The use of partitioning interwell tracer testing (PITT) using short-lived radioisotopic tracer techniques can be viewed as the next evolution in partitioning tracer testing and offers significant benefits over currently available technologies. By injecting conservative and partitioning short-lived radioisotopic tracers into the subsurface and continuously measuring their presence in monitoring wells with moveable downhole detectors, the location and amount of dense nonaqueous phase liquids (DNAPL) can be measured to a much greater extent than currently can be achieved by any other method.
The objective of the proposed research is to develop PITT using short-lived radioisotopic tracers as an effective characterization technique for DNAPL in the subsurface.
The technical approach for this project is to develop the radiochemical techniques for making tagged tracers together with assembling suitable detectors. After the field prototype has been tested, the tracers and sensors will be used in a field application to further develop the method. The field testing and the interpretation of the field results will be guided by detailed fluid flow modeling. The tasks for this project are the following: (1) detector and logging system development, (2) tracer selection and radiochemistry techniques, (3) laboratory testing, (4) pre-test modeling and field test planning, (5) field testing, (6) inverse modeling (data analysis), and (7) development of a guidance document.
Work to date includes the preliminary identification of tracers and radioisotopes and concepts for the radiotagging of the tracers. Also, concepts have been developed for specific testing to determine the depth of field and detector responses.
The proposed research will develop an innovative, nonintrusive radiotracer methodology for reliably detecting, quantifying, and determining the horizontal and vertical extent of non-aqueous phase liquids in the subsurface environment. The proposed research will lead to a cost-effective technique for more precisely locating DNAPL sources, estimating the mass, and monitoring the transport and/or reduction of the mass over time, all of which are critical aspects of cost-effective cleanup. It is anticipated that the costs to implement the developed technology will be comparable to those of conventional partitioning interwell tracer tests, while producing significantly more characterization information.