UNIT FOR PREVENTING BACKFLOW FOR DOWNHOLE OPERATIONS Russian patent published in 2021 - IPC E21B34/12 

FIELD: mining industry.

SUBSTANCE: group of inventions relates to backflow prevention systems for downhole tools. The downhole system contains an internal column with a first rock-breaking device located at its end, an external column with a second rock-breaking device at its end. The internal column is made with the possibility of moving inside the external column, the first rock-breaking device is made with the possibility of drilling a first-size borehole in the bottom-hole reservoir, the second rock-breaking device is made with the possibility of expanding the borehole in the bottom-hole reservoir. The unit for backflow prevention contains a case that restricts the cavity and is a part of the external column, and a movable flow meter pipe located inside the case between the internal column and the external column. The movable flow meter pipe includes one or more coupling elements made with the possibility to accommodate a part of the internal column and containing a rubber material, and it is made with the possibility to move axially inside the external column. The backflow prevention device contains a flap and a sealing seat. The flap is shifted to the closed position and is supported in the open position by means of a movable flow meter pipe and is placed inside the case cavity when it is in the open position. The flap and the seal seat form a hydraulic seal that prevents fluid from flowing into or through the movable flow meter pipe in the closed position. When the movable flow meter pipe moves from the first position holding the flap in the open position to the second position, the backflow prevention device is triggered to move the flap to the seal seat and hermetically close the backflow prevention device. In the second position, the first rock-breaking device is located up the wellbore relatively to the flap. The method for operation of the unit for backflow preventing of the downhole system is proposed.

EFFECT: increased efficiency of drilling the wellbore and cementing during one descent and lifting operation.

13 cl, 22 dwg