Chinguetti Deep-Water Oil Field, Mauritania: Field Development in a Mid-Slope Turbidite Setting

Smith, G.C., S. Goodworth, A. Johnson, S. Polomka, M. Rice, L. White, Woodside Energy Ltd, Perth, Australia

The Chinguetti Field was discovered in 2001 offshore Mauritania in 800m of water. It comprises deep water, mid-slope, unconsolidated turbidites, trapped in a dome over a salt diapir. The gross hydrocarbon column is around 700m thick, mainly comprising oil. The field is compartmentalised by the main radial faults and has small gas caps. The reservoir comprises several Miocene high resolution sequences some of which include major chan­nel systems. Hence, although the total field net:gross is low some sequences are domi­nated by sand.

The main subsurface uncertainties identified as part of the field development studies were: channel amalgamation, fault seal, hydrocarbon contacts, channel distribution, rock­fluid interaction and fluid composition. These and other uncertainties were assessed using a statistical Experimental Design for 27 scenarios to model the probability distribution of reserves. A 3D model for each was run through a dynamic simulator to estimate economic ultimate recovery which is more rigorous than using mid, high and low case models.

The discovery well, 2 appraisal wells and an early development well (with an extended production test) were used with 3D seismic to design the Field Development Plan. The first phase of the FDP includes 6 producers and 5 injectors. Development drilling began late 2004 and should be complete by mid 2005. Intersecting the axis of channel systems at several levels has been the main subsurface challenge since: the axes of the channel systems are not vertically stacked; the seismic resolution is not able to clearly image the individual chan­nels; and the wells are highly deviated from pre-determined manifolds.