Book Description

Activity in all areas of geosciences, well testing, numerical modelling, and analysis are reported. Brief reports are presented for the following geoscience tasks: seismic studies, geochemistry, hydrology, and physical properties of rocks. Also included is a report on numerical modelling, which outlines the current status of the study on free convection in a multi-layer geothermal reservoir with application to the Kapoho Geothermal Field. Six cases are under review to determine the effects of different Rayleigh numbers and length to height ratios on reservoir characteristics. The well testing program and to the preliminary analysis and interpretation of data are emphasized. A 1000-hour (42-day) flow test was completed. Initially it had been the intent to conduct a 90-day flow test, but the nuisance effect of both the noise and the hydrogen sulfide emissions - in conjunction with the fact that the pressure-time curves seemed well-stabilized after five time cycles on a semi-log plot - led to the decision to terminate the test after six weeks. The well testing data for HGP-A, continues to look quite favorable, whether considered from the quality of the fluid or the probable reliability and longevity of the well. Each flashing cycle results in slight improvement in flow rate, indicating either that the skin damage effect is diminishing or that additional microfracturing may be taking place. In reservoir engineering, a first cut is taken on establishing resasonable models both for HGP-A and for the Kapoho Geothermal Reservoir. These include three pre-drilling speculative models of the drill site, as well as broader modelling of the reservoir associated with HGP-A. Estimates are also presented on the possible magnitude and lifetime of reservoirs in the Puna Rift zone.