Ultralow to low-frequency oscillatory phenomena of elastomechanical nature have been observed in a number of geothermal areas. These include pressure and water level oscillations in the tidal frequency range 10{sup -6} to 10{sup -4} Hz (White, 1968), flow oscillations at around 10{sup -3} Hz (Bodvarsson and Bjornsson, 1976) and ground noise in the range 10{sup -1} to 10 Hz (Douze and Sorrel, 1972). The presence of such oscillations conveys certain information on the underlying geothermal systems which is of both theoretical and practical interest. In the following, we will very briefly discuss a few aspects relating to the interpretation of oscillatory field data with the main emphasis on borehole tides. 3 figs., 4 refs.

Japan is scarce in domestic natural resources. In fact, the degree of dependence on imports of basic raw materials is quite high. This paper describes primary energy supply as a background to the status of geothermal energy developments, and geophysical well logging in geothermal wells. 3 refs., 5 tabs., 5 figs.

A multiphase consolidation theory is presented which considers a three-dimensional deformation field coupled with a three-dimensional hydrologic flow field. The governing system of equations describes the components of displacement, the fluid pressures and the saturations. The system of equations governing saturated-unsaturated consolidation is obtained as a subset of the above equations. A mixed stress-displacement formulation of the governing equations is introduced, and it facilitates handling of load type boundary conditions while solutions in terms of displacements are still possible. Finite element Galerkin theory is used for spatial approximations, and a weighted implicit finite difference time-stepping scheme is employed to approximate the time derivative terms. Due to the nonlinear nature of the problem, an iterative solution scheme is necessary within each time step. The model predicts the commonly ignored horizontal displacements in a variably saturated system undergoing simultaneous desaturation and deformation, while using a completely interconnected coupling of the stress and pressure fields within the medium. The model is applied to obtain vertical and horizontal displacements, pressure (head) and saturation values due to pumpage in a phreatic aquifer. 1 tab., 10 figs., 13 refs.

A well interference testing program of the Salton Sea Geothermal reservoir is being conducted as part of a resource evaluation study by the Earth Sciences Geothermal Industrial Support Program of the Lawrence Livermore Laboratory. Studies to date indicate the reservoir rock to be composed of layered sequences of shales and sands. Wells involved in the testing program are being used in support of, or are in the vicinity of, the MAGMA-SDG&E Geothermal Loop Experimental Facility (GLEF), located in the Salton Sea Geothermal Field (SSGF). Between these wells, a shale layer has been correlated which appears to divide the reservoir into an upper and lower portion. Other thick sand and shale sequences may provide additional stratification. This report describes work in progress on a well testing program designed to determine the horizontal and vertical transmissivity and storage parameters between wells in the vicinity of the GLEF. These tests are being conducted with the cooperation and support of Magma Power Company and San Diego Gas and Electric Company. 3 figs., 4 refs.