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METHOD FOR RE-OPENING PRODUCTIVE FORMATIONS

[Category : - OTHER]
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The invention relates to the petroleum industry and can be used for improving petroleum recovery by means of more-fully processing formations in difficult geological conditions. A method for re-opening productive formations using helicoid perforation involves perforation, which is carried out by moving a perforator along the axis of a borehole while simultaneously rotating same around its own axis, thus forming perforation channels; the rates at which the perforator moves and rotates are selected under the condition that the produced perforation is in the form of a helicoid, with the forming of a hollow space in the formation to be processed; wherein, the perforator is in the form of a hydraulic perforation attachment (hydraulic perforator), the pitch of the produced helicoid is 10cm, and the pitch of the helicoid comprises 0.7 of the maximum height of the gap. The perforation channels can unite with one another within the formation due to the small pitch of the helicoid, and a cylindrical excavated opening with a radius of more than 0.5m is formed in the space surrounding the column. The liquid filtration area from the formation to the borehole is 5 times greater than in an open borehole shaft, thus lowering the skin factor to a level at which the formation is hydraulically fractured without destroying the top or the base of the formation or the barriers within the formation. The invention allows for creating an open well face (cavity) with a radius which exceeds 0.5 m, for decreasing filtration resistance, for decreasing the risk of a "stop" from a hydraulic fracture in the formation, and for increasing filtration efficiency.