Online Only, you must pre-register to receive access instructions.
NOTE: You Must Be Logged In to Register.
Speaker: Ben Hardy (Ikon Science)
One of the important steps in the seismic data conditioning is checking for consistency of amplitudes laterally. This is especially important with land seismic data as it is common to find variation in lateral amplitudes due to near-surface geology over-printing amplitudes at our zone of interest. Ideally, we would be able to remove the over-print from our zone of interest before any type of inversion workflow, as inversion results are particularly sensitive to seismic amplitudes. Near surface geology with poor transmissibility tends to cause low amplitudes from the top of the seismic section downwards. This creates vertical bands of low amplitude on seismic sections that overprint the true amplitude response of the target geology. This effect is exacerbated in the near-angle stacks as the seismic energy travels through the poor transmissibility geology twice, while far angles may undershoot poor transmissibility or “average out” as the down-going wave may travel through poor transmissibility formation while the up-going wave travels through high transmissibility formation.
The problem can be diagnosed by calculating RMS maps over small intervals at different depths and comparing the results. We expect geology to vary greatly with depth, while remaining more constant laterally. If we note features in the shallow RMS maps that are repeated in the deeper RMS maps, we can deduce that the near surface geology is contaminating the amplitudes deeper in the section. After working projects in multiple onshore U.S. basins, we have found that the issue of near surface geology overprint to be:
Angle dependent (near angles are more adversely affected) and
Depth dependent (deeper RMS maps show less correlation to the shallow RMS maps).
This makes the task of correcting for the issue rather difficult as it appears that the scaling required to correct for near surface effects varies laterally, vertically and across the angle range. In this talk, we present a fast solution for tackling near-surface effects in partial angle stack seismic using RMS amplitude maps. The resulting seismic is suitable for use in any AVO analysis and Quantitative Interpretation (QI) workflows. The seismic data used as an example is from the Delaware Basin, which is the larger of the two major lobes of the Permian Basin. While there are certainly limitations on when the workflow may be applied, we believe that it is helpful when timeline pressures prohibit a more comprehensive solution.
Speaker Biography Ben Hardy:
Ben graduated from Curtin University of Technology in Perth Australia with a Bachelor of Science (Honours) in Geophysics. His first job was on a seismic acquisition vessel with PGS offshore of Mumbai, India before moving into onshore processing, again with PGS in Perth. After a brief sabbatical to travel around Brazil, he began working in mudlogging off the east and west coast of Australia. After a while he began to pine for a job back “on the beach” and gave up the rig lifestyle for a cubicle in the Perth office of RPS Energy. There he flirted with seismic interpretation, and prospect evaluation/ranking before finally settling into quantitative interpretation at Ikon Science. Ben has been working for Ikon Science for the past 12 years. The first 4 years in Perth focusing on basins in Australia, S.E Asia and Africa and the last 8 years in Houston. The change of location and contract-nature of the Ikon Science Services Team means that Ben has performed quantitative interpretation work on datasets from every continent on Earth (with the exception of Antarctica). In the past few years Ben has performed projects in the Eagle Ford, Permian, Bakken and Marcellus Basins. Ben specializes in rock physics, seismic data conditioning (SDC) and seismic inversion and has taught courses on SDC and Inversion at Ikon. In his spare time, he enjoys playing guitar and piano, rock climbing, coding and attempting to speak Russian with his wife.