Method of recovering geothermal energy

Claim 1

A method of recovering geothermal energy from a low permeability subterranean geothermal formation having a preferred vertical fracture orientation, comprising the steps of: a. providing a first and a second well which extend from the surface of the earth and penetrate said geothermal formation at an angle of at least 10* measured from the vertical and extend into the formation in a direction transversely of said preferred vertical fracture orientation; b. hydraulically fracturing said formation to provide a plurality of vertical fractures which are spaced laterally one from the other a predetermined distance measured in a direction approximately normal to the preferred vertical fracture orientation and which fractures extend into the formation and intersect said first and said second wells; c. providing fluid communication intermediate each of said plurality of vertical fractures with each of said first and said second wells; d. injecting a fluid via one of said first and said second wells into said plurality of vertical fractures; e. flowing said fluid through said plurality of vertical fractures to heat said fluid; and f. producing said heated fluid from said plurality of vertical fractures via the other of said first and said second wells.

Claim 2

A method of recovering geothermal energy from a low permeability subterranean geothermal formation having a preferred vertical fracture orientation, comprising the steps of: a. providing a first and a second well which extend from the surface of the earth and penetrate said geothermal formation at an angle of at least 10* measured from the vertical and extend into the formation in a direction transversely of said preferred vertical fracture orientation; b. hydraulically fracturing said formation to provide a plurality of vertical fractures which are spaced laterally one from the other a predetermined distance measured in a direction approximately normal to the preferred vertical fracture orientation and which fractures extend into the formation and intersect said first and said second wells; c. providing fluid communication intermediate each of said plurality of vertical fractures with each of said first and said second wells; d. injecting a fluid via one of said first and said second wells into said plurality of vertical fractures; e. flowing said fluid through said plurality of vertical fractures to heat said fluid; and f. producing said heated fluid from said plurality of vertical fractures via the other of said first and said second wells.

Claim 6

A method of recovering geothermal energy from a permeable subterranean geothermal formation having a preferred vertical fracture orientation, comprising the steps of: a. providing a first well and a second well which extend from the surface of the earth and penetrate said geothermal formation at an angle of at least 10* measured from the vertical and extend into said formation in a direction transversely of said preferred vertical fracture orientation; b. hydraulically fracturing said formation to provide at least a first vertical fracture and a second vertical fracture which extend into said geothermal formation and intersect said first well and said second well, said fractures being spaced laterally one from the other a predetermined distance measured in a direction approximately normal to said preferred vertical fracture orientation and which fractures extend into the formation and intersect said first and said second wells; c. providing fluid communication intermediate said first vertical fracture and said first well and providing no fluid communication intermediate said first vertical fracture and said second well; d. providing fluid communication intermediate said second vertical fracture and said second well and providing no fluid communication intermediate said second vertical fracture and said first well; e. injecting a fluid via said first well into said first vertical fracture and driving said fluid through said geothermal formation intermediate said first and said second vertical fractures and into said second vertical fracture; and f. producing said heated fluid via said second vertical fracture and said second well.

Claim 7

A method of recovering geothermal energy from a permeable subterranean geothermal formation having a preferred vertical fracture orientation, comprising the steps of: a. providing a first well and a second well which extend from the surface of the earth and penetrate said geothermal formation at an angle of at least 10* measured from the vertical and extend into said formation in a direction transversely of said preferred vertical fracture orientation; b. hydraulically fracturing said formation to provide at least a first vertical fracture and a second vertical fracture which extend into said geothermal formation and intersect said first well and said second well, said fractures being spaced laterally one from the other a predetermined distance measured in a direction approximately normal to said preferred vertical fracture orientation and which fractures extend into the formation and intersect said first and said second wells; c. providing fluid communication intermediate said first vertical fracture and said first well and providing no fluid communication intermediate said first vertical fracture and said second well; d. providing fluid communication intermediate said second vertical fracture and said second well and providing no fluid communication intermediate said second vertical fracture and said first well; e. injecting a fluid via said first well into said first vertical fracture and driving said fluid through said geothermal formation intermediate said first and said second vertical fractures and into said second vertical fracture; and f. producing said heated fluid via said second vertical fracture and said second well.

Claim 11

A system for producing geothermal energy from a low permeability subterranean geothermal formation having a preferred vertical fracture orientation, comprising the combination of: a. a first deviated well and a second deviated well which extend from the surface of the earth and penetrate said geothermal formation in a direction transversely of said preferred fracture orientation; b. a first vertical Fracture and a second vertical fracture spaced laterally one from the other, said first and said second vertical fractures extending into said geothermal formation to intersect said first and said second wells and having fluid communication with said first and said second wells; and c. a means for regulating flow of fluid installed in said first well intermediate said first and said second vertical fractures.

Claim 12

A system for producing geothermal energy from a low permeability subterranean geothermal formation having a preferred vertical fracture orientation, comprising the combination of: a. a first deviated well and a second deviated well which extend from the surface of the earth and penetrate said geothermal formation in a direction transversely of said preferred fracture orientation; b. a first vertical Fracture and a second vertical fracture spaced laterally one from the other, said first and said second vertical fractures extending into said geothermal formation to intersect said first and said second wells and having fluid communication with said first and said second wells; and c. a means for regulating flow of fluid installed in said first well intermediate said first and said second vertical fractures.