The Congro field (Campos Basin, Brazil) contains considerable reserves located in a extremely heterogeneous, very low-permeability carbonate reservoir. For many years after its discovery, this reservoir was considered non- economic. However, a newly drilled horizontal well showed encouraging results. An advanced, integrated reservoir study showed that the exploitation of the reservoir can be economically attractive if non-conventional wells are used.

In this work, we demonstrate how cutting-edge technology plus interdisciplinary efforts involving geophysics, geology, and reservoir engineering were the key to make a noneconomic asset into an economic one. Two major problems were faced: the short available time (only two months for the whole study) and the lack of data. The lack of data was overcome by using analogy with a similar, well- sampled reservoir. The time constraint was handled by taking an integrated approach where the geophysical, geological, and numerical simulation models were built almost simultaneously.

Stochastic reservoir models were generated using a geostatistical method called truncated Gaussian technique to assess uncertainty on facies distribution. Three different types of wells were considered: vertical fractured, horizontal, and multilateral. As multilateral wells showed better economics, we optimized the number of legs and their length based on numerical simulation.

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