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