689 research outputs found
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Report of Investigations No. 123 Petroleum Potential of the Palo Duro Basin, Texas Panhandle
UT Librarie
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Potential for Petroleum Resources in the Palo Duro Basin Area, Texas Panhandle
Investigations of the petroleum potential of the Palo Duro Basin have been underway since 1978. This report contains the results of studies carried out during the 1983-84 fiscal year, which have not yet been published.
The section of this report dealing with pre-Pennsylvanian units in the basin represents the final results of work done on these rocks. Work is continuing on Pennsylvanian and younger strata as further data become available.
The second part of this report presents additional data recently gathered on these units.Bureau of Economic Geolog
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Stratigraphy of the Palo Duro Basin- A Status Report
Since the beginning of Bureau research into the Palo Duro Basin area in 1979, more than 150 geologic reports have been completed and published. Approximately 30 are currently in press. Because of continuing research in the area, however, a great deal of additional work still remains unpublished. This report provides an update on ongoing, as yet unpublished research into the stratigraphy of the Palo Duro Basin (fig. 1).
Although investigations on some scale are being carried out on essentially all of the stratigraphic horizons in the Palo Duro Basin area (fig. 2), only those units which have recently been the focus of relatively concentrated research efforts are reported herein. This necessarily includes those units being analyzed for hydrocarbon potential (Mississippian and Pennsylvanian Systems), those that are the focus of hydrologic studies (Permian Wolfcamp Series and Permo-Triassic Dockum Group and Dewey Lake Formation), and the proposed waste repository horizon (Permian San Andres Formation). Work on other stratigraphic units is of lower priority and is being carried out peripherally. Table 1 indicates researchers responsible for contributions to this report and those who are continuing to study various stratigraphic units in the area.Bureau of Economic Geolog
Graph-Based Approach to the Edit Distance Cryptanalysis of Irregularly Clocked Linear Feedback Shift Registers
This paper proposes a speed-up of a known-plaintext attack on some stream ciphers
based on Linear Feedback Shift Registers (LFSRs). The algorithm consists of two basic steps:
first, to guess the initial seed value of one of the LFSRs, and then to use the resulting binary
sequence in order to deduce useful information about the cipher parameters. In particular, the
proposed divide-and-conquer attack is based on a combination of graph-based techniques with
edit distance concepts. While the original edit distance attack requires the exhaustive search over
the set of all possible initial states of the involved LFSR, this work presents a new heuristic optimization
that avoids the evaluation of an important number of initial states through the identification
of the most promising branches of the search graph. The strongest aspects of the proposal
are the facts that the obtained results from the attack are absolutely deterministic, and that many
inconsistent initial states of the target LFSRs are recognized and avoided during search.This work was supported by the Spanish Ministry of Science and Innovation and European
FEDER Fund under Project TIN2008-02236/TSI as well as by CDTI (Spain)and the companies INDRA, Unin Fenosa, Tecnobit, Visual Tool, Brainstorm, SAC and
Technosafe under Project Cenit-HESPERIA.Peer reviewe
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An Assessment of the Natural Gas Resource Base of the United States
The distribution of natural gas in the United States comprises proved reserves in known reservoirs, inferred reserves, undeveloped resources within these reservoirs, and undiscovered resources. Beyond proved reserves, all volumes of future natural gas supply are estimates based on information derived from past and current experience in gas production and reservoir development. Even proved reserves are subject to periodic revision. This assessment begins with an understanding of major components of the natural gas supply derived from existing resource estimates that use established methodologies. In addition to historically defined elements of the resource base, a new component—reserve growth in heterogeneous reservoirs—is quantified in this study.
Resource assessments proceed in their planning and compilation from reasonably well-known quantities (proved reserves) to increasingly less well-known quantities (undiscovered resources). Furthermore, natural gas reservoirs termed unconventional are typically given separate consideration and include gas in low-permeability reservoirs, gas in shale formations such as the Devonian of the Eastern U.S., and coalbed methane resources. This approach has been followed in this assessment. Special note was made of Alaskan gas reserves as they are significant and proven, but transportation for North Slope gas to the Lower 48 states is lacking.Bureau of Economic Geolog
Work functions, ionization potentials, and in-between: Scaling relations based on the image charge model
We revisit a model in which the ionization energy of a metal particle is
associated with the work done by the image charge force in moving the electron
from infinity to a small cut-off distance just outside the surface. We show
that this model can be compactly, and productively, employed to study the size
dependence of electron removal energies over the range encompassing bulk
surfaces, finite clusters, and individual atoms. It accounts in a
straightforward manner for the empirically known correlation between the atomic
ionization potential (IP) and the metal work function (WF), IP/WF2. We
formulate simple expressions for the model parameters, requiring only a single
property (the atomic polarizability or the nearest neighbor distance) as input.
Without any additional adjustable parameters, the model yields both the IP and
the WF within 10% for all metallic elements, as well as matches the size
evolution of the ionization potentials of finite metal clusters for a large
fraction of the experimental data. The parametrization takes advantage of a
remarkably constant numerical correlation between the nearest-neighbor distance
in a crystal, the cube root of the atomic polarizability, and the image force
cutoff length. The paper also includes an analytical derivation of the relation
of the outer radius of a cluster of close-packed spheres to its geometric
structure.Comment: Original submission: 8 pages with 7 figures incorporated in the text.
Revised submission (added one more paragraph about alloy work functions): 18
double spaced pages + 8 separate figures. Accepted for publication in PR
H.E.S.S. observations of gamma-ray bursts in 2003-2007
Very-high-energy (VHE; >~100 GeV) gamma-rays are expected from gamma-ray
bursts (GRBs) in some scenarios. Exploring this photon energy regime is
necessary for understanding the energetics and properties of GRBs. GRBs have
been one of the prime targets for the H.E.S.S. experiment, which makes use of
four Imaging Atmospheric Cherenkov Telescopes (IACTs) to detect VHE gamma-rays.
Dedicated observations of 32 GRB positions were made in the years 2003-2007 and
a search for VHE gamma-ray counterparts of these GRBs was made. Depending on
the visibility and observing conditions, the observations mostly start minutes
to hours after the burst and typically last two hours. Results from
observations of 22 GRB positions are presented and evidence of a VHE signal was
found neither in observations of any individual GRBs, nor from stacking data
from subsets of GRBs with higher expected VHE flux according to a
model-independent ranking scheme. Upper limits for the VHE gamma-ray flux from
the GRB positions were derived. For those GRBs with measured redshifts,
differential upper limits at the energy threshold after correcting for
absorption due to extra-galactic background light are also presented.Comment: 9 pages, 4 tables, 3 figure
Discovery of VHE gamma-rays from the high-frequency-peaked BL Lac object RGB J0152+017
Aims: The BL Lac object RGB J0152+017 (z=0.080) was predicted to be a very
high-energy (VHE; > 100 GeV) gamma-ray source, due to its high X-ray and radio
fluxes. Our aim is to understand the radiative processes by investigating the
observed emission and its production mechanism using the High Energy
Stereoscopic System (H.E.S.S.) experiment. Methods: We report recent
observations of the BL Lac source RGB J0152+017 made in late October and
November 2007 with the H.E.S.S. array consisting of four imaging atmospheric
Cherenkov telescopes. Contemporaneous observations were made in X-rays by the
Swift and RXTE satellites, in the optical band with the ATOM telescope, and in
the radio band with the Nancay Radio Telescope. Results: A signal of 173
gamma-ray photons corresponding to a statistical significance of 6.6 sigma was
found in the data. The energy spectrum of the source can be described by a
powerlaw with a spectral index of 2.95+/-0.36stat+/-0.20syst. The integral flux
above 300 GeV corresponds to ~2% of the flux of the Crab nebula. The source
spectral energy distribution (SED) can be described using a two-component
non-thermal synchrotron self-Compton (SSC) leptonic model, except in the
optical band, which is dominated by a thermal host galaxy component. The
parameters that are found are very close to those found in similar SSC studies
in TeV blazars. Conclusions: RGB J0152+017 is discovered as a source of VHE
gamma-rays by H.E.S.S. The location of its synchrotron peak, as derived from
the SED in Swift data, allows clearly classification it as a
high-frequency-peaked BL Lac (HBL).Comment: Accepted for publication in A&A Letters (5 pages, 4 figures
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Play Analysis and Digital Portfolio of Major Oil Reservoirs in the Permian Basin: Application and Transfer of Advanced Geological and Engineering Technologies for Incremental Production Opportunities
A play portfolio is being constructed for the Permian Basin in west Texas and southeast New Mexico, the largest onshore petroleum-producing basin in the United States. Approximately 1,300 reservoirs in the Permian Basin have been identified as having cumulative production greater than 1 MMbbl (1.59 x 10{sup 5} m{sup 3}) of oil through 2000. Of these significant-sized reservoirs, approximately 1,000 are in Texas and 300 in New Mexico. There are 32 geologic plays that have been defined for Permian Basin oil reservoirs, and each of the 1,300 major reservoirs was assigned to a play. The reservoirs were mapped and compiled in a Geographic Information System (GIS) by play. The final reservoir shapefile for each play contains the geographic location of each reservoir. Associated reservoir information within the linked data tables includes RRC reservoir number and district (Texas only), official field and reservoir name, year reservoir was discovered, depth to top of the reservoir, production in 2000, and cumulative production through 2000. Some tables also list subplays. Play boundaries were drawn for each play; the boundaries include areas where fields in that play occur but are smaller than 1 MMbbl (1.59 x 10{sup 5} m{sup 3}) of cumulative production. Oil production from the reservoirs in the Permian Basin having cumulative production of >1 MMbbl (1.59 x 10{sup 5} m{sup 3}) was 301.4 MMbbl (4.79 x 10{sup 7} m{sup 3}) in 2000. Cumulative Permian Basin production through 2000 was 28.9 Bbbl (4.59 x 10{sup 9} m{sup 3}). The top four plays in cumulative production are the Northwest Shelf San Andres Platform Carbonate play (3.97 Bbbl [6.31 x 10{sup 8} m{sup 3}]), the Leonard Restricted Platform Carbonate play (3.30 Bbbl [5.25 x 10{sup 8} m{sup 3}]), the Pennsylvanian and Lower Permian Horseshoe Atoll Carbonate play (2.70 Bbbl [4.29 x 10{sup 8} m{sup 3}]), and the San Andres Platform Carbonate play (2.15 Bbbl [3.42 x 10{sup 8} m{sup 3}]). Detailed studies of three reservoirs are in progress: Kelly-Snyder (SACROC unit) in the Pennsylvanian and Lower Permian Horseshoe Atoll Carbonate play, Fullerton in the Leonard Restricted Platform Carbonate play, and Barnhart (Ellenburger) in the Ellenburger Selectively Dolomitized Ramp Carbonate play. For each of these detailed reservoir studies, technologies for further, economically viable exploitation are being investigated
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