METHOD FOR DETECTING DAMAGED SPOT IN TECHNOLOGICAL BORE-HOLE STRINGS Russian patent published in 1997 - IPC

FIELD: oil and gas production industry. SUBSTANCE: this is intended for checking tightness of technological pipe strings in extracting oil and gas. According to method, injected into annular space is liquid which is insoluble in water and is of specific gravity less than specific gravity of water with subsequent measuring of steady-state gauge pressure at well head in tubular and annular spaces. Depth of damaged spot is determined according to following relation: H = 10(P₁-P₂)/(γ₁-γ₂),, where P₁ - steady-state pressure in annular space at well head, kgf/sq.m; P₂ - steady-state pressure in tubular space at well head, kg/sq.m; γ₁ - specific gravity of water in tubular space, kg/cu.m; γ₂ - specific gravity of liquid injected into annular space, kg/cu. m; H - depth of damaged spot in string, m. If gauge pressure drops to zero, measured are static levels of liquid in tubular and annular spaces of well, and depth of damaged spot in string is determined according to following relation: H = (H₁γ₁- H₂γ₂)/(γ₁-γ₂),, where H₁ - depth of static level of water in tubular space, m; H₂ - depth of static level of liquid injected into annular space. EFFECT: high efficiency. 1 dwg