Application of Pulse Neutron Logging to Determine Residual Oil Saturation in a Mature West Texas Carbonate Field Under

For the past several years, carbon dioxide (CO2) has been injected into the gas cap of a mature West Texas carbonate field to enhance the current recovery mechanism of gravity drainage. A key uncertainty in the process is quantification of residual oil saturation (ROS). Understanding both the volume and vertical profile of the ROS in the reservoir will lead to an effective placement of CO2 in the gas cap. A number of saturation logging options exist today for the purpose of measuring ROS in either a cased-hole or an open-hole environment. This paper examines the application of a couple of cased-hole pulsed neutron logging tools used to measure ROS across a gas cap and on into a residual oil zone (ROZ).