Direct estimation of shale oil potential by the structural insight of Indian origin kerogen

Abstract

Structural insight of Indian origin kerogen has been investigated by Solid State 13C Cross Polarization Magic Angle Spinning Nuclear Magnetic Resonance (13C CPMAS NMR) and Infrared (IR) Spectroscopic techniques. Cross Polarization (CP) with decoupling using two pulse phase modulation (TPPM) and Bloch decay experiment with 1H decoupling have been performed on each kerogen sample. Direct estimation of oil potential present in Indian origin kerogen has been done utilizing developed method based on IR and 13C CPMAS NMR techniques. The IR methods have been developed using both transmission and DRIFT reflectance spectra by employing standard blends of oil shale (1–12%) with Vacuum Gas Oil (VGO) range products. Models were developed by correlating the IR intensity in 3000–2700 cm−1 region with the % oil shale in VGO. Validation has been done by estimating aliphatic carbon (Calip) and aromatic carbon (Carom) content obtained by 13C CPMAS NMR method and a comparison has been made between 13CMAS NMR with and without dipolar dephasing, with and without CP. 13C MAS NMR spectra of Indian origin have been compared with Estonia and US Green River origin oil shale, containing high oil potential. Both IR and NMR methods have been applied to number of samples from different Indian sources. Results from these comprehensive studies indicate that both 13C CPMAS NMR and IR techniques are quite useful for structural inputs and direct determination of oil potential from different origin oil shale.