WELL COMPLETION METHOD Russian patent published in 2016 - IPC E21B33/14 C09K8/493 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, and specifically to completion of wells at deposits and underground gas storages. Method involves well drilling with opening of productive formation. Borehole is divided to at least three intervals and average temperature value in each interval is determined. At average temperature values obtained, static shear stress of grouting mortar is determined. Bottom-hole pressure reduction is calculated, caused by suspension of column grouting mortar on walls of well, by analytical expression. Prior to lowering of production string, borehole in range of productive formation is filled with fluid of bottom hydraulic lock, represented by specified composition in certain proportions. Before and after specified composition, separation liquid is pumped based on xanthane biopolymer. Production string is lowered to roof of productive formation. Flushing liquid is represented by drilling mud, which is pumped in turbulent conditions. Liquid of upper hydraulic lock is represented by other specified composition in certain proportions. Placed above backfill solution up to well head. Flushing of grouting mortar is carried out in turbulent conditions until achieving maximum allowable pressure upon productive formation, and then in sub-laminar conditions. Counter pressure in waiting period of cement hardening is created from the moment of equality of bottom-hole and formation pressures until the moment of initial setting of grouting mortar on well bottom, while increasing wellhead pressure in accordance with analytical expression. Then counter pressure is maintained until end of waiting for cement hardening. Bottom-hole pressure is defined as difference between static pressure of fluid column in annular space at the moment of flushing completion, and value of bottom-hole pressure reduction caused by suspension of column routing mortar on walls of well.

EFFECT: technical result is increased efficiency of well completion due to tightness of annular space and maintaining natural permeability of bottom-hole zone in productive formation.

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