Reservoir Engineering of Shallow Fault - Charged Hydrothermal Systems

Introduction Many of the low-to-moderate temperature ( < 15OOC) hydrothermal resources being developed in the United States occur in near-surface aquifers. These shallow thermal anomalies, typical of the Basin and Range and Cascades are attributed to hydrothermal circulation. The aquifers are often associated with faults, fractures, and highly complex geological settings; they are often very limited in size and display anomalous temperature reversals with depth. Because of the shallow depth and often very warm temperatures of these resources, they are attractive for development of direct-use hydrothermal energy projects. However, development of the resources is hindered by their complexity, the often limited manifestation of the resource, and lack of established reservoir engineering and assessment methodology.