Hi-- I'm the author of CTG. The CTG mod totally changes all generation of land / water (it is moved into an on_chunk_generated handler). I had a user who said that with CTG + Cargo Ships they were unable to get any deep water oil patches.

I looked at the code for Cargo Ships and believe I see two reasons for this:
(1) Since "cargo-ships" comes alphabetically before "ctg", I think your mod's on_chunk_generated is called before mine, so there is no water available to place oil patches on. An optional dependency "?ctg" should hopefully resolve this.
(2) For technical reasons, my mod (typically) only places shallow water. I saw that on line 269 of your control.lua file you have a special case for this issue with SeaBlock; if you also check for "ctg" I believe that will address this as well.

If you wish to test whether it worked, the easiest settings to use for CTG are to keep "Remove default water" (in the startup settings) checked on, use the Terrain preset "cross", and to turn the "Big scan" setting on. This will generate a large amount of terrain that is almost all shallow water, to see if oil patches are being spawned properly in it.

Thanks for looking into this compatibility issue!

Hi!
I uploaded a version with the changes you proposed! Since you figured everything out yourself this was an easy fix on my side. thanks for the work!

I was the one who initially brought this issue to Erst's attention and I gotta say you two just made my day! I was holding off on starting my 0.17 playthrough until this was working so now knowing when I get home from work I can actually start that has got me giddy!

Thank you both for looking into this and resolving it so quickly. Proving once more than the factorio community is one of the best around! Kudos to you both and keep up the great work.

Just got home and tested it. Works like a charm and deep sea oil patches are spawning again!