Hao Xie

• Nanjing University

Position-specific (PS) carbon isotope compositions of light hydrocarbons such as propane and butane isomers (n-butane and i-butane) can provide a wealth of information on the history of natural gases in the subsurface reservoirs and other environments. For PS carbon isotope analysis of butane isomers, we have established a GC-pyrolysis-GC-isotope r...

We present a method for measuring the clumped isotope composition of molecular hydrogen (H2) using a high-resolution mass spectrometer, the Thermo 253 Ultra, improved to address subtle artifacts arising from instrument baselines and non-linear responses. We also present methods for purification and concentration of H2 from natural and experimental...

Thermal cracking of complex organic matter can occur under many geological settings. However, the role of thermal cracking vs. other chemistries (e.g., metallic catalysis or Fischer-Tropsch-type reactions) in petroleum formation remains controversial. Realistic modeling of isotope effects in chemical reaction networks involving thermal cracking mig...

Carbon capture and storage (CCS) is a key technology to mitigate the environmental impact of carbon dioxide (CO 2 ) emissions. An understanding of the potential trapping and storage mechanisms is required to provide confidence in safe and secure CO 2 geological sequestration 1,2 . Depleted hydrocarbon reservoirs have substantial CO 2 storage potent...

The doubly-substituted ('clumped') isotopologues of methane, 13CH3D and 12CH2D2, provide two new independent constraints that can resolve ambiguities in its provenance and add fresh tools for understanding the environments and chemical mechanisms of natural methane formation. We highlight the scientific added value of combined classical stable (δ13...

Microbial methanogenesis is a significant component in the global carbon cycle, a driver of greenhouse warming from atmospheric methane, and contributes to natural gas resources. There are several metabolic pathways of methanogenesis, and it is challenging to discriminate between them and quantify their relative contributions in natural settings. H...

Naturally occurring hydrocarbon fluids in sedimentary basins have economic, geological and environmental significance. Connecting sedimentary basin temperature-time evolution with petroleum generation and transformation is a long-studied problem. In this study, we investigate the use of a novel tool – multiply substituted isotopologues of methane,...

Investigation of the biology and biochemistry of the deep subsurface provides invaluable information regarding the limit of life in extreme environments and its role in the global carbon cycle. It has been observed that subsurface microbial CH4 can form in apparent isotopic equilibrium, both with respect to methane clumped isotopic species and D/H...

Methane clumped isotope analysis is a tool used to constrain the formation or equilibration temperatures of methane, or to differentiate methane of thermogenic, microbial or ‘abiotic’ origins. Geothermometry applications are based on the temperature dependence of relative abundances of multiply-substituted isotopologues in thermodynamic equilibrium...

This white paper describes the analytical capabilities of the Thermo Scientific™ Ultra™ High Resolution Isotope Ratio Mass Spectrometer (HR-IRMS) for the analysis of doubly substituted isotopologues (‘clumped isotopes’) of methane, including both ¹³CH₃D and ¹²CH₂D₂, and for analysis of the δ¹³C and δD signatures of methane with exceptional precisio...

Intramolecular isotope distributions, including isotope clumping and position specific fractionation, can provide proxies for the formation temperature and formation and destruction pathways of molecules. In this study, we explore the position-specific hydrogen isotope distribution in propane. We analyzed propane samples from 10 different petroleum...

Significance The mechanisms of natural gas formation are important to the carbon cycle and predicting where economical amounts of natural gas form. However, the formation mechanisms of natural gas are not clear, with hypotheses including both irreversible chemical processes such as thermal cracking of long-chain hydrocarbons and thermodynamic equil...

The Gulf of Mexico (GOM) produces 5% of total U.S. dry gas production (USEIA, 2016). Despite this, the proportion of microbial and thermogenic methane in discovered and producing fields from this area is still not well understood. Understanding the relative contributions of these sources in subsurface environments is important to understanding how...

Intramolecular isotope distributions can constrain source attribution, mechanisms of formation and destruction, and temperature-time histories of molecules. In this study, we explore the D/H fractionation between central (-CH_2-) and terminal (-CH_3) positions of propane (C_3H_8) — a percent level component of natural gases. The temperature depende...

Organic compounds are ubiquitous in the Earth's surface, sediments and many rocks, and preserve records of geological, geochemical and biological history; they are also critical natural resources and major environmental pollutants. The naturally occurring stable isotopes of volatile elements (D, ¹³C, ¹⁵N, 17,18O, 33,34,36S) provide one way of study...

Organic compounds are ubiquitous in the Earth's surface, sediments and many rocks, and preserve records of geological, geochemical and biological history; they are also critical natural resources and major environmental pollutants. The naturally occurring stable isotopes of volatile elements (D, ^(13)C, ^(15)N, ^(17,18)O, ^(33,34,36)S) provide one...

Hydrogen isotope compositions of n-alkanes, including intermolecular fractionations, site-specific intramolecular fractionations, and 13C-D or D-D ‘clumping’, can potentially provide geothermometers that constrain the temperature histories of petroleum systems (i.e., conditions of hydrocarbon formation, migration, and/or storage). We experimentally...