METHOD FOR CEMENTING A FIBERGLASS CASING STRING (OPTIONS) Russian patent published in 2022 - IPC E21B33/14 

FIELD: oil and gas industry.

SUBSTANCE: inventions group relates to the oil and gas industry, in particular to methods for cementing a fiberglass casing string in a wellbore. The method for cementing includes lowering a fiberglass casing string into the well, cementing by sequential injection of a buffer fluid, cement slurry into the fiberglass casing string and its displacement with drilling fluid. The fiberglass casing is preliminarily equipped with a check valve at a height of 50-55 m from the bottom of the well, the check valve is installed in such a way that when it is subjected to fluid flow pressure from the annulus, the check valve throttle opens inside the fiberglass casing, communicating the annular space with the internal space of the fiberglass casing, and when the fluid moved in the opposite direction, the check valve was hermetically closed. The first 50 m of the lower part of the fiberglass casing is made of steel pipes with a threaded connection identical to the entire pipe string, the fiberglass casing is lowered to a depth exceeding 50-55 m from the planned one, cementing is carried out in two stages. At the first stage, buffer fluid, cement slurry in the amount necessary to fill the annular and internal space of the lower part of the fiberglass casing string to a height not exceeding the level of the check valve setting are sequentially pumped into the fiberglass casing with the check valve closed, which is then forced through with the displacement fluid in the amount required to leave the cement column inside the bottom of the fiberglass casing string, then the string is left under operating pressure while waiting for the cement to harden for at least 4 hours. At the second stage, back-cementing of the upper non-cemented fiberglass casing string is performed by successive pumping into the annulus of a buffer fluid, cement slurry through a check valve, after the cementing process is completed, the fiberglass casing string is left under pressure for a waiting time for the cement to harden for at least 4 hours.

EFFECT: increasing the efficiency of cementing the fiberglass casing string, in reliable fixation of the fiberglass casing string due to the preliminary fastening of the lower part of the string in the well and holding the fiberglass casing string inside oil and gas wells; invention also ensures the exclusion of the rise of the string during the cementing process, the possibility of cementing with cement slurry of any density.

2 cl, 4 dwg