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Then it is also useful to include the uncertainty around the wells. This is best done by combining our uncertainty with the object well uncertainty and showing that as a simple offset towards us o c ‘no go’ bound y fo h other well. Now we can see that the green and blue wells might be dangerously closer than we think. To avoid the blue well we would want to be above our current plan around 2300 ft. and to avoid the green we should perhaps be a little more to the right.
Figure 98: Traveling Cylinder Plot – marker points and uncertainty area.
20.13 Travelling Cylinder Options
h
wo op ons fo c ng
lngcylnd plo s,“Hgh d ” f nc do “ o h” f nc d.
h fs xmpl shown n hsscon s “Hgh d” f ncd
l ng cyl nd plo . h s op on h s h
advantage of being easier to understand but it suffers from a peculiarity in top hole as follows.
Consider how a vertical well would appear against a well drilled roughly towards and then away from it.
The red well is our well and from points A to C it would be plotted on our high side. However from points D to F it would be plotted on our low side since we have changed direction. This is the x mpl “Hgh d ” l ng cyl nd plot shown on the right above. It appears that we will drill or have drilled straight through the blue well.
Figure 99: Traveling Cylinder Plot – marker points and uncertainty area.
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