Capacitive electromagnetic formation surveillance using passive source

A hydrocarbon-bearing formation monitoring system comprising:

• an electromagnetic sensor positioned adjacent to a borehole formed in a hydrocarbon-bearing formation, the electromagnetic sensor configured to measure passive, naturally-occurring, electromagnetic signals generated by interaction of solar wind with earth's magnetosphere adjacent the borehole, wherein the electromagnetic sensor comprises:
• a first capacitive electric-field sensor comprising:
• a first plurality of plates configured to detect fluctuating passive, naturally-occurring electric signals adjacent the borehole, and
• first electrical circuitry connected to the first plurality of plates, wherein the fluctuating passive, naturally-occurring electric signals induce a first displacement current in the first electrical circuitry;
• a borehole sensor positioned within the borehole, the borehole sensor configured to measure, over a period of time, electromagnetic signals generated within the borehole, wherein the electromagnetic signals change over the period of time due to variations in fluid distributions within the hydrocarbon-bearing formation;
• and
• a computer system comprising:
• one or more processors;
• and
• a computer-readable medium storing instructions executable by the one or more processors to perform operations comprising:
• determining electromagnetic changes to the electromagnetic signals generated within the borehole and to the passive, naturally-occurring electromagnetic signals over the period of time;
• and
• generating a computational model of the hydrocarbon-bearing formation based in part on the electromagnetic changes.

A hydrocarbon-bearing formation monitoring system comprising:

• an electromagnetic sensor positioned adjacent to a borehole formed in a hydrocarbon-bearing formation, the electromagnetic sensor configured to measure passive, naturally-occurring, electromagnetic signals generated by interaction of solar wind with earth's magnetosphere adjacent the borehole, the electromagnetic sensor comprising:
• a first capacitive electric-field sensor comprising:
• a first plurality of plates configured to detect fluctuating passive, naturally-occurring electric signals adjacent the borehole, and
• first electrical circuitry connected to the first plurality of plates, wherein the fluctuating passive, naturally-occurring electric signals induce a first displacement current in the first electrical circuitry;
• a borehole sensor positioned within the borehole, the borehole sensor configured to measure, over a period of time, electromagnetic signals generated within the borehole, wherein the electromagnetic signals change over the period of time due to variations in fluid distributions within the hydrocarbon-bearing formation, the borehole sensor comprising:
• a second capacitive electric-field sensor comprising:
• a second plurality of plates configured to receive fluctuating electric signals from within the borehole, and
• second electrical circuitry connected to the second plurality of plates, wherein the fluctuating electric signals induce a second displacement current in the second electrical circuitry;
• and
• a computer system comprising:
• one or more processors;
• and
• a computer-readable medium storing instructions executable by the one or more processors to perform operations comprising:
• determining electromagnetic changes to the electromagnetic signals generated within the borehole and to the passive, naturally-occurring electromagnetic signals over the period of time;
• and
• generating a computational model of the hydrocarbon-bearing formation based in part on the electromagnetic changes.