Strict reserves are about 10 Tcf but could increase to about 400 Tcf depending on economics and technology. Prime example is the deep basin of Alberta which is just about completely impregnated. The gas bleeds into the reservoir and leaks slower than it fills. Production depends on artificially fracturing the reservoir. Elmsworth Field in Canada is the best example.
Extraction is problematic.
Being solid, hydrates cannot migrate into commercial traps. The USA is consuming its endowment of conventional natural gas and Europe has privatized the gas business which will have the same consequence. Europe can import from the huge reserves of the FSU, and eventually the Middle East and Africa, even Nigeria. The USA is more depleted than anywhere else.