Seismic Imaging of Imbricate Structures in Mountainous Area: Case Studies

Summary The hydrocarbon prospects in mountainous areas require solving a most challenging problem in seismic imaging --irregular topography associated with a rugged terrain, complexity of the nearsurface that includes high-velocity layers and outcrops with significant lateral velocity variations, complexity of the overburden, and the complexity of the target imbricate structures themselves. We present case studies that demonstrates a workflow to solve this challenging problem: (1) The nearsurface model is estimated by nonlinear traveltime tomography that accounts for topography, and resolves lateral and vertical velocity variations. (2) Several different strategies are developed for near-surface corrections, which are based on wavefield extrapolation rather than shot-receiver statics. (3) The velocity model for prestack time migration is bulit based on migrated images combined with powerful interactive tools to pick rms velocities that are structurally consistent and the substratum model is estimated by half-space velocity analysis. (4) The subsurface image is obtained by wave equation based prestack depth migration of shot gathers from topography. Theroritical examples and real data cases will be exhibited to demonstrate the methodology.