Papers by Geoffrey Thyne
36Th Annual Lunar and Planetary Science Conference, Mar 1, 2005
Simple reactions involving water and rock at low temperatures (as low as 0°C) are sources of geoc... more Simple reactions involving water and rock at low temperatures (as low as 0°C) are sources of geochemical energy that are able to support metabolism for potential martian microbes.
Currently there are several different carbon capture technologies either available or in active d... more Currently there are several different carbon capture technologies either available or in active development for coal- fired power plants. Each approach has different advantages, limitations and costs that must be integrated with the method of sequestration and the physiochemical properties of carbon dioxide to evaluate which approach is most cost effective. For large volume point sources such as coal-fired power
International Journal of Astrobiology, 2005
We have explored chemical weathering of likely martian materials at low temperatures based on the... more We have explored chemical weathering of likely martian materials at low temperatures based on the increasing evidence for non-hydrothermal water at or near the martian surface. Chemical weathering of minerals at low temperatures (as low as 0°C) in aqueous environments on Mars can produce geochemical energy to support construction of potential martian organisms. Here, we examine the geochemical energy available from the interaction of martian surface or near surface materials with lowtemperature water. We calculate Gibbs free energy for 13 different weathering reactions that are likely to be important on Mars. The aqueous weathering of 1 kg of an ultramafic rock like Chassigny meteorite at present martian conditions can support the construction of ~30 grams of microbes. The aqueous weathering of 1 kg of a basaltic rock on Mars can support the construction of ~ 26 grams of biomass at present martian conditions and ~32 grams for conditions likely in the past. This means that ~1.3x10 19 grams of potential biomass could have been supported from weathering a global layer of rock 1 m thick. Thus, low-temperature water-rock reactions on Mars can produce geochemical energy for potential martian microbes.
Ground Water, 2007
This article presents a method for estimating chemical thermodynamic constants from experimental ... more This article presents a method for estimating chemical thermodynamic constants from experimental data using the two computer programs UCODE_2005 and PHREEQC. As an example, the conditional stability constant for lead (Pb) complexation by a remediation agent (carboxymethyl-b-cyclodextrin) is estimated, but the method can be applied to estimate other thermodynamic parameters such as sorption constants and degradation rate constants. Advantages of this technique include estimation of uncertainties associated with estimated parameters, evaluation of information content of observations, statistical evaluation of the appropriateness of the conceptual model, and statistical-based comparison of different models.
Ground Water, 2009
We all agree on the urgent need to develop solar, wind, and biofuel energy resources, but this ed... more We all agree on the urgent need to develop solar, wind, and biofuel energy resources, but this editorial is not about alternative energy. We should first admit that all of us depend on petroleum energy consumption. We drive to work, heat our houses, fly to conferences or to vacations on sunny beaches, and buy goods from the grocery store. However, we also face an economic imperative to reduce consumption, particularly our reliance on foreign oil and gas. As our petroleum reserves decline, energy companies are focusing on development of natural gas and unconventional reserves such as oil shale and coalbed methane. Development of these resources will consume significant amounts of water and generate large volumes of water that require treatment. Many of the most promising unconventional deposits are in the western United States and Canada, where water resources are scarce. Thus, the joint sustainability of petroleum-energy production and water resources has emerged as an evermore important technical challenge.
Geochimica et Cosmochimica Acta, 1995
Environmental Geology, 2004
Evaluation of 12 years of landfill leachate chemical data from a lined cell of municipal waste in... more Evaluation of 12 years of landfill leachate chemical data from a lined cell of municipal waste in south Florida, USA shows an overall declining trend in major ion chemistry. The leachate is dominantly Cl, Na, HCO 3 and organic solutes. There are significant short-term variations in concentration that appear to be related to rainfall, rather than fundamental changes to leachate composition. Inorganic parameters related to pH, such as alkalinity, calcium, and magnesium appear to be chemically buffered. Chromium, cobalt, vanadium, zinc, and the metalloid boron display significant short-term co-variance with a decreasing trend. Iron and manganese concentrations increased significantly after capping. Based on the predominance of ammonia, historic methane generation, and increasing trends for iron and manganese after closure, the landfill cell has an anaerobic (reducing) interior environment. The reducing conditions were enhanced by capping and caused the most redox sensitive metals (manganese and iron) to become more mobile.
Capture and storage of carbon dioxide in deep underground geologic formations (geologic carbon se... more Capture and storage of carbon dioxide in deep underground geologic formations (geologic carbon sequestration) is currently the most advanced technology for reducing or mitigating anthropogenic carbon dioxide emissions. There are a number of scientific challenges associated with injection and storage of large amounts of CO2 in geologic formations. Understanding the chemical reactions that can occur among reservoir rocks, aqueous fluids,
ABSTRACT Flexible gold bag hydrothermal autoclaves and were used to measure the dissolution rate ... more ABSTRACT Flexible gold bag hydrothermal autoclaves and were used to measure the dissolution rate of supercritical (sc) CO2 into brine. To simulate dissolution into brine in a porous media, a sand packed stainless-steel autoclave was utilized. 1 m NaCl brine was tested at 40 and 75°C, and pre-injection pressures of 10 and 20 MPa. Liquid CO2 was quantitatively injected into reactors, where it converts rapidly to a supercritical fluid in the hot reactor. Reactors were oriented horizontally through the duration of the experiments to maximize contact surface area between the fluids and they were not mechanically mixed. The pressure in the experiments was allowed to rise during injection. The pressure decay was logged as scCO2 transferred into brine. This decay curve was used to calculate the mass transfer rates of scCO2 to brine. CO2 analysis of the brine at steady state pressure conditions was used to calculate the solubility. The measured solubility of CO2 into brine at these conditions compares well to the predicted values from Duan and Sun (2003). Calculated rates for scCO2 mass transfer are significantly lower than published values for CO2 hydration, indicating that the experiments are mass transfer limited and not limited by chemical kinetics at these conditions. Mass transfer rates in the brine only experiments were 3-5 E-07 mol/cm2s, comparable to other published experiments at lower pressures (Yang and Gu 2006). The mass transfer rate into the brine + porous media experiment was significantly lower at ~5 E-08 mol/cm2s. Calculated effective diffusion coefficients for the brine and brine + porous media experiments were ~0.1 - 3 E-03 cm2/s and ~4 E-05 cm2/s, respectively. These experimental results are compared to model simulations using a simple diffusion model and numerical methods in 3-D with PFLOTRAN and FEHM. Although rates are relatively rapid for high permeability situations, the permeability of the porous media significantly impacts the mass transfer rates. The assumption of simple equilibrium in predicting the behavior of a sequestration reservoir is likely adequate for long time periods, these results suggest that effective near-well and near-term reservoir pressure management may require inclusion of scCO2 mass transfer processes.
In this paper, we describe the various morphologies
of hydrocarbon residue found in the Miocene
M... more In this paper, we describe the various morphologies
of hydrocarbon residue found in the Miocene
Monterey Formation in California. Scanning electron
microscope photomicrographs clearly show various
shapes of hydrocarbon droplets in microchannels in
the Monterey Formation and hence provide insight
not only into the shape of hydrocarbon droplets during
migration, but also about the migration pathways
themselves. The small (5–10 μm) diameter droplets
are observed to have various shapes that include
spherical droplets, amalgamated droplets, sausageshaped
droplets, and elongate rod-shaped droplets.
Observations suggest that hydrocarbon droplets
move through the rock matrix into microchannels
where they coalesce into larger droplets and then
move into larger fractures. Different morphologies
are simply a result of amalgamation of simple
droplets during migration.
The Madison Limestone on the Moxa Arch, southwest Wyoming, USA contains large volumes (65–95%) of... more The Madison Limestone on the Moxa Arch, southwest Wyoming, USA contains large volumes (65–95%) of
supercritical CO2 that it has stored naturally for 50 million years. This reservoir also contains supercritical H2S,
aqueous sulfur complexes (SO4
2− and HS−), and sulfur-bearing minerals (anhydrite and pyrite). Although SO2
is not present, these sulfur-bearing phases are known products of SO2 disproportionation in other water–rock
systems. The natural co-occurrence of SO4
2−, S2−, supercritical CO2 and brine affords the opportunity to
evaluate the fate of a carbon–sulfur co-sequestration scenario.
Mineralogic data was obtained from drill core and aqueous geochemical data from wells outside and within
the current supercritical CO2–sulfur–brine–rock system. In addition to dolomite, calcite, and accessory sulfurbearing
minerals, the Madison Limestone contains accessory quartz and the aluminum-bearing minerals
feldspar, illite, and analcime. Dawsonite (NaAlCO3(OH)2), predicted as an important carbon sink in
sequestration modeling studies, is not present. After confirming equilibrium conditions for the Madison
Limestone system, reaction path models were constructed with initial conditions based on data from outside
the reservoir. Addition of supercritical CO2 to the Madison Limestone was simulated and the results compared
to data from inside the reservoir. The model accurately predicts the observed mineralogy and captures the
fundamental changes expected in a Madison Limestone-brine system into which CO2 is added. pH decreases
from 5.7 to 4.5 at 90 °C and to 4.0 at 110 °C, as expected from dissolution of supercritical CO2, creation of
carbonic acid, and buffering by the carbonate rock. The calculated redox potential increases by 0.1 V at 90 °C
and 0.15 V at 110 °C due to equilibrium among CO2, anhydrite, and pyrite. Final calculated Eh and pH match
conditions for the co-existing sulfur phases present in produced waters and core from within the reservoir.
Total dissolved solids increase with reaction progress, mostly due to dissolution of calcite with an
accompanying increase in dissolved bicarbonate. The Madison Limestone is a natural example of the
thermodynamic end point that similar fluid–rock systems will develop following emplacement of a
supercritical CO2–sulfur mixture and is a natural analog for geologic carbon–sulfur co-sequestration.
Porosity and permeability data for the Mississippian Madison Group in southwestern Wyoming were
c... more Porosity and permeability data for the Mississippian Madison Group in southwestern Wyoming were
compiled and evaluated to relate these properties to stratigraphic facies in the Madison Group. The study was
performed to provide baseline data for a geologic model required to sequester carbon in the study area. Public
domain geological and petrophysical data provided the basis for the evaluation. Using the available database
of wire-line logs and core from wells that penetrate the Madison Group, we place the wells within the regional
structural and sequence-stratigraphic framework and detail porosity-permeability relationships. The highest
porosity and permeability in the study area is present in the lower portion of the formation in dolomitic
packstone-to grainstone-dominated facies near the top of the transgressive systems tract. Wire-line logs were
used to calculate porosity values that correlate well with the more limited core-based data. The porosity in
the Madison Group has a tri-modal distribution with porosity related to depositional facies. The first group
is characterized by low porosity (<4 percent) with highly variable permeability for low porosity units. The
second has intermediate porosity (4–12 percent) with variable porosity-to-log permeability; the last is high
porosity (>12 percent) with a strong log permeability to porosity covariance. While lateral variations in porosity
related to depositional facies can be traced over tens of kilometers, natural fractures appear to be a significant
control on permeability in the lower porosity portions of the Madison.
The weathering of silicate minerals is an important long-term control on the global carbon budget... more The weathering of silicate minerals is an important long-term control on the global carbon budget. While the rate of mineral
weathering is influenced by the atmospheric variations in atmospheric carbon dioxide, the only measurements of those effects have
occurred during dissolution experiments at temperatures much higher than earth surface conditions. Thus, any climate models that
include such a relationship may not be able to fully couple variations in atmospheric carbon dioxide with the lithospheric sinks.
Our study presents a relationship for the dependence of plagioclase dissolution rates on PCO2 based on field data from a site in
the southeastern Sierra Nevada drainages. A series of canyons that have similar drainages show wide variability in water chemistry
that is attributed to variations in PCO2 from geothermal sources. This setting allowed us to isolate the effect of PCO2 on weathering
rates in conditions relevant to climate models. The results show that mineral dissolution rates are proportional to PCO2
0.45 when the
observed variations are attributed solely to variations in PCO2. This relationship is likely to be more applicable to climate models
than prior laboratory derived data.
Enhanced Oil Recovery by Geoffrey Thyne
Current economic conditions have challenged producers to find methods to lower costs and improve ... more Current economic conditions have challenged producers to find methods to lower costs and improve production. The current 50% reduction in oil prices means we need significant changes to stay competitive. Reservoir wettability can have a pronounced effect on hydrocarbon recovery and offers a method to substantially improve well performance and increase reserves for little investment. We know that each reservoir has a wettability state that leads to maximum recovery, but the initial wettability of a reservoir is usually not optimal. Traditionally, we have used surfactants and chemical agents to try and optimize reservoir wettability and recovery, but this process is expensive and does not always produce the desired results. This talk will outline recent advances in the science of reservoir wettability, as well as a practical methodology to realize the goal of increasing well recovery in unconventional and conventional reservoirs.
First, laboratory and field examples of successes and failures are considered. Using this basis, a theory is developed that directly links water chemistry and reservoir wettability. The theory also illuminates the key characteristics of the reservoir that control wettability. The approach can explain the successes and failures of low salinity waterflooding and provide the basis for designing the correct fluid chemistry while minimizing negative effects such as reservoir damage. This provides the ability to optimize reservoir wettability with simple systematic changes to the water chemistry of well fluids in both unconventional and conventional reservoirs.
The successful approach to reservoir wettability alteration requires several key steps: screening the formation to evaluate the applicability of the technique, simple laboratory tests to determine the optimal water chemistry and quantify the increased recovery, economic evaluations to estimate costs and benefits, and finally, comprehensive geochemical models to design the wettability-modifying fluids. The technique has several advantages compared to current methodologies for wettability alteration including substantially lower costs, no environmental impacts and ease of application.
We describe here a method for modifying the bulk composition (pH, salinity, hardness) of fracturi... more We describe here a method for modifying the bulk composition (pH, salinity, hardness) of fracturing fluids and overflushes to modify wettability and increase oil recovery from tight formations. Oil wetting of tight formations is usually controlled by adhesion to illite, kerogen, or both; adhesion to carbonate minerals may also play a role when clays are minor. Oil-illite adhesion is sensitive to salinity, dissolved diva-lent cation content, and pH. We measure adhesion between middle Bakken formation oil and core to verify a surface complexation model of reservoir wettability. The agreement between the model and experiments suggests that wettability trends in tight formations can be quantitatively predicted and that the bulk compositions of fracturing fluid and overflush compositions might be individually tailored to increase oil recovery. Introduction There is an enormous incentive to improve tight formation oil recoveries from their typically low value of 6–8% of the original oil in place. Increased oil recovery would boost reserves while lowering unit operating costs. Here we examine how oil recovery might be increased by designing the bulk composition of the fracturing fluid (salinity, pH, hardness), or that of ''squeeze job " overflushes, to make the formation more water-wet. We focus on chemically enhancing oil recovery, but expect that new physical procedures such as high intensity fracturing, refracturing, and choking will aid the chemical enhancement as well since the chemical and physical processes are largely independent. To do this, we identify the primary wettability-affecting reactions in tight formations and build a geochemical surface complexation model to predict how these reactions respond to changes in fluid chemistry. We then test the model by measuring the effect of salin-ity and pH on adhesion of middle Bakken oil to core. These measurements are combined to describe how fracturing or squeeze job fluids might be altered to increase water wetting and recover more oil from the middle Bakken. The general approach should apply to other tight formations as well. Tight formations such as the Bakken and the Eagle Ford are source-reservoir systems primarily made up of quartz, feldspar, calcite, dolomite, illite clay, and as much as 5–10% percent kerogen. Table 1 shows approximate mineralogies of the three largest tight formations/basins in the US. Oil tends to be associated with illite, or kerogen when present, or both (Bryndzia and Braunsdorf, 2014). A thin layer of water separates oil from the surface of reservoir minerals (Buckley et al., 1989; Dubey and Doe, 1993) as shown schematically in Fig. 1. Illite, the solid in Fig. 1, possesses a negative charge on its basal plane because of heterovalent substitution in the lattice. Illite negative surface charge is balanced by cations from solution, such as Na + , and by positively charged groups present at the oil-water interface, e.g. nitrogen bases, –NH + , and calcium-terminated carboxyls, –COOCa +. Electrostatic attraction between positively charged oil surface groups and negatively charged clay basal planes, is likely to control oil adhesion in sandstones containing clays such as illite or smectite (Brady and Krumhansl, 2013). While the number of negatively charged basal plane clay groups is fixed by lattice composition, the abundance of charged oil surface groups depends upon the history of the oil and chemistry of the oil and the connate fluid (e.g. pH, salinity, Ca + Mg). High numbers of –NH + and –COOCa + groups should favor formation of electrostatic ''bridges " and oil adhesion – that is increase the degree of oil wetting. Decreasing the numbers of –NH + and –COOCa + groups should reduce oil adhesion, making the formation more water wet, resulting in greater oil mobility and recovery.
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Papers by Geoffrey Thyne
of hydrocarbon residue found in the Miocene
Monterey Formation in California. Scanning electron
microscope photomicrographs clearly show various
shapes of hydrocarbon droplets in microchannels in
the Monterey Formation and hence provide insight
not only into the shape of hydrocarbon droplets during
migration, but also about the migration pathways
themselves. The small (5–10 μm) diameter droplets
are observed to have various shapes that include
spherical droplets, amalgamated droplets, sausageshaped
droplets, and elongate rod-shaped droplets.
Observations suggest that hydrocarbon droplets
move through the rock matrix into microchannels
where they coalesce into larger droplets and then
move into larger fractures. Different morphologies
are simply a result of amalgamation of simple
droplets during migration.
supercritical CO2 that it has stored naturally for 50 million years. This reservoir also contains supercritical H2S,
aqueous sulfur complexes (SO4
2− and HS−), and sulfur-bearing minerals (anhydrite and pyrite). Although SO2
is not present, these sulfur-bearing phases are known products of SO2 disproportionation in other water–rock
systems. The natural co-occurrence of SO4
2−, S2−, supercritical CO2 and brine affords the opportunity to
evaluate the fate of a carbon–sulfur co-sequestration scenario.
Mineralogic data was obtained from drill core and aqueous geochemical data from wells outside and within
the current supercritical CO2–sulfur–brine–rock system. In addition to dolomite, calcite, and accessory sulfurbearing
minerals, the Madison Limestone contains accessory quartz and the aluminum-bearing minerals
feldspar, illite, and analcime. Dawsonite (NaAlCO3(OH)2), predicted as an important carbon sink in
sequestration modeling studies, is not present. After confirming equilibrium conditions for the Madison
Limestone system, reaction path models were constructed with initial conditions based on data from outside
the reservoir. Addition of supercritical CO2 to the Madison Limestone was simulated and the results compared
to data from inside the reservoir. The model accurately predicts the observed mineralogy and captures the
fundamental changes expected in a Madison Limestone-brine system into which CO2 is added. pH decreases
from 5.7 to 4.5 at 90 °C and to 4.0 at 110 °C, as expected from dissolution of supercritical CO2, creation of
carbonic acid, and buffering by the carbonate rock. The calculated redox potential increases by 0.1 V at 90 °C
and 0.15 V at 110 °C due to equilibrium among CO2, anhydrite, and pyrite. Final calculated Eh and pH match
conditions for the co-existing sulfur phases present in produced waters and core from within the reservoir.
Total dissolved solids increase with reaction progress, mostly due to dissolution of calcite with an
accompanying increase in dissolved bicarbonate. The Madison Limestone is a natural example of the
thermodynamic end point that similar fluid–rock systems will develop following emplacement of a
supercritical CO2–sulfur mixture and is a natural analog for geologic carbon–sulfur co-sequestration.
compiled and evaluated to relate these properties to stratigraphic facies in the Madison Group. The study was
performed to provide baseline data for a geologic model required to sequester carbon in the study area. Public
domain geological and petrophysical data provided the basis for the evaluation. Using the available database
of wire-line logs and core from wells that penetrate the Madison Group, we place the wells within the regional
structural and sequence-stratigraphic framework and detail porosity-permeability relationships. The highest
porosity and permeability in the study area is present in the lower portion of the formation in dolomitic
packstone-to grainstone-dominated facies near the top of the transgressive systems tract. Wire-line logs were
used to calculate porosity values that correlate well with the more limited core-based data. The porosity in
the Madison Group has a tri-modal distribution with porosity related to depositional facies. The first group
is characterized by low porosity (<4 percent) with highly variable permeability for low porosity units. The
second has intermediate porosity (4–12 percent) with variable porosity-to-log permeability; the last is high
porosity (>12 percent) with a strong log permeability to porosity covariance. While lateral variations in porosity
related to depositional facies can be traced over tens of kilometers, natural fractures appear to be a significant
control on permeability in the lower porosity portions of the Madison.
weathering is influenced by the atmospheric variations in atmospheric carbon dioxide, the only measurements of those effects have
occurred during dissolution experiments at temperatures much higher than earth surface conditions. Thus, any climate models that
include such a relationship may not be able to fully couple variations in atmospheric carbon dioxide with the lithospheric sinks.
Our study presents a relationship for the dependence of plagioclase dissolution rates on PCO2 based on field data from a site in
the southeastern Sierra Nevada drainages. A series of canyons that have similar drainages show wide variability in water chemistry
that is attributed to variations in PCO2 from geothermal sources. This setting allowed us to isolate the effect of PCO2 on weathering
rates in conditions relevant to climate models. The results show that mineral dissolution rates are proportional to PCO2
0.45 when the
observed variations are attributed solely to variations in PCO2. This relationship is likely to be more applicable to climate models
than prior laboratory derived data.
Enhanced Oil Recovery by Geoffrey Thyne
First, laboratory and field examples of successes and failures are considered. Using this basis, a theory is developed that directly links water chemistry and reservoir wettability. The theory also illuminates the key characteristics of the reservoir that control wettability. The approach can explain the successes and failures of low salinity waterflooding and provide the basis for designing the correct fluid chemistry while minimizing negative effects such as reservoir damage. This provides the ability to optimize reservoir wettability with simple systematic changes to the water chemistry of well fluids in both unconventional and conventional reservoirs.
The successful approach to reservoir wettability alteration requires several key steps: screening the formation to evaluate the applicability of the technique, simple laboratory tests to determine the optimal water chemistry and quantify the increased recovery, economic evaluations to estimate costs and benefits, and finally, comprehensive geochemical models to design the wettability-modifying fluids. The technique has several advantages compared to current methodologies for wettability alteration including substantially lower costs, no environmental impacts and ease of application.
of hydrocarbon residue found in the Miocene
Monterey Formation in California. Scanning electron
microscope photomicrographs clearly show various
shapes of hydrocarbon droplets in microchannels in
the Monterey Formation and hence provide insight
not only into the shape of hydrocarbon droplets during
migration, but also about the migration pathways
themselves. The small (5–10 μm) diameter droplets
are observed to have various shapes that include
spherical droplets, amalgamated droplets, sausageshaped
droplets, and elongate rod-shaped droplets.
Observations suggest that hydrocarbon droplets
move through the rock matrix into microchannels
where they coalesce into larger droplets and then
move into larger fractures. Different morphologies
are simply a result of amalgamation of simple
droplets during migration.
supercritical CO2 that it has stored naturally for 50 million years. This reservoir also contains supercritical H2S,
aqueous sulfur complexes (SO4
2− and HS−), and sulfur-bearing minerals (anhydrite and pyrite). Although SO2
is not present, these sulfur-bearing phases are known products of SO2 disproportionation in other water–rock
systems. The natural co-occurrence of SO4
2−, S2−, supercritical CO2 and brine affords the opportunity to
evaluate the fate of a carbon–sulfur co-sequestration scenario.
Mineralogic data was obtained from drill core and aqueous geochemical data from wells outside and within
the current supercritical CO2–sulfur–brine–rock system. In addition to dolomite, calcite, and accessory sulfurbearing
minerals, the Madison Limestone contains accessory quartz and the aluminum-bearing minerals
feldspar, illite, and analcime. Dawsonite (NaAlCO3(OH)2), predicted as an important carbon sink in
sequestration modeling studies, is not present. After confirming equilibrium conditions for the Madison
Limestone system, reaction path models were constructed with initial conditions based on data from outside
the reservoir. Addition of supercritical CO2 to the Madison Limestone was simulated and the results compared
to data from inside the reservoir. The model accurately predicts the observed mineralogy and captures the
fundamental changes expected in a Madison Limestone-brine system into which CO2 is added. pH decreases
from 5.7 to 4.5 at 90 °C and to 4.0 at 110 °C, as expected from dissolution of supercritical CO2, creation of
carbonic acid, and buffering by the carbonate rock. The calculated redox potential increases by 0.1 V at 90 °C
and 0.15 V at 110 °C due to equilibrium among CO2, anhydrite, and pyrite. Final calculated Eh and pH match
conditions for the co-existing sulfur phases present in produced waters and core from within the reservoir.
Total dissolved solids increase with reaction progress, mostly due to dissolution of calcite with an
accompanying increase in dissolved bicarbonate. The Madison Limestone is a natural example of the
thermodynamic end point that similar fluid–rock systems will develop following emplacement of a
supercritical CO2–sulfur mixture and is a natural analog for geologic carbon–sulfur co-sequestration.
compiled and evaluated to relate these properties to stratigraphic facies in the Madison Group. The study was
performed to provide baseline data for a geologic model required to sequester carbon in the study area. Public
domain geological and petrophysical data provided the basis for the evaluation. Using the available database
of wire-line logs and core from wells that penetrate the Madison Group, we place the wells within the regional
structural and sequence-stratigraphic framework and detail porosity-permeability relationships. The highest
porosity and permeability in the study area is present in the lower portion of the formation in dolomitic
packstone-to grainstone-dominated facies near the top of the transgressive systems tract. Wire-line logs were
used to calculate porosity values that correlate well with the more limited core-based data. The porosity in
the Madison Group has a tri-modal distribution with porosity related to depositional facies. The first group
is characterized by low porosity (<4 percent) with highly variable permeability for low porosity units. The
second has intermediate porosity (4–12 percent) with variable porosity-to-log permeability; the last is high
porosity (>12 percent) with a strong log permeability to porosity covariance. While lateral variations in porosity
related to depositional facies can be traced over tens of kilometers, natural fractures appear to be a significant
control on permeability in the lower porosity portions of the Madison.
weathering is influenced by the atmospheric variations in atmospheric carbon dioxide, the only measurements of those effects have
occurred during dissolution experiments at temperatures much higher than earth surface conditions. Thus, any climate models that
include such a relationship may not be able to fully couple variations in atmospheric carbon dioxide with the lithospheric sinks.
Our study presents a relationship for the dependence of plagioclase dissolution rates on PCO2 based on field data from a site in
the southeastern Sierra Nevada drainages. A series of canyons that have similar drainages show wide variability in water chemistry
that is attributed to variations in PCO2 from geothermal sources. This setting allowed us to isolate the effect of PCO2 on weathering
rates in conditions relevant to climate models. The results show that mineral dissolution rates are proportional to PCO2
0.45 when the
observed variations are attributed solely to variations in PCO2. This relationship is likely to be more applicable to climate models
than prior laboratory derived data.
First, laboratory and field examples of successes and failures are considered. Using this basis, a theory is developed that directly links water chemistry and reservoir wettability. The theory also illuminates the key characteristics of the reservoir that control wettability. The approach can explain the successes and failures of low salinity waterflooding and provide the basis for designing the correct fluid chemistry while minimizing negative effects such as reservoir damage. This provides the ability to optimize reservoir wettability with simple systematic changes to the water chemistry of well fluids in both unconventional and conventional reservoirs.
The successful approach to reservoir wettability alteration requires several key steps: screening the formation to evaluate the applicability of the technique, simple laboratory tests to determine the optimal water chemistry and quantify the increased recovery, economic evaluations to estimate costs and benefits, and finally, comprehensive geochemical models to design the wettability-modifying fluids. The technique has several advantages compared to current methodologies for wettability alteration including substantially lower costs, no environmental impacts and ease of application.
This paper provides information pertinent to the oil recovery by law salinity flooding which could be utilized to maximize the response of experimental system, better understand the mechanism, and help screen candidates for low salinity waterflooding.
Set of experiments were performed by using low salinity brine for the tertiary waterflood recovery method where oil saturated cores were first flooded with high salinity brine to simulate the secondary recovery method. In the second set of experiments, oil saturated cores were directly flooded with the low salinity brine. Conductivity and pH analysis of effluent brines were performed in all the single phase and two phase experiments.
Increase in oil recovery with low salinity brine as the invading brine was observed in both secondary and tertiary modes (2-8% OOIP) with Berea sandstone. However, higher oil recoveries (5-8% OOIP) were observed when low salinity waterflooding was implemented as a secondary recovery method. Minnelusa reservoir cores had little to no response to low salinity brine when it was used as a tertiary recovery method. However, Minnelusa cores showed an increase in oil recovery (10-22 % OOIP) with both types of crude oils when it was used as a secondary recovery method. An increase in pH of the effluent brine was observed during the low salinity brine injection in both Minnelusa and Berea cores. However, magnitude of the pH increase was smaller with the Minnelusa cores compared to Berea cores.
The level of investigation into the mechanism of low salinity incremental production has sharply increased in the past two years. Most of the studies focus on core floods using the tertiary mode. Our work contributes systematic coupled secondary and tertiary mode experiments that offer an expanded dataset for all researchers to use in investigation of the mechanisms.
This document contains a short review of shale oil and gas production, an overview of the relevant features of shale pore systems, and briefly summarizes the Bakken and Eagle Ford Shale properties of interest as regards wettability. A review of the current standard methodologies for measuring wettability and their limitations showed that current methods are unable to provide fast quantitative results. A new method is aloso reviewed that offers rapid measurement of wettability with semi-quantitative results that can be easily refined. This modified flotation method offers the advantages of low cost and rapid measurement of many samples over a short time. The method allows measurement of not just wettability, but also pH and associated aqueous parameters and can be performed at elevated temperature applicable to the formations of interest. The table below summarizes the important aspects of each technique.
samples and 11 hydrochemical variables) from southeastern California by fuzzy c-means
(FCM) and hierarchical cluster analysis (HCA) clustering techniques is performed and
its application to hydrochemical facies delineation is discussed. Results from both FCM
and HCA clustering produced cluster centers (prototypes) that can be used to identify
the physical and chemical processes creating the variations in the water chemistries. There
are several advantages to FCM, and it is concluded that FCM, as an exploratory data
analysis technique, is potentially useful in establishing hydrochemical facies distribution
and may provide a better tool than HCA for clustering large data sets when overlapping or
continuous clusters exist.
can be conceptualized as dual-porosity flow systems subject to one-dimensional advective-dispersive transport in
the bedrock fractures and diffusive transport in the bedrock matrix. This article demonstrates how the physical
characteristics of such flow systems can be parameterized for use in PHREEQC, it provides a method for minimizing
numerical dispersion in PHREEQC simulations, and it compares PHREEQC simulations with results of
an analytical solution. The simulations assumed a dual-porosity conceptual model involving advective-reactivedispersive
transport in the mobile zone (bedrock fracture) and diffusive-reactive transport in the immobile zone
(bedrock matrix). The results from the PHREEQC dual-porosity transport model that uses a finite-difference
approach showed excellent agreement compared with an analytical solution.
water chemistry samples into homogeneous groups is an
important tool for the characterization of hydrologic systems.
In this paper we test the performance of the many
available graphical and statistical methodologies used to
classify water samples including: Collins bar diagram,
pie diagram, Stiff pattern diagram, Schoeller plot, Piper
diagram, Q-mode hierarchical cluster analysis, K-means
clustering, principal components analysis, and fuzzy
k-means clustering. All the methods are discussed and
compared as to their ability to cluster, ease of use, and
ease of interpretation. In addition, several issues related
to data preparation, database editing, data-gap filling,
data screening, and data quality assurance are discussed
and a database construction methodology is presented.
The use of graphical techniques proved to have limitations
compared with the multivariate methods for large
data sets. Principal components analysis is useful for data
reduction and to assess the continuity/overlap of clusters
or clustering/similarities in the data. The most efficient
grouping was achieved by statistical clustering
techniques. However, these techniques do not provide information
on the chemistry of the statistical groups. The
combination of graphical and statistical techniques provides
a consistent and objective means to classify large
numbers of samples while retaining the ease of classic
graphical presentations.
alternating mountains and alluvial basins. Surface water resources are limited in this arid region and water demand is mainly
met by groundwater pumpage. In a classic Basin and Range groundwater system, water flows from recharge areas in the
mountains to discharge areas in adjacent valleys. Discharge areas are generally occupied by playas where large amounts of salt
deposition occur due to evaporating groundwater.
Hydrochemical data from a total of 1368 spring, surface, and well water samples collected over an 80-year period were used
to evaluate water quality and to determine processes that control water chemistry. Q-mode hierarchical cluster analysis (HCA)
was employed for partitioning the water samples into hydrochemical facies, also known as water groups or water types. Five
major water groups resulted from the HCA analysis. The samples from the area were classified as recharge area waters (Ca–
Na–HCO3 water and Na–Ca–HCO3 water), transition zone waters (Na–HCO3–Cl water), and discharge area waters (Na–Cl
water and more concentrated Na–Cl water). Spatial plots of the major statistical groups show that the samples that belong to the
same group are located in close proximity to one another suggesting the same processes and/or flowpaths. Inverse geochemical
models of the statistical groups were developed using PHREEQC to elucidate the chemical reactions controlling water
chemistry. The inverse geochemical modeling demonstrated that relatively few phases are required to derive water chemistry in
the area. In a broad sense, the reactions responsible for the hydrochemical evolution in the area fall into four categories: (1)
silicate weathering reactions; (2) dissolution of salts; (3) precipitation of calcite, amorphous silica, and clay minerals; and (4)
ion exchange.
specific solutes or isotopes as tracers of groundwater
flow.We present a technique that uses standard hydrochemical
information to create statistically based
hydrochemical facies, which are then used as tracers
of groundwater flow. This approach reduces potential
subjective bias during interpretation of single tracer
data in complex systems with multiple sources or conflicting
multiple tracer data. Standard hydrochemical
data from 1,368 water samples that spanned more
than 80 years were analyzed using cluster analysis
to decipher groundwater flow paths in Indian Wells
Valley (IWV), California. The statistically derived hydrochemical
facies form distinct spatial patterns in
which all major-ion concentrations increase progressively
from Sierra Nevada (recharge) to China Lake
playa (discharge), consistent with the topographically
driven flow of groundwater (the typical case for basin
and range flow systems). However, once individual
samples could be placed in the context of the normal
hydrochemical evolution, anomalies are readily identifiable.
The distribution of water chemistry in the
southeastern part of the IWV does not conform to
the regional trend. Groundwater from that part of the
IWV is statistically more similar to waters from the
Kern Plateau area (in the high Sierra Nevada outside
the local watershed) than to waters from the local
watershed. The groundwater is interpreted to originate
from the fracture-directed interbasin flow from
the Kern Plateau area that is directly recharging the
alluvial aquifer in the subsurface. Inclusion of this flow
could substantially alter current water budgets and
water resources management approaches.
as high as 0.211 mg/L in the Kern Fan Element of the Kern Water
Bank, a proposed groundwater recharge project. General
constituent analyses and stable isotopes were utilized to identify
four distinct groundwater types: 1) a Sierra Nevada-sourced,
Na-HCOj water (eastside groundwater); 2) a Coast Rangesourced,
S04-rich water (westside groundwater); 3) an easternsourced
anthropogenically altered, mixed-ion water (anthro-east
groundwater); and 4) a western-sourced anthropogenically altered
Na-Cl water (anthro-west groundwater). Oil field and agricultural
activities such as brine disposal and pesticide application
account for anthropogenically altered waters.
The highest concentrations of dissolved As are closely associated
with the Na-HC03 water. Low As concentrations (<0.005 mg/L)
in Sierran recharge waters at the head of the flow path, combined
with minimal increases in total dissolved solids along the
groundwater flow path, suggest dissolution of aquifer framework
materials are the likely source of As in the main aquifer.
The western anthropogenically altered waters have slightly elevated
As concentrations and show evidence of possible alteration
by brine disposal, indicating human activities may be a potential
source of As. However, the western-altered waters are not
well connected hydraulically to the main aquifer; therefore human
activities appear to be relatively insignificant as a source of
dissolved As.