Oil Seeps on the Seafloor of Perdido, Mexico

Abstract

Abstract

After decades of estate monopoly, Mexico launched in the end of 2015 the first bid round of deep water blocks, in a context of extremely low oil prices. In this scenario, it is crucial to use tools to help the prioritization of investments, increase success rates and reduce exploratory costs. This work presents an exercise for improving exploratory efficiency in Mexican GoM.

The strategy was to remotely identify areas on the seafloor where oil is seeping. Remote investigation presents reduced costs and can guide local investigation, reducing its cost also. The location of seep sources on the seafloor provides evidence of HC charge and a direct connection between oil seeps and geologic features in offshore basins, reducing risk.

Hundreds of images of Synthetic Aperture Radar, onboard of satellites, were used to detect oil seep slicks on the sea surface in Cuenca Salina and Perdido, the two regions offered in the bid. The seeps confirmed the presence of a huge charge and active petroleum systems in deep waters in both regions, indicating a great potential for new discoveries.

The seep dynamics in Cuenca Salina is more intense than in Perdido, whilst hydrodynamics is less intense, resulting in the generation of many seep clusters on the sea surface in Cuenca Salina, i.e., the presence of many slicks in the same position in different dates. In this case, the probable origin of these seeps on the seafloor is the vertical projection of the center of the cluster.

However, in Perdido the seep slicks are less frequent and are spread on the sea surface, not generating clusters. The joint action of currents and winds can horizontally displace oil seeps more than 50 km far from their origin on the seafloor.

To solve this problem, two computational models were used to estimate the origin of the seeps on the seafloor. The hydrodynamic model rebuilds the 4D Ocean circulation in the date of detection of each seep; and the oil seep inverse model defines the trajectory of the oil, back in time, between the position where it was detected by satellite and the area in sea bottom, where the oil escaped to the ocean. Recent work demonstrated the ability of this technology to increase in 139% the success in finding HC shows in piston core campaigns.

In this work, we present results of the inverse modeling of the oil seeps in the region of the offered blocks in Perdido: slicks on the sea surface, their origin on the seafloor and a geologic interpretation of these results.

AAPG Datapages/Search and Discovery Article #90260 © 2016 AAPG/SEG International Conference & Exhibition, Cancun, Mexico, September 6-9, 2016