The methods for evaluating the efficiency of EOR by SWCTT & PITT tracer tests

Background: In Russia, as well as in the whole world, the number of oil fields that at the last stage of development and characterized by a high water cut of the production is growing. In order to extend the period of their cost-effective operation, a transition from classical waterflooding to the use of chemical methods to enhanced oil recovery (hereinafter - EOR) is required, which implies a preliminary assessment of their potential effectiveness.

Aim: To select and evaluate chemical compositions, test on core materials with subsequent recommendation of effective compositions.

Materials and methods: This paper reviews a description of the SWCTT and PITT and evaluation is made of the place of these technologies in the chain of implementation of EOR from laboratory experiments to commercial implementation. The SWCTT method was developed in the 1970s to measure residual oil saturation in the near-wellbore zone after the application of oil enhancement methods. This method is based on the use of partitioning oil-soluble tracer, which forms a secondary non-separable water-soluble traces in the near-wellbore zone due to the hydrolysis process. Evaluation of residual oil saturation is carried out by the time delay in the arrival of the oil and water partitioning tracers.

Results: As a result of the pilot project, experience was gained in implementing SWCTT technology to evaluate the effectiveness of surfactant flooding at a producing oil well in one of the fields of the Khanty-Mansiysk Autonomous Region.

Conclusion: The evaluation and effectiveness of the technology with the selected formulations using simulation and the use of alternative SWCTT/PITT tracer methods has been proven by field tests.