The application of SWCTT for evaluating the efficiency of low-salinity water flooding at the carbonate reservoir of the Kharyaginskoye oil field

UDK: 622.276.43

DOI: 10.24887/0028-2448-2020-7-109-113

Key words: enhanced oil recovery (EOR) evaluation, low-salinity water flooding, single well chemical tracer tests (SWCTT), carbonate reservoir, evaluation of residual oil saturation

Authors: Yu.A. Keller (SIAM Master LLC, RF, Tomsk), A.A. Uskov (SIAM Master LLC, RF, Tomsk), A.N. Krivoguz (SIAM Master LLC, RF, Tomsk), N.O. Kuhlenkova (SIAM Master LLC, RF, Tomsk), O.N. Zoshchenko (ZARUBEZHNEFT-Dobycha Kharyaga LLC, RF, Moscow), A.S. Aleschenko (ZARUBEZHNEFT-Dobycha Kharyaga LLC, RF, Moscow)

The paper presents the results of the single well chemical tracer tests (SWCTT) conducted in the Kharyaginskoye carbonate reservoir to estimate residual oil saturation before and after of low-salinity water flooding. Previously core-studies were conducted to estimate the effectiveness of low-salinity water flooding. The SWCTT is based on chemical transformations of substances into the bottomhole zone of the well. Reactive chemical tracer is injected into the reservoir through the production well. After that the volume of tracers is pushed into the reservoir with an additional volume of water. The well is then 'shut in' while some of the reactive tracer is allowed to undergo a hydrolysis reaction within the reservoir. Following 'shut in' period, the well is produced to bring back the fluid, with sampling and analysis for the presence of indicators. The reaction product, alcohol tracer and unreacted ester tracer undergoes a chromatographic separation. The magnitude of this separation depends on the oil/water ratio in the reservoir and the ester partition coefficient, thereby allowing to calculate residual oil saturation. The depth of investigation area was roughly 3.5 m from the wellbore. Effectiveness of flooding is estimated, based on the values of the residual oil saturation before and after the treatment. The article also presents the results of laboratory tests on core samples to determine the effectiveness of low-saline water injection, the values of the separation and hydrolysis coefficients required when interpreting the SWCTT results, and describes the practical part on the field of the experiment. As a result of the work, a numerical assessment of the effectiveness of low-saline water injection in the Kharyaginskoye oil field was obtained. References 1. Patent 3623842 USA, Method of determining fluid saturations in reservoirs, Inventor: Deans H.A. 2. Tomich J.F., Dalton R.L., Deans H.A. et al., Single-well tracer method to measure residual oil saturation, SPE-3792-PA, 1973. 3. Deans H.A., Carlisle S., Single-well chemical tracer test handbook, Laramie, Wyoming: Chemical Tracers, Inc., 2007. 4. Al-Abbad M., Balasubramanian S., Sanni M. et al., Single-well chemical tracer test for residual oil measurement: field trial and case study, SPE-182811-MS, 2016. 5. Jerauld G.R., Mohammadi H., Webb K.J., Interpreting single well chemical tracer tests, SPE-129724-MS, 2010. 6. Akhmetgareev V.V., Issledovanie protsessov razrabotki neftyanykh kollektorov nizkomineralizirovannym zavodneniem na osnove modelirovaniya (na primere mestorozhdeniy Respubliki Tatarstan) (The study of the processes of developing oil reservoirs by low-mineralized waterflooding based on modeling (on the example of oilfields in the Republic of Tatarstan)): thesis of candidate of technical science, 2016. 7. De Zwart A.H. et. al., Numerical interpretation of single well chemical tracer tests for ASP injection, SPE-141557-MS, 2011.