METHOD OF TIGHTNESS TESTING OF INJECTION WELL Russian patent published in 2015 - IPC E21B47/117 G01M3/28 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, namely to method of tightness testing of the cased injection well. Methods includes: determination of actual pressure difference on the packer ΔC_{p_a}=P_wh1-P_fr-C_wh2+C_fr2-P_err1-P_err2, where P_wh1 and P_wh2 are measured wellhed pressure on injection to top and bottom reservoirs, respectively, C_fr1 and P_fr2 are pressure losses for friction during water movement via short and long strings. respectively, P_err1 and P_err2 are absolute errors of measurements by technical pressure gauge in short and long strings, respectively, atm. At that criterion of the tightness estimation is the pre-specified critical pressure difference ΔC_{d_cr}. System tightness is estimated by comparison of the actual pressure difference on packer ΔC_{p_a} and pre-specified critical pressure difference at |ΔC_{p_a}|>|ΔC_{d_cr}| the system is tight. Method of the tightness testing of the injection well contains stages at which: pressure change is registered in well blocked by the packer, by wellhead pressure measuring at input to tubing string in top and bottom reservoirs, respectively. Data analysis is performed, and tightness is determined. At that preliminary current water flowrate via pipeline is measured Q. Tightness is estimated if the following condition is met: $$\frac{\Delta C_{w\_c}}{\Delta C_{w\_a}}\ge {\left(\frac{Q_c}{Q_a}\right)}^2,$$ where ΔC_{w_c} and Q_c are measured current wellhead pressure difference and current water flowrate, respectively; ΔP_{w_a} and Q_a are actual measured current wellhead pressure difference and current water flowrate, respectively. If the condition is met the well is tight.

EFFECT: decreased number of tightness tests in wells operated under process of simultaneous-separate injection.

16 cl, 2 tbl, 2 dwg