Turbidite Facies
Analysis Through Integration of Electrical Images with Openhole Logs, Mudlogs
and Map Data,
Xu, Chunming1,
Thomas Cronin2, Brad Steer2, Thal Mcginness2,
Thomas Pickens1 (1) Schlumberger,
Houston, TX (2) BP,
Integration of electrical borehole
images with openhole logs,
mudlogs, and map data has been carried out over the Red Oak and Fanshawe
Formation intervals (Middle Atoka) in the study area. This analysis records a
clastic intra-slope transition from a well-amalgamated channel facies (Red Oak)
upwards through an overlying canyon cut-and-fill facies (Fanshawe). Ten wells
with image and/or dip data were analyzed and integrated into the study. The
resultant re-interpretation of the area has led to an updated geologic model
and a better understanding of current and potential reservoir intervals.
The Red Oak Sands are dominated by well-amalgamated channel
facies. The relative lack of lobe and levee facies is probably due to sandy
channel amalgamation in a restricted fairway. Borehole
images reveal
well-defined internal inclined-bedding bounded by erosional amalgamation
surfaces in the sand units. In contrast to the current cross beds in fluvial
channels, the azimuth statistics of these inclined-bedding in turbidite
channels are widely scattered.
Fanshawe sands are
dominated by finer grained and less amalgamated sheet turbidites. The thick
section of thin parallel-laminated sandy silts seen in borehole
images are
either a levee-lobe component of a large single channel system, or sheet
turbidites of continuous hyperpycnal flows. The best reservoir sands in the
Fanshawe are associated with debris flows on the top of the sequence. The
methodology developed in this project to extract and interpret turbidite
elemental information from different wireline logs may provide valuable
insights for more expensive deepwater exploration projects.