Pilot Tests of New EOR Technologies for Heavy Oil Reservoirs

Abstract

Thermal-steam stimulation (TSS) is considered as the most effective among all up-to-date methods for heavy oil production. However problem consists in lower coverage by steam injection and decreased TSS efficiency at later stage of the development. Paper presents the results of solving this problem by combining thermal-steam and physicochemical stimulations and using "cold" technologies involving thermotropic gel-forming and oil-displacing systems: gels increase reservoir coverage, whereas oil-displacing systems increase oil displacement. In 2008-2013 172 wells were treated on the Permian-Carboniferous reservoir of high-viscosity oil in Usinsk oilfield using IPC SB RAS technologies. As a result the increase in oil production rate ranged of 3-24 ton/d per one well and incremental oil production amounted to 980 tons per one well treatment. It is promising to use integrated technologies alternating injection of steam, gel-forming and oil-displacing systems. They are commercially produced in Russia and China. In 2014 to improve TSS efficiency pilot tests of new technologies were successfully carried out: using gelled system based on surfactants with controlled viscosity to increase simultaneously reservoir coverage and oil-displacement factor; using polymer gel-forming system – for selective water shutoff in production wells. TSS is effective, but expensive method. It is promising to use "cold" technologies. To enhance oil recovery from high-viscosity reservoirs at 20-40 °С we propose to use gels and sols based on low temperature inorganic gel-forming system and oil-displacing alkaline and acid systems based on surfactants, inorganic buffer solution and polyol with controlled viscosity, from tens to hundreds mPa·s, and low freezing point, -20÷-60 °С. In 2014 pilot tests of new "cold" technologies were carried out in Usinsk oilfield. Alkaline system was injected into 5 and acid system into 10 low productivity production wells. After injections oil production rate increased by 5-15 ton/d, fluid flow rate increased by 15-25 m3/d. The technologies were recommended for commercial application.

Thermotropic Gel-Forming and Sol-Forming Systems for Enhanced Oil Recovery and Technologies of Their Joint Application with Thermal Methods for Oil Production

“…The use of new environmentally safe technologies intended to enhance oil recovery and stimulate oil production will enable to increase the final oil recovery factor by 2-7%; to decrease water cut of well production by 5-30%; to stimulate oil production 1.2-1.3 times and to carry out technological operations in the temperature range of 20-320°C and formation water salinity up to 300 g/dm 3 . Large-scale commercial application of the newly developed EOR technologies will enable to extend the profitable exploitation of deposits at the later stage of their development and engage in the development deposits with difficult-to-recover hydrocarbon reserves including high-viscosity oil pools and Arctic deposits.…”

“…The studies of physicochemical properties, rheological characteristics and oil-displacing ability of the sol-and gel-forming systems, based on "Al saltcarbamide-water" system added with substances regulating hydrophilic-lipophilic balance and gelation temperature, showed the possibility of their application in field conditions at a reservoir temperature 20-320°C, with a high water salinity, up to 300 g/dm 3 , to regulate filtration flows [6, p. 1], to enhance oil recovery and reservoir coverage at water flooding and thermal-steam stimulation.…”

“…The thermotropic sol-and gel-forming systems have the following characteristics: can be used in a wide range of reservoir temperatures (20-320°C); have a low freezing point, homogeneity; retain their viscosity characteristics; exhibit high thermal-oxidative stability in highly saline reservoir waters, up to 300 g/dm 3 ; high penetrability, stimulate reservoir microflora and can be used in the formations with polymictic, carbonate and other reservoirs of different structure and permeability, from 1mD to 20 D, including low-permeable, highly heterogeneous and fractured reservoirs developed by water flooding or thermal-steam stimulation.…”

Multifunctional Composition Based on Surfactants and a Complex of Buffer Systems to Enhance Oil Recovery of High-Viscosity Oil Deposits

“…13, 15] has a high buffer capacity in the acidic pH range, 2-4 units pH, compatible with saline formation waters, has a low freezing point (minus 20 ÷ minus 60 °C), low interfacial tension at the boundary with oil, is applicable over a wide temperature range, from 10 to 200 °C, is most effective in carbonate reservoirs due to prolonged action on the rock. As a result of the GBK composition interaction with the carbonate reservoir, CO 2 is released, which dissolves in oil and reduces its viscosity by 1.2-2.7 times, this contributes to an increase in the degree of oil recovery.…”

Enhanced Oil Recovery from Permian-Carboniferous Deposit of High-Viscosity Oil in the Usinsk Oilfield with Physicochemical and Complex Technologies

“…В ИХН СО РАН созданы «интеллектуальные» композиции с регулируемой вязкостью, плотностью и щелочностью: термотропные неорганические и полимерные золе-и гелеобразующие композиции, а также нефтевытесняющие композиции на основе поверхностно-активных веществ (ПАВ) для закачки в нефтяные пласты с целью увеличения нефтеотдачи, снижения обводненности добывающих скважин и интенсификации добычи нефти в осложненных условиях эксплуатации [5][6][7][8][9]. На пермо-карбоновой залежи высоковязкой нефти Усинского месторождения ООО «ЛУКОЙЛ-Коми» предприятия ООО «ЛУКОЙЛ-Инжиниринг» и ООО «ОСК» совместно с ИХН СО РАН с 2003 г. проводят промысловые испытания и осуществляют промышленное использование комплексных технологий паротеплового и физико-химического воздействия, а также «холодных» физико-химических технологий в естественных условиях, без теплового воздействия с целью увеличения нефтеотдачи и интенсификации добычи тяжелой нефти [8][9][10][11][12][13][14].…”