METHOD FOR DRILLING HORIZONTAL WELL HAVING DISTANT BOTTOM Russian patent published in 2006 - IPC E21B7/04 

FIELD: well drilling, particularly special methods or apparatus for directional drilling.

SUBSTANCE: method involves drilling vertical well section from well head, initial well deviation section with increasing zenith angle up to value not exceeding critical value corresponding to well wall stability loss, well section characterized by zenith angle stabilization and increase to 90°; drilling horizontal well bore and communicating the bore with design tunnel of productive bed after zenith angle increase to magnitude exceeding 90°; drilling production well section. Vertical well section, initial well deviation section and zenith angle stabilization section are drilled up to point of anticline productive bed roof penetration along trajectory corresponding to maximal possible well bore length. Minimal possible distance from formation roof penetration point to gas-water surface or oil-water surface must meet the condition determined from mathematical expression. Well deviation sections with zenith angle increase to 90° and ascending near-horizontal sections are drilled in bottom ascending anticline formation zone. If productive zone is located on descending anticline part opposite to well head ascending near-horizontal well section is drilled up to point spaced from productive part inlet for distance calculated from mathematical expression.

EFFECT: increased reliability in the case of drilling of well having remote bottom at productive bed anticline and spaced from drilling rig in unstable caving rock.

2 cl, 3 dwg, 1 tbl, 1 ex