Pore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.

I estimate overpressure in a seismic cross-section along a 12km traverse associated with a 2D/4C OBC line in the Columbus Basin, Trinidad, West Indies, where shallow gas reduces both data quality and apparent seismic velocity for P-waves, using a modified Eaton's equation for PS-waves. Pore pre...

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Main Author: Kumar, Kimberly Melissa, 1981-
Format: Others
Language:English
Published: 2015
Subjects:
Online Access:http://hdl.handle.net/2152/30297
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spelling ndltd-UTEXAS-oai-repositories.lib.utexas.edu-2152-302972015-09-20T17:32:06ZPore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.Kumar, Kimberly Melissa, 1981-Pore pressure predictionNatural gasNatural gas explorationI estimate overpressure in a seismic cross-section along a 12km traverse associated with a 2D/4C OBC line in the Columbus Basin, Trinidad, West Indies, where shallow gas reduces both data quality and apparent seismic velocity for P-waves, using a modified Eaton's equation for PS-waves. Pore pressure prediction using the modified Eaton's method involves velocity analysis, conversion of the stacking velocities to interval velocities via the Dix's equation, converting the interval velocity trends to pressures and mudweights, and comparison of the predictions to 3 wells surrounding the seismic line. In the presence of shallow gas, the magnitude and areal extent of seismically derived P-wave and PS-wave velocity deviates from regional trends along the seismic line. PS-waves show a more accurate areal extent of velocity deviation due to overpressure than the P-wave, which is also affected by the presence of shallow gas. I verify my derived velocities and predicted-pressure values using sonic log data and observed pressure from 3 wells. Direct comparison between the sonic-derived velocities and the seismic-derived velocities shows that shallow gas reduces P-wave velocity, and that PS-wave velocity is less affected. Pressure prediction is verified using mudweights and formation tests from well logs and drilling reports. I find pressure predictions associated with P-waves, especially in areas of shallow gas are less reliable than for pressure predictions using PS-waves. I conclude that PS-wave velocity provides a superior map of overpressure in this region in areas with shallow gas clouds.text2015-08-06T20:16:42Z2015-08-06T20:16:42Z2006-052015-08-06Thesiselectronichttp://hdl.handle.net/2152/30297engCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.Restricted
collection NDLTD
language English
format Others
sources NDLTD
topic Pore pressure prediction
Natural gas
Natural gas exploration
spellingShingle Pore pressure prediction
Natural gas
Natural gas exploration
Kumar, Kimberly Melissa, 1981-
Pore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.
description I estimate overpressure in a seismic cross-section along a 12km traverse associated with a 2D/4C OBC line in the Columbus Basin, Trinidad, West Indies, where shallow gas reduces both data quality and apparent seismic velocity for P-waves, using a modified Eaton's equation for PS-waves. Pore pressure prediction using the modified Eaton's method involves velocity analysis, conversion of the stacking velocities to interval velocities via the Dix's equation, converting the interval velocity trends to pressures and mudweights, and comparison of the predictions to 3 wells surrounding the seismic line. In the presence of shallow gas, the magnitude and areal extent of seismically derived P-wave and PS-wave velocity deviates from regional trends along the seismic line. PS-waves show a more accurate areal extent of velocity deviation due to overpressure than the P-wave, which is also affected by the presence of shallow gas. I verify my derived velocities and predicted-pressure values using sonic log data and observed pressure from 3 wells. Direct comparison between the sonic-derived velocities and the seismic-derived velocities shows that shallow gas reduces P-wave velocity, and that PS-wave velocity is less affected. Pressure prediction is verified using mudweights and formation tests from well logs and drilling reports. I find pressure predictions associated with P-waves, especially in areas of shallow gas are less reliable than for pressure predictions using PS-waves. I conclude that PS-wave velocity provides a superior map of overpressure in this region in areas with shallow gas clouds. === text
author Kumar, Kimberly Melissa, 1981-
author_facet Kumar, Kimberly Melissa, 1981-
author_sort Kumar, Kimberly Melissa, 1981-
title Pore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.
title_short Pore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.
title_full Pore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.
title_fullStr Pore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.
title_full_unstemmed Pore pressure prediction using multicomponent PS-wave seismic velocities : Columbus Basin, Trinidad W. I.
title_sort pore pressure prediction using multicomponent ps-wave seismic velocities : columbus basin, trinidad w. i.
publishDate 2015
url http://hdl.handle.net/2152/30297
work_keys_str_mv AT kumarkimberlymelissa1981 porepressurepredictionusingmulticomponentpswaveseismicvelocitiescolumbusbasintrinidadwi
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