Use of Well Logs To Characterize Fluid Flow in the Maljamar CO2 Pilot

Abstract

The Maljamar CO/sub 2/ pilot in Lea County, NM is a 5-acre (2 x 10/sup 4/ -m/sup 2/) inverted five-spot pattern. Two zones are being flooded: a Grayburg dolomitic sand at 3,7000 ft (1130 m) and a San Andres dolomite at 4,050 ft (1230 m). Two logging observation wells, completed with fiberglass casing through the section of interest, are located in line with the center injector and one of the corner producers. Nine months of freshwater injection in the center well was followed by 9 months of brine injection. A series of induction logs monitored the passing of the freshwater/brine interface, providing data for a preliminary characterization of flow in the zones. The brine also established a uniform salinity at the observation wells for saturation determination. Gamma-emitting tracers were injected into each zone of the center well as part of a well-to-well tracer study. Frequent gamma ray logs were run in the observation wells to see whether the movement of the tracers could be detected and used to characterize water movement. The results were very encouraging and provided better vertical and time resolution than the induction logs. The numerous responding layers in each zone could be classified by tracer arrivalmore » times into only few basic types, injection of CO/sub 2/ and follow changes in water and CO/sub 2/ saturation as the flood progressed.« less