Land Seismic Survey Design
This course presents an integrated approach to modern land 3D seismic survey design as it has a key role in the seismic value chain going from acquisition to processing, imaging and inversion & characterization. It will describe the main technology advances in land seismic acquisition: high-channel count single sensor (point receiver), simultaneous source high-productivity vibroseis, broadband and wireless nodal systems. New acquisition technology has in turn inspired progress in processing, imaging and inversion & characterization. Seismic survey designs have changed accordingly, wide azimuth high-density surveys are now the norm in many environments. And the survey design workflow now includes single sensor, single source, simultaneous source, broadband, symmetric sampling, cross- spreads, spatial continuity and more powerful 5D interpolation methods. It has also become more integrated, with requirements from processing, imaging and inversion & characterization feeding back to the design and hence acquisition.
The purpose of this course is to understand:
- The main parameters related to land survey design;
- The generic land seismic survey design workflow;
- The impact of the new acquisition technology on survey design;
- How design and acquisition affects processing, imaging and inversion and characterization.
- Introduction: setting the stage discussing the survey design process as part of the seismic value chain and from the perspective of integrated project design;
- Survey design workflow: generic survey design workflow introducing the basic design parameters and explaining how they are estimated. Among other things this involves survey objectives, resolution, signal and noise. In the next sections, we will show the impact of the new technologies;
- The advent of high-channel count systems has enabled single sensor (or point receiver) recording. This can provide unaliased sampling of signal and noise enabling easy removal of in particular near surface source generated noise;
- Simultaneous source hi-productivity vibroseis: acquiring data from multiple (groups or single) vibrators simultaneously from different source locations, which can improve spatial sampling and reduce cost by increasing productivity;
- Broadband: driven by imaging and inversion requirements, there has been a major technology effort to increase bandwidth, mostly on the low but also on the high frequency side of the spectrum;
- Wireless nodal systems significantly improve operational flexibility in restricted areas; increasingly being used with single sensors. Nodal technology is developing fast with higher channel counts while improving Wifi & Bluetooth technology enables better QC;
- The impact of survey design at the data processing stage includes receiver sampling for adequate noise suppression, improved source sampling for well sampled gathers (cross-spread, source, receiver) and fold (trace density). When we design the survey, we can for instance ensure well interpolated & regularized input to imaging, understanding of multiple behaviour, and enable good surface wave inversion for near surface modeling;
- At the imaging stage we should ensure spatial continuity, good spatial sampling (CMP bin), trace density, azimuth/offset sampling for azimuth preserving OVT migration, sufficient migration aperture and bandwidth. We can model for good illumination;
- To ensure optimum inversion – in particular pre-stack and AVOAz – and reservoir characterization, wide azimuth, high-density survey designs can provide good azimuth/offset sampling and S/N. Low frequency data (broadband) will reduce the dependency on well data, high frequency data and good spatial sampling will optimize resolution;
- Finally, there will be a quick look at some future developments like ongoing research efforts in the area of vibroseis sources, simultaneous sources and wavefield interpolation.
Acquisition geophysicists who are naturally involved in survey design but also processing geophysicists and interpreters who wish to understand how acquisition programmes can be tailored to tackle their problems. The course may also be beneficial to geoscience (geophysics and geology) students.
Participants are assumed to have basic knowledge of seismic acquisition and processing techniques.
About the Instructor
With more than 20 years industry experience principally with Schlumberger, Paul Ras has worked in land seismic acquisition, survey evaluation & design, data processing, inversion & reservoir characterization. He is currently a geophysical consultant based in the Netherlands, teaching and consulting for Schlumberger NExT and working with geophysics startups. Paul began his career at TNO Institute of Applied Geoscience and Delft Geophysical in the Netherlands, working in software development and as a seismologist on field crews. He then worked in various roles for Geco-Prakla, on crews and in the survey evaluation and design group. After a three year secondment at Saudi Aramco followed by starting up WesternGeco’s data processing center in Saudi Arabia, he moved to inversion and reservoir services working for Schlumberger’s DCS segment based in Cairo. Then came various technical and project management roles mainly involving new technology like the land UniQ acquisition system, land demultiple processing and seismic guided drilling. From 2013 until 2015 he worked as a land area geophysicist for WesternGeco based in the UK. Paul is a graduate in Applied Geophysics from Delft University of Technology in the Netherlands.