| 摘要 |
A improved method for abstracting geothermal energy has water injected into underground strata by a series of bores (1), equally spaced about a second set of bores (4) which collect the heated water. The heat is extracted by a heat exchanger (6) and the cooled water is re-injected into the strata. Each collecting bore is surrounded by a set of injecting bores in a polygonal array, e.g. six injection bores around a collecting bore. The spacing (S) between the injector and collector bores is selected for optimum heat collection and is typically 200 to 800 metres. For improved efficiency the collecting bores reach deeper than the injecting bores by about 5 percent of the bore spacing and are wider than the injecting bores. The injection and collecting pipes have inlet/outlet ports spaced through depth of the hot strata. For added collection efficiency the strata between the bores can be fragmented, e.g. by hydraulic fragmentation.
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