companies that mapped (the, 0) shale reserves

Question

A quote from the Economist ("The Father of Fracking")

His company counted on support from various government agencies, including those that mapped the shale reserves (demonstrating that they were plentiful) and promoted the development of technologies such as diamond-studded drill bits.

Does THE here points at some specific reserves in the territorial sense (say in the US, not anywhere or in general)? Is it the parenthesized "demonstrating that they were plentiful" that makes the use of THE imperative?

If the parentheses are cut, can we substitute "THE" with the zero article? Would that switch the meaning from "US reserves" to reserves in general (reserves-mapping firms in general)?

His company counted on support from various government agencies, including those that mapped shale reserves and promoted the development of technologies such as diamond-studded drill bits.

Is that O.K.?

Answer 1

"The shale reserves" would refer to some specific reserves, but I'm not sure what you mean by "in the territorial sense". At some prior point, the Economist article must have specified what reserves are meant.

Even if the company restricted its shale reserves mapping operations to the U.S., the phrasing would be "U.S. shale reserves", not "the shale reserves". The use of the definite article would be ungrammatical unless some specific reserves have been indicated earlier.

The answer to your second question is yes, dropping the parenthetical phrase and the definite article yields a perfectly grammatical sentence. So does dropping the parenthetical phrase by itself, assuming that the specific reserves have been identified earlier.