Posted 05.10.2018 09:23 by Magnus Tvedt
This is Oseberg turf, right next to another exploration well 30/6-11. Utsira, Balder/Sele/Lista, Draupne, Heather and Brent. We're drilling deep, expecting reservoir around 3400 m TVD and temperatures around 120-140 C.
Huldra is a little north with high pressure and temperature, but rather homogeneous overburden. Shetland is shales, Heather and Draupne are mostly present above the Brent reservoir.
Veslefrikk, to the north east, has similar geology, but is known for high pressures and temperatures and narrow drilling windows.
Looking at casings, there seems to be some inconsistencies. Conductor set in seabed (Nordland), Surface casing set in top Hordaland, then the 17 1/2" section vary between lower Hordaland, in Rogaland, or in Shetland. I would look more into reasons for deviations with more time.
In Huldra exploration wells, they have set casing in Cromer Knoll gp, before entering Draupne and Heather in Viking gp. In Oseberg, the Heather and Draupne fms are not so strongly present in the north - towards our well.
Very few pilot holes have been reported in the area.
Casing setting depths in Rogaland Group at Oseberg and Huldra Field
The 30/6-11 well is clearly most similar to the Oseberg in temperatures and pressures. I got a bit of a surprise here, as I thought Huldra was a Oseberg like field, but Huldra exploration wells are drilled with fluid densities up to 2.0 sg!
Oseberg is drilled with standard fluid systems at densities up to 1.5 sg, I expect 1.4 to 1.5sg would keep the operations safe in our exploration well.
One note is that there can be traces of high pressure zone leakages from the Huldra field. Some shallow gas is reported in Huldra, not sure if that is from migration from reservoir or from other sources.
Fluid Program and Formation Tests
This was five minutes with data driven well planning where we scratched the surface of the Rungne well. It looks like a fairly straight forward well, but I would dig more into experiences with drilling close to high pressure zones, challenge geologists on potential leaks of gas which could be a surprise.
With our software, the next step would be to design a couple of well designs to get more into the details of alternative designs to discover more experiences from our rich data history. When we start looking at drilling logs for relevant wells we can reveal drilling hazzards like cavings and stuck pipe scenarios, as seen in a neighbor well.
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Previous well planning has been about reacting to hazards in operations, data driven operations are all about planning for predicted, high performance in operations.
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