SURFACE EXCITATION RANGING SYSTEM FOR SAGD APPLICATION Russian patent published in 2018 - IPC E21B47/22 E21B7/04 G01V3/26 

FIELD: drilling soil or rock.

SUBSTANCE: invention relates to directional drilling wells. In particular, proposed is a downhole distance determination system, which comprises: first and second wellbore; current injection system, containing an AC source on the surface, an emitter electrode and a return electrode; and an electromagnetic (EM) sensor located inside the second wellbore. First wellbore comprises a first end in close proximity to the wellhead on the surface of the formation and a second, distal, end, arranged along a portion of the support axis coaxially with at least a portion of the first wellbore, wherein the reference axis comprises a support point thereon, and wherein the elongated conductive member is disposed within at least a portion of the first wellbore. In addition, the emitter electrode is located adjacent to the wellhead, and the return electrode is placed on the surface at a location that, in essence, minimizes the distance between the return electrode and the support point and provides optimization of the current in the first wellbore.

EFFECT: technical result is improved accuracy of determining the distance and direction between the wellbores.

33 cl, 19 dwg