--> --> Abstract: Impact of Fine-Scale Turbidite Channel Architecture on Deepwater Reservoir Performance, by Faruk Alpak, Jean-Christophe Noirot, Mark Barton, and Steve Naruk; #90124 (2011)

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Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA

Impact of Fine-Scale Turbidite Channel Architecture on Deepwater Reservoir Performance

Faruk Alpak1; Jean-Christophe Noirot1; Mark Barton1; Steve Naruk1

(1) Shell International E&P Inc., Houston, TX.

Operators have made a large number of significant discoveries in the late Tertiary deepwater provinces of the Gulf of Mexico, Niger delta slope and NW Borneo slope. Early well performance from these discoveries has in many cases met and in some cases surpassed expectations established at the time of project sanction. Good connectivity is reported by some operators in channelized turbidite reservoirs in large West African submarine valley fill reservoirs based on interference testing and early production. In some other cases, industry has encountered severely impaired reservoirs. These shortfalls are attributed in large part to reservoir compartmentalization. Stratigraphic compartmentalization related to sub-seismic channel architecture and the presence of shale drapes has emerged as a major subsurface uncertainty to be addressed in dynamic modeling studies prior to production. Typical pre-production models of channelized turbidite reservoirs often treat the stratigraphic architecture in a simplistic fashion leaving out many of the geological features observed in outcrops and shallow analogs. Comparisons of actual historical production performance with pre-production forecasts show that simplistic models overpredict dynamic performance leading to misinformed investment decisions.

Accurate pre-production forecasts typically require explicit inclusion of major geological features in dynamic models. Alternatively or in combination with the latter approach, one can resort to an effective property approach that incorporates the dynamic effects of fine-scale architecture via pseudo-properties into simulation models. Regardless of the modeling methodology, it is essential that the dynamic effects of various architectural features are well understood and rigorously polarized for various development schemes (e.g. water/gas injection and depletion) such that modeling work will focus on the high-impact parameters.

We carried out a comprehensive simulation study to test and analyze the relative importance of fine-scale stratigraphic features of channelized turbidite architecture to reservoir performance. Over 1700 simulations were performed using high-resolution sector models. The results show that in turbidite channel reservoirs dynamic performance is governed by architectural parameters such as meander belt width, net-to-gross, and degree of amalgamation, and parameters that describe the shale architecture, e.g. shale drape coverage and frequency of occurrence.