The Application of Rock Physics and Pre-Stack
AVO
Analysis
for Gas Identification in Deepwater Sediments, Rakhine Bain, offshore Myanmar
Zuo, Guoping
As geophysical exploration technologies, Rock Physics and Pre-stack
AVO
analysis
are widely used in oil and gas exploration, it enjoys an irreplaceable position since it was first used in
amplitude
detection, such as bright point, flat point, etc.
Rock Physics
analysis
has been carried out in this research based on wells in order to prove the probability of
AVO
method. According to forward modeling and fluid substitution, the curve characteristics corresponding to
amplitude
are defined, and relevant
AVO
attributes are calculated, which serve as the basis for following seismic
AVO
attribute
analysis
. The findings of this research include that when reservoir contains gas, the result of forward modeling indicates that
amplitude
increases with
offset
, it belongs to class 3
AVO
response, in addition, through rock physics
analysis
, P-wave velocity, P-wave impedance, Fluid factor, intercept × gradient (P×G) and Poisson ratio all change fast, on the other side, using fluid substitution, the gas was replaced by brine, then, the result of forward modeling indicates that
amplitude
changes little with
offset
, the rock physics attributes only show tiny changes. So, these sensitive attributes for gas reservoir can be used to detect gas reservoir.
Through
AVO
analysis
, based on Aki & Richards equation and Shuey equation, a set of attributes are obtained from seismic data. According to rock physics
analysis
, the attributes sensitive to hydrocarbon are used to detect gas reservoir.
Combining those attributes with cross plot method,
AVO
method is much more effective to detect gas reservoir. Class 3
AVO
abnormity can be distinguished easily in the cross plot of P and G. In addition, in the cross plot of far angle stack and near angle stack, it is easier to feature gas reservoir which has the characteristic of that
amplitude
of far angle stack is stronger than near angle stack.
In this research, P×G, fluid factor, Poisson ratio and P-wave impedance, near angel stack and far angle stack data are selected to analyze due to their sensitivity to gas layers. Through rock physics and
AVO
analysis
, many objectives have been discovered in the study area. The application of rock physics and
AVO
analysis
has achieved remarkable effect in gas layer identification.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013