A review of tracer testing techniques in porous media specially attributed to the oil and gas industry

Abstract

The significance of the tracer testing technique is widely accepted in reservoir performance analysis in hydrology as well as in hydrocarbon exploration and production. The subsurface reservoir delineation for hydrocarbon exploration and optimum production is one of the most critical aspects of petroleum system analysis. The quality of the reservoir and its performance prediction require extensive knowledge of qualitative reservoir geology, its depositional environment, facies heterogeneity and engineering properties of subsurface formations. Tracer testing is amongst the few techniques available in the oil and gas (O&G) industry, which stands up to these expectations and is successfully used for quantitative determination and analysis of sub-seismic scale structural and stratigraphic heterogeneities. Tracer testing is also being utilized in determining residual oil saturation (Sor) and lateral correlation of reservoir properties in the subsurface. Apart from the O&G industry, the concentration-based applications of tracer testing have been proved in hydrology, geothermal and medical science. A comprehensive review is presented to explain the application of tracer testing technique to investigate porous media, mainly in O&G industry. The type of tracers used, their selection criteria, concentration, and natural versus gradient and qualitative to a quantitative application are discussed in the current review. Generally, two types of tracers (chemical and radioactive) are preferred in the petroleum industry for gas/fluid flow assessment, waterflood optimization and establishing connectivity between multiple wells. The current paper reviews both types of tracer tests, namely single well and inter well, in detail discussing the objectives, calculations, designing, injection, sampling, laboratory analysis and knowledge integration. The preliminary aim was to provide a review of the tracer testing technique used in reservoir evaluation and well-to-well connectivity analysis.