CONSTRUCTION METHOD FOR SLIM-HOLE WELL Russian patent published in 2013 - IPC E21B43/00 

FIELD: oil and gas industry.

SUBSTANCE: according to the method drilling, casing and anchoring of pipe, surface pipe and production string. While drilling the production string a well is drilled with a natural water suspension. When a water-containing formation is open transfer is done to a dense mud in order to prevent spilling of formation water; when the formation is open and after complete loss of mud transfer is done to a natural water suspension maintaining volume of the mud in the upper part over the formation with complete loss of mud. As the well does deeper, volume of mud becomes less in the upper part of the well and intermittent changes in level and spills of borehole fluid occur then volume of mud is added in the upper part of the well till intermittent changes and spills are stopped.

EFFECT: increased efficiency of method.

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