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Characterization of Flow Units in Shaly Sand Reservoirs: A Case Study—Hassi R’Mel Field, South of Algeria, North of Africa


Aggoun, Chawki Redha, Yassine Amokrane, Salime Kaouche, Sonatrach, Hassi R’Mel, Laghouat, Algeria


The concept of hydraulic flow units (HFU) as viewed by Tiab and Amaefule et al was first initiated in the industry for the aim of permeability prediction in uncored intervals. This con­cept is strongly related to the flow zone indicator (FZI), which is assumed to be the unique parameter that can distinguish between HFU. However, so far almost all work using this con­cept use RQI Versus PHIz plots to identify flow units regardless of depth which leads in some instances to locate the same flow units in non adjacent horizons . Hence some ques­tions can be aressed, such as: (1) how can we determine the location of the Flow Units? (2) Is the Flow Zone Indicator (FZI) sufficient to characterize them? (3)Is it possible to deter­mine Flow Unit pattern? If yes, then how? And (4) what kind of information can bring such a characterization?

This work is devoted to answer these questions and to characterize Flow Units in shaly sand reservoirs using the stochastic approach in a section of the Oil Rim of Hassi R’Mel field (South of Algeria, North of Africa).

In this study, we have first characterized shale by the determination of its amount, type and form of deposition. A new correlation was proposed to determine horizontal permeabil­ity in uncored intervals. Using available data, very acceptable correlations to estimate verti­cal permeabilities were found. Combining geological units with FZI Layering, it was possible to identify and locate flow units depth wise, giving birth to a new practical FU definition. Using the estimated vertical permeabilities a new Flow Zone indicator notion (FZIv) was introduced. Geostatistical techniques of Sequential Gaussian Simulation was used to obtain 3 equiprobable realizations of the reservoir attributes such as porosity, horizontal and verti­cal permeabilities, shale volume, FZI and FZIv.