Low frequency shadows is one of hydrocarbons indicators. It can be
detected by means of a time-frequency decomposition which can provide higher
frequency resolution at lower frequencies and higher time resolution at higher
frequencies. This is des
irable for analyzing seismic data, because the
hydrocarbons in reservoir are diagnostic at lower frequencies. we have carried
out such analyses with post-stack data sets on Fahda field which is located in
Aleppo uplift, it contains oil. Adding a frequency axis to a 2D seismic section
makes the data 3D axis. The comparison of the single frequency sections from
such 3D volume can be utilized to detect low frequency shadows. A
preferentially illuminated single frequency section at lower frequencies from
Fahda field, shows high amplitude low frequency anomalies beneath oil zones.
These anomalies disappear at higher frequencies.
This research focused on re-assessment for Sarhit and shdeha fields in Euphrates
graben.
The two fields is mainly anticline structure which is consist of two horsts Sarhit
and Shdeha fields separated by a graben Sarhit.
Nine wells has been drille
d in Sarhit field, and eleven wells in Shdeha field, all
the wells are producers, except (SHD111).
The research based on new seismic interpretation using GeoFrame program.
Create new velocity models using two different methods (linear regression, V0K
algorithm), using Petrel program.
To confirm the study results, we created geological models for each velocity
model, then calculated the Stuck Tank Oil Initial In Place (STOIIP), and the
recovery factor (RF), for each field.
The first chapter summarized the geology of Euphrates graben, and general
information about the two fields including: the geology of study area and
reservoir properties.
More over the research objectives and the data availability.
The second chapter consist of structural seismic interpretation in terms of
traditional workflow (horizons and faults interpretation), and created seismic
attribute maps.
The third chapter: the waves and seismic velocities overview.
Build velocity models using two different methods: linear regression, v0k
algorithm.
Then for each velocity method, we built geological model, calculated the
STOIIP and RF, for each field.
As a result we have noticed a decrease in the RF for the two fields by using V0K
algorithm, comparing with linear regression method.
Chapter four: results and recommendations
