Dynamic response of high-speed rail foundations...

27

Weaver Distinguished Professor
Dept. of Chemical Eng.
Colorado School of Mines

GP581/681 Presentation

Thanksgiving Recess

3D Geomechanical Modeling at Rulison field, Piceance Basin, CO

Abstract
Self-potential signals are electrical potentials passively recorded in boreholes or at the surface of the Earth. They evidence polarization of electrical charges occurring in the ground. The self-potential method is one of the oldest of all geophysical methods; but, until recently, it was mainly considered as a qualitative method with problems regarding the acquisition of the data and the separation of multiple source contributions. Recently, the development of a fundamental pore-scale model of the different contributions of self-potential signals for electro-poro-elastic bodies (all rocks and soils) and the development of very stable non-polarizing electrodes have helped to interpret self-potential signals in a quantitative way. In this presentation, I will review recent developments in pore-scale modeling, the forward and the inverse problem in the interpretation of self-potential signals. The interpretaion of self-potential signals corresponds to quasi-static potential field problems (like those encountered in gravity and magnetism). The inverse problem, based on Tikhonov regularization, can be used to invert the pattern of water flow in the ground. Regarding applications with the oil industry, this method can be used to detect an encroaching water front moving towards a borehole or to develop efficient methods for electro-osmotic pumping of oil and gas in low-permeability reservoirs.

Biography
 André Revil joined the Department of Geophysics at the Colorado School of Mines as an associate professor in Fall 2007. Prior to that he worked with the CNRS (Centre National de la Recherche Scientifique) inn Zix en Provence, France, where he headed the research team for hydrogeophysics and porous media at CEREGE. He holds a PhD degree of engineering from IPG of Strasbourg. He held a postdoctor fellow position at Cornell University from 1995-1997, working with Drs. L. M. Cathles and O. Brévart. In 1999 he received a French Young Scientist Award (ACI-Jeune) from the Minister of Research and Education. In 2003, he received the Bronze Medal from CNRS for outstanding research activity. In 2004, the American Rock Mechanics Assocation (ARMA) honored his with an Award of Excellence. He is interested int he development of geoelectrical methods (including self-potential, electrical resistivity, and induced polarization), combining his expertise in petrophysics and the development of new algorithms for forward and inverse modeling of geophysical data.

Invitation to Participate
Come and compete in a quiz contest of a geoscience nature.  We have room for eight, two-person teams competing in the rapid fire, push-the-buzzer, who-can-answer first contest.  All geoscience students are encouraged to participate in this unique event which combines knowledge, competition, and fun.  The format will consist of single and multiple-choice questions from a range of geophysical (and geological) topics.  The winning team will receive an all expense paid trip (sponsored by the Denver Geophysical Society) to SEG's 77 th Annual Meeting and International Exhibition in San Antonio where they will compete in the 2 nd Annual SEG Challenge Bowl.  We are organizing teams, so if you are interested in participating in this exciting event or have any questions, please contact Jim Gaiser (jgaiser@gxt.com).  If you just want to watch the contest you are more than welcome as well.

Read about other preliminaries that have been held by visiting http://seg.org/publications/webonly/challengebowl2007-3.shtml.

Abstract
Salt and hydrocarbon contamination of the near surface are widespread problems. Electrical geophysical methods can provide spatially extensive data that can be used to improve the accuracy of site characterization. Accurate characterization of contaminated soils can lead to improved remediation design, early intervention when remediation methods are not performing as designed and easier agreement on site closures. The site of a salt spill has been monitored with three dimensional time-lapse electrical resistivity imaging (ERI) for three years. Three dimensional surveys are required to avoid distortion of images by out-of-plane resistivity variations. To infer changes in salt concentrations, auxiliary measurements of temperature and soil moisture are needed to account for varying environmental conditions. Time-lapse ERI results show preferential leaching along the lines of tile drain installations and show preferential leaching due to depression focused recharge. Two sites with weathered hydrocarbon bodies and one site with a light non-aqueous phase (LNAPL) hydrocarbon plume were surveyed with ERI and induced polarization (IP). IP anomalies were seen near boundaries of the known hydrocarbon at all three sites. Although not definitive, the results indicate that IP may be a useful tool for mapping hydrocarbon contamination. Recently reported results have indicated that spontaneous potential (SP) can be used to map low redox potential zones associated with hydrocarbon plumes. SP measurements were made at two sites with known LNAPL plumes. In both cases the SP gradients were in the opposite direction to that expected due to streaming potential and site redox conditions. Laboratory and modeling studies are being conducted in an attempt to explain these apparent contradictions.

Biography
 Dr. Bentley received his B.A. in Physics from Hamilton College in 1971 and his M.Sc. in Geology & Geophysics from the University of Hawaii in 1974. He worked for 10 years with Western Geophysical Company as a party manager, supervisor and research geophysicist. In 1985, Dr. Bentley returned to university to study subsurface flow and transport modeling. He received his Ph.D. from the Department of Civil Engineering, Princeton University in 1990. After a one year post doctoral fellowship at the University of Vermont, he joined the faculty of the University of Calgary in 1991. He is currently a professor in the Department of Geoscience. His current research interests include hydrogeology, groundwater modeling and near surface geophysical applications to hydrogeology. (www.geo.ucalgary.ca/~bentley )

Abstract
Understanding the dynamic response of a high-speed railway foundation and the surrounding area is of critical importance for the high-speed rail industry. High-speed trains generate ground-borne vibration which travels through underlying soil to the surrounding environment. This vibration can have a strong effect on human comfort and can cause structural damage as well as malfunctioning of sensitive equipment. A proposed method for mitigating ground-borne vibration generated by high-speed trains is the usage of rubber-modified asphalt concrete as a ballast mat material. To gauge this material's influence in vibration control, a dynamic finite element code that models distinct intrinsic damping properties in a large, nonhomogenous system such as a railway foundation was created. A linear hysteretic damping model is used to capture the dissipative mechanisms of each material; frequency domain substructuring is used for computational efficiency. Vibratory responses utilizing different ballast mat materials in a high-speed rail foundation are compared. It is shown that rubber-modified asphalt concrete results in a general reduction of motion, particularly in directions horizontally parallel and perpendicular to the train's passage. The described modeling procedure may be used for any dynamic analysis in a large, nonhomogenous system where the preservation of material damping characteristics is desired.

Biography
Judith Wang earned her B.S.E., M.S., and Ph.D. degrees in civil engineering from Case Western Reserve University in Cleveland, Ohio. She also earned a B.A. in english from Case Western Reserve University. Dr. Wang was previously a National Science Foundation Graduate Research Fellow at Case Western Reserve University where she studied dynamic soil-structure interaction, specifically in vibration control of high-speed rail foundations. Her current research interests involve numerically modeling intrinsic damping mechanisms in large, nonhomogenous systems. Her work in this area has been published in The Journal of Vibration and Control, ASCE's Journal of Materials in Civil Engineering, and Soil Dynamics and Earthquake Engineering. Dr. Wang also has a research interest in the history of civil engineering, particularly in tunneling operations; she co-authored a paper detailing the history of the first subaqueous tunnel in New York City that has just won the ASCE Technical Council on Forensic Engineering's Outstanding Paper Award for 2006.

Abstract
Methane hydrates are ice-like compounds that occur in deep water seafloor sediments and permafrost regions of the globe. They may influence future climate change and could become an important source of methane gas for future energy needs. Knowledge of the seismic wave properties of methane-hydrate-bearing sands is important for the future geophysical exploration and monitoring of hydrate reservoirs. A team of researchers at Southampton set out to quantify seismic wave velocity and attenuation in methane-hydrate sands as a function of hydrate content using the newly designed gas hydrates resonant column (GHRC). Initial results for P- and S-waves obtained on methane-saturated sand with hydrate cement showed rapid increases in velocity with hydrate saturation, and a curious attenuation peak. In fact, the presence of hydrate cement led to significantly higher attenuation than in non-hydrate-bearing sand. The results are currently being used to explore the validity of various rock physics models. These included grain cementation theory and viscous fluid flow loss mechanisms. Ultimately, such studies will enable seafloor hydrates to be identified and delineated using seismic survey data (e.g., in the absence of a bottom simulating reflector), and interpreted in terms of hydrate content that is needed to estimate in situ hydrate reserves (in combination with assumptions about hydrate cage occupancy). Also, when deep water hydrate sand reservoirs eventually come to be exploited, careful seismic monitoring of gas evolution during production will be essential if seabed slope stability issues are to be adequately addressed.

Biography
Dr. Best received his B.Sc in Geological Geophysics with Subsidiary Mathematics in 1988 from Reading University, United Kingdom ( UK). He worked for one year as a logging geologist in the North Sea petroleum industry before returning to Reading University to pursue his Ph.D studies on the seismic properties of hydrocarbon reservoir rocks, graduating in 1993. After a 2 year research fellowship at Reading University and Imperial College, London, he joined the Institute of Oceanographic Sciences, Wormley, UK in 1995 which later the same year moved to Southampton to become part of the National Oceanography Centre, Southampton (NOCS). Since then, he has been conducting research into the acoustic properties of marine sediments, including gas hydrate-bearing sediments and gassy sediments. In 2004 he established the NOCS Rock Physics Research Laboratory dedicated to improving the understanding of seismic and electromagnetic wave propagation in rocks for marine scientific studies and industry applications. He is an Associate Editor (Rock Physics) for Geophysical Prospecting, and is a member of the Geological Society of London, European Association of Geoscientists and Engineers, and the Society of Exploration Geophysicists.

Abstract
The Devonian-Mississippian Bakken Formation of the Williston Basin has been the focus of several cycles of exploration activity since the 1950s. The discovery and development of the Elm Coulee area of Montana is the latest and most significant of the cycles to date. Expansion of the play into North Dakota is currently underway.

The Bakken consists of three members: upper and lower organic-rich black shale (TOC’s average 11%); a middle member (silty dolostone or limestone to sandstone lithology). The Bakken ranges in thickness from a wedge edge to over 140 ft. Published estimates of Bakken oil generated from the two source beds range from 10 billion barrels to 400 billion barrels. Abnormally high pressure gradients (0.5 to 0.7+ psi/ft) created by hydrocarbon generation occurs in the Bakken in areas where the source beds are considered mature. High resistivity is also associated with mature source-rocks which have generated hydrocarbons and are saturated with oil and gas.

Elm Coulee, a new resource play, has produced in excess of 41 million barrels of oil and 24 BCF gas from over 400 horizontal wells. The field is being developed using horizontal drilling in the middle member of the Bakken. The Bakken is generally fracture stimulated with gelled water and sand (~5,000 bbls gelled water and 400,000 pounds of sand per horizontal lateral). The area was targeted for vertical drilling in the late 1990s and horizontal drilling began in 2001. The middle Bakken in this area is interpreted to be a dolomitized carbonate bar complex. The reservoir is developed over a large area (450 square miles) and has relatively low porosity (8-10%) and permeability (0.05 md). Natural fracturing is thought to contribute to production. Initial production from wells ranges from 200 to 1900 BOPD. The field is being developed on 640 and 1280 drilling and spacing units. The Elm Coulee area has many of the characteristics of a resource play (i.e., continuous accumulation, large areal extent, predictable, repeatable, technology driven, etc.). Estimated recovery per well is 350 to 600 MBO. Estimated ultimate recovery for the field is greater than 200 MMBO.

The North Dakota Bakken play has focused in two general areas: sandstone play around the Nesson anticline and carbonate play in the southern area. Both areas have wells with significant initial potentials. Further drilling will determine if these areas have similar potential to the Elm Coulee area.

Thickness variations in the Bakken result from a variety of factors including varying depositional rates, paleostructures created by either basement fault movement or Prairie evaporite dissolution and onlap of units towards the basin edges. Structural features such as the Nesson anticline have dramatically influenced Bakken depositional patterns and also influenced hydrocarbon migration. Dissolution of the Devonian Prairie evaporite occurred during the Mississippian.

An understanding of Bakken tectonics, stratigraphy and diagenesis may lead to the discovery of new resource play areas in the Bakken.

Biography
Dr. Stephen A. Sonnenberg is a Professor and holds the Charles Boettcher Distinguished Chair in Petroleum Geology at the Colorado School of Mines. He specializes in sequence stratigraphy, tectonic influence on sedimentation, and petroleum geology. A native of Billings, Montana, Sonnenberg received BS and MS degrees in geology from Texas A&M University and a Ph.D. degree in geology from the Colorado School of Mines. He has over twenty five years experience and is a consulting geologist.

Steve has served as President of several organizations including the American Association of Petroleum Geologists, Rocky Mountain Association of Geologists, and Colorado Scientific Society. He also served on the Colorado Oil and Gas Conservation Commission from 1997-2003 and was the Chair of the Commission from 1999-2003.

He is the recipient of the Young Alumnus Award, Outstanding Alumnus Award, and Mines Medal from the Colorado School of Mines, Distinguished Achievement Medal from Texas A&M University, distinguished service awards from AAPG and RMAG, and honorary membership awards from RMAG and the Colorado Scientific Society.

Abstract
While near-surface and classical seismic explorations obey the same laws of physics, the relative importance of those laws is different for the two types of surveys. These differences have led to some eccentric experiments with unexpected and occasional serendipitous outcomes. Progress attained by our research group has occurred through a mixture of stupid experiments that turned out to be clever and clever experiments that turned out to be stupid. Shallow seismic methods have matured noticeably since the time 25 years ago when the world’s scientific literature contained few refereed papers on shallow reflection. Much of the maturation is related to the revolution in microelectronics and the associated several orders of magnitude decrease in computational costs, while developments in sources, seismographs, and field methods have all played a role to differing degrees. However, other driving factors in this improvement have included demonstrable attainment of objectives such as providing structural contour maps of bedrock beneath alluvium, delineating shallow faults, evaluating near-surface stratigraphy to detect preferential groundwater flow paths, and detecting underground cavities. By 1999, we had demonstrated seismic reflection images from depths of less than a meter, easily within reach of a marginally competent grave digger. Detecting such shallow reflectors is expensive, however, because of the requirement to plant geophones at intervals of 10 cm or less. The effective resolution potential of classical seismic exploration data recorded on land is often determined by geologic conditions in the upper few tens of meters; in addition, the majority of statics problems commonly occur in the upper 30 meters. We are currently experimenting with methods of making near-surface three-dimensional seismic imaging more cost-effective.

Biography
 Don Steeples is McGee Distinguished Professor of Geophysics and Vice Provost for Scholarly Support at KU. Don earned a BS in geophysics (1969) and an MS in geology (1970) from Kansas State University where he was a member of both the varsity football and varsity track teams. After two years as a lieutenant in the US Army Corps of Engineers at Ft. Belvoir, Virginia and Ft. Wainwright, Alaska from 1970-72, he returned to graduate school and received an MS (1974) and PhD (With Distinction, 1975) in geophysics from Stanford University. He was at the Kansas Geological Survey (a KU Research Division) from 1975 until 1992, serving in various positions including Associate Director for Research and as Deputy Director. Since 1977, he has specialized in shallow high-resolution seismic imaging, an area in which he has practical experience in more than 20 states and several foreign countries. He served the Society of Exploration Geophysicists as elected Editor of Geophysics in 1989-91. He has done consulting for more than 50 companies and government agencies through Great Plains Geophysical, Inc. his wholly owned consulting company. With his brother, he operates a 1900-acre wheat farm at Palco, Kansas. His wife since 1967 (Tammy) earned a PhD in Special Education at KU. They have two married sons (Flint, 35, and Brad, 31) who graduated from KU and both received MBA's in finance from SMU in Dallas.

Abstract
Natural gas hydrates are inclusion compounds which contain perhaps as much energy as all the other hydrocarbon sources combined. We will look together at hydrates in nature, and ask the question, “ How do natural and artificial hydrates differ?” using both field and laboratory studies.

A summary of eight principles will be suggested, relating to energy, geomechanics, and climate, which lead to one way forward in hydrate research. Finally, we will discuss how mankind is dealing with expanding knowledge base which has accounted for over 4,000 refereed publications in the last decade. This presentation will abstract a portion of Clathrate Hydrates of Natural Gases (3 rd Ed) published on September 14, 2007.

Biography
E. Dendy Sloan, Jr.,Ph.D., P.E., holds the Weaver Chair of Chemical Engineering and is Director of the Center for Hydrate Research at the Colorado School of Mines, where he co-directs a group of 25 researchers on natural gas hydrates. Prior to coming to Mines, he was a Senior Engineer with E.I. DuPont deNemours, Inc. Sloan currently chairs both the Federal Methane Hydrate Advisory committee, and the CODATA International Hydrate Database Task Group. He has over 150 refereed hydrate publications, including two books: Clathrate Hydrates of Natural Gases, 3 rd Ed (2007), co-authored by C.A. Koh and Hydrate Engineering (2000). He is a Fellow of the American Institute of Chemical Engineers.

Abstract
A series of 13 explosive eruptions occurred at Augustine Volcano, Alaska, from January 11-28, 2006. Each of these eruptions lasted 2.5 to 19 minutes and produced ash columns 3-14 km high. We investigated a number of parameters to determine systematic trends, including durations, seismic amplitudes, frequency contents, signal characteristics, peak acoustic pressures, ash column heights, and lengths of pre-event and post-event quiescence. At the time of this writing we do not know individual tephra volumes for the various eruptions. In general, we find few strong correlations in the data set. For example, there is no clear correlation between acoustic peak pressure and ash column height, or between seismic amplitude and duration. Thus it is difficult to give a simple number or ratio to characterize the explosive eruptions. However, several events stand out as being end members in their attributes. Two events (11 January 13:44 UT and 28 January 08:37 UT) are short (180 and 140 sec respectively) and have very impulsive and high acoustic peak pressures of 93 and 105 Pa, as well as high seismic amplitudes. We interpret these to be mainly gas releases, although some tephra was erupted. Two of the largest events followed quiescent intervals of 2 days or longer: 16 January 16:58 UT, and 28 January 05:24 UT. These two events had reduced displacements (DR) of 13.9 and 13.3 cm2 respectively, larger than all others except the two gas release events cited above. While these DR values are typical for eruptions with ash columns to 9-14 km, most other DR values of 3.3 to 5.8 cm2 are low for the 8-11 km ash column heights observed. The combination of short durations, small DR and high ash columns suggests that these events are more explosive than most other euprtions, in agreement with the vulcanian eruption type. Several events had long durations on individual seismic stations but not on others; we interpret these to represent pyroclastic flows passing near the affected stations so that fallout of material from the cloud adds energy to the ground only near those stations. The eruption on 28 January 05:24 UT had abundant lightning, whereas two others that followed (29 January 11:04 UT and 16:42 UT) had no lightning. The 05:24 UT eruption had a much longer duration (1180 sec compared to <460 sec for the others), a slightly higher ash column height 9 vs. 8 km) and higher acoustic peak pressure (83 vs. 66 and 24 Pa). The data suggest that the lightning-rich 05:24 UT eruption produced more tephra than the following eruptions, hence there were more charge carriers available. The parametric data outlined here are most useful when combined with other data to address specific research questions. Caution should be exercised in using such data to estimate eruption conditions in near real time.

Abstract

By mid-September 2007 sea-ice coverage of the Arctic Ocean reached the smallest extent since record keeping. This message was just the latest in an ever-increasing number of signals that the climate is changing and that the globe is warming up. But how can we be so sure that this recent trend is man-made and not just an artifact from a too short instrumental record and that other factors, such as internal variability or changes in solar activity, might be responsible for what is happening right now? Just how do these and possible future anthropogenic signals actually measure up against the range of natural variations? Clean separation of anthropogenic from natural climate change is not always easy. Process studies as well as the time-perspective gained from past climates allow for a better understanding of the ongoing change, and the respective roles of natural and human contributions can be assessed.

This presentation will focus on the available data that strongly supports the notion of human induced climate change and where climate science is currently heading to improve projections of relevant issues. Results of high-resolution climate reconstructions as well as state-of-the-art climate models indicate that natural forcing factors have dominated climate before the 20th century. Increased emissions of greenhouse gases are, however, responsible for the current rapid warming. If emissions are not reduced in the near future, then the Earth's climate system will undoubtedly experience drastic changes that far exceed the range of what civilizations have experienced. But simulations also show that strong reductions of emissions can keep climate changes in check.

Biography

Caspar Ammann is currently performing climate change research in the Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, Colorado. Read his CV.

Abstract

Electrical borehole images offer a unique view of the subsurface to geologists and petrophysicists. Images from traditional electrical imaging tools are readily interpreted in
terms of key geological characteristics such as structural and stratigraphical features of the formation and today, highresolution electrical images are available while-drilling.

The drilling environment surprisingly, offers an ideal platform for electrical borehole imaging. At the time of drilling, the borehole wall rugosity is often minimal and electrical images generated by sensors that rotate with the drill string provide a full coverage of the borehole (when compared to the pad coverage observed on conventional wireline borehole images). It is also an opportunity for real-time geological analysis and ultimately decision making that can reduce rig-time and vastly improve reservoir net hydrocarbon. Images sent to the surface give an early indication as to the angle of entry into a given formation and allow for a more accurate/precise geosteering and possible geomechanical information that may mitigate drilling hazards.

This presentation reviews the advances in resolution and application of a while-drilling resistivity imaging technology through a variety of case examples.

Biography

Dr Jeremy (Jez) Lofts received his PhD from Leicester, UK in 1993 and he is a Chartered Geologist. He has worked as an image interpretation specialist and lectures externally/internally on the subject of Borehole Image Interpretation. Jez is author of +25 papers on geological and petrophysical oilfield applications and is SPWLA 2007 Distinguished Speaker. His coauthored paper (Ritter et al 2004) on StarTrak won best paper in Petrophysics for 2005. He is currently the Director for Formation Evaluation Product Lines (LWD-Coring-Surface logging) at INTEQ (a division of Baker Hughes). He is currently also Honorary Industrial Associate and Lecturer at the University of Leicester, UK, Department of Geology.

Abstract

The dielectric permittivity of water is applicable in all areas of science, namely for the reason that water content of a material can be extracted from the material's dielectric permittivity. This is extremely useful in the millimeter wave region of the spectrum because the relaxation mechanisms of water occur here. Reflection measurements exploiting a Fabry-Perot geometry using a novel millimeter wave vector network analyzer are presented. The Fabry-Perot geometry allows for multiple measurements at each frequency. Also, an analytic solution can be found to fit to the data. Debye relaxation models are used to model the dielectric permittivity of water.

Biography
Jared Peacock is a native of Colorado who enjoys the outdoors. He is currently pursuing happiness and enlightenment while attempting a Ph.D. in physics at CSM and at the same time training for the 2008 US Olympic trials in the 800m. He earned a B.S. degree from CSM in geophysics (2005) and has nearly completed a M.S. degree, also in geophysics.

Abstract
Antarctica is a key element in Earth’s geodynamic and climatic systems, yet we lack fundamental geologic and geophysical data from the deep interior of this vast continent. Coastal exposures record the 3500 million-year history of a continent that participated in the formation and breakup of two supercontinents, Rodinia and Gondwana. East Antarctica occupied the center of both supercontinents and may represent ~15% of Earth’s Precambrian crust. Despite the central role that Antarctica has played in shaping the present global environment, basic, first-order parameters such as bedrock elevation, lithology, structure, age, tectonic history and ice volume remain poorly known over large portions of the continent. Given the extensive ice cover, airborne geophysical data, constrained by field-based geologic mapping, ground-based geophysics, and petrologic, geochemical and geochronological analysis of outcrop and drill-hole samples, is the best way to define the origin and evolution of broad areas of the Antarctic lithosphere. This talk will focus on aeromagnetic mapping of sub ice geology and discuss links between the geology and the ice sheet.

Biography
Carol Finn is a Senior Research Geophysicist at the U. S. Geological Survey. Her major research interests include geological interpretation of potential field data worldwide, volcano hazards, and tectonics studies. She received her B.A. in Geology at Wellesley College; M. S. and Ph. D.’s in Geophysics at the University of Colorado. Finn currently serves as the General Secretary of the American Geophysical Union, is a Fellow of the Geological Society of America and has a place named after her in Antarctica, Finn Spur (79 degrees 17' S, 156 degrees 37' E), in recognition of Antarctic project leadership .

Abstract
Production induced changes in pore pressure cause changes in the effective stress of the reservoir. These pressure and stress changes are responsible for time-lapse seismic signatures present in the data for Rulison field. A three dimensional model of reservoir stresses has been built that shows effective stress changes due to production. These changes are then compared to available seismic data for further study.

Biography
Kurt Wikel was born in North Dakota and raised on a ranch in Montana. He received his bachelor's degree in geology from the University of Montana in 2005. Kurt then worked as a geophysical field technician for Gradient Geophysics, Inc., in Montana for nine months, before returning to school in fall of 2006. Kurt is proud to be a left-handed Canadian citizen who enjoys curling and beer.

Abstract
The appropriate use of technology is the only way to improve the recovery of producing gas and oil fields, so in this framework seismic methods play a main role. As part of the CSM Reservoir Characterization Project (RCP), this research aims for the dynamic characterization of tight-gas sandstones in Rulison Field, Colorado, by using time-lapse seismic and multi-component (4D-9C) seismic data to obtain high-resolution, 4D Vp/Vs ratio volumes. It has been demonstrated in previous studies that both P- and S-waves modes are sensitive to reservoir pressure changes in a time-lapse basis, so Vp/Vs ratio volumes could be a way to consider simultaneously both wave modes in a time-lapse basis and improve the sensitivity of seismic data to reservoir changes due to its development. Therefore this time-lapse, multi-component attribute could be mapped into the pore pressure domain in order to obtain a reservoir parameter that helps improving the dynamic characterization and development of this unconventional reservoir.

Biography
Ramses Meza is a MS candidate in geophysics at the Colorado School
of Mines. After receiving his bachelor degree in geophysical engineering (1999) from the Universidad Simon Bolivar (Caracas, Venezuela) he worked for PDVSA (Venezuelan National Oil Company) as a seismic interpreter-reservoir geophysicist (2000-2003) in Eastern Venezuela Basin, and as seismic interpreter for Harvest-Vinccler C.A. (2003-2006) also in Eastern Venezuela Reservoirs. His academic research focuses on time-lapse multi-component analysis and how the seismically-derived attributes can help on dynamic and static reservoir characterization of tight-gas sandstones.