A systematic methodology for evaluating and comparing chemical water shut-off agents for conformance control in heterogeneous reservoirs

UDK: 54-4:622.276

DOI: 10.24887/0028-2448-2025-10-86-92

Key words: water shut-off, gelling compounds, rheology, thermal stability, coreflooding studies, resistance factor

Authors: D.V. Nuriev (Gazprom Neft Companу Group, RF, Saint Petersburg); Y.V. Dolgikh (Gazprom Neft Companу Group, RF, Saint Petersburg); G.Y. Shcherbakov (Gazprom Neft Companу Group, RF, Saint Petersburg); A.S. Makoveev (Gazprom Neft Companу Group, RF, Saint Petersburg); S.A. Nazarychev (Kazan (Volga Region) Federal University, RF, Kazan); A.O. Malakhov (Kazan (Volga Region) Federal University, RF, Kazan); М.А. Varfolomeev (Kazan (Volga Region) Federal University, RF, Kazan)

This paper presents a methodological approach to studying and comparatively characteristics of chemical reagents used in flow-diverting technologies, illustrated by laboratory evaluation of various water shut-off compositions under conditions of two Western Siberian oil fields (OF-1 and OF-2). Twenty compositions from seven categories were evaluated: curing, gelling (polymer and inorganic), suspension systems, inverted emulsions, water-swelling and precipitation-gelling systems. The comprehensive methodology comprised six research stages: assessment of physical-chemical properties, gelation behavior, thermal stability, degradation resistance, rheological properties, and coreflood experiments on reservoir rock models. Given the diverse physical-chemical nature of the compositions, key selection criteria included: thermal stability (only 47 % of compositions remained stable for 30 days at OF-1 and 37 % at OF-2), gelation time of at least 3 hours to ensure safe injectivity (only four compositions met this criterion), and degradability (more than 90 % breakdown to minimize formation damage was achieved by seven compositions). Coreflood experiments enabled evaluation of selected compositions under near-reservoir conditions. Quantitative selectivity criteria were established based on the ratio of resistance factors measured in water- and oil-saturated core samples. The proposed approach enables systematic evaluation of water shut-off agent performance and identification of optimal compositions for specific geological and petrophysical field conditions.

References

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