US Patent 10107927 Quick 4D detection seismic survey

A method for monitoring a subsurface during a 4-dimensional (4D) survey. The method includes obtaining an area of the subsurface that needs to be monitored; identifying receiver and source locations for the area and source frequencies to be emitted into the area based on demigration or inverse ray tracing; performing a light base survey for the area; performing a light monitor survey for the area; and generating an image of the area based on a comparison of (i) the light base survey, and (ii) the light monitor survey for the area.