Effect of volcanic bodies on hydrocarbon reservoirs in the northeastern part of the Chicontepec Foredeep, Mexico

Abstract

Shallow intrusive and extrusive volcanic events are common in the northeastern part of Chicontepec Foredeep where the close proximity of these volcanic bodies add to the complexity of the Paleocene-Eocene age tight and complex turbidite reservoirs. In accordance with studies in other basins, outcrop analogs of the Chicontepec reservoirs indicate the potential of enhanced natural fracturing and hence the increase of effective porosity in the host rock. We focus on exploring the validity of this observation in seismic and well data, which is rare in the literature. The preliminary results support the hypothesis of the potential increase of effective porosity including indication of dual-porosity systems in some areas, which would influence detailed studies aided by seismic data for considering Chicontepec reservoirs influenced by volcanic intrusions as additional target zones. Geologic setting During the Late Cretaceous Laramide (Cordilleran) Orogeny, the Farallon (Pacific) plate began subducting under the North American plate resulting in island arc complexes along the western margin of Mexico (Morán-Zenteno, 1994; Alzaga-Ruiz et al., 2009). The northeastward movement of the Farallon plate continued into the Latest Cretaceous and Early Paleocene period. This movement of the Farallon plate accreted and uplifted the Mesozoic sedimentary layers of the former passive margin of the Gulf of Mexico forming the Sierra Madre Oriental fold and thrust belt. Tectonic pulses in the Sierra Madre Oriental continued until the Early Eocene (Alzaga-Ruiz et al., 2009). The Chicontepec foreland flexural basin developed in front of this thrust front, with syn-tectonic sedimentation within the foredeep. The Tuxpan platform is situated in the eastern part of the basin (Figure 1). The Early Paleocene Velasco Formation provided the initial sedimentation within the Chicontepec Foredeep, which was followed by Upper Paleocene Lower Chicontepec deposition. A basin-axis-parallel amalgamated channel system was a major source of sediment in the Lower Chicontepec turbidites. A major tectonic pulse beginning during the late Upper Paleocene initiated syn-tectonic basin-axis-perpendicular sediment flows from the direction of the Sierra Madre Oriental. These basin-axis-perpendicular channel-fan systems were the major contributor to the Middle and Upper Chicontepec Formation. These Paleocene-Eocene turbidites represent tight hydrocarbon reservoirs (porosity: 1%-10%; permeability: 0.001-5 mD) that can be primarily attributed to the mineralogical immaturity of the sandstone and extensive diagenetic processes. In spite of their low porosity and permeability, the Chicontepec Formation represents one of Mexico's most important hydrocarbon plays. Tristán-González et al. (2009) summarize the volcanic activities in east-central Mexico from the Late Cretaceous to the Miocene (Figure 2). Subduction volcanism indicative of tectonic activities was dominant until the culmination of the Laramide orogeny during Late Eocene time followed by transitional volcanism fro...

In-context interpretation: Avoiding pitfalls in misidentification of igneous bodies in seismic data

“…These saucer-shaped, high-amplitude reflections exhibit the same morphology as those documented by DuToit (1920), Planke et al (1999), and others from the rifted European side of the North Atlantic margin, Brazil, and Australia, where rifting facilitates mafic magmatism due to decompression and partial melting of the ultramafic mantle. Furthermore, Sarkar and Marfurt (2017) describe similar andesitic saucer-shaped sills drilled and logged on the way down to deeper turbidites in the Chicontepec Basin of eastern Mexico. Regardless of their composition, the appearance of these sills below Kora is similar to those formed due to extension and subduction-related magmatism.…”

“…Igneous intrusion will produce contact metamorphism in the host rocks nearby the intrusion. These thermally altered rocks or "hornfels," such as those studied in outcrop by Liborius and Tazzo (2012) and Sarkar and Marfurt (2017) are often fractured, allowing hydrocarbons to migrate into the fractured igneous bodies (Delpino and Bermudez, 2009;Rodriguez Monreal et al, 2009;Senger et al, 2017;Rabbel et al, 2018) SL34 Interpretation / November 2018 volume of the magma displaces that of the sediments or the intrusions are virtually incompressible with respect to the surrounding sedimentary rocks that do not compact, and therefore develop a structural dome. Figure 14a shows a sill complex in the Upper Cretaceous sequence and corresponding forced folds directly above the igneous intrusions (green arrows) as an example of postemplacement deformation.…”

Volcanic reservoirs: historic and current context

“…In Argentina, petrophysical and geochemical analysis (Sruoga & Rubinstein, 2007) have been used to study the quality of potential reservoirs and improvements in the quality of 3D seismic data applied to the detection of fractured intrusive bodies (Delpino & Bermúdez, 2009;Spacapan et al, 2020), beyond the application of seismic modelling for better accuracy in seismic interpretations (Rabbel et al, 2018). In Mexico, the extraction of attributes is practical for the study of seismofacies and the behaviour of igneous rocks in well logs, in addition to the use of petrophysics and petrology for a better definition of volcanic reservoirs (Lenhardt & Götz, 2011;Sarkar et al, 2017).…”