AVO 1D

AVO 1D Sandbox V1.0

Tiny synthetic gather, AVO curve, and live inversion. Change fluid, geology, noise, angle coverage and fluid factor mix, and see how intercept A, gradient B, Ip and fluid factor respond.

Model controls

Geologic scenario Reference shale over sand Shallow soft sand under shale Deeper consolidated sand under shale Carbonate reservoir under shale Reservoir fluid Gas sand (soft, strong AVO) Oil sand (moderate AVO) Brine sand (weak AVO) Tight high impedance sand AVO mode Shuey A B (intercept gradient) Aki Richards (three term fit) Fatti style inversion (Ip and fluid factor) Reflector depth (km)

Depth: 2.0 km. Used to limit maximum angle coverage.

Noise level

Relative noise: 10 percent of maximum reflectivity.

Maximum offset (km)

Max half offset: 3.0 km. Depth and offset together set max angle.

Fluid factor mix k (Fatti)

Fluid factor k: 1.5. Fatti uses FF = ΔIp − k ΔIs.

Overburden: Vp = 2800 m/s, Vs = 1500 m/s, rho = 2.30 g/cc. Reservoir (gas sand): Vp = 2200 m/s, Vs = 1200 m/s, rho = 2.00 g/cc.

Synthetic CMP gather

AVO curve

Crossplot

Intercept A: 0.0000

Gradient B: 0.0000

Extra: 0.0000

Move the controls to see how gather, AVO curve, and inversion respond.

Physics is simplified. Reflection coefficients use a two term Shuey style approximation and a simple Fatti type linear inversion for Ip and Is. The goal is to make trends visible, not to represent a full processing flow.