Multi-sensor workflow for evaluation of gas flow in multiple casing strings

摘要

A distance of a gas flow path and a velocity of the gas flow therein are calculated using pulsed neutron data and noise data. The gas saturation and distance to flow path obtained from the pulsed neutron data and gas velocity and distance to flow path obtained from the noise data are compared with each other to obtain a first calculated distance and a first calculated velocity. The distance and the velocity of the gas flow are calculated using Doppler data. The distance and velocity values are compared with the first calculated distance and first calculated velocity to obtain a second calculated distance and velocity values. The distance and the velocity of the gas flow are calculated using temperature data. The distance and velocity values are compared with the second calculated distance and velocity to determine a distance of a cement interface and a velocity of a gas flow therein.

主权项

1. 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 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 located at a cement interface in the wellbore and a first distance of the flow path 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 from the tool string and a first velocity of a gas flow in the flow path 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 and a first calculated velocity of the gas flow in the flow path; calculating a third distance of the flow path from the tool string and a second velocity of the gas flow in the flow path 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 and a second calculated velocity of the gas flow in the flow path; calculating a fourth distance of the flow path from the tool string and a third velocity of the gas flow in the flow path 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, a distance of the cement interface from the tool string, and a velocity of a gas flow in the cement interface.