ÇAĞRILI KONUŞMALAR / KEYNOTES Invited Speeches ... - TPJD

The Effects of Porosity on the Angle Dependent Reflectivity
Volkan Uğur Karagöl, Hülya Kurt
İstanbul Technical University, Department of Geophysic Engineering, İstanbul
Forward modeling of the Amplitude Versus Offset or Angle (AVO/AVA) response can provide
useful information for petroleum or natural gas exploration. In this study, the seismic reflection
amplitudes with variation of incidence angle over a horizontal interface have been calculated
by Zoeppritz Equations. Angle dependent reflectivity of shale layer, which can be considered
a trap for petroleum and natural gas environment over a limestone or sandstone have been
studied with various porosity ratios for natural gas, petroleum and brine saturated reservoir
rocks. Reflection amplitude values of reflected P waves (Rpp) for high porous reservoir rocks are
around -0.2, -0.3 and -0.4 for brine, petroleum and natural gas saturated respectively. Saturation
of natural gas or petroleum in an environment with high porosity is more sensitive to incidence
angle than brine saturated case. This anomaly in reflection amplitudes is more significant in
reflected S waves (Rps). Accordingly, reflection amplitudes for a salt trap over high porosity
limestone or sandstone reservoir rock reaches up to 0.3.
Keywords: Zoeppritz Equations, AVA, Porosity, Forward Model, 3D model
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