| Abstract | Lithological zoning is the first and one of the most important steps in log analysis of
clastic reservoirs. Traditionally, it is done using GR and SP log. In this study,
application of an approach using dipole sonic data was applied to calculate Vp/Vs
curve and use this new type of curve for lithological zonging in the block 15-1,
Cuulong basin of Vietnam.
Well log data were collected from six boreholes, denoted from BH-1X to BH-6X,
where the dipole sonic data are available.
First of all the correlation between GR and others curves of Vp, Vs, Vp/Vs, and
Poisson ratio (μ) was investigated. The results found a relatively good correlation
for BH-1X, BH-2X and Bh-6X. Then, the BH-1X was selected for zoning. The
lithological zoning applied for D & E sequence at well BH-1X using Vp/Vs curve vs
using GR curve. The results showed a good matching between lithological zoning
by these methods.
The D sequence (middle Oligocene) in this borehole is located from 2,100 to 3,850
mTVDss. The E sequnece (lower Oligocene) is located from 3,850 to 4,400
mTVDss. 16 zones of shalem shally sand and sand were found in sequence D, and
2thick zone of shale and sand, respectively were found in sequence E by both
methods using GR and Vp/Vs. |