EVALUATION OF CEMENT STONE DENSITY IN WELLS OF UNDERGROUND GAS STORAGES WITHOUT LIFTING OF OIL-WELL TUBING Russian patent published in 2015 - IPC G01V5/10 E21B47/00 

FIELD: physics, geophysics.

SUBSTANCE: invention relates to nuclear geophysics and is used for estimation of cement stone density of buried gas storages in their operation without lifting of oil-well tubing. Claimed method comprises measurement of current magnitudes A as Ca/Si ratio in wells by devices of wide-band spectrometric neutron gamma-logging, selection of A_min and A_max of Ca/Si) ratio, and determination of double difference parameter from measurement results (DDP_(Ca/Si)) by formula $$DD{P}_{\left(Ca/Si\right)}=\frac{A-A_{\min }}{A_{\max }-A_{it}}.$$ Spectrometer calibration is performed by static method based on interrelations between double difference parameter (DDP_(Ca/Si)) and magnitudes of density boundaries of normal cement stone selected from the condition: maximum magnitude 1 of DDP_Ca/Si corresponds to density of cement stone - 1.95 g/cm³ - upper boundary of normal cement stone density, mean magnitude of 0.57 DDP_Ca/Si corresponds to current density of cement stone - 1.65 g/cm³ - lower boundary of cement stone density. Density of gamma-radiation (γ_sngl) is calculated by the formula: γ_sngl=1.25+0.7 DDP_Ca/Si.

EFFECT: higher accuracy of data.

3 dwg