Fossil Fuels

Fossil fuels are found within the top layer of the earth's crust and are the result of dead plants and animal remains that have been chemically changed by the heat and pressure of the earth over hundreds of millions of years. Almost 90% of the earth.s energy is derived from the burning of these fossil fuels - supplies of which are often seen as the catalyst of regional and global conflict.

Because of the significant amount of time it takes to develop natural fossil fuels, this fuel source is seen as "non-renewable". Therefore as the earth's population continues to grow and develop, the demand for these types of fuels dramatically increases. To address this increased demand there is there is large amounts of money and time being spent in the development of renewable fuels sources. However until there is a significant breakthrough in the production, refinement, and transportation of these renewable energy sources, continued fossil fuel research, recovery, and refinement still represents a major component of the global energy portfolio, and will for years to come.

There are two main types of oil and gas recovery around globe - conventional and unconventional, and University of Kansas researchers are working cross departmentally to develop the latest innovations in each. Programs like TORP (tertiary, oil, recovery, project), Geology, and the Kansas Geological Survey regularly collaborate to maximize the amounts of oil and gas industry is able to recover while exploring advancements in technology that promote clean emissions and CO2 storage.

This section highlights some of these advancements and the cross-discipline work going through the University of Kansas Energy Council.

• Conventional oil and gas recovery:

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  • Enhanced Oil Recovery:

  Despite what you have heard about pools of "black gold", oil is actually found in rock. The oil resides in the small spaces or pores that exist between the solid particles that form the rock. The area where oil exists in the rock is called the reservoir. In order for the oil to be produced there has to be a fluid available to displace the oil and a force to push the oil through the rock to the well bore.

  In primary production, nature supplies the force and fluid to move the oil. Gas associated with oil or water from an aquifer is the driving force and fluid that moves the oil through the rock. In this scenario oil can simply pumped to the surface. When the cost of pumping the oil exceeds the value of the oil due to the loss of the natural driving force, then another method has to be selected to produce the oil.

  During secondary production water is injected in the reservoir to displace and produce additional oil that was not recovered during primary production. In most cases an additional 10% to 20% of the oil in a reservoir can be recovered during this stage. This process is called waterflooding and is economical because water is more efficient than gas in displacing the oil. However, after primary and secondary recovery methods have both reached their economic limits, typically around two-thirds of the original oil still remains in the reservoir.

  This unrecovered oil amounts to roughly 300 billion barrels nationally; 10 billion in the State of Kansas.

  Enhanced, oil recovery is generally expensive and involves the use of chemicals to mobilize trapped oil, or heat to thin the oil so it flows more freely. However an additional 5% to 15% of the oil in a reservoir can be recovered during this stage. So, after primary, secondary and tertiary, or enhanced oil recovery techniques have been applied - on the order of 50% of the oil in the reservoir will have been recovered.

  Recently, in a project linking KU Energy Council members from the Kansas Geological Survey and the Tertiary Oil Recovery Project, in conjunction with representatives from Industry, the State of Kansas Department of Commerce, and the U.S. Department of Energy a field demonstration was conducted in central Kansas aimed at showcasing the potential of the use of miscible flooding to enhance oil recovery.

  • Microbial techniques:

  Geomicrobiology is an emerging interdisciplinary field that combines concepts and techniques from microbiology, geology, chemistry, physics, and mathematics. Microorganisms represent a living component of subsurface systems and impact both water and rock through their metabolic processes.

  This particular field is shows particular promise in the recovery of fossil fuels.

  • Coal bed methane:

  Since the early 1980s, natural gas has been intentionally produced from coalbeds. Spurred on initially by significant tax credits, this sub-industry has grown rapidly in recent years, now contributing in excess of 5% (1 tcf) of the nation's natural gas production. The term "coalbed methane" (CBM) is derived from the coal mining industry, describing the gas which is a common hazard in coal mining operations. Methane typically comprises 95 to 100 percent of the hydrocarbon constituents present in coalbed gas, although it is common for the mixture to contain a number of different hydrocarbon gases, plus minor amounts of nitrogen and carbon dioxide.

  In the early Twentieth century, "shale gas" was commonly produced in the midcontinent oil and gas fields. The common source of this gas was later proven to be the coalbeds, which are prevalent in the region. Coalbed methane reservoirs of the midcontinent are high, volatile bituminous A, B, and C coals. Gas can be produced from coals of nearly every rank; however, some of the less attractive coals (e.g., lignite) may require substantial bed thickness to develop adequate reserves. The industry continues to grow, and is active in nearly every sedimentary basin in the United States, primarily the San Juan, Black Warrior, and Raton basins.

  Coal, a very complex mixture of organic and inorganic compounds, differs from other sedimentary reservoirs as the gas is adsorbed within the matrix of the rock rather than compressed in pore spaces. A typical one-foot thickness of coal six hundred feet deep is capable of containing as much gas as a typical sandstone reservoir five thousand feet deep. Another unique characteristic of coalbed production is its producing behavior. In most cases, initial production of gas is quite low while water production may be high. As the water is withdrawn, and the bottom-hole pressure decreases in the reservoir near the wellbore, gas production gradually increases. During the first few producing months the water-producing rate will continue to decrease accompanied by an increase in the gas-producing rate, until a pseudo-steady state occurs for both phases.

  Due to its unique characteristics, coalbed evaluation requires methods not prevalent in other oil and gas producing operations. Coal rank is determined by measuring the light reflected from the surface of coal samples - vitrinite reflectance. Drill cuttings or core samples are analyzed for gas-in-place content by means of a canister test. Proximate analysis of coal, the same method utilized by the mining industry to determine coal quality, is a usable tool to estimate gas absorbing potential of various coals. The plot of a laboratory measurement of a coals gas-absorbing capability, the isotherm, is useful in determining the gas-content of coals, critical pressures, and estimating residual gas at abandonment.

  The gas storage capacity of a coal is a complex function of reservoir temperature and pressure, composition, micropore structure and molecular properties of the adsorbed gas. In addition the geology of the coal deposit and the surrounding rocks can affect gas content and deliverability (e.g., cleat structure). Core samples are being collected from continuous cores using the KGS's coring rig and wells of opportunity. Samples are analyzed to determine the gas-in-place value, gas composition, and gas storage capacity. Selected samples of key coals are characterized as to cleat structure and by proximate analysis to determine ash content, moisture, volatile matter and fixed-carbon content.

  The Kansas Geological Survey in cooperation with several companies active in the area has undertaken a research project to evaluate the coals of eastern Kansas. The project is a broad based resource assessment of coalbed gas in eastern Kansas and western Missouri.

  • Co2 sequestration:

  Carbon dioxide's possible role in global climate change has challenged scientists to find ways to keep this gas out of the atmosphere. Pumping carbon dioxide (CO2) in deep underground rock formations, a process called CO2 sequestration, may be one way to safely dispose of CO2 over long periods of time.

  Members of the KU Energy Council have worked on projects that have partnered with five midwestern state geological surveys to provide tools to analyze the amount of carbon dioxide available from a source, the geological feasibility of using underground reservoirs, the long-term effects on the reservoir, and the cost of compression and transportation from the CO2 source to the sequestration site.

  In addition to the potential environmental benefits of CO2 sequestration, pumping CO2 into reservoirs can also enhance the recovery of oil from these underground rocks. Carbon dioxide is pumped under high pressure into the reservoir through injection wells, creating a CO2 flood bank. The front of this flood bank mixes with the trapped oil, causing it to become more mobile. As more oil is encountered, an oil bank forms in front of the CO2 and is pushed toward producing wells where it is pumped to the surface.

  • Biosurfactants:

  The US domestic oil production has been in a steady decline for the past 30 years. Significant effort has been devoted to improving oil recovery by using various secondary and tertiary recovery methods. Although these efforts have resulted in a significant increase in recovery efficiency, almost 2/3 (~350 billion barrels) of the US oil reserve still remains stranded and unproduced.

  Previous research has demonstrated that the injection of surfactants into oil reservoirs can be very effective in mobilizing stranded oil. However, the economics of surfactant injection have rarely been favorable in actual field applications because of the cost associated with high-concentration chemical surfactants.

  Members of the KU Energy Council are working on a three-year research project to evaluate the use of low-cost biosurfactants produced from high-starch agriculture process waste streams (e.g., potato or rice process effluents) to improve oil recovery in fractured carbonate reservoirs.

  The project examines the ability of the biosurfactants to mediate wettability changes that positively affect oil recovery in fractured carbonate rock by accelerating the spontaneous imbibition process during waterflooding. The successful completion of this project will not only significantly increase the domestic oil production by recovering the previously unrecoverable stranded oil but also benefit the environment by promoting the beneficial reuse of agriculture process waste products.

  The hypothesis of this research is that dilute solutions of biosurfactants produced from agriculture process waste streams can compete favorably both in performance and process economics with dilute chemical surfactants in mediating changes in wettability that positively impact oil recovery in fractured carbonate reservoirs.

  To test the hypothesis, the performance of the biosurfactants are being evaluated using the key variables that affect process economics. These key variables include incremental oil recovery, surfactant loss due to adsorption and retention, surfactant cost, and surfactant injection cost. A commercial chemical surfactant has been selected as the benchmark for performance and process economics comparisons.

  
  

• Key research:




• Unconventional oil and gas recovery:

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• Sequence stratigraphy:

• Petroleum geology:

Petroleum may occur in any porous rock, but it is usually found in sedimentary rocks such as sandstone or limestone. Sedimentary rocks are grouped into three major classes: clastic, carbonate, and evaporitic.

Clastic rocks are those that are formed by the accumulation and cementation of sedimentary particles derived from weathered fragments of preexisting rocks. Weathering processes, such as freezing and thawing, rain, wind, and other similar events, break down the parent rock into small particles that can then be transported by wind and rain runoff. Streams carry the mud, sand, and gravel from the source area down to its final resting place, be that a stream channel, floodplain, lake, or ultimately the sea. There it accumulates, is buried and compacted by later-arriving sediments, and cemented to form sedimentary rocks. The mud compacts to shale or mudstone, the sands are cemented by silica or calcite to form sandstones, and the gravels become conglomerates. Sandstones, because of the inherent porosity between their grains, often become excellent reservoirs for oil or natural gas.

Carbonate rocks are limestones and dolomites. They usually form in warm seawater at shallow depths, ankle deep to about 20 ft (6 m), where various plants and animals thrive. The hard, usually calcareous parts of the organisms pile up on the seafloor over time, forming beds of lime particles. Algae, simple plants, are one of the greatest contributors of lime particles, but any shelled animal may contribute whole or fragmented shells to the pile. Reefs, banks of lime mud, and lime sand bars are commonly found preserved in rocks.

Evaporites are formed by the direct precipitation of minerals by evaporation of seawater. Resulting rocks are ordinary salt (halite-sodium chloride), gypsum (calcium sulfate with some water), and various forms of potash salts. When gypsum is buried to considerable depths, the water is expelled from the crystals and "anhydrite" (meaning simply "without water"), a harder crystalline rock, results. Evaporites are not porous, although they are readily dissolved by water and are not source rocks for petroleum. However, they may be formed in highly stagnant water where black mud, rich in organic matter, may also be deposited, and so are commonly associated with good source rocks. Because they are impermeable, evaporates often form seals on other reservoir rocks. Evaporites of the Sumner Group form the upper seal of Chase Group carbonate reservoirs in the giant Hugoton gas area in southwestern Kansas.

• Geochemistry and diagenesis:

• Carbonate geology:

New research will include industry-sponsored work on experimental carbonate precipitation and dissolution examining novel approaches to understanding quantifying carbonate diagenesis in natural systems.

• Clastics:

In clastic sedimentology, diagenesis, and stratigraphy, we have five faculty, Anthony Walton and Diane Kamola, teach courses in petroleum geology, basin analysis, and terrigenous depositional systems. Bob Goldstein and Lynn Watney work on the sedimentology and sequence stratigraphy of mixed carbonate/clastic/evaporite systems and also studies the diagenesis of clastic reservoirs. Steve Hasiotis integrates trace fossils with the sedimentology and stratigraphy of continental systems. Tim Carr is active in research into strata hosting coal-bed methane resources and incised valley fill sandstones in Kansas.

Currently, many students do research in the areas of three-dimensional analysis of clastic reservoir systems and their outcrop analogs. Students are exceptionally well prepared for working in areas of quantitative three-dimensional visualization of clastic reservoirs, and others have carefully integrated clastic reservoirs and fluid flow.

• Geophysics:

Geophysical research and teaching at the University of Kansas are centered in the Department of Geology and Department of Physics and Astronomy. Both departments have graduate programs leading to the Master of Science and Doctor of Philosophy degrees, with emphasis in geophysics. The Kansas Geological Survey, which is part of the university, contributes significantly in research, teaching, and student support through Rick Miller and the Exploration Services team. This cooperation is a real strength of the geophysics program at KU. Our graduate curriculum in geophysics provides students with a strong foundation in physics, geology, and geophysics, as well as advanced education, both in the classroom and in the field, and in theoretical and applied geophysics. The program consists of four faculty. Rick Miller has an active an innovative program applying seismic techniques to imaging the subsurface. Don Steeples concentrates on developing new high resolution seismic techniques. Ross Black is interested in processing, structure of the crust of the western US, and GIS techniques.

• Reservoir modeling:

One of the world's giants in natural gas production, the Hugoton Natural Gas Field in southwestern Kansas has seen production declines over the past decade. Study by the Kansas Geological Survey is helping operators extend the life of the field and more efficiently recover the gas that remains. Ten industry partners joined with KGS scientists to produce a computer model to help determine how much gas is left in the field and where it is located. Based on the model, researchers estimate 65% of tgas (35 trillion cubic feet) may have been removed from the field since its discovery in 1922. The Hugoton field has long been a major source of royalties, tax revenue, and other income generated in 10 counties of southwestern Kansas. Besides enriching the Hugoton's prospects, the studies findings can be applied to similar gas reservoirs worldwide. Most of the remaining natural gas is in less permeable rock layers where the gas moves more slowly and can be more difficult to produce.

• Linked energy systems