Smith et al (1975) have proposed the creation of man-made geothermal energy reservoirs by drilling into relatively impermeable rock to a depth where the temperature is high enough to be useful; creating a reservoir by hydraulic fracturing; and then completing the circulation loop by drilling a second hole to intersect the hydraulically fractured region.

The initiation of hydraulically created fluid reservoirs in highly impermeable hot dry rock must by definition take place in a wellbore. The nature of these initiation sites will provide the initial resistance to flow into the reservoir and therefore will strongly influence the rate of energy withdrawal. The nature of the interception site in a second wellbore which has been directed to intersect the reservoir will have a similar effect.

The program to create and study such artificial geothermal reservoirs in hot dry rock is being pursued by the Los Alamos Scientific Laboratory and has been presented to these workshops by Murphy (1975) and Murphy et al (1976). In parallel with the drilling of the two boreholes rather complete suites of wellbore geophysical logs were run followed by further diagnostic logging both during and after fracturing operations. This paper discusses some aspects of what has been learned about the entrances and exits of some of the hydraulic fractures created in both the GT-2 and EE-1 wellbores. Table 1 gives the location of the more important fractures and the types of logs used to both identify the location of these fractures and to measure some of their properties.

Press the Back button in your browser, or search again.

Copyright 1977, Stanford Geothermal Program: Readers who download papers from this site should honor the copyright of the original authors and may not copy or distribute the work further without the permission of the original publisher.