Abstract

The Mexican Gulf of Mexico is a proven world class hydrocarbon province. With 56 BBOE cumulative production and proven 1P, 2P, and 3P reserves of around 80 BBOE, it is estimated to still hold prospective conventional resources of around 52 BBBOE (www.pemex.com). Despite this significant potential, since 2007, production began to decline from the mature fields and new fields were slow to come on stream.

To revitalize the economy and exploration for oil and gas, in 2013 Mexico introduced new reforms, inviting participation from international exploration players, generating a lot of interest in the country, and resulting in several major seismic acquisition and enhancement campaigns to support bid round evaluation and future exploration campaigns. In 2017, this new initiative led to the Zama discovery, operated by Talos Energy. This is a great example of the importance of utilizing modern, high fidelity seismic processing to realize the potential of the extremely prolific Sureste Basin. Other similar more recent examples from the Sureste Basin are the Cairn Saasken and Repsol Polok and Chinwol discoveries, where seismic imaging played a key role in revealing the potential associated with these salt flank plays.

The multiple stages of tectonic evolution of the Sureste Basin, together with the influence of salt tectonics, have resulted in a complex geometry. An initial rifting stage during the Triassic to Middle Jurassic was followed by the deposition of the Callovian salt, a passive margin stage during Late Jurassic to Late Cretaceous, and finally a compressional stage from Late Cretaceous to Recent. The geometry has been largely influenced by salt tectonics with reactive, passive and active salt structures all present. In order to identify potential hydrocarbon traps in this type of environment, where both salt flank and subsalt structures can contain significant hydrocarbon columns largely associated with the sealing capacity of the salt, seismic imaging is a critical element. In 2017, the merging and reprocessing of 3 legacy Pemex 3D seismic volumes, Holok-Alavarado, Cequi, and Bolol Norte, resulted in enhanced imaging observed in both KPSDM (Kirchoff prestack depth migration) and RTM (reverse time migration) volumes. As can be seen in Figure 1, which goes through one of the recent discovery wells, the RTM volume gives a sharper image with clearer salt flank definition as it is more accurately located, but also has a lower frequency content and lower resolution. In contrast, the KPSDM has higher resolution and amplitude content, allowing a more accurate definition of the stacked reservoirs. As illustrated by the review of recent discoveries under this dataset, to ensure exploration success, it is essential to use both datasets in this type of environment.