Keynote Presentation: Surface and Wellbore Positioning Errors and the Impact on Subsurface Error Models and Reservoir Estimates

Key Points:

1. Geospatial on positional errors often get compounded as we go from the first well within a basin forward to making detailed maps on specific reservoir units.
2. As we attempt to knit together the framework of our reservoir models, the data from one well is compared and contrasted to the next well and is often tied into seismic data to connect or separate various reservoir units.
3. When positional errors are present, they begin to unravel the fabric and framework and our confidence in our models
4. As additional wells are drilled the existing errors and the newly created errors show up as:
   1. geologic markers coming in shallower or deeper than anticipated
   2. as apparent differences in gas/oil, gas/water, or oil/water contacts between wells
   3. as apparent differences in fluid pressure gradients
5. Any discrepancies, even the smallest, causes frustration and confusion
   1. This can lead to bad decisions and lost value Additionally reservoirs often being incorrectly broken up into compartments
   2. This can lead to wells not being drilled
6. Infill wells, particularly horizontal wells can miss large sections of the reservoir, or can be accidentally placed closer to fluid contacts when gross errors are present;
   1. resulting in early breakthrough of water or gas
   2. resulting in significant lost value
   3. often delaying or sometimes stopping entire development program
7. Both Geologists and Reservoir Engineers are for the most part unaware of or do not know how to deal with the standard positional error models.

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Surface and Wellbore Positioning Errors and the Impact on Subsurface Error Models and Reservoir Estimates

 

Ed Stockhausen

 

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