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Boletín de la Sociedad Geológica Mexicana Volumen 72, núm. 2, A151219, 2020 |
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Diagenésis de la Formación Eagle Ford y sus marcadores térmicos como productora de
gas no convencional
Diagenesis of the Eagle Ford Formation and its thermal markers as a producer of
unconventional gas
Aurea Yahaira González Betancourt1,*, Eduardo González Partida2, Noé Piedad Sánchez3, Alejandro Carrillo Chávez1, Luis Eduardo González Ruiz4, Daniel González Ruiz5
1, 2 Centro de Geociencias, campus Juriquilla, Querétaro, Universidad Nacional Autónoma de México, Blvd. Juriquilla 3001, 76230, Querétaro, México.
3 Innovación Tecnológica Aplicada a las Geociencias - Academia de Investigación A.C. Carboneras, Mineral de la Reforma, 42183, Hidalgo,México.
4 Geologia Minería y Consultoría, S.A. de C.V. Ciprés 104 F, Frac. Jurica, 76100, Querétaro, México.
5 Centro Nacional de Investigaciones Avanzadas en Petrofísica CENIAPET, S. A. de C. V. Ciprés 104 F. Frac. Jurica, 76100, Querétaro, México.
* Autor para correspondencia: (A. González) This email address is being protected from spambots. You need JavaScript enabled to view it.
How to cite this article:
González Betancourt, A. Y., González Partida, E., Piedad Sánchez, N., Carrillo Chávez, A., González Ruiz, L. E., González-Ruiz, D., 2020, Diagenésis de la Formación Eagle Ford y sus marcadores térmicos como productora de gas no convencional: Boletín de la Sociedad Geológica Mexicana, 72 (2), A151219. http://dx.doi.org/10.18268/BSGM2020v72n2a151219
Abstract
There are several organic matter-rich shale geologic formations in Mexico that could be considered non-conventional potential oil reservoirs; one of those formations is the Eagle Ford Formation (Late Cenomanian – Turonian), aim of this study. The Eagle Ford Formation is located within the Sabinas paleobasin and along the Burros-Peyote paleoplatform, in the Coahuila State. This formation has been previously described as a transgression system deposited in a shallow marine environment with a total organic carbon between 0.5 to 8% with type II organic matter. For these reasons, it could be considered a potential source for non-conventional hydrocarbons. Therefore, it is considered that a reservoir of shale gas must have certain requirements, such as: 1) high total organic carbon (> 2% of COT), 2) presence of types II and III kerogen, 3) vitrinite reflectance values greater than 1.2% Ro (0.7% for shale oil), 4) thickness greater than 30 m and large extension, 5) fracturability (<40% clays or absence of expandable clays) or the presence of a microcracking system, 6) overpressure, 7) adequate depth, 8) heterogeneity, and others. A systematic sampling was carried on outcrops of Coahuila State with the goal to determine the thermal maturity degree of the Eagle Ford Formation using a detailed stratigraphic analysis of three columns (CSI, CSII and CSV) and micro-thermometric of fluid inclusions. Our results indicate that the Eagle Ford Formation is a sedimentary sequence rich in organic matter, locally composed of carbonaceous carbonate shale in laminar stratification alternating with shaly limestone (mudstone-wackestone) and clastic o bioclastic limestone (packstone-grainstone). Regarding the diagenetic alteration, primary porosity is affected by compaction and cementation processes. However, it was also observed a secondary micro-porosity development due to neomorphism, dolomitization, fracturing and stylolitization processes. Measured homogenization temperatures (Th) in fluid inclusions are between 65 °C and 125 °C, reaching the temperature window to generate oil and humid gas. The thermal evolution through its facies changes in the basin is not homogeneous. Our results indicate that the Eagle Ford Formation is a sedimentary sequence rich in organic matter, locally composed of carbonaceous carbonate shale in laminar stratification alternating with shaly limestone (mudstone-wackestone) and clastic o bioclastic limestone (packstone-grainstone).
Keywords: Non-Conventional hydrocarbon reservoir, petrography, fluid inclusions, gas, diagenesis.
