INSTALLATION METHOD OF CEMENT BRIDGE IN WELL Russian patent published in 2018 - IPC E21B33/13 C09K8/467 

FIELD: oil and gas industry.

SUBSTANCE: method includes pumping of buffer liquid, grouting mortar through coil tubing string in specified interval in volume required for installing the cement bridge with forcing thereof into the well by successively pumped buffer liquid and forcing solution, washing out the excess grouting mortar, waiting for cement hardening. Tubing string, run in the well after removal of pumping equipment therefrom, is additionally run in or pulled, so that the distance from the tubing string bottom to the upper boundary of the cement bridge is 200 m. The perforation intervals are sealed by a blocking composition. Tubing string is run in by installing coil tubing into the tubing string at 0.25 m/s rate up to the lower boundary of the cement bridge with continuous flushing. The space between the tubing and coil tubing strings is sealed at the wellhead of the production well. The grouting mortar with 1430 kg/m³ density is prepared at wellhead for installation of cement bridge from the lower to the upper boundaries of the cement bridge. The grouting mortar consists of 84.45% cement PCT-II-50, 15% foam glass, 0.5% water loss reducer, 0.05% defoamer, 0.1 m³ of buffer fluid, grouting mortar in the prepared volume, and 0.1 m³ of buffer liquid and forcing fluid in volume required for extrusion of grouting mortar from coil tubing string are successively pumped in the coil tubing string. Simultaneously the coil tubing is pulled to the upper boundary of the cement bridge. It is exposed for 5 min. The coil tubing string is pulled 5 m above the upper boundary of the cement bridge. The excess of the grouting mortar is washed from the well by direct flushing in one and a halve volume of the well above cement bridge. The coil tubing string is removed from the well at 0.28 m/s rate.

EFFECT: improved efficiency of cement bridges installation.

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