METHOD OF WELL ABANDONMENT Russian patent published in 2014 - IPC E21B33/13 

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to abandonment of evaluation and survey wells at thick oil deposits. Proposed method comprises lowering of string into well with casing string to operate to beds, placing of cement plug in well from mouth to bottom. At abandonment, part of casing string is cut from lower bed bottom to upper bed roof. Then, core sampler is lower in interval of cut section to sample to core located in said cut. Core is analysed to prepare clay with composition complying with that of rock is said cut. Then, small-diameter string plugged from below is lowered from wellhead to bottom. Thereafter, first cement plug is set from bottom to well interval 5 m abode lower bed bottom. Clay bridge is arranged in the well from top end of first cement plug to interval 5 m above upper bed rood. Thereafter, second cement plug is arranged from clay plug upper end to wellhead. First and second cement plugs are fitted using the heat-resistant cement with addition of fibres in amount of 0.2 wt % of dry cement. Small-diameter string is filled antifreeze fluid and FO is lowered down to bottom. Temperature variations are intermittently recorded in borehole after abandonment.

EFFECT: higher efficiency and reliability.

4 dwg