Abstract: A system for near-surface geophysical subsurface imaging for detecting and characterizing subsurface heterogeneities comprises an instrument that outputs probing electromagnetic signals through a ground surface that interact and are affected by scattered signals of acoustic waves that travel through the ground surface and further senses vibrational modes of a subsurface below the ground surface; an imaging device that dynamically generates a time sequence of images of properties of the acoustic waves and maps elastic wave fields of the acoustic waves; and a processor that analyzes dynamic multi-wave data of the images to quantify spatial variations in the mechanical and viscoelastic properties of the subsurface.

Abstract: A method is provided for the reduction of inflow of rock particles from an earth formation into a wellbore for the production of hydrocarbon fluid. The method comprises creating a zone of reduced compressive stiffness around the wellbore by removing rock material from the wall of the wellbore.