A method of reducing surface-scattered noise includes receiving seismic data associated with a marine region, where the marine region includes an ocean bottom, a first zone including water above the ocean bottom, and a second zone including earth subsurface layers below the ocean bottom, and the received seismic data includes signals reflected from the earth subsurface layers and surface-scattered noise reflected from the ocean bottom and an ocean surface; determining a water velocity for the first zone; determining bathymetric values of the ocean bottom; based on the determined water velocity and the bathymetric values, determining a velocity model for the marine region; based on the determined velocity model and wavelet functions of seismic source signals, calculating the surface-scattered noise by solving a wave equation; and determining the signals reflected from the earth subsurface layers by subtracting the calculated surface-scattered noise from the received seismic data.

A computer implemented method that constrains prestack seismic wavefront attributes is described. The method includes estimating wavefront attributes in intervals sized to include a representative subset of an original seismic dataset and applying a semblance threshold to the wavefront attributes based on an estimated semblance value, wherein wavefront attributes that satisfy the semblance threshold are retained. The method also includes transforming the retained wavefront attributes to reduce a range of possible values and selecting minimum and maximum values of the wavefront attributes based on statistical criteria. The method includes estimating wavefront attributes for the original seismic dataset using the selected minimum and maximum values.

Waves from cement bond logging with a sonic logging-while-drilling tool (LWD-CBL) are often contaminated with tool waves and may yield biased CBL amplitudes. The disclosed LWD-CBL wave processing corrects the first echo amplitudes of LWD-CBL before calculating the BI. The LWD-CBL wave processing calculates a tool wave amplitude and a phase angle difference as the difference of the phases between the tool waves and casing waves. The tool waves are then used to correct the LWD-CBL casing wave amplitude and remove errors introduced from tool waves. In conjunction with the sets of operations described, the LWD-CBL wave processing also includes array preprocessing operations. Array preprocessing may employ variation of bandpass filtering and frequency-wavenumber (F-K) filtering operations to suppress tool waves.