Technologies for improved oil recovery by deep cleaning of the bottom-hole zone of wells with RBS-3 and DGK-2 reagents

UDK: 622.276.6

DOI: 10.24887/0028-2448-2020-7-116-119

Key words: improved oil recovery (IOR), chelating compounds, reagent RBS-3, reagent DGK-2, dispersion of barite deposits, cleaning of the bottom-hole formation zone, laboratory studies, pilot tests, liquid and oil flow rate increase

Authors: R.N. Fakhretdinov (Multifunctional Company ChemServiceEngineering LLC, RF, Moscow), D.F. Selimov (Multifunctional Company ChemServiceEngineering LLC, RF, Moscow), A.A. Fatkullin (Multifunctional Company ChemServiceEngineering LLC, RF, Moscow), S.A. Tastemirov (Multifunctional Company ChemServiceEngineering LLC, RF, Moscow), E.A. Pasanayev (Multifunctional Company ChemServiceEngineering LLC, RF, Moscow)

The article discusses the unique technology for improved oil recovery using RBS-3 and DGK-2 reagents. The content of chelating compounds in the RBS-3 and DGK-2 reagents makes it possible to clean the bottom-hole formation zone fr om contamination that is not removed by other reagents. The reactivity of the reagents is maintained at temperatures up to 200°C. The technology based on the RBS-3 reagent is intended for cleaning the bottom-hole zone of wells from clay drilling crust, drilling mud residues with barite fillers, deposits of insoluble heavy metal salts, clay particles, iron oxides and hydroxides, insoluble products of the reaction of hydrochloric acid with rock, hydraulic fracturing gels based on guar and polyacrylamide. The DGK-2 reagent is an acidic form of the RBS-3 reagent with increased reactivity for carbonates. The technology based on DGK-2 is intended for processing production and injection wells in carbonate reservoirs as an alternative to hydrochloric acid treatments, in parts wh ere they do not produce an effect or a weak effect during repeated acid treatments, and under certain conditions – and hydraulic fracturing. RBS-3 and DGK-2 reagents have passed the stage of laboratory testing and field tests. Thus, at exploratory well on the one of the fields in the Republic of Kalmykia, when testing the search object in the carbonate deposits of the Lower Triassic formation, characterized by abnormally complex reservoir conditions - a depth of 5300 m, a pressure of 91.5 MPa, a temperature of 177°C, after unsuccessful attempts to cause an influx using traditionally used acid compositions, the use of technology based on the RBS-3 reagent allowed to obtain an industrial inflow of gas and condensate and open a new hydrocarbon field. The DGK-2 treatment of production wells at the carbonate reservoir in the Timan-Pechora region allowed increasing the flow rates of liquid by 2.9-4.0 times and oil by 2.0-2.7 times, which is comparable to the efficiency of hydraulic fracturing. The average increase in oil production was almost 9 tons per day, and the volume of additional oil production for the 7 months since the start of operations – 5600 tons or 1400 tons per well. Technologies for intensifying oil production with the use of reagents RBS-3 and DGK-2 are recommended for wide industrial applications for cleaning the bottom-hole formation zone from various types of production induced pollution in difficult reservoir conditions. References 1. Patent RU 2581859 C1, Composition for treatment of bottomhole formation zone, Inventor: Fakhretdinov R.N. 2. RF patent application no. 2019120610. Sostav dlya obrabotki prizaboynoy zony karbonatnogo kollektora (Composition for processing bottom-hole zone of carbonate reservoir). 3. Khimiya i khimicheskaya tekhnologiya. Khelanty (Chemistry and chemical technology. Chelants), In: Spravochnik khimika 21 veka (21st Century chemist handbook), URL: https://chem21.info/info/427626/ 4. Khelaty (Chelates), In: Bol'shaya rossiyskaya entsiklopediya (Great Russian Encyclopedia), URL: https://bigenc.ru/chemistry/text/4664013