To do this, you need to:


1) Make islets (small islands), that is big enough to support a/an: a) oil pump, b) power transformer, c) oil pump

2) Place your oil pumps on those said islets. (3 is recommended)

3) Connect your oil pumps with pipes, and into 3:1 pipe pumping stations. (Or whatever setup you like, but for me, this is efficient.)

4) Merge those pipes with your land based oil refinery build.

5) Power up the transformers since your oil pumps won't work without electricity.

Here are pictures taken from my own savegame from the Lyubinsk (populated) map, which should serve as an example:

https://ibb.co/276x5nX
https://ibb.co/xFrCct9
https://ibb.co/M5Fx5Gv
https://ibb.co/0m3m79x


I am hoping that they would add oil platforms into the game in the future, so it would serve the purpose of offshore oil that I intended to place. Hope this helps, and good luck, comrade.