Compliance with current and evolving federal and commercial regulations require the monitoring of injected carbon dioxide for geological sequestration. The goal of this project is to provide geophysicists with tools to quantitatively interpret seismic data for the amount of carbon dioxide retained in subsurface reservoirs. Rock physics can be used to predict the effects on the seismic response of injecting carbon dioxide on the reservoir. However, classical rock physics models fail when chemical reactions alter the microstructure of the host rock. These chemically induced changes can stiffen or soften the rock frame by precipitation or dissolution, respectively, of minerals in the pore space. Increasing pore pressure is another effect of sequestering carbon dioxide. The amount of change in the microstructure due to chemical reactions and pressure variations depends on the reservoir into which the fluid is injected. Therefore, measuring velocities on site-specific subsurface core samples may provide the ability to differentiate between chemical reactions and pressure variations on the elastic properties of the reservoir rock. Core samples come from the Lower Tuscaloosa Sandstone of the Cranfield study area in Mississippi. The experiments consisted of injecting core plugs with carbon dioxide rich brine and measuring compressional and shear velocities at different effective pressures. The elastic moduli of the rock frame are calculated from the measured elastic wave propagation velocities at specific injected pore volumes and effective pressures. Injecting carbon dioxide rich brine into sandstone core samples, which are composed on average of 80% quartz and 20% clay minerals, resulted in softening of the rock frame due to the dissolution of iron bearing minerals. The moduli exponentially decreased with injected pore volumes and were linearly proportional to effective pressure. The bulk modulus and rigidity of the more quartz rich sample decreased by 13% and 6.5%, respectively, due to a combined effect of changing differential pressure from 35 MPa to 27 MPa and injecting CO₂-rich brine. For the more clay rich sample, the moduli decreased by even larger percentages (39.0% and 20.1%, respectively), which could have significant implications on time-lapse seismic data and subsequent estimations of injected CO₂ volumes. / text

Coastal areas in many parts of the world are vulnerable to tsunami waves. Large tsunamis are strong enough to bring about a substantial amount of sediment mobilization. Several post-tsunami field investigations performed in recent years have documented destruction induced by scouring process. For example, the 1993 Nicaraguan earthquake centred 100km off the Nicaraguan coast caused devastating tsunami-induced scour around structures and bridges (Satake et al., 1993). Differences in the scour depths were related to soil properties, shapes of structures, and tsunami hydrodynamics (Jayaratne et al., 2016). Furthermore, depending on the soil permeability, the flow and pressure propagate at different speeds within the soil, which affects water table fluctuations and the soil strength (e.g., Tonkin et al., 2003; Yeh and Li 2008). The primary objective of this research was to study the effect of different inland-propagating dam-break bore heights on pore pressure variations and scour evolution in saturated beds with two different bed slopes (i.e., zero and +5% slope) by performing comprehensive laboratory studies at a 1:40 scale. To achieve the objective, tsunami-like dam-break bores generated by rapidly opening a swing gate and propagated towards and over a sediment section and hit a structure centred within a sediment bed. The secondary objective of this experimental investigation was finding a relation between scour depths and pore pressure values as a function of still-to-impoundment water depth ratio. The results of this experimental investigation showed that effective pore pressures were consistently greater in the front face of a model than in the side face. Besides that, the highest effective pore pressures took place near the saturated bed surface. Such that, due to the propagation of supercritical bores the maximum effective pore pressure in the bottom of the front corner was 50% larger than the exact same location in the side face. While, this difference decreased to 10% in the case of subcritical bores. For the same hydrodynamic bore conditions, the maximum difference between effective pore pressure in the two faces of the model reduced by 70% in the inclined bed test than the horizontal bed tests and this difference was only 15%. However, the peak effective pore pressure around the model doubled in the inclined bed tests compared to the horizontal ones. The 5% upsloping decreased the maximum scour depths by two times as a result of the same hydrodynamic loading conditions.

Pore water pressure in a silt slope in Sollefteå, Sweden, was measured from 2009-2016. The results from2009-2012 were presented and evaluated in a publication by Westerberg et al. (2014) and this report is an extension of that project.In a silt slope the pore water pressures are generally negative, contributing to the stability of theslope. In this report the pore water pressure variations are analyzed using basic statistics and a connection between the pore water pressure variations, the geology and parameters such as temperature, precipitation and soil moisture are discussed.The soils in the slope at Nipuddsvägen consists of sandy silt, silt, clayey silt and silty clay. The main findings were that at 2, 4 and 6 m depth there are significant increases and decreases in the pore water pressure that can be linked with the changing of the seasons, for example there is a significant increase in the spring when the ground frost melts. As the seasons change, so do the temperature and amount and type of precipitation. Other factors that vary with the season are the amount of net radiation, wind speed and relative humidity, all of which affect the amount of evapotranspiration. At greater depths the pore water pressue is most likely affected by a factor/factors that varies from year to year, possibly the total amount of rainfall. Therefore, the anticipated increase in precipitation in Scandinavia due to climate change could be an important factor influencing slope stability.What precipitation, temperature and evapotranspiration have in common is that they affect the amount of water infiltrating the soil, and thereby the soil moisture content. How the soil moisture is distributed and flows through the soil (sub-surface flow) is governed by the different soil types and their mutual order in the slope, as well as by factors affecting the structure of the soil, e.g. animal burrows and aggregation. The formation of ground frost also affects the way in which the water present in the soil is redistributed.At c. 14 m depth in the slope, there is a saturated layer with positive pore water pressures, which could be one of several such layers. The overall groundwater situation in a silt slope is complex; several different bodies of water can develop, and to get a complete picture of the ground water situation (andthereby also the pore water pressure variations) thorough hydrological surveys are needed. / Under  2009-2016  mättes  porvattentrycket  i  en  siltslänt  i  Sollefteå.  Resultaten  från  2009-2012presenterades och utvärderades i en publikation av Westerberg et al. (2014) och detta examensarbete är en förlängning av det projektet.I en siltslänt är porvattentrycket vanligtvis negativt vilket bidrar till stabiliteten i slänten. I den härrapporten är variationerna av porvattentrycket analyserade med hjälp av enkel statistik och en koppling mellan variationerna och geologin samt parametrar så som temperatur, nederbörd och fukthalt i marken diskuteras.Jordarterna i slänten vid Nipuddsvägen består av sandig silt, silt, lerig silt och siltig lera. Slutsatsen var att på 2, 4 och 6 m djup ökade och minskade porvattentrycket med årstiderna, till exempel ökade porvattentrycket signifikant vid tjällossningen. När årstiderna skiftar ändras även temperaturen och mängden, och typen, av nederbörd. Andra faktorer som varierar över året är netto-instrålningen, vindhastigheten och den relativa fuktigheten och dessa faktorer påverkar i sin tur evapotranspirationen. På större djup beror antagligen portrycksvariationerna på någon eller några faktorer som skiljer sig åt från år till år, möjligtvis den totala mängden nederbörd. Därmed skulle den ökade nederbörd som förväntas i Skandinavien på grund av klimatförändringarna kunna påverka släntstabiliteten.Vad nederbörd, temeperatur och evapotranspiration har gemensamt är att de påverkar mängden vatten som infiltrerar marken, det vill säga de påverkar markens fukthalt. Hur vattnet är födelat i marken beror på de olika jordarterna och deras inbördes ordning i slänten, men också av faktorer som påverkar markens struktur så som aggregation och uppluckring av jorden på grund av marklevande djurs aktivitet. Även formationen av tjäle på vintern har troligtvis en viss inverkan på hur vattnet i marken omfördelas.På 14 m djup finns ett vattenmättat lager med positiva porvattentryck vilket skulle kunna vara ett av flera sådana lager. I en siltslänt är grundvattensituationen mycket komplex, flera magasin av vatten kan bildas. För att få en bra bild av grundvattensituationen (och där med också porvattentrycksvariationerna)behöver noggranna hydrologiska undersökningar genomföras.