Summary
OLGA has been proven to be a reliable and inexpensive source of information on the composition and spatial distribution of gases at depth - in real time. It is suitable to detect fluid-bearing horizons, shear zones, open fractures, sections of enhanced permeability and methane hydrate occurrences in the subsurface of fault zones [3, 4, 6, 7], volcanoes and geothermal areas [5], permafrost regions [2], and others. Off-site isotope studies on mud gas samples help reveal the origin, evolution, and migration mechanisms of deep-seated fluids [4]. It also has important application to aiding decisions if and at what depth rock or fluid samples should be taken or formation testing should be performed.
References
- Erzinger, J., Wiersberg, T. and Zimmer M. (2006) Real-time mud gas logging and sampling during drilling, Geofluids 6, 225-233
- Wiersberg, T., Erzinger, J., Zimmer, M., Schicks, J., and Dahms, E. (2004) Real-time gas analysis at the Mallik 2002 Gas Hydrate Production Research Well; in Scientific Results from Mallik 2002 Gas Hydrate Production Research Well Program, Mackenzie Delta, Northwest Territories, Canada, (ed.) S.R. Dallimore and T.S. Collett; Geological Survey of Canada, Bulletin 585 pp. 15
- Erzinger J., Wiersberg T. and Dahms E. (2004) Real-time mud gas logging during drilling of the SAFOD Pilot Hole in Parkfield, CA, Geophys. Res. Lett. 31, L15S18, doi:10.1029/2003GL019395
- Wiersberg T. and Erzinger J. (2007) A helium isotope cross-section study through the San Andreas Fault at seismogenic depths, G-cubed 8, No. 1, doi: 10.1029/2006GC001388
- Tretner, A., Zimmer, M., Erzinger, J., Nakada, S., Saito, M. (2008) Real-time drill mud gas logging at the USDP-4 drilling, Unzen volcano, Japan. Journal of Volcanology and Geothermal Research, 175(1-2):28-34
- Wiersberg T. and Erzinger J. (2008) On the origin and spatial distribution of gas at seismogenic depths of the San Andreas Fault from drill-mud gas analysis, Applied Geochemistry 23, 1675-1690, doi:10.1016/j.apgeochem.2008.01.012
- Wiersberg, T. and Erzinger, J. (2011) Chemical and isotope compositions of drilling mud gas from the San Andreas Fault Observatory at Depth (SAFOD) borehole: Implications on gas migration and the permeability structure of the San Anreas Fault,. Chemical Geology, 284, 1-2, 148-159, doi: 10.1016/j.chemgeo.2011.02.016