Geoscience for GIS - Zolnai · 2 Grid/contours vs. ESRI tools • Evenly spaced points • 2.5D topography, culture • Use GRID or TIN directly • Use Spatial Analyst • Interpolate

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Geoscience for GIS

Andrew Zolnai

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Grid/contours vs. ESRI tools

• Evenly spaced points• 2.5D topography, culture• Use GRID or TIN directly

• Use Spatial Analyst • Interpolate surface from points• Contour interpolated surfaces

• IDW (allow barriers)• Spline (smooth or tension)• Krigging (geologic model)

• Display in 3D and Spatial Analyst• Draping• Shading to show structures• Thickness and trend relationships

• Use Model Builder• Link together several processes• Use canvas to mimic workflows

• Overlay other datasets• Culture, permits, parks etc.• Satellite imagery, and• Real-time tracking data

• Unevenly scattered points• 3D Wells, reservoirs• 2D / 3D seismic surveys

• Use gridding algorithm• To interpolate even datasets• Size / direction to reflect geology

• Use contouring algorithm• Similar algorithms• Model the geology

• Display results• 3rd party application

• Read web services• Read server services

• Export to GIS• Use grid or raster• Think of 3rd party as pre-process• Think of GIS as post-process

• Link to any tool at right• GIS is not just for mapmaking• Maps only report from database

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ESRI tools vs. Other tools

• Upcoming release with simple grid/contouring in 3D Analyst • Enhance current extension with

simple industry-standard code• Use the 3D-, Spatial- or

Geostatistical-Analyst • Note current restriction: single ZM

per XY (topologic integrity constraint)• Create multi-patches

• not easy to implement but resources do exist

• Use ArcMap Model Builder to integrate other desktop grid/contouring

• note that this is less evident and needs some scripting skills

• Use ArcGIS Server SDK to integrate other server-side grid/contouring• note that this is not evident and

needs programming skills

• Download a script from ESRI• ArcScripts page

• Download / buy shareware• such as ETgeowizard

• Buy software that extracts, transforms and loads (ETL)• Safesoft FME Workbench

• Use existing integrator tools such as:• ArcView extensions by CGG, Landmark

or Schlumberger• Direct data exchange tools such as

• OpenSpirit• ESRI Data Interoperability

extension (a subset of FME Workbench)

• Let ArcMap read web services that post grid/contours• Such as Petrosys

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Let’s use what we already have at hand

• ESRI GIS…• Overlay as many any datasets as possible• Get simple surface and thickness trends• Use model builder to implement workflows

• … extensions…• Spatial Analyst (raster integration)• 3D Analyst (simple surface analysis)• Interoperability (link other datasets)• Output (ArcReader, MapBook, Schematic etc.)

• … and web services• ArcIMS (old but stable and widespread)• ArcWeb services (on-line community)• ArcGIS- and Image-server (new and improved)

• The intent here is to• Provide rough sketches with existing tools @ hand• As first step to further integrate with other systems

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Simple Thickness Workflow

• ArcMap• Have two horizons as raster files• Raster Calculator is in Spatial Analyst menu• Subtract the two surface to get a thickness

• ArcScene• Drape the thickness on the lower surface• Contour from 3D Analyst | Surface Analysis

(more complete contouring in next section)• Drape the contours on formation top

(that which is seen on logs or seismic)• Extrude them down from the top

• Quick area and Volume from thickness• Mimic porosity effect by using Z value

• Show simple volumes in vector space• Multi-patches for wellbore representation

DATA: from EarthSoft's EQuIS website

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Contouring Workflow

• Three options

• IDW (Inverse Distance Weighted, similar to Natural Neighbours)• Non-interpretive computation on neighbouring points• Calculates from fixed raster surrounding sample• Honours faults as polyline barriers

• Spline• Force a curved surface through the raster points• Regularised: smoothest shape (stratigraphic plays)• Tension: tune the stiffness (structural plays)• No barriers but tuning parameters

• Kriging• Average from a cloud of surrounding points• Can be made very complex (Geostatistical Analyst)• Can be shaped to mimic geology • E.g.: structural trend s.a. fracturing

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Display Options

• Viewing the data

• In ArcScene• Use transparency and priority

to show various datasets• Use the illumination to view

trends

• In ArcMap• Use the paint tool to compare

overlaps• Use the same tool to verify

raster (surfaces) and vector data (faults) coincide

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Interpretation

• How is it interpreted?• If for example thickness increases with elevation (with or without a mirror

image if the entire structure is preserved), that may be an indication of thickening via fracturation atop an anticline, and therefore of structural trap and play (below left)

• If however thickness decreases with elevation (below right), that may be an indication of a pinch-out and therefore of a stratigraphic trap and play (usually these also occur alone, and do not have an adjacent mirror image).

• The presence of conjugate faults (two fault trends that are at a low angle to each other, below left) is often aligned with a regional fold or bend, and may also indicate a structural play.

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Conclusion

• What more can be done?• More factors can be taken into consideration using more Spatial

or 3D Analyst and other extensions• Model Builder can be used (see option at the end)

• concatenate several repetitive calculations and operations• thus mimic entire workflows • briefly described in next section

• Note• ArcMap tools are used as-is to show what can be with GIS tools

out-of-the-box, plus two extensions• neither scripting nor programming was used here

• This will not replace gridding / contouring or reservoir analysis packages • GIS is meant to work in conjunction with those packages,

as noted in the opening table

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Model Builder

Optional

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Model Builder - 1

• A canvas allows to link together tools from ArcToolbox:

• Based on input data and a process• Output data is next process’s input

• Running the model steps through each process:

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Model Builder - 2

• Resulting model:

• Resulting surface:

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Model Builder - 3

• What was done? • Inverted a formation top into a raster slope • Modelled surface water flow as an analogue to subsurface petroleum flow• Draped the result onto the original formation top• Thus approximated up-slope subsurface fluid flow

• What was used?• Spatial Analyst extension to process rasters• 3D Analyst extension to display vectors• Model Builder tool canvas to tie it altogether• Only with available pop-up and drop-down tools

• Caveats• This is a surface flow model adapted to subsurface flow• Flow will diverge not converge, and create many vertices• To be further refined with additional surface factors

• Such as described in the contouring section above

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Further Resources

• Best Practices: GIS for Petroleum• ESRI 2007, online PDF

• Visualizing integrated three-dimensional datasets (multipatches)• Ford, A • ArcUser (ESRI), January - March 2007

• Introduction to GIS for the Petroleum Industry• Gaddy, D.E.• PennWell, 2003

• Geographic Information Systems in Petroleum Exploration and Development• Coburn, T.C. and J.M. Yarus• AAPG, 2000

• Contouring Geologic Surfaces with the Computer• Jones, T.A., D.E. Hamilton, and C.R. Johnson• Van Nostrand Reinhold, 1986

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Thank you

http://consult.zolnai.cawww.GeoSolveIT.com