying the possible main uncertainties, (3) building Pollux reservoir models accordingly.
A methodology based on seismic amplitude and hydrocarbon pore volume maps according to modeled reservoir uncertainties suggests the most promising locations for potential wells on Pollux prospect. For the screening of the optimal number of wells, the use of creaming curves, which represent oil production cumulative (at a specific forecast date) as a function of wells number, is crucial. Nevertheless, their application in a deterministic way could lead to sub-optimal development decisions. The robust development strategy screening methodology defined in this work has the advantage of incorporating all the reservoir uncertainties by implementing an uncertainty quantification on all potential development strategies.
The selection of the best development scenario, accounting for all identified reservoir uncertainties is a particularly critical issue for any study. In the present work, this activity is carried out by implementing a risk analysis approach on multiple development strategies.
The applied workflow kicks off with an uncertainty analysis, a geo-models screening and a macro-history match of the producing reservoir, in order to identify and incorporate in the risk analysis all the key uncertainties of the undrilled prospect.
The following optimization of the future wells locations and the robust screening of the development strategy are the key phases of the proposed methodology.