METHOD FOR DETERMINING THE COEFFICIENT AND BULK GAS SATURATION IN RESERVOIRS OF GAS WELLS BY TWO-PROBE NEUTRON LOGGING IN GAS-FILLED WELLS Russian patent published in 2019 - IPC G01V5/10 E21B47/00 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas production technology and can be used to diagnose the composition of hydrocarbons in reservoirs of oil and gas wells. In the known method, consisting in measuring the intensities of thermal neutron fluxes J_M3 and J_b3 on small and large neutron-neutron logging probes (2NNK_t) and subsequent determination of the porosity function F(Kp) as a ratio of the intensities of the fluxes of thermal neutrons on small and large probes F(Kp)=J_m3/J_b3 2NNK_T and saturation functions F_dd as an inverse of the product of measured thermal neutron fluxes on a large and small probes F_dd=1/J_m3*J_b3 with a subsequent cross-dense analysis of F_dd and F(Kp) in the Cartesian coordinate system (X, Y), in which the abscissa axis X is the function F(Kp), and the Y-axis is the function F_dd dependence corresponding to water-saturated formations (F_ddws), characterized in that on the cross-raid F_dd from F(Kp), apply a lower line of reference water-saturated layers at the level Kr=Kr_rest=20–30 % and approximate it by a quadratic function F_ddws=a*F(Kp)2+b*F(Kp), where a and b are coefficients determined from a cloud of cross-raft points, the definition of the function F_ddgs saturation of gas-saturated reservoirs is defined as the ratio of the current value of the function F_ddgptec saturation of the gas-saturated reservoir to the function F_ddws saturation of the water-saturated reservoir F_ddgs=F_ddgstek/F_ddws, then construct a cross-raft F_ddgs from F(Kp), in which the abscissa axis X is the function F_ddws, and the Y-axis is the function F(Kp), and the coefficients Kr of the gas saturation of the reservoir are determined from the mathematical relation Kr=arctg{[F(Kp)_max-F(Kp)_min/(F(Kp)_tek-F(Kp)_min)]*F_ddgptek/F_ddgsmax*K_n/0.9}, and the volume content of gas in the pore space of the reservoir – from the mathematical relation Kr*Kp=(F(Kp)_tek-F(Kp)_min)*F_ddtek/F_ddgstek*Kr*Kp_max, where F(Kp)_max – the maximum value of the porosity function of the water-saturated reservoir, F(Kp)_min – minimum value of saturation function of oil-gas-saturated or gas-saturated reservoir, F_ddgstek, F_ddgsmax, F_ddgsmin – the current, maximum and minimum values of the saturation function in the gas-saturated reservoir, Kr*Kp is the accepted value of bulk gas saturation for a gas-saturated reservoir according to tabular geological data.

EFFECT: expansion of analytical capabilities of known neutron methods.

1 cl, 3 dwg