Print this pageComparison of the Microbial Oil Survey Technique (MOST) with Seismic Surveys and Drilling Results in the Chaco Basin, Bolivia
TUCKER, JAMES, D. CARLOS VARGAS, and DANIEL C. HlTZMAN
Tesoro Bolivia conducted a large seismic and surface geochemical evaluation of their Chaco Basin Tarija block in southern Bolivia during 1992. Additional geochemical surveys were conducted during 1995. The Microbial Oil Survey Technique (MOST) was used to rank the hydrocarbon microseepage potential of various structures identified by the seismic evaluations of the block. In microbial surveys, shallow soil samples are screened for a specific suite of microorganisms which indicate the presence of light hydrocarbons, particularly butane. The microbial results provided the additional layer of information related directly to the presence or absence of hydrocarbons. Those seismic structures with associated large, continuous hydrocarbon indicating microbial populations have the greatest potential for accumulations of hydrocarbon. Using the integrated seismic and microbial data sets, Tesoro was able to more thoroughly evaluate and rank the potential drilling targets within the area. From this integrated data sets, not only were several drilling targets proposed, but also drilled with successful results. Comparison of the microbial, geophysical and drilling results will be presented.