Apparatus and methods for providing information about one or more subterranean feature

A method of approximating or determining at least one dimension or other characteristic of at least one underground geological feature in an earthen formation, the at least one geological feature being at least partially located within a zone of interest in the earthen formation proximate to a subterranean well bore, the method comprising:

• while the well bore and at least one geological feature at least partially contain conductive fluid,
• generating an electric field in the zone of interest,
• at least one target object in the zone of interest having an electrical impedance that differs from the electrical impedance of the conductive fluid and creating perturbations in the electric field,
• providing at least two sensing electrodes in the well bore,
• the sensing electrodes detecting differences therebetween in electric potential caused by at least one target object and providing data relating thereto to at least one data processing system;
• delivering proppant containing a plurality of signal generating devices into the at least one geological feature;
• at least some of the signal generating devices generating a detectable signal in response to at least one downhole condition or property;
• at least one receiver receiving at least one of the detectable signals and providing data relating thereto to at least one data processing system;
• and
• at least one data processing system approximating or determining at least one dimension or other characteristic of the at least one geological feature based at least partially upon data provided by the sensing electrodes and at least one receiver.

Apparatus for approximating or determining at least two dimensions of at least one hydraulic fracture formed in an earthen formation from a subterranean well bore, the at least one hydraulic fracture being at least partially located within a zone of interest in the earthen formation that is proximate to the well bore, the apparatus comprising:

• a conductive fluid disposed at least temporarily in at least part of the well bore and at least one hydraulic fracture;
• at least two spaced-apart electric field generating electrodes configured to create an electric field in the zone of interest;
• at least one target object disposed within the zone of interest outside the well bore, having a different electrical impedance as compared to said conductive fluid and capable of creating perturbations in the electric field;
• at least two spaced-apart sensing electrodes disposed within the well bore and configured to detect differences therebetween in electric potential measured in volts caused by said at least one target object and provide data relating thereto;
• proppant containing a plurality of signal generating devices and being configured to be delivered into the at least one hydraulic fracture, at least some of said signal generating devices being configured to generate a detectable signal in response to at least one downhole condition or property;
• at least one receiver configured to receive at least one of the detectable signals and providing data relating thereto;
• and
• at least one data processing system configured to approximate or determine at least two dimensions of the at least one hydraulic fracture based at least partially upon data provided by said sensing electrodes and said at least one receiver.