Reconstruction of water encroachment history in 4D in a brown field using a time-lapse pulsed neutron capture log – A case study

The objective of this paper is to illustrate the use of pulsed neutron capture log in reconstruction of water encroachment history in time and space in a brown field. Time-lapse pulsed neutron logs tracked the movement of oil-water contact in wells through time. This data from multiple wells was used to reconstruct the oil-water contact surfaces at different times for the area studied. The study resulted in a remaining oil column height map for the area and also predicted future water movement patterns. The remaining reserves at different times were calculated using a static model and these fluid contact surfaces. Estimated production between these time surfaces as computed from the static model matched well with the recorded actual production giving credence to the study.