METHOD FOR ASSESSING INTEGRITY OF GRAVEL BEDDING OF FILTER IN UNDERGROUND GAS STORAGES BASED ON DATA OF PULSED NEUTRON-NEUTRON LOGGING OF CASED WELLS WITH EXPANDED BOTTOMHOLE Russian patent published in 2024 - IPC G01V5/10 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry, to nuclear-physical methods of geophysical surveys of wells, to methods of determining integrity of gravel bedding of filters in cased wells (C) with an expanded bottomhole in underground gas storages (UGS). Initial porosity Kpf0 is determined on the model of the gravel filter, and in the models of the formations readings of 2PNNL are measured and normalized to the readings of the sondes in the tank with water, and a calibration curve is plotted. Results of measurements of 2PNNL in C of UGS are displayed graphically as decay curves of neutron flux density of sondes Jss(T) and Jbs(T) in the interval of time delays T, then on the obtained graph of decay curve Jss(T) the signal zone from C walls is selected, filter zone – Tfilter and formation zone – Tfor, in which the decay decrement is determined for calculation of gas saturation coefficient – Kg of the formation. In the zone from Tfilter to Tfor, the water-normalized parameter of the ratio of readings Jss(T) and Jbs(T) is calculated, from which the value of hydrogen content of the filter – Wf is determined using a calibration curve. Using Kg and Wf, the filter porosity coefficient – Kp_f, which is compared with Kp_f0 of the gravel filter model, is calculated using the enclosed formulas.

EFFECT: expansion of functional capabilities of double-sonde pulse neutron-neutron logging (2PNNL), which consists in realization of possibility to determine degree of destruction of C filter in UGS.

1 cl, 4 dwg