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00000cam a2200000Ka 4500 |
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in00002118964 |
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20151103064700.0 |
| 006 |
m f d |
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cr unu-------- |
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060502s2006 txu sbm 000 0 eng d |
| 035 |
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|a (OCoLC)ocm68043595
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| 035 |
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|a (TxCM)http://handle.tamu.edu/1969.1/3282
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| 040 |
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|a TXA
|c TXA
|d UtOrBLW
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| 049 |
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|a TXAM
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| 099 |
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|a 2005
|a Thesis
|a K276
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|a Karakurt, Necdet, 1973-
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| 245 |
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|a Estimating attenuation properties of bentonite layer in Cut Bank oil field, Glacier County, Montana /
|c by Necdet Karakurt.
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| 264 |
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|a [College Station, Tex.] :
|b [Texas A&M University],
|c [2006]
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| 336 |
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|a text
|b txt
|2 rdacontent
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| 337 |
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|a computer
|b c
|2 rdamedia
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| 338 |
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|a online resource
|b cr
|2 rdacarrier
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| 500 |
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|a "Major Subject: Geophysics"
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| 500 |
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|a Title from author supplied metadata (automated record created on Apr. 14, 2006.)
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| 500 |
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|a Vita.
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| 500 |
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|a Abstract.
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| 502 |
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|b M. S.
|c Texas A&M University
|d 2005.
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|a Includes bibliographical references.
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|a Text (Thesis).
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|a Acquisition and interpretation of 3-D seismic data led DeAngelo and Hardage (2001) to describe the channel system in the south central Cut Bank area in Glacier County,Montana. The presence of a low velocity layer called Bentonite was also discovered in the area with the help of well-logs. Bentonite is a volcanic ash, which lies on both sides of the channel system and is absent within the channel. DeAngelo and Hardage (2001) shot a vertical seismic profiling (VSP) survey at well # 54-8 to analyze the formation structure in depth, since seismic signals around the reservoir area were unclear in the 3-D survey. This research attempts to estimate the attenuation properties of the Bentonite layer in the Cut Bank oil field. VSP data is processed for velocity information and estimation of seismic Q using the spectral ratios method (SRM). The SRM theoretically assumes that the propagating signal is a plane seismic wave traveling vertically from one point to another in a homogeneous model. The amplitudes at the start and end points are known and relate to each other with the attenuation coefficient in a frequency range. The relation between the seismic amplitudes at z distance from each other can be expressed as a linear function of frequency after a few modifications. SRM uses the linearity of the logarithmic ratio of the seismic amplitudes over a frequency range. In theory, ratios plotted against a frequency range must producea flat line. However, in practice, the logarithmic ratios are expected to draw an approximate line (curve), where some of the data points deviate from the origin of the line. Thus fitting a line to the ratios curve and calculating the slope of this curve are necessary. Slope of the curve relates to the seismic attenuation coefficient and further to the seismic Q. The SRM results suggest that Bentonite may have a Q value as low as 5. This highly attenuative and thin (20 to 40 feet throughout the south central Cut Bank Unit) layer alters seismic signals propagating through it. A thorough analysis of the amplitude spectra suggests that seismic signals dramatically lose their energy when they pass through Bentonite. Low energy content of the signals below the Bentonite layer highlights that the recovery of the seismic energy is less likely despite the presence of multiples, which are known to affect the seismic signals constructively. Therefore, separation of reflected events is a greater challenge for the thin reservoirs and units lying underneath the Bentonite layer. Thus the Bentonite layer in the Cut Bank oil field has to be taken seriously and data processing should be done accordingly for better accuracy.
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| 538 |
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|a Mode of access: World Wide Web.
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| 538 |
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|a System requirements: World Wide Web access and Adobe Acrobat Reader.
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| 500 |
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|a Electronic resource.
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| 650 |
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|a Major Geophysics.
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| 653 |
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|a Seismic Q
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| 653 |
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|a Seismic attenuation
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| 653 |
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|a Q estimation
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| 653 |
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|a Spectral ratios method
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| 653 |
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|a Bentonite
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| 653 |
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|a attenuation analysis
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| 653 |
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|a Cut Bank oil and gas field
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| 653 |
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|a VSP
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1 |
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|a Gibson, Richard L.,
|e thesis advisor.
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| 856 |
4 |
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|u http://hdl.handle.net/1969.1/3282
|z Link to OAK Trust copy
|t 0
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| 948 |
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|a cataloged
|b cmulkey
|c 2006/5/2
|d 12:22:43 pm
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| 994 |
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|a C0
|b TXA
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| 999 |
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|a MARS
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| 999 |
f |
f |
|s 5cccbf7c-1e4a-390c-affd-3572c9b6d139
|i 4ec7c58e-9bb6-39e6-bd76-65ad4a6ced6a
|t 0
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| 952 |
f |
f |
|a Texas A&M University
|b College Station
|c Electronic Resources
|s www_evans
|d Available Online
|t 0
|e 2005 Thesis K276
|g Electronic
|h Other scheme
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| 998 |
f |
f |
|a 2005 Thesis K276
|t 0
|l Available Online
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