Abstract: A system for subsurface measurements in a wellbore, with a first tool including a first plurality of pads to be positioned against a surface of the wellbore, each of the pads having a first plurality of electrodes disposed thereon to emit and receive electric alternating current between the electrodes and a second plurality of electrodes disposed thereon between the first plurality of electrodes to measure an electromagnetic parameter. Also including a second tool including a second plurality of pads to be positioned against a surface of the wellbore, each of the pads having a first plurality of electrodes disposed thereon to emit and receive electric alternating current between the electrodes and a second plurality of electrodes disposed thereon between the first plurality of electrodes to measure an electromagnetic parameter.

Abstract: An apparatus for generating a seismic signal in a wellbore includes an elongated housing configured to be disposed in the wellbore; a piston slidably disposed in an internal bore in the elongated housing; a strike plate fixed on the elongated housing proximate one end of the internal bore; and an energizing mechanism configured to move the piston to hit the strike plate. A downhole system for seismic survey of a formation penetrated by a wellbore includes at least one seismic receiver; a seismic source; and at least one inflatable packer configured to separate the seismic source and the at least one seismic receiver in different compartments in the wellbore when inflated.