Utilization of Gravimetric Data for Estimation of Hydrothermal Reservoir Characteristics in the East Mesa Field, Imperial Valley, California

Abstract

This paper presents an attempt at correlating the observed phenomena of small positive gravity anomalies and self-sealing in some geothermal systems with possible geochemical, thermal and flow properties of Such systems. In particular, the East Mesa geothermal area in the Imperial Valley, California shows up to 6 milligal positive residual gravity anomaly. Calculations show that the maximum depth to the center of gravity of the anomalous mass is a few kilometers, which is less than the depth to the basement in the area. We hypothesize that the presence of this gravity anomaly in the midst of a reasonably regular alluvial basin is due to deposition of minerals in pore spaces of sediments by upward rising plumes of geothermal water over geological time.