Using GIS to scout a land seismic survey

A 3D land seismic crew has the potential to be a big operation. How big?

“A land seismic survey conducted in 2005 had 400,000 sensors per square kilometer; by 2009, that number had reached 36 million. From 2005 to 2009, the average volume of data gathered on an eight-hour shift grew from 100 gigabytes to more than 2 terabytes…The number of channels on a crew grew from 8,000 in 2005 to 40,000 in 2009. This year [2015], CGG had more than 100,000 channels for a land seismic crew, with the goal of reaching one million” http://www.rigzone.com/news/oil_gas/a/140418/Big_Data_Growth_Continues_in_Seismic_Surveys

“During acquisition, daily production peaked at over 10,000 vibrator points per day…. Point-source and point-receiver spacing of 12.5 m” http://www.slb.com/resources/case_studies/westerngeco/uniq_uae_crescent_cs.aspx

Land seismic crews can have easily over 200 people working at any one time with a computing capacity greater than most small offices.

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Image of a seismic field crew taken from Wikipedia https://en.wikipedia.org/wiki/Reflection_seismology , under a creative commons license CC BY-SA 3.0

Logistics, Logistics, Logistics

There are numerous factors that can influence a seismic survey. For example, lightning strikes on the spread of receivers can damage equipment and severely hamper the survey progress. A period of bad weather can mean production is suspended while equipment is repaired or replaced. The location you are operating in could suffer political unrest and cause the crew to shut down for a period of days. In short there are just some things you cannot model.

What can you model? Of all the factors that can affect the operation, perhaps the most consistent is the terrain. A good terrain model can be used as an input (but not necessarily the sole solution) to begin to address questions like:

  • Where is the best location for the campsite?
  • What kind of vehicles will we need in this project?
  • What type of seismic source shall we use?
  • Are there any areas that are going to cause the operation to slow down or allow it to speed up?
  • How will the surface impact on the quality of the seismic data?

Terrain Model

Using data derived from Earth Observation satellites is an obvious starting point. The EO4OG project has a section on seismic planning that is worth visiting at this point. If you are not familiar with this project I have written extensively about it http://www.acgeospatial.co.uk/blog/eo4og/

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Image taken from the EO4OG project website https://earsc-portal.eu/display/EO4/EO4OG+Challenges+-+seismic+planning

When scouting for a project the resolution of the imagery provided by Landsat8 and Sentinel-2 combined with the best available DEM data is normally sufficient to build a terrain model that will highlight expected terrain classes. It will provide a broad overview of the survey area (remembering areas can be very large).

sat_image_terrain

terrain_image

Terrain image examples. Images created from Landsat 8 data by Andrew Cutts

 

Why GIS?

Terrain models and Earth Observation data have a natural home in a GIS system. By building up a series of layers more information can be added to these terrain models. What other data could be added?

  • Other raster data sources, old scanned maps perhaps
  • Infrastructure, buildings, roads
  • Oilfield infrastructure
  • Areas of no go (Military areas, sites of cultural/historical value)
  • Agricultural areas
  • Utility information

The GIS is the system used to help de-risk the operation and hold all the surface data; it is a great planning tool. 10-15 years ago paper maps and CAD systems dominated, now the need to manage information better (and permitting is a great example of this https://www.linkedin.com/pulse/geofencing-exploration-andrew-cutts) requires an information based system. Once you have all this data then suggested locations to scout to can be made. Why is it useful? – because it provides the ability to quantify risk for a relativity low cost.

Scouting a land seismic job properly is critical for the competence of the crew. If HSE events can be anticipated and mitigated against (for example the roll-over of vehicles on unsuitable terrain), then lives are potentially saved. Imagine again 10,000 seismic shots a day (and some crews are achieving plenty more), you might have 20 vibroseis vehicles working on a 24 hour operation. The step change in source and receiver density on the ground in only 10 years means that good scouting and planning is essential. A location based tool that stores and delivers and derives information about different places can only enhance any field operation. This is the answer to “why GIS?”.

Want to learn more about GIS and EO for Oil and Gas? Then my page contains all my blogs, plus case studies and links http://gis.acgeospatial.co.uk/

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