AN APPLICATION OF CHEMICAL TRACERS IN MONITORING INJECTION IN VERTICAL HYDROCARBON MISCIBLE FLOODS

Chemical tracers have been utilized to effectively monitor injected fl uid movement in two vertical hydrocarbon miscible floods in the Rainbo w Field, Alberta. By placing small slugs of chemical tracers, consisti ng of sulphur hexafluoride (SF6) and chlorinated fluorocarbons (CFC) o r halocarbons within the injectants, the spreading and development of chase gas and solvent banks were monitored, and in some cases, reservo ir flow channels identified. In addition, geological units were confir med and well workover planning improved, resulting in increased cost e ffectiveness in operating the miscible floods. The chemical tracer pro gram commenced with the first field application conducted in the Rainb ow Keg River ''A'' (R.K.R.A.) Pool secondary miscible flood on January 31, 1991, where chase gas injection into two wells was traced. Subseq uently a program of tracing chase gas and solvent was initiated at one well location in November, 1991 in the Rainbow Keg River ''B'' (R.K.R .B) Pool tertiary miscible flood, and later at six additional chase ga s and solvent co-injection wells. This paper presents the design of th e tracer programs, the significance to the operation of the miscible o il recovery schemes and alternative tracers considered for the future.