COMPATIBLE BUFFER LIQUIDS MADE OF LOW-CRYSTALLINE SILICON DIOXIDE Russian patent published in 2022 - IPC C09K8/40 C09K8/50 C09K8/60 

FIELD: mining industry.

SUBSTANCE: present invention relates to buffer fluids for use in underground operations. The invention concerns a method for displacing borehole fluids, including providing a buffer additive containing a biopolymer containing diutan resin and a cleaning material selected from a group consisting of pumice, perlite, colloidal silicon dioxide and their combinations, where the buffer additive contains a dry mixture of biopolymer and cleaning material, where the buffer dry mixture has a mass ratio of diutan resin to the cleaning material from about 2.4 to about 97.6, and where the buffer dry mixture essentially does not contain crystalline silicon dioxide; obtaining a buffer liquid by combining water and a buffer additive, while the buffer liquid does not essentially contain clay; and introducing a buffer liquid into the wellbore to displace at least part of the first fluid in the wellbore. The invention also concerns options for the method for displacement of borehole fluids.

EFFECT: improved compatibility of the buffer fluid with displaced fluids, such as oil-based drilling fluids, improved resistance to gelation in contact with oil-based drilling fluids in the wellbore, improved extraction of oil-based drilling fluids and a decrease in the equivalent circulation density.

17 cl, 4 ex, 13 tbl, 3 dwg