19 Depositional systems and resource distribution in eastern and southern North America: from orogens to coastal plains

We welcome studies related to the sourcing, dispersal, and deposition of clastic sediments from the hinterlands to the coast, including the provenance, paleogeography, sedimentology, and economic significance of these deposits.

Tuesday, 10 March 2026
8:30 AM - 11:30 AM
RCC, 105

Depositional Environment Assessment of the Edwards Formation, Maverick Basin, Texas via Core Analysis and Log Correlation

Paper number: 19-3
Program: Technical Sessions
Time: 9:05 AM – 9:20 AM

Authors

Abstract

Understanding the depositional patterns and reservoir quality in a carbonate-dominated system is critical in identifying lower risk exploration areas with a potentially higher prospectivity. Although carbonate reservoirs have a complex and heterogeneous porosity nature, which often results in large variations in permeability for any given porosity, they may involve intricate layer successions, typically as vertically heterogeneous yet laterally continuous layers. This research focuses on the Lower Cretaceous Edwards Formation, a regional carbonate aquifer in south central Texas with high porosity and permeability and characterized by shallow-marine carbonate facies associated with reef and inter-reef deposits. The objective of this work is twofold: (1) to decipher the depositional environment and heterogeneity and (2) to evaluate the reservoir quality, storage potential, and hydrocarbon distribution of the intrashelf Maverick Basin. Observations will be compiled to produce a 3D depositional model, an isopach map, and a fence diagram, to evaluate facies distribution, thickness variation, and hydrocarbon potential. Chittim Ranch 28-1 well core samples within the 3910-4351.65 ft depth interval were used to ascertain lithology through sedimentological analysis, while a suite of well logs comprising gamma ray, resistivity, and spontaneous potential from 37 wells spaced approximately 29,500 ft apart were employed to support lithofacies correlation using IHS Petra software. Results from gamma ray and spontaneous potential log responses indicate the presence of distinct sand and shale zones interpreted as sand, shaly sand, and shale lithofacies. Core analysis shows laminations, bioturbation, and stylolites, with lithological transitions from fine-grained calcite minerals to coarser-grained evaporite minerals, which reflect the heterogeneity observed in the formation. Preliminary assessments suggest the depositional system is a carbonate shelf-to-basin transition system, with sedimentation occurring within a restricted to open-marine depositional environment. Reservoir quality across the basin is considered good, suggesting favorable prospect conditions for further exploration and production potential.

 

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411521

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