Rio Vista Gas Leak Study: Belleaire Gas Field, California. Topical Report, April1989-January 1991

摘要

The Rio Vista gas leak study evaluated methods for remotely sensing gas leaksfrom buried pipelines and developed methods to elucidate methane transport and microbial oxidation in soils. Remote-sensing methods were evaluated by staging gas leaks along an abandoned Pacific Gas and Electric (PG&E) gas field collection line in northern California and applying surface-based and airborne remote-sensing techniques in the field, including thermal imaging, laser imaging, and multispectral imagery. The remote-sensing techniques exhibited limitations in range and in their ability to correlate with ground truth data. To elucidate methane transport and microbial oxidation in soils, a study of a controlled leak permitted field testing of methods so that such processes could be monitored and evaluated. Monitoring and evaluation techniques included (1) field measurement of soil-gas concentrations, temperatures, and pressures; (2) laboratory measurement of soil physical/chemical properties and activity of methane-oxidizing microorganisms by means of field samples; and (3) development of a preliminary numerical analysis technique for combined soil-gas transport/methane oxidation. Soil-gas concentrations at various depths responded rapidly to the high rate of gas leakage. The number of methane-oxidizing microorganisms in site soils rapidly increased when the gas leak was initiated and decreased after the leak was terminated. The preliminary field, laboratory, and numerical analysis techniques tested for the study of a controlled gas leak could be successfully applied to future studies of gas leaks.