METHOD OF WELL HEAD CONDUCTOR OR EXTENSION PIPE PART AIR-TIGHTNESS DETERMINATION IN PRODUCTION GAS WELL Russian patent published in 2006 - IPC E21B47/10 

FIELD: oil and gas industry, particularly well operation.

SUBSTANCE: method of air-tightness determination involves measuring background pressure in tubing-casing annulus; providing gas-dynamic connection at well head between hole annuity and tubing-casing annulus at moment of background pressure stabilization in tubing-casing annulus; increasing background pressure in tubing-casing annulus in several stages to reach maximal possible test pressure , wherein the pressure increase is 1 MPa for each stage, along with performing time-delay at each stage to relax and stabilize tubing-casing annulus pressure. If tubing-casing annulus pressure is time-stabilized at last stage well head conductor or extension pipe part air-tightness is assumed to be perfect. If tubing-casing annulus pressure is reduced at one stage after relaxation operation the pressure value is recorded in relaxation termination period. Then time-delay is carried out until pressure stabilization in tubing-casing annulus, time-delay duration and pressure values are recorded and compared with background pressure value. If tubing-casing annulus pressure exceeds background pressure one may make a decision that the well may be operated under above tubing-casing annulus pressure, which does not exceed recorded stabilization pressure value. If tubing-casing annulus pressure is equal to background pressure one may make a decision that well head conductor or extension pipe part has not sufficient air-tightness. Then gas is discharged from tubing-casing annulus to obtain value of 0.9P_st with taking into consideration time and volume of gas to be discharged and with time delay, which provides pressure release and stabilization in tubing-casing annulus. The last values are recorded and residual gas is released from tubing-casing annulus. Then constant inflowing gas yield is measured and tubing-casing annulus gas leakage value is determined from a given relation. If gas leakage value is lesser than 70 m³/day one may make a decision that well may be operated along with tubing-casing annulus gas bleeding for gas combustion in flare when pressure value reaches value equal to background pressure value. If gas leakage value is greater than 70 m³/day one may make a decision that well operation must be stopped to perform well isolation works.

EFFECT: increased information validity.

3 dwg, 2 ex