Publications

Tracer testing in the reservoir is a well-established method to establish communication patterns in the subsurface and it is the only way to directly prove mass transport between specific injection points to a sampling point (typically a production well). Reservoir tracers are therefore relevant to all projects that inject water or gas. It should be noted that tracer technology also is a natural choice for surveillance in carbon capture and storage (CCS/CCUS) projects. Specialized tracer technologies such as the single well chemical tracer test (SWCTT) and the partitioning interwell tracer test (PITT) are often used to assess residual oil saturation (Sor) or remaining oil saturation (ROS) when initiating enhanced oil recovery (EOR) projects. Both tests are based on the time-separation of two different tracers; one ideal water tracer and one oil/water partitioning tracer that partitions into the oil and is delayed by stagnant oil. In the last decade significant improvements of the methodologies have been made. Simultaneously, the methodologies have also become more relevant, as enhanced oil recovery (EOR) has come more relevant to answer the world’s increased need for energy. In this paper we review recent enhancements of the PITT and SWCTT methods and present a novel application of the partitioning tracer methodology, aiming to investigate the relative permeability of oil and water on a field scale level. Briefly, the method uses one ordinary and one partitioning interwell tracer curve as input data to match a simulation model. The model has a single parameterized relative permeability curve described by a limited number of parameters. The parameters were tuned using a a Levenberg–Marquardt approach and the inverse modelling provides the oil/water relative permeability curve as the result. The method presented has the potential to provide relative permeability information on on a scale significantly larger than that of core samples and can therefore complement information available from special core analysis.