Two field experiments were conducted with the surface electrical potential measurement system. The first was an MHF experiment with G.P.E. (Gas Producing Enterprises) on March 15 south of Vernal, Utah. This fracture was a joint ERDA-industry funded experiment. Approximately 640,000 gallons of fluid and 1.1 million pounds of proppant were injected into multilayered gas pay zones from a depth of 6500 feet to 8000 feet. This analysis of the data has produced several new and different concepts related to fracture design and growth. The second experiment conducted was the CONOCO hydrofracture that was performed as a part of their tertiary oil recovery experiment in the Big Muddy Field east of Casper, Wyoming. It was a small fracture (300 bbl) initiated at a depth of approximately 3500 feet. Eighteen pairs of potential probes were placed at 20/sup 0/ intervals around the fracture well at spacings of 1000 feet and 2000 feet. In addition, the relative potential was measured on six wells adjacent (<1000 feet) to the fracture well. These wells contained the CONOCO pressure gages to monitor formation pressure during the fracture and subsequent recovery operations. Potential measurements were made at twenty second intervals on alternate current probes: one a downhole sinker bar at formation depth and the other the casing of the fracture well. The downhole data analysis indicates an asymmetric fracture in the easterly direction. Electrical modeling effort has continued and has been centered on the design and fabrication of the model facility. This facility should be completed next quarter and allow several configurations of fracture to be studied. Seismic work has been completely shifted to the downhole, wall clamped system. Fabrication has been completed and testing will begin during the next quarter.