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Application of Previous Hit3-DNext Hit Previous HitVersusNext Hit 2-D Velocity Model: Implications of Previous HitDepthNext Hit Conversion Hayat-Yaser-Kenz Fields (Khalda Concession,Western Desert, Egypt)

By

 Ali Mohamed Bakr1, Fred Wehr1, Sheldon Plahn1

(1) Apache Egypt, Cairo, Egypt

 Multiplying a simple 2D velocity grid by a Previous HittimeNext Hit grid to generate a Previous HitdepthNext Hit grid can result in inaccurate predictions of geological tops, faults, fault patterns, and reservoir volume. This paper addresses the problem and demonstrates the value of 3D Previous HitdepthNext Hit conversion in the Khalda area.

Apache has acquired approximately 2500 km2 of 3D seismic data in the Khalda Concession in the Western Desert of Egypt. Hayat, Yasser and Kenz are major oil fields in the Khalda concession, producing from reservoirs in the Bahariya and AEB Formations (Cretaceous). Three main 3D velocity models were constructed over Hayat-Yasser- Kenz and compared to the 2D estimating method. The three 3D velocity models are: (1) stacking/Previous HitmigrationNext Hit velocity (using only seismic stacking velocities), (2) Previous HittimeNext Hit-Previous HitdepthNext Hit velocity (using only Previous HittimeNext Hit-Previous HitdepthNext Hit pairs from wells data), and (3) Previous HitmigrationNext Hit velocity calibrated with T-D pairs (using both stacking velocities and well control).

Calibrated models provide more reliable results, including a more accurate tie to wells as well as a more structurally admissible fault pattern. The entire seismic data set, including traces, horizons (Previous HittimeNext Hit), and faults are converted to the Previous HitdepthNext Hit domain using the proper velocity model. This enables much tighter integration of seismic interpretation and well data.

The reservoir Previous HitdepthNext Hit map out of this volume was used for validity check and it shows ± (10 feet) prediction error. Results confirm more reliable well top prediction and possible additional propectivity using the Previous Hit3-DNext Hit calibrated velocity models Previous HitversusTop the 2-D average velocity methodology.