Here's how they extract clathrate

There's more than just pillars, coal, gas, and oil off the northern shores of Attland. King Yarl had banked on the seafloor to have more than scientifically discovered amounts of clathrate. King Yarl was the first one to discover and confirm that clathrates under seaflor do contain hydrocarbons, and off Attland's shores, they contain propanes, butanes, pentanes, hexanes and sometimes higher hydrocarbon alkanes.
The Oilbelt Corporation's platform looks like it is an oil drilling type, but it is actually a clathrate extraction platform (note the absence of the rig.) Clathrate is heated and processed to separate hydrocarbons, which are concentrated and stored to be offloaded into the company service tankers.