Print this pageGregor P. Eberli1, Jose Luis Massaferro2, Carlos Fonseca1, Jürgen Grötsch3, Asab Asset Team4
(1) Shell International Exploration and Production, Rijswijk, Netherlands
(2) Shell RTS, Rijswijk, Netherlands
(3) Shell Abu Dhabi, Abu Dhabi
(4) SIEP Carbonate Development Team, N/A
ABSTRACT: Calibration of High-Resolution Sequence Stratigraphy with FMI Data - An Example from the Thamama Group, Asab Field, Abu Dhabi
High-resolution sequence stratigraphy was applied to five cores within the Thamama B and C intervals (Barremian) in the Asab field to define flow units and to assess reservoir heterogeneities. A hierarchy of cyclicityi is recognised on cores and calibrated with wireline logs and particularly with FMI logs. This calibration allows for a better definition of the reservoir architecture and its facies and diagenetic partitioning, responsible for the primary reservoir heterogeneity. The reservoir intervals of the Thamama B and C consist of fining- and coarsening-upward cycles that are formed by high-frequency changes of sea level and energy. The lower portions of the reservoirs (transgressive units) are generally finer grained while the upper portions (regressive units) are coarse, highly porous and permeable. The transgressive part of the sequences form the reservoir-separating dense zones. Thinner dense layers within Thamama B and C are preferentially situated in the turnaround from transgressive to regressive portions of the larger units. High-K zones occur in leached zones of the regressive parts and in dolomitized parts of transgressive cycles. The thin and often discontinuous dense units and thin, high-K contribute most to the reservoir heterogeneity. The different order of cyclicities are also recorded by wireline logs and particularly FMI. Conductive intervals correspond to regressive sequences that are often massive, with higher porosity and low gamma ray values. Resistive intervals are tighter, well bedded, with stylolites and high gamma ray values. Other identified features include hardgrounds, bioturabation, and erosive contacts. Quantification of textural variations from calibrated images can be related to porosity/permeability trends within the reservoir.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado