Events

UTIG Discussion Hour: Nanna Karlsson, GEUS

DeFord Lecture | Peter Eichhubl

Fracture growth processes under reactive subsurface conditions—Relevance for the New Energy Economy by Dr. Peter Eichhubl, Jackson School of Geosciences, UT Austin

Abstract:

Fracture systems and faults control the strength of the Earth’s crust, fluid flow, and heat and mass transport at a wide range of scales. In addition to the significance of fractures to natural crustal-scale and geomorphic processes, natural and induced fractures are of fundamental importance to oil and gas production, geothermal energy extraction, and the subsurface storage of CO₂ and hydrogen. Understanding how fractures form, under what stress conditions, how fast, and how their growth is influenced by chemical reactions is of fundamental importance.

The formation of rock fractures under upper crustal conditions is conventionally regarded as a primarily brittle mechanical process. This view is now evolving with the recognition of the significance of coupled chemical reactions for fracture growth. This is particularly relevant to systems where the formation is in contact with fluid far out of chemical equilibrium, conditions expected for enhanced oil recovery, hydraulic fracturing, enhanced geothermal systems, CO₂ storage, and hydrogen storage in porous formations.

In combination with field structural observations of fractures in a variety of natural settings, my students and postdocs conducted laboratory fracture mechanics tests of shale and sandstone of varying composition in the presence of aqueous fluid of varying pH and salinity to quantify the effect of chemical reactions on fracture growth. We also synthesized fractures in geomaterials under reactive laboratory conditions to define characteristics of fractures and fracture systems that form in chemically reactive systems and to understand how such reactive fracture systems differ from purely mechanical brittle fracture processes.

We find that chemical reactions can both enhance and inhibit fracture growth depending on the mineral and fluid composition and the reactions involved. Acidic pore water enhances fracture growth in carbonate-rich shale lithologies, whereas high salinity impedes fracture growth in clay-rich shales. Silicification under geothermal or epithermal conditions can lead to significant strengthening with a three-fold increase in fracture toughness, whereas chlorite-clay alteration reduces fracture toughness. Silicified rock is more susceptible to fracture growth under alkaline aqueous conditions.

Fracture growth experiments demonstrate that fractures formed in chemically reactive environments are generally characterized by wider kinematic apertures compared to fractures forming under less reactive conditions, with fracture shapes that deviate from predicted elliptical profiles. Such deviations in fracture profile may enhance or impede fracture growth.

These results apply to natural as well as engineered fracture systems and are thus of direct relevance to the stability of shale caprocks in CO₂ and hydrogen storage systems, and to induced fracture performance in enhanced geothermal systems and unconventional oil and gas reservoirs. Because chemical reactions can both enhance and inhibit fracture growth, these processes provide the opportunity to optimize fracture outcomes under managed fluid chemical conditions.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating EPS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

UTIG Seminar Series: Nanna Karlsson, GEUS

NOTE: This talk will not be recorded.

Speaker: Nanna Bjørnholt Karlsson, Senior Scientist, Geological Survey of Denmark and Greenland

Host: Benjamin Keisling & Ginny Catania

Title: From ice to fjords and ocean: The complex interactions between the Greenland Inland Ice and its watery margins

Abstract: Since the early 2000s, the Greenland Inland Ice has been one of the largest contributors to rising sea levels. In recent years, studies have highlighted that the ice sheet also exerts a significant influence on local fjord environments. Meltwater from the marine-terminating glaciers of the ice sheet promotes mixing of fjord waters and enhances primary biological productivity. Moreover, this meltwater may carry sediments that influence marine ecosystems and affect coastal zone dynamics. While we have made considerable progress in understanding the large-scale ice flux from the Inland Ice, we are still lacking accurate representations of these processes on a local fjord scale. This gap hampers our ability to predict future changes and assess their potential socio-economic consequences for local communities.

In my presentation, I will share the latest findings from our ongoing research efforts, which aim to quantify the volume and seasonality of ice flux into the fjords, including recent in-situ measurements from South Greenland. Additionally, I will discuss insights gained from utilizing paleo-records to reconstruct ice and sediment fluxes from the recent past.

Hot Science - Cool Talks: "Tarsiers - Tiny Terrors of the Tropics"

Have you ever wondered what an insect’s worst nightmare is? Dive into the wonderful weirdness of tarsiers with Dr. Chris Kirk in “Tarsiers – Tiny Terrors of the Tropics!”. These primates have freaky adaptations, but in many ways, they are also just like us!

Cool Activities: 5:30 – 6:40 p.m.

Talk with Q&A: 7:00 – 8:15 p.m.

Chris Kirk is a native Austinite and third-generation Longhorn (B.A. in Anthropology, class of 1992). He completed his Ph.D. at Duke University, where he spent many hours in the company of lemurs and lorises at the Duke Lemur Center. Dr. Kirk has participated in paleontological research in Egypt, Botswana, Turkey, and various sites across the U.S. Since 2005 he has made regular trips to collect Eocene fossils in the Big Bend region of Texas. Dr. Kirk’s research focuses on primate evolution – he is particularly interested in using the relationship between form and function to better understand the adaptations and ecology of fossil species.

Hot Science – Cool Talks provides front-row seats to world class research. For additional information about the Hot Science events, please visit http://www.hotsciencecooltalks.org.  

UTIG Discussion Hour: Nicolas Montiel, UTIG

DeFord Lecture | Atul Jain

Water, Energy and Carbon Footprint from Bioethanol Production

by Dr. Atul Jain, University of Illinois Urbana-Champaign

Abstract: Bioethanol crops have the potential to meet future energy demands and mitigate climate change by partially replacing fossil fuels. However, the large-scale cultivation of these crops may also impact climate change through changes in land cover, terrestrial water and energy balance, carbon and other nutrient dynamics, and their interactions. This represents a pivotal challenge within the Food-Energy-Water System (FEWS) nexus. Our study estimates potential bioethanol yield across the US based on crop field studies and conversion technology analysis for three crops – corn, Miscanthus, and two cultivars of switchgrass (Cave-in-Rock and Alamo). This presentation will provide a detailed analysis of the implications of growing bioethanol crops on water and energy resources and GHG emissions. Additionally, the presentation will explore how the growing challenges of extreme climate conditions, including droughts and heat waves, are shaping these critical factors across the US.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating EPS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

UTIG Seminar Series: Erik Fredrickson, UTIG

Speaker: Erik Fredrickson, Distinguished Postdoctoral Fellow, University of Texas Institute for Geophysics

Host: Laura Wallace

Title: Seafloor Pressure Geodesy for Observing Transient Slip Processes in Offshore Subduction Systems

Abstract: Tectonic plate boundaries host a range of solid-Earth physical processes of scientific and societal interest, including the majority of the world’s volcanism and earthquakes. However, their location primarily beneath the oceans poses significant challenges for observation and study. There is currently a major push in the tectonics and hazards scientific communities to expand seafloor geodetic efforts and instrument the offshore segments of subduction zones. I’ll present an overview of seafloor pressure geodesy in the context of slow slip earthquakes and discuss the techniques developed from my thesis work in the Cascadia and Alaska margins for parsing out centimeter-scale tectonic signals amidst a sea of oceanographic noise. I’ll also talk about my ongoing work here at UTIG using offshore geodesy to characterize slow slip earthquakes in the Hikurangi margin.

UTIG Discussion Hour: Graciela Lopez Campos, UTIG

DeFord Lecture | Alan Whittington

Space Lava! Adventures Beyond the Terrestrial T-X limits of Igneous Petrology

 by Dr. Alan Whittington, The University of Texas at San Antonio

Abstract: As planetary geology reaches the edges of the solar system and prepares for the leap to exoplanets, we should be ready to encounter igneous processes occurring over a much wider range of T-X space than is familiar to terrestrial petrologists. Volcanism on Earth is typically restricted to compositions that can be generated by partial melting of the Earth’s mantle and/or crust, and through subsequent modifying processes such as magma mixing, assimilation, and fractional crystallization. This leads to the familiar range of terrestrial lava compositions, limited at the present day to foidites (e.g., Nyiragongo, DRC) at the low-SiO2 end, and high-silica rhyolites (e.g. Obsidian Dome, USA) at the other. Carbonatites represent a rare departure from silicate volcanism on Earth. At much lower temperatures, cryovolcanism is the probable mechanism for the extrusion of sodium carbonate-rich domes on Ceres. Sulfate, chloride, and carbonate-rich brines are likely cryovolcanic materials at Europa, Enceladus, and other ocean worlds.

Impact melts are composed primarily of target material, whose composition is dictated by surface processes that extend beyond the realm of igneous petrology. Consequently, they span a much wider range. On terrestrial bodies with primary crusts, such as the anorthositic lunar highlands, impact melts can resemble monomineralic melts, which could never form by any other mechanism. Where impacts remelt secondary crusts, for example the lunar maria, the same magma could be reborn but at a much higher temperature than during initial formation and emplacement. These superheated sheets of lava have tremendous erosive power, both thermal and mechanical, until they cool below their liquidus.

Finally, in situ resource utilization (ISRU) on the Moon or Mars will likely require melting to produce glass and ceramics for construction and technical applications. Energy requirements can be minimized by using starting materials with a glassy component, sourced from volcanic or impact melt deposits (including micron-scale agglutinates). The tendency for finer grained lunar regolith to also be more feldspathic and glassier raises the possibility that physical sorting by size can also sort for composition and crystallinity, facilitating brick/ ceramic production in locations where the bulk regolith is less suitable.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating EPS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

UTIG Seminar Series: Camilla Cattania, MIT

Speaker: Camilla Cattania, Assistant Professor, Massachusetts Institute of Technology

Host: Demian Saffer

Title: Seismicity and rupture behavior in geometrically complex fault zones

Abstract: Faults are geometrically complex at all scales: from the fractal topography of individual surfaces, to kilometer-scale features such as bends and step-overs, to widespread damage zones surrounding major faults. Although this complexity has long been recognized as an essential aspect controlling earthquake rupture and seismicity patterns, a quantitative understanding of the link between fault geometry and its seismic behavior is still limited.

In this talk I will present recent progress in this area, focusing on a few studies across a range of spatial scales and tectonic settings: 1. Slip complexity mediated by fault roughness during slow slip events (SSEs); 2. The role of subducting seamounts in earthquake nucleation and arrest; 3. Seismicity patterns in the damage zone.

Back-propagating rupture fronts are commonly observed during slow slip events, offering an opportunity to probe the frictional properties of heterogeneous faults. We find that this behavior spontaneously emerges in numerical simulations of SSEs on rough, rate-state faults with a rate-strengthening transition at high slip rates. Back propagating fronts are triggered as a consequence of a “delayed stress drop” near the crack tip, caused by large local fluctuations slip rate as the rupture propagates through the heterogeneous stress field, coupled with rate-strengthening friction. While small scale heterogeneity favors this process, we demonstrate that back-propagating ruptures can also be included by large scale stress heterogeneity induced by far-field loading, offering a possible explanation for “boomerang earthquakes” along transform faults.

Subducted seamounts are an example of large-scale structural heterogeneity, and they have often been associated with earthquake nucleation and arrest. Here we use quasi-dynamic, elastic simulations to investigate how seamounts affect the seismic cycle. Seamount subduction modifies the state of stress on the subduction interface, creating regions of enhanced and reduced normal stress downdip and updip of the seamount. We find that this pattern can facilitate creep and earthquake nucleation, although the enhanced compression can cause ruptures to arrest. We identify different regimes, controlled by the amplitude of stress heterogeneity, and find that they are well explained by fracture mechanics criteria that account for spatial variations in stress drop and fracture energy modulated by normal stress. These results extend previous criteria for the occurrence of partial ruptures and super-cycles on heterogeneous faults, and qualitatively explain the variability in earthquake behavior observed along subduction megathrusts.

Planetary Habitability Seminar: Eva Scheller, MIT

Speaker: Eva L. Scheller, Heising-Simons Postdoctoral Fellow, Massachusetts Institute of Technology

Title: Searching for Mars’ missing carbonates

Abstract: Mars’ current frozen conditions, marked by a thin 6 mbar CO₂ atmosphere, contrast with its geological and mineralogical records of a once aqueous environment. These findings have fueled the hypothesis of a denser atmosphere on ancient Mars, raising pivotal questions about its thickness and subsequent depletion over time. On Earth, a CO₂-rich atmosphere undergoes sequestration, transforming into carbonate minerals through aqueous interactions—a process anticipated to have occurred on Mars. Despite this expectation, the paucity of carbonates detected via orbiters and rovers on Mars’ surface has posed a conundrum, informally termed as “the missing carbonates”.

Upon the Perseverance rover’s landing in Jezero Crater in February 2021, it identified carbonate compounds within the ancient ultramafic terrain and the crater’s fluvio-lacustrine deposits – unpredicted by orbital datasets. Furthermore, the Perseverance rover confirmed that Mars’ carbonate formation is predominantly governed by carbonation, dictated by the dissolution kinetics of olivine in, specifically, ultramafic terrains in the crust. The Perseverance rover’s findings not only broaden our understanding of Mars’ atmospheric loss but also provide a geochemical framework indicative of low water activity. These revelations offer a significant leap towards unraveling the fate of Mars’ sequestered atmosphere, enhancing our comprehension of planetary atmospheric evolution. Join me as I delve into these fascinating developments and edge closer to solving the Martian carbon puzzle.

UTIG Discussion Hour: Morgan Carrington (JSG)

DeFord Lecture | Alex Bump

Not your grandfather’s petroleum system: The Goldrush for CO₂ Storage and the Underrated Role of Pressure by Dr. Alex Bump, Bureau of Economic Geology, UT Austin

Abstract: The Gulf of Mexico is a petroleum super-basin, a maker of fortunes and a major driver of American industry.  Early indications are that it may be similarly spectacular for Carbon Capture and Storage (CCS), a key climate change mitigation technology.  It has some of the densest clusters of point-source CO₂ emissions in the US and proven reservoirs at every stratigraphic level from Jurassic to Pleistocene.  Application of petroleum-inspired volumetric analysis suggests that the Texas coast Miocene section alone could offer 125Gt in storage capacity, enough to store ~2 decades of emissions for the entire US. Recent reforms to the tax code and passage of the Inflation Reduction Act have transformed the incentives for CCS, raising the reward from /ton of CO₂ stored to /ton.  As of November 2023, at least 49 new storage projects have been announced on the US Gulf Coast, with a total claimed storage capacity greater than 7Gt.  A new gold rush is on.

However, CO₂ injection is not petroleum production and application of petroleum-inspired volumetrics can yield dazzling but wholly unrealistic numbers.  Both petroleum accumulation and CO₂ injection require displacing pre-existing pore fluids (brines), but the similarity ends there.  Petroleum accumulates on geologic time, pushing the native brines out slowly, at pressure equilibrium, and reliably saturating a predictable reservoir volume.  Not so for injected CO₂.  Injection at industrial rates favors the highest permeabilities.  Sweep efficiency is often poor and always hard to predict. More significantly, brine displacement is limited by faults, depositional edges and the same confining zones required to retain CO₂.  Most of the storage space for injected CO₂ must come from compression of rock and preexisting brines, neither of which is very compressible. Pressure build-up is inevitable and it, not saturation, is the key limitation on storage capacity.  Combined with the exponential growth of announced storage projects, that realization raises new questions: What is realistically achievable? What is the potential for interference between projects? What is the value of the storage resource? And how much space is required between projects to avoid interference?

To address these questions, we introduce the concept of pressure space, which we define as pore volume times allowable pressure increase, similar to a gas storage tank whose capacity is defined by volume and pressure rating.  Using new algorithms on the grids developed for the original Miocene static capacity assessment, we find that the Texas coastal Miocene section offers ~10Gt in pressure-based capacity, if all reservoirs within it are pressured up to the statutory limit of 90% of frac pressure.  While still substantial (and only a small fraction of the total Gulf of Mexico), that is an order of magnitude less than the original estimate and equates to less than 0.5% pore volume occupancy (storage efficiency), on average.  For comparison, the 200+ saline storage projects in the global OGCI Storage Resource Catalog claim storage efficiencies from <1% up to 25%.  While some may get these numbers, our work makes clear that they can only be achieved by producing brine and/or consuming pressure space beyond the project boundaries.  Gigaton-scale storage is clearly possible, but it may require more acreage than current project developers are calculating.  Competition for pressure space is predictable and like all gold rushes, this one is likely to yield benefit for society at large, but uneven fortunes for the project developers.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating EPS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.