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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS017 Oral Presentation 2362
Interpretation and mathematical modelling of temporal changes of
temperature observed in borehole YAXCOPOIL-1 within the CHICXULUB
impact structure, Mexico
Dr. Jan Safanda
Department of Geothermics Geophysical Institute Prague IASPEI
Helmut Wilhelm, Philipp Heidinger, Vladimir Cermak
The geothermal research of the Chicxulub impact structure on the Yucatan Peninsula, Mexico, included
repeated temperature logs of the 1.5 km deep borehole Yaxcopoil-1, which were done following 0.3-0.8,
15, 24, 34 and 50 months after shut-in of drilling operations. A gradual distortion of the linear
temperature profile by a cold wave of the 0.8 -1.6 C amplitude was detected propagating downward
from 145 m to 317 m within the observational period of 50 months (March 2002 April 2006). As an
explanation of this unusual phenomenon, the hypothesis of a downward migration of the drilling mud,
accumulated within the overlying and cooler highly porous and permeable karstic rocks during the
drilling, was proposed. Velocity of the downward propagation of the cold wave decreased appreciably
between the last two logs (December 2004 April 2006). It may indicate that the mud migrating
downward through the system of interconnected caverns and conduits reached a bottom of the
secondary porosity zone. We present results of simulations of thermal effects of the downward
migrating drilling mud, obtained by a numerical solution of the heat transfer equation in a set of
geothermal models of the borehole and its surroundings.
Keywords: yucatan peninsula, thermal conditions, hydraulic properties