Developments and Challenges in VSP imaging

I will discuss recent developments and challenges in VSP imaging, including Reverse Time Migration (RTM), Least Squares Reverse Time Migration, and Source-free converted-wave (SFCW) RTM. We first show RTM and Least Squares RTM applied to a field data set and compare their results. The SFCW reverse-time migration imaging is an alternative way to image the subsurface when source information is missing or the overburden velocities are complex. However, it is challenging due to its limitations and complexities. SFCW imaging conditions are derived using the coupled P- and S-potential equations and small-perturbation approximations. I will show that the images obtained from this SFCW imaging condition are second-order approximations to the shear modulus perturbations. The images produced by the proposed imaging conditions are free of polarity reversal and have clear physical meanings. We also show that the scalar wave equations can be used to back propagate the recorded P- and S-potentials and the resulting image has the same kinematic accuracy and fewer unphysical mode-conversion artifacts than the SFCW image obtained by using the elastic wave equations. With multiple numerical examples, we demonstrate the accuracy of the proposed method and discuss its proper applicability.

Arthur C.H. Cheng is a Professor in the Department of Civil and Environmental Engineering, specializing in Petroleum Geosciences, at the National University of Singapore. Prior to taking his current position in September 2014, he was Senior Manager for Acoustics and Borehole Seismics at Halliburton Technology, where he led the development of the Xaminer® Sonic Imager tool. He received a Sc.D. in Geophysics from MIT in 1978. He was one of the co-founders of the Earth Resources Laboratory in 1982, and was Project Leader of the Borehole Acoustics and Logging Consortium until 1996, when he joined Western Atlas as Manager of Acoustic Science. He had also worked for Baker Atlas, Baker Hughes Inteq, SensorWise, and RockSolidImages in various managerial and consulting capacities. He had published over 120 papers and holds 21 patents, with a number more pending. He has co-authored two books on borehole acoustics. His current research interests are rock physics modeling and quantitative seismic reservoir characterization.

Arthur has served on a number of academic and industry positions through the years including the Visiting Committee for EAPS from 2004-2008. He is currently an Assistant Editor for Geophysics, and a member of the SEG Foundation Board of Directors. He received the Life Membership Award from SEG in 2013, the Distinguished Technical Achievement Award from SPWLA in 2015, and the SPE Formation Evaluation Award in 2016.

MIT Earth Resource Laboratory's Friday Informal Seminar Hour (FISH) takes place most Fridays while classes are in session, 12-1pm in 54-209. Most talks are also livestreamed on ERL's Youtube channel. Topics include seismology/inversion, rock physics, geomechanics, and machine learning for geophysics, and speakers range from PhD students to senior professors and industry leaders. Speaker and topic will be posted here once they are confirmed.