FIELD: soil or rock drilling; mining.
SUBSTANCE: invention relates to drilling wells and can be used to control location of drilled well relative to target well. In particular, downhole ranging system is proposed, comprising: the first optical waveguide, located in first formation well, wherein first optical waveguide is disposed along portion of axial length of first well; at least second optical waveguide placed along at least same axial length of first well as first optical waveguide; and sound source disposed in second well and acoustically associated with said formation. Moreover, optical waveguides are arranged under different opposite azimuthal positions around first well to determine transverse displacement of sound source from first well.
EFFECT: proposed invention is aimed at providing effective "passive" range-finding technique without need to use current guidance in target well.
23 cl, 6 dwg
