Evaluating Reservoir and Seal Integrity in the San Juan Basin for Carbon Capture and Storage (CCS)

The San Juan Basin located in the Four Corners region of the southwestern United States, has long been recognized as a prolific hydrocarbon province, with decades of oil and gas production contributing to a well-understood subsurface geology. With growing global interest in CO₂ capture and storage (CCS) as a strategy to reduce greenhouse gas emissions, this study evaluates basin potential for long-term geological storage.

We focus on Mesozoic reservoir units—particularly those historically associated with conventional and unconventional hydrocarbon production. This work assesses the reservoir quality, seal integrity, and structural configuration of the basin through analysis of well logs, 2D/3D seismic data, and existing geologic studies. Criteria for site selection and potential risk factors for leakage were also examined.

The Entrada Formation, composed of Middle Jurassic sandstones, was identified as a particularly promising reservoir, with thicknesses up to 250 ft, porosities reaching 25%, and permeabilities ranging from 180 to 450 mD. The overlying Todilto Formation, consisting of limestone and evaporites, serves as an effective local seal. Additionally, regional sealing units such as the Mancos Shale and Lewis Shale enhance long-term CO₂ storage. These findings support the viability of the San Juan Basin as a CO₂ storage site, especially in proximity to industrial emission sources such as thermal power plants.