METHOD FOR CHECKING STATE OF BORE-HOLE CASING Russian patent published in 1998 - IPC

FIELD: oil and gas production industry. SUBSTANCE: this is used for geophysical investigation of wells and for checking technical state of their case-off, that is casing string and cemented ring in hole clearance and also pipe-compressor pipes lowered into well. According to method, lowered into casing string or into pump-compressor pipes is instrument with shortened measuring levers. Lower levers of them when lifted by means of springs are pressed against inner surface of string or pump-compressor pipes and their upper ends move along rheochord sliding contact or core in induction coil, thus creating surface adjustable variation of electric voltage in proportion to distance between lower ends of opposite measuring levers. Simultaneously recorded are changes of electric voltage which are proportional to intensity and spectrum of frequencies of bore-hole noises. These voltage changes are received from built-in body bottom-hole instrument converting acoustic oscillations into electric, and which is rigidly connected with upper ends of measuring levers which in this case function as waveguides from converter to casing string. Prevented is distorting influence of medium inside string on results of measured intensity and spectrum of bore-hole noises. EFFECT: high efficiency. 4 dwg