Abstract: A New Exploration Approach in the Search for Anomalously Pressured Hydrocarbon Accumulations in the Neuquen Basin, Argentina

FERNANDEZ-SEVESO, FERNANDO, and RONALD C. SURDAM*

New exploration technology developed at the Institute for Energy Research (University of Wyoming) indicate that the giant hydrocarbon accumulations at the Loma La Lata field in the Neuquen Basin, Argentina, are situated just below a regional pressure surface boundary. This boundary marks the transition from a fluid-flow system that is primarily water and that follows a hydrostatic gradient (i.e., normal pressure), to a multiphase fluid-flow system that contains a pervasive and significant hydrocarbon phase and that deviates from a hydrostatic gradient (i.e., anomalous pressure). This regional pressure surface boundary is subparallel to conventional stratigraphic unit boundaries. Huge hydrocarbon accumulations below the pressure surface boundary are clearly detected and delineated by the new technology (e.g., based on isolation of anomalous sonic and seismic velocities). The distribution of the accumulations can be explained by hydrocarbon compartments constrained by volumes of enhanced porosities.

Most importantly, this technology suggests that there are unexplored exploration targets to the east of the giant gas field. It is likely that the hydrocarbon accumulations below the pressure surface boundary have a fluid-flow system dominated by hydrocarbon generation, storage, reaction and expulsion and not by hydrodynamic disequilibrium compaction. If this is the case, the techniques developed at the IER will provide a new and more efficient way to explore for anomalously pressured hydrocarbon accumulations in the Neuquen Basin.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria