Research

Research

Yun Yang is a Assistant Professor at the Department of Petroleum Engineering at the University of Houston and a Guest Scientist in the Earth and Environmental Sciences Division at Los Alamos National Laboratory. Her research focuses on understanding and controlling multiscale, multiphysics flow and transport processes in fractured porous media to realize the full potential of subsurface energy recovery and geologic repository applications. Dr. Yang develops an integrated experimental–theoretical framework that combines advanced material characterization techniques with high-pressure, high-temperature gas adsorption and diffusion measurements to elucidate how fluids are stored, mobilized, and transported in heterogenous, nanoporous geomedia (e.g., shale and coal). Her work bridges pore-scale mechanisms with reservoir-scale behavior, with applications to unconventional oil and gas production, CO₂ and H₂ geologic storage, and subsurface waste disposal. Dr. Yang joined the Department of Petroleum Engineering as a tenure-track assistant professor in September 2026 after completing research scientist, postdoctoral appointments at the University of Wyoming, Los Alamos National Laboratory and the University of Calgary. She earned her Ph.D. in Energy and Mineral Engineering from Pennsylvania State University in December 2020.

Research Themes

1. Unconventional Gas Recovery (Shale Gas and Coalbed Methane)

This research investigates the fundamental mechanisms governing hydrocarbon retention in nanoporous shale and coal matrix, where low recovery factors and sustained low production rates are primarily controlled by matrix diffusion and desorption from tight rock matrix. I designed a high-pressure, high-temperature gas adsorption experimental system with high sensitivity, enabling accurate measurements of very small adsorption capacities and difffusion coeffcieints in coal and shale under geologic conditions. Using advanced pore structure characterization techniques, I developed analytical models grounded in fractal theory to predict gas adsorption capacity and diffusion rates from pore-structure parameters. These models provide closure relationships for explicitly representing nanopore heterogeneity in reservoir-scale simulations, improving long-term production predictions and informing operational strategies to maximize gas recovery from shale and coal reservoirs. Building on this framework, I demonstrated that cryogenic fracturing with liquid nitrogen can significantly modify pore structure and enhance gas recovery by more than 20%, offering a promising pathway to improve ultimate recovery in unconventional gas reservoirs.

2. CO₂ Mineralization in Olivine-Rich Rocks

This research focuses on understanding and optimizing CO₂ mineralization in silicate-rich formations, where reduced-flow fracture zones act as preferential sites for permanent carbon storage. I investigate how real fracture characteristics govern reaction rates, secondary mineral precipitation, and long-term storage efficiency in olivine-rich rocks using various surface geochemistry and microstructural characterization techniques, including optical microscopy, Raman spectroscopy and surface profilometry. I designed synthetic forsteritic olivine fractures with controlled aperture and surface roughness and reacted them with supercritical CO₂ at optimized reaction conditions (13.7 MPa, 185 °C). Results show that rougher surfaces promote iron oxide precipitation, which passivates olivine surface and slows dissolution, and limits mineralization efficiency. A geochemical model incorporating surface topography and passivation effects was developed, reproducing the observed trends and confirming roughness-induced reactivity reduction. This research highlights the importance of considering fracture microstructure when predicting olivine’s CO₂ mineralization.

3. Underground H₂ Storage in Depleted Hydrocarbon Reservoirs

This research focuses on H₂ diffusion in nanoporous seal rocks and its impact on storage integrity and retrievability in underground hydrogen storage within depleted hydrocarbon reservoirs. Diffusion is the dominant caprock leakage mechanism prior to capillary breakthrough because of the small molecular size and low viscosity of H₂ molecules. I established a bench-scale H₂ through-diffusion system to quantify effective diffusion coefficients in representative reservoir rocks and shale caprocks. Experimental results show that H₂ diffuses approximately one to two orders of magnitude faster than methane, raising concerns for caprock sealing efficiency. Diffusion measurements across shale samples with contrasting mineralogy and total organic carbon indicate that mineral composition, particularly calcite content and organic matter distribution, strongly influences effective H₂ diffusivity by regulating pore connectivity and gas–surface interactions. By integrating these experimentally measured diffusion datasets into high-fidelity reservoir simulation, my work indicates that caprock diffusion is a critical leakage mechanism for underground hydrogen storage in depleted hydrocarbon reservoirs, with direct implications for site selection and long-term risk assessment under cyclic injection and withdrawal.