The Pimienta Formation as a Self-Sourced Unconventional Play in Tampico-Misantla Basin, Onshore Mexico

Abstract

Abstract

The Tampico-Misantla Basin is the first-developed and still one of the most prolific oil basins in Mexico. We analyzed samples from excellent source rocks (i.e., Santiago, Taman and Pimienta Formations) deposited in the Upper Jurassic of the Tampico-Misantla Basin. This contribution synthetizes the petrographic and stratigraphical results obtained for the Tithonian Pimienta Fm.

In the study area, the Pimienta Fm. consists mainly of argillaceous mudstone, rich in redox-sensitive elements, with average thickness of 70 m (up to 200 m), and bounded by two surfaces of regional significance: a maximum flooding surface at its base, and a sequence boundary at its top. We interpret the Pimienta Fm. as deposited in an outer shelf, under recurrent anoxic conditions, during the regressive part of a 2^nd-order cycle. The underlying Taman Fm. (Kimmeridgian) represents the transgressive part of a 2^nd-order cycle.

Detailed petrographical analysis revealed two main units in the Pimienta Fm. The lower unit contains abundant echinoderms and is characterized by high organic matter content (TOC>2%). The upper unit is characterized by mudstones diagenetically overprinted, abundant siliceous radiolaria replaced by calcite, poor organic content. Both units show tens of cm-thick bentonites (volcaniclastic material deposited by Plinian explosions and transformed into clay during the burial). A particular unit rich in bentonites is the “Bentonite Member” of the Lower Tamaulipas, overlying the Pimienta Fm. We found bentonites useful as stratigraphic markers, hence characterizing lateral facies variability, and as key elements defining geomechanical units. In fact, the presence of thick bentonites (10-30 cm) is of paramount significance for completion and production since these layers can act as mechanical unit boundaries for hydraulic fracture containment.

The study emphasizes that the thickness, the extensive distribution and the favorable petrographic characteristics of the Pimienta Fm. can make it a world-class self-sourced Unconventional play in onshore Mexico.

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