Salt Tectonics Versus Evaporite Tectonics in Southeast Mexico

Abstract

Abstract

Salt tectonics and evaporite tectonics that have contributed to deformation in Southeast of Mexico, have been modeled to regional scale and their impact on reservoir have been characterized to field scale.

To regional scale the linked system of extension-compression has been observed as the main mechanism that control the formation of compressive structures in deepwater south-southeast Gulf of Mexico. Cross-sections retrodeformation have revealed an important interaction between salt and shale creating overpressured zones, and mud volcanoes have been formed where salt bodies were interpreted before.

To reservoir scale, passive salt tectonism occurred long before the main horizontal deformation stage in Miocene times, and affected large portion of southeast of Mexico, has been identified as very active at the moment to generate the main structural and stratigraphic traps in several Mesozoic fields, considered as naturally fractured.

Using 2D balanced cross-sections, it has been characterized the interaction structure-sedimentation, where Jurassic diapir structure was elevated and collapsed lately in several times and different periods, due to salt evacuation. These movements triggered deposition of rock avalanches and debris flow in adjacent basinal depocenters. These rocks were subsequently affected by dissolution and dolomitization, vuggy porosity, not tectonic fractures controlling permeability and connectivity of reservoirs.

In other areas passive salt tectonics triggered both abnormal thickening and erosion of carbonated sequences, creating caverns and “karstified” fracturing parallel to master faults of structures.

On the other hand, evaporite tectonics, identified in other areas, developed beautiful anticline structures type fault bend fold, currently hosting one of the very important fields of southeast Mexico.

Excellent analogues models on surface exist in Northeast of Mexico where vertical pulses of a diapir triggered deposition of rocks and debris avalanches in different levels of the sedimentary column. Also, in central Mexico, outcrops the evaporitic Formation called “Guaxcama”, which gypsum, anhydrite, limestones and sandstones were involved during deformation.

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