METHOD FOR ESTIMATING GAS SATURATION OF FORMATIONS IN UNDERGROUND GAS STORAGES BASED ON DATA OF PULSED NEUTRON-NEUTRON LOGGING OF CASED WELLS WITH EXPANDED WORKING FACE, EQUIPPED WITH GRAVEL BEDDING FILTER Russian patent published in 2024 - IPC G01V5/10 

FIELD: measurement; mining.

SUBSTANCE: invention relates to nuclear-physical methods of geophysical surveys of wells, to methods for determining gas saturation (G) of formations in cased wells (C) with an expanded face equipped with a gravel bed in underground gas storages (UGS). Proposed is the method of estimating gas saturation of formations in underground gas storages according to pulsed neutron-neutron logging of cased wells with expanded working face, equipped with a gravel bed, according to which readings of pulsed neutron-neutron logging sondes 2PNNC are preliminary measured in models of formations, they are normalized to readings of sondes in a water tank and a calibration curve is plotted. Results of measurements of 2PNNC in wells of UGS are displayed graphically as curves of decay of neutron flux density of sondes Jss(T) and Jbs(T) in delay time interval T, further, on the obtained curve of the decay curve Jss(T), the signal zone from the well walls, the filter zone – Tfilter and the formation zone – Tform are selected. Using the Jss(T) readings in the Tform zone, the damping decrement is calculated, as per which the G – Kg coefficient of the formation is calculated. Using the values on the graph of the Jss(T) and Jbs(T) decay curves in the zone from Tfilter to Tform, the water-normalized parameter of the ratio of the Jss(T) and Jbs(T) readings is calculated, according to which the value of hydrogen content of the filter – Wf is determined by means of calibration dependence.

EFFECT: broader functional capabilities of the method of double-sonde pulse neutron-neutron logging (2PNNC), which enable to determine the G of the zone of the gravel-packed filter in the interval C in UGS.

1 cl, 3 dwg