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CWP Seminars - 2015 Spring

CWP seminars discuss topics pertaining to our broad areas of research interests. These seminars are led by CWP faculty, students and, on occasion, by guest presenters. CWP seminars are held every Monday at 4 p.m. in the Green Center on the Colorado School of Mines campus. Click here to see previous CWP Seminars.

Note: To view weekly seminar schedules of individual CWP teams, click a link below:

A-Team seminars

C-Team seminars

iTeam seminars

Steam seminars


Spring 2015 CWP seminars

Date Speaker(s) Title Abstract

Esteban Díaz Pantin

Esteban Díaz Pantin

Data-domain tomography using local-correlations

Wavefield tomography in the data domain is usually formulated by using the data difference as the misfit criterion. The data difference however, is very susceptible to cycle skipping which leads to convergence into local minima. To overcome the strong non-linearity, a multi-scale approach to the inversion is often needed. The success of this approach relies on the low-frequency content of the data. Here, we define the data domain tomography-misfit criterion using local (windowed) correlations. Less correlation cross-talk leads to cleaner adjoint sources, and hence, cleaner gradients. We further improve the gradients using a penalty function that is consistent with the bandwidth of the seismic data, which is more realistic than linear penalty functions that annihilate infinite bandwidth data.


Xinming Wu

Xinming Wu

Moving faults while unfaulting 3D seismic images

Unfaulting seismic images to correlate seismic reflectors across faults is helpful for seismic interpretation, especially for seismic horizon extraction. Most unfaulting methods assume the fault geometry does not change when unfaulting a seismic image. This assumption is not valid for images with multiple faults, especially intersecting faults, and often yields unnecessary distortions in the corresponding unfaulted images. I will discuss two methods to compute vector shifts that move fault blocks and faults themselves simultaneously to obtain an unfaulted image with minimal distortions.

3/9 No seminar - CSM Spring Break

Nori Nakata

Nori Nakata

Ambient-noise body-wave tomography at Long Beach, California

In contrast to surface-wave extraction, body-wave extraction is much more difficult from ambient-noise fields because of smaller energy of body waves and strict stationary locations. To characterize elastic media even in the isotropic case, however, we need to determine both shear and compressional moduli. Therefore, I develop a signal-processing technique to extract P diving waves from ambient seismic noise and use them for tomography to estimate 3D P-wave velocities. The technique is a post-correlation process and contains a waveform matching filter and a noise suppression filter. This is the first body wave tomography result obtained from only ambient noise recorded at the ground surface. The estimated velocity structure has higher resolution than using surface waves.


Vladimir Li

Vladimir Li

Anisotropy signature in RTM extended images for VTI media

I will discuss the defocusing in RTM extended images due to inaccuracy in an anisotropy model. I will show the influence of the anellipticity parameter eta, and the Thomsen coefficient delta. I will discuss the sensitivity of differential semblance optimization (DSO) and stack-power objective functions to eta and delta. Using a model with a single homogeneous layer, I will show DSO sensitivity kernels and gradients for the anellipticity parameter eta.


2/16 No seminar - Presidents' Day holiday


Yuting Duan

Gradient computation and regularization for elastic waveform tomography

Elastic waveform tomography uses multicomponent waveform recordings and elastic wave equation modeling to reconstruct models of subsurface properties. Equations needed for elastic waveform tomography to reconstruct P- and S-wave velocity models are derived using the adjoint-state method. Synthetic tests demonstrate that, for a given acquisition geometry, P- and S-waves in general will update different areas of the subsurface. Moreover, certain areas might be updated by only one wave mode, and, as a result, the velocity model corresponding to the missing wave mode will not be well constrained. To better constrain the inversion, we introduce a regularization term that penalizes unrealistic relations between Vp and Vs.


Hui Wang

Anisotropic waveform tomography with pseudo-acoustic equations

Multi-parameter seismic waveform inversion especially with anisotropic parameters is intriguing but challenging due to the computational cost and the huge null-space introduced by the imperfect model parameterizations. I will briefly discuss the theory and the implementation of the gradients using the well-known adjoint-state method. Some computational cost issues associated with the modeling and adjoint modeling will be addressed. I will also illustrate the sensitivity kernels of different parameters using some synthetic models. If the time allows, I will introduce one possible set of inequality constraints to the inversion which can also be treated as the regularization term.

2/2 No seminar - CSM Department of Geophysics presentation

Roel Snieder

Roel Snieder

Walking in the footsteps of Michael Berry

I will give an overview of research that I did during my sabbatical. This includes super-resolution without evanescent waves, seismic waves as a Foucault pendulum (or not), interferometry in caustics, and time-lapse changes.


Elias Arias

Elias Arias

Internships with our sponsors and hackathon fun

BHP Billiton Petroleum Geoscience Internship
Hawkville, Red Hawk, and Black Hawk oil and gas fields comprise the Eagleford asset for BHP Billiton Petroleum. My summer internship was aimed at maximizing production for the Hawkville field given a newly processed seismic
dataset (pre-stack orthorhombic depth migration) and a large well log database.

ExxonMobil Exploration Company Geophysics Internship
I will give a quick general overview to my project and some key learnings.

SEG 2014 Geophysics Hackathon
As an undergraduate at CSM, a summer field session must be completed as part of the geophysics degree requirements. At this point, seismic acquisition and processing are vague concepts. Wouldn't it be nice to have a mobile app that helps you choose acquisition parameters so that the top and bottom of the layer being targeted is sure to be imaged? Well look no further, GeoRZA for Android can provide this service.


1/12 1st CWP seminar of the Spring 2015 semester (CWP administrative topics)


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