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URPC Proceedings
Internship in the Exploration and Development Department at YPFB
Chaco S.A., a Bolivian Oil Company.
Alvaro Puente, Andrew Moore † , Meg Streepey †
YPFB Chaco S.A.
apuente07@earlham.edu
The exploration and exploitation of oil reservoirs is a field that, has been, and still is
growing in Bolivia. Taking into account that both geology and geophysics have an important
role in these two processes, I decided to work as an intern for YPFB Chaco S.A.,
an oil company based in Santa Cruz, Bolivia. During the three months, I worked mostly
with the geophysics department on the planning of a 3D seismic profile acquisition project.
Using the observer’s report data of previous 2D seismic projects I developed a statistical
analysis of the regions, within the acquisition territory, in which the drilling of shot points
was to be difficult. I found that 30% of the acquisition site had to be drilled with equipment
more powerful than usually required. I also worked at a drilling camp assisting the
head geologist in the analysis of samples obtained from the BBL 10 well which was still
in the perforation stage. With this information it was possible to make a lithostratigraphic
correlation between this well and two others, which had been previously drilled, and were
completed and under production.
Using Oxygen Fugacity to Learn about the Chemical Evolution of the
Bushveld Complex
Edward W. Marshall, Jill VanTongeren †
AMNH REU 2010
edmarshall4@gmail.com
The chemical evolution of the Bushveld Complex and other layered igneous intrusions
has long remained a mystery. Whether the Bushveld Complex evolves toward iron enrichment
(Fenner trend) or silica (Bowen trend) is still unknown. This study seeks find which
trend was followed in order to uncover the composition of the final residual liquid. Oxygen
fugacity is one of indicators that can point to which evolution trend occurs. By discovering
the oxygen fugacity of the Bushveld Complex one can deduce the evolution trend of the
magma. Oxygen fugacity was calculated from magnetite–ilmenite pair compositions using
the oxybarometers QUILF (Anderson et al, 2003) and the Fe-Ti Oxide Geothermometer
(Ghiorso and Evans, 2008), and from vanadium in magnetites and clinopyroxenes using a
relation between fugacity and the partition coefficient of vanadium in clinopyroxene (Toplis
and Corgne, 2002). The Fe–Ti oxide results seem to point to a Si-enriching Bowen trend,
while the vanadium results remain inconclusive.
URPC-8