Integrated Solutions to Igneous Rock Developed in the Near Surface in Fushan Sag

Igneous rocks developed near the surface in Fushan sag bring great challenges to seismic data acquisition and processing. Due to the shielding effect of igneous rocks, seismic energy is very difficult to propagate downwards and thus makes the seismic data very poor; the velocity and thickness of the near surface changes greatly and statics is complicated. The existence of the igneous rocks results in strong multiples and very small velocity difference between multiple and primary. These problems have been successfully solved with a set of solutions including (1) uphole based accurate near-surface investigation to design the shooting parameters point by point; (2) a long spread, wide azimuth and high fold acquisition technique to enhance the raw data quality; (3) using pre-stack 4D-denoise to improve the signal-to-noise ratio; (4) using a tomographic inversion static correction based on uphole and marked layer, interactive layered and segmented first arrival static correction, global optimization reflection residual and non-surface consistent static correction to solve the static problems; (5) using an adaptive subtraction method with constructing multiple model to remove the multiples. Good results have been achieved by using these methods, suggesting our methods are feasible.