The discussions, conclusions, and recommendations of the Magma/Hydrothermal Drilling and Instrumentation Workshop, Albuquerque, NM, May 31--June 2, 1978 are summarized. Three working groups were organized as follows: Drilling Location and Environment, Drilling and Completion Technology, and Logging and Instrumentation Technology. The first group discussed potential drilling sites and the environment that could be expected in drilling to magma depth at each site. Sites suggested for early detailed evaluation as candidate drilling sites were The Geysers-Clear Lake, CA, Kilauea, HI, Long Valley-Mono Craters, CA, and Yellowstone, WY. Magma at these sites is expected to range from 3 to 10 km deep with temperatures of 800 to 1100{sup 0}C. Detailed discussions of the characteristics of each site are given. In addition, a list of geophysical measurements desired for the hole is presented. The Drilling and Completion Group discussed limitations on current rotary drilling technology as a function of depth and temperature. The group concluded that present drilling systems can be routinely used to temperatures of 200{sup 0}C and depths to 10 km; drilling to 350{sup 0}C can be accomplished with modifications of present techniques, drilling at temperatures from 350{sup 0}C to 1100{sup 0}C will require the development of new drilling techniques. A summary of the limiting factors in drilling systems is presented, and recommendations for a program directed at correcting these limitations is described. The third group discussed requirements for instrumentation and established priorities for the development of the required instruments. Of highest priority for development were high resolution temperature tools, sampling techniques (core, formation fluids), chemical probes, and communications techniques. A description of instrumentation requirements for the postulated hole is given, and the tasks necessary to develop the required devices are delineated.
