Geothermal Investigations of California Submerged Lands and Spherical Flow in Naturally Fractured Reservoirs

A large portion of California State-owned land is the tidal and submerged land along the coastline and around the islands that extends seaward for three geographical miles. Other large areas of State-owned lands form the beds of lakes and navigable rivers. Some evidence, such as the proximity of hot springs, indicates there may be important geothermal potential on these lands. The purpose of this project is to develop methods, tools, and interpretive techniques to explore for and evaluate geothermal resources on submerged lands. Presently, the state of the art is primitive because there has been little interest or effort in assessing the resource potential of submerged lands, and the limited work carried out thus far has been for scientific purposes. There has been a moderate amount of water temperature measuring for oceanographic or limnologic studies and fairly reliable techniques exist. There have been limited measurements of the temperature, thermal gradient, and heat flow in bottom sediment of the ocean area off California and from the lakes. Probably less than a dozen data points exist for State-owned land. This work was done using large equipment, such as piston corers with outrigger-mounted thermistors arrayed along the core barrels. To achieve penetration, such equipment requires heavy weights, strong cable, heavy duty winches, large crews and oceanographic research-type vessels or large barges, and this entails considerable expenses and logistical problems. Clearly, many hundreds, or thousands of data points are required for a remotely reliable evaluation of the resources. The first problem is to assess existing methods and develop others that will enable economical and efficient exploration for geothermal resources on submerged lands