GAS SAND DETECTION USING ROCK PHYSICS AND PRE-STACK SEISMIC INVERSION, EXAMPLE FROM OFFSHORE NILE DELTA, EGYPT | ||||
| Al-Azhar Bulletin of Science | ||||
| Article 1, Volume 27, Issue 2-D, December 2016, Page 65-72 PDF (737.45 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/absb.2016.42881 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| Hamed Z. El-Mowafy* | ||||
| Department of Geology, Al-Azhar University, Cairo, Egypt | ||||
| Abstract | ||||
| Well logs and three-dimensional (3-D) partial angle stacks and full angle stack seismic volumes are used in this study with the purpose of detecting gas sands using rock physics and pre-stack inversion workflows. Integration of pre-stack inversion and rock physics analysis can improve the characterization of the late Pliocene gas sandstone reservoir, offshore Nile Delta. The inversion was performed using a deterministic wavelet set. Rock physics was used to enhance the VP, VS, and density volumes from the inversion. The present study performed in three phases: AVO analysis, pre-stack inversion, and lambda-mu-rho (LMR) analysis. The results from the different crossplots, such as P-Impedance vs. Vp/Vs, show that the gas sands are clearly separated from brine sands and shale. By maximizing the potential offered from the elastic properties such as λρ, μρ and Vp/Vs ratio we were able to define the limits and cutoffs which sufficiently separate the gas sand bodies. The resulted volumes were used to better define the late Pliocene reservoir and optimize a new well location. The pre-stack inversion and AVO/rock physics studies resulted in a new Gas Initial In Place (GIIP) calculation that was doubled in the P50 case from the original estimation based only on the seismic amplitude data. The chance of success was increased and a new well is proposed to drain the gas in the eastern flank of Channel 1. | ||||
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