A method, comprising: introducing a tool string into a wellbore, the wellbore at least partially lined with a first casing and a second casing concentrically overlapping a portion of the first casing, wherein a first annulus is defined between the first and second casings (108a,108b) and filled with a first cement, and a second annulus is defined between the second casing and the wellbore and filled with a second cement; obtaining data from a pulsed neutron sensor, a noise sensor, a Doppler sensor, and a temperature sensor, all included in the tool string; determining a gas presence in a flow path (208a,b,c,d) located at a cement interface (206a,b,c,d) in the wellbore, the cement interface (206a,b,c,d) being either the interface between the first casing and the first cement, the second casing and the first cement, the second casing and the second cement or the wellbore and the second cement, and a first distance of the flow path (208a,b,c,d) from the tool string,using a pulsed neutron log borehole model and the data obtained from the pulsed neutron sensor; calculating a second distance of the flow path (208a,b,c,d) from the tool string and a first velocity of a gas flow in the flow path (208a,b,c,d) using a noise log borehole model and the data obtained from the noise sensor; correlating the first distance and the gas presence with the second distance and the first velocity to obtain a first calculated distance of the flow path (208a,b,c,d) and a first calculated velocity of the gas flow in the flow path (208a,b,c,d); calculating a third distance of the flow path (208a,b,c,d) from the tool string and a second velocity of the gas flow in the flow path (208a,b,c,d) using a Doppler borehole model and the data obtained from the Doppler sensor; comparing the third distance and the second velocity with the first calculated distance and first calculated velocity, respectively, to obtain a second calculated distance of the flow path (208a,b,c,d) and a second calculated velocity of the gas flow in the flow path (208a,b,c,d); calculating a fourth distance of the flow path (208a,b,c,d) from the tool string and a third velocity of the gas flow in the flow path (208a,b,c,d) using a temperature borehole model and the data obtained from the temperature sensor; and comparing the fourth distance and the third velocity with the second calculated distance and the second calculated velocity, respectively, to determine a width of the cement interface (206a,b,c,d), a distance of the cement interface (206a,b,c,d) from the tool string, and a velocity of a gas flow in the cement interface (206a,c,b,d). introducing a tool string into a wellbore, the wellbore at least partially lined with a first casing and a second casing concentrically overlapping a portion of the first casing, wherein a first annulus is defined between the first and second casings (108a,108b) and filled with a first cement, and a second annulus is defined between the second casing and the wellbore and filled with a second cement; obtaining data from a pulsed neutron sensor, a noise sensor, a Doppler sensor, and a temperature sensor, all included in the tool string; determining a gas presence in a flow path (208a,b,c,d) located at a cement interface (206a,b,c,d) in the wellbore, the cement interface (206a,b,c,d) being either the interface between the first casing and the first cement, the second casing and the first cement, the second casing and the second cement or the wellbore and the second cement, and a first distance of the flow path (208a,b,c,d) from the tool string,using a pulsed neutron log borehole model and the data obtained from the pulsed neutron sensor; calculating a second distance of the flow path (208a,b,c,d) from the tool string and a first velocity of a gas flow in the flow path (208a,b,c,d) using a noise log borehole model and the data obtained from the noise sensor; correlating the first distance and the gas presence with the second distance and the first velocity to obtain a first calculated distance of the flow path (208a,b,c,d) and a first calculated velocity of the gas flow in the flow path (208a,b,c,d); calculating a third distance of the flow path (208a,b,c,d) from the tool string and a second velocity of the gas flow in the flow path (208a,b,c,d) using a Doppler borehole model and the data obtained from the Doppler sensor; comparing the third distance and the second velocity with the first calculated distance and first calculated velocity, respectively, to obtain a second calculated distance of the flow path (208a,b,c,d) and a second calculated velocity of the gas flow in the flow path (208a,b,c,d); calculating a fourth distance of the flow path (208a,b,c,d) from the tool string and a third velocity of the gas flow in the flow path (208a,b,c,d) using a temperature borehole model and the data obtained from the temperature sensor; and comparing the fourth distance and the third velocity with the second calculated distance and the second calculated velocity, respectively, to determine a width of the cement interface (206a,b,c,d), a distance of the cement interface (206a,b,c,d) from the tool string, and a velocity of a gas flow in the cement interface (206a,c,b,d).