AVO analysis of Post-Stack Seismic data of Cretaceous Lumshiwal Formation in Kabirwala Block, Central Indus Basin Pakistan
Keywords:
Amplitude-versus-offset (AVO), Lumshiwal Formation; Shear wave log (S-wave log), Fluid Replacement Model (FRM), Gradient˗Intercept cross˗plot, 4th quadrantAbstract
The current study intends to use the amplitude versus offset (AVO) analysis technique for future hydrocarbon exploration by using post-stack seismic and well data (Panjpir 01) of Kabirwala Block, Pakistan. This analysis encompasses the estimation of AVO intercept and gradient from the amplitude of first arrivals (P-wave) to the sine squared of the angle of incidence in Lumshiwal Formation. Fluid replacement model is also used to calculate the shear component by replacement of fluids (oil, gas, and water) by using Gassmann equations. The offset synthetic seismogram is constructed by using P-wave sonic, density and S- wave logs response for the analysis of intercept and gradient of reflections in both gas and water cases. Interpretation of Gradient˗Intercept analysis revealed that Lumshiwal Formation's sands lying in 4th quadrant of gradient-intercept cross-pots which depicts there is a gas anomaly, such sands also having 20% effective porosity.
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