Журнал геологии и геофизики
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Prediction of Water Saturation Applying the Extended Elastic Impedance Inversion, Offshore Nile Delta, Egypt

Adel AA Othman , Mohamed Fathi Mohamed Ali , Ahmed Saied Ali2*, Farouk Ibrahim Metwally

Extended Elastic Impedance (EEI) is very useful seismic reconnaissance attribute. EEI logs can be directly corresponds to the petro physical properties of the reservoir and the seismic. EEI reflectivity volumes can be obtained directly from the pre-stack seismic data. A better discrimination between the seismic anomaly caused by either lithology or fluid content can be utilized applying this approach. The concept of extended elastic impedance is used to derive the petro physical properties and distribute the reservoir facies. The study area was a Pliocene gas field that lies in the deep marine, Offshore Nile Delta, Egypt. The workflow is simple, efficient and uses very few inputs. We started with the fluid/ lithology logs and investigated the optimum projection in the intercept/gradient domain. Then, we used the conditioned angle stacks, to calculate the intercept/gradient volumes, using Shuey’s two terms Approximation. The intercept and gradient volumes are converted directly to the fluid and lithology 3D volumes, without any of the pre-stack inversion’s constrains. The outputs were tested using a blind well and the correlation exceeds 80%. The results show that the EEI is a worthy effort to highlight the difference between the reservoir and non-reservoir sections, to identify the hydrocarbon area.