Swisher 5 min well review
5 min well review of the ongoing Equinor exploration well in the Fram area
Near field exploration is valuable business. You can tie-in to existing infrastructure for production and you have lots of offsets to work on.
Within 10 kilometers of the Swisher well, we find dozens of wells and almost 50 well bores, both exploration and production wells.
Heather in Viking Group the reservoir?
Based on offsets, they are either drilling for the Viking group, or they are drilling for the deeper Brent formations. The Viking group has proven hydrocarbons in Heather sands (also known as Fensfjord and Sognefjord) in the area, at depths around 2800-3200 mTVD. Discoveries show oil/condensate and gas.
The sands are known to be of low porosity, shaly and low permeability, according to offset wells, so Equinor probably has some plan to stimulate the reservoir mechanically or hydraulically.
Looking at offsets, the sands in the otherwise shaly Viking group stands out with a significant drop in GR, should be easy to navigate after if they want to do more advanced or precise well placement. Take a look at the GR and ROP plot below to see an example of GR signature.
Looking at the well they are currently drilling, the offsets don't seem to carry any very strong features, except for one well with shallow water flow problems. Shallow water flow is always a potential issue. A costly problem we should look to find a solution to than to try and fail with a pilot hole from the conductor.
This well should be drilled slim, a 13 3/8 from surface and down to the stringers in the Shetland group. The Balder, Sele and Lista formations should be stable with proper mud treatment. Below you can see two alternative designs, which greatly influence your mud volumes. The deeper you go with the 13 3/8", the more mud you are transporting and using - a big cost.
The benefit of drilling deep with the 13 3/8" is that you have more contingencies for later problems, but at the cost of performance, equipment and fluids.
Looking at offsets, it's not easy to say there is a standard to setting depths, but a 13 3/8" set before the Shetland group and a 9 5/8 set above the reservoir seems a decent solution.
Compare the mud volumes above and below. They show a 35% increase in theoretical mud volumes. With regulations about available volumes, this is about 200 m3 extra mobilized to the rig. From tank to boat, to rig, to pits, to well, and back.
They might want to drill the 13 3/8" with water based mud and then switch to oil based for the 9 5/8", that would make it a more reasonable environmental aspect as the oil based mud is more challenging to handle.
Speaking of mud, looking at the offsets, this well can be drilled with really low mud weights, reducing costs and optimizing progress.
Assuming a pore pressure curve as shown in the illustration from the Pro Well Plan platform below, you see the offsets fit in nicely. Mud weights below 1.3 cuts it.
This looks dull, but offsets show little to no pressure buildup in the area, one well has a pressure gradient to the reservoir below water density. Five wells have been drilled with densities below 1.3sg muds, but some other have been pushing for much higher mud weights.
It's a frequent issue that mud weights are pushed up 'just to be safe', but the consequence of flooding reservoirs with particles from the mud can be costly when the tap is opened.
You want to balance the mud weights so you don't take kicks, and for deviated wells add some weight so the hole won't collapse while running casing.
Most wells in the area seems to be targeting the same formations, so there could be some depletion from production. But that seems unlikely, given the distances.
Zooming in on ther Heather formation, you can see the mud weights used for this formation are quite low, except for a few much deeper wells, just rushing through.
Best of luck!
That's it for this five minute well review of Equinors Swisher well, all the information has been gathered and compiled in the Pro Well Plan platform, used by the best drilling teams in the world.
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Thanks for reading, this article was written by Magnus Tvedt, the founder and CEO of Pro Well Plan. A visionary ambassador for modernizing the oil and gas industry.
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