Total Organic Carbon Determination by 13C CP/MAS Solid-State NMR in Unconventional Oil/Gas Source Rocks: A Case Study from the Neuquén and Cuyo Basins in Argentina

GARRO LINCK, YAMILA; MARTINEZ DELFA, GERARDO; DONADELLI, JORGE ANDRÉS; SILLETTA, EMILIA V.; VELASCO, MANUEL I.; FRANZONI, MARIA BELÉN; G.A. MONTI; SMAL, CLARA; ACOSTA, RODOLFO H.

Energy and Fuels

American Chemical Society

Año: 2024

One of the key parameters in assessing the production potential of unconventional oil and gas reservoirs is the quantification of organic matter, which is generally determined by pyrolysis. Laboratory nuclear magnetic resonance (NMR) is widely used in the oil industry; being a non-destructive method, it enables the possibility to perform several analyses on the same sample, which is desirable due to the heterogeneity of these types of geological formations. 13C spectra provide much information, from speciation to maturity determination. The main drawback of this technique is the inherently low signals obtained for these nuclei, rendering extremely long experimental times. A solution is using cross-polarization schemes that transfer the high polarisation of nearby 1H nuclei to 13C ones with the penalty that quantification is a priori not feasible. In this work, we analyse the cross-polarization evolution and conclude that quantifying total organic content (TOC) is possible for a wide range of organic matter content and maturities for rock samples corresponding to the Neuquén and Cuyo basins in Argentina.