METHOD FOR DETERMINING TUBING TIGHTNESS IN INJECTION WELLS Russian patent published in 2019 - IPC E21B47/117 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil industry and can be used in operation of injection wells equipped with a tubing string (TS) and packer. Method for determining leak-tightness of tubing string in injection wells includes assembling at wellhead and lowering into well of tubing string with diameter of 48–114 mm with packer with diameter of 82–146 mm, pre-production string is templateed with length of 1–4 m, tubing string is assembled on high-tight couplings or couplings with sealant on thread, prior to installation of packer, pressure testing of pipes is performed in the following sequence, pressure line is assembled, pressure line is pressurized by 1.5 times pressure from planned pressure of pressure test TS, TS is pressurized to pressure of 100–250 atm (depending on operating conditions of pipes), during well operation after introduction of downhole pump equipment, an inadequate investigation of system tightness is performed TS-packer-EC, for this purpose well is stopped, recording of pressure change in intertube space overlapped with packer, and pressure measurement at wellhead inlet to tubing string, pressure change is recorded comparing pressure before and after well shutdown by rate of pressure drop at wellhead and in tube space after shutdown of operating well and comparing pressures before and after well start for injection by rate of pressure increase at wellhead and in annular space after well start-up for pumping, wherein when determining the tightness of the annular space after the criterion for evaluating tightness of the annular space, a design value of the flow rate of the fluid entering or leaving the annular space of the well is received, in system hermeticity TS-packer-EC and absence of excess pressure in annular space during operation (under condition of detected EC violations) TS pressurized are considered to be pressurized before PRS, RNC is not performed, if necessary for pressure testing TS before repair of wells after packer failure, pressing of system is performed TS-packer-EC with the help of pump unit by annular space at pressure allowable on EC 50–200 atm, at system tightness or pressure drop by 5 % TS hermetically sealed, when the system is unsealed, shut-off device of pressure testing valve is lowered into pipes, process fluid is pumped into TS to bring valve (shutoff element) to locking ring (seat), pressure is created in TS equal to 50–250 atm, held for 15–30 minutes, with pressure reduction in TS by 0–5 % TS sealed.

EFFECT: provides higher efficiency of method due to exclusion of well export from sound, tight TS and their subsequent expensive repair in specialized enterprises.

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