Analysis of the Static and Dynamic Imbibition Effect of Surfactants and the Relative Mechanism in Low-Permeability Reservoirs

Tian, Fang; Zhao, Yong; Yan, Yang; Gou, Xiaoting; Shi, Liming; Qin, Feixiang; Jin, Shi; Lv, Jinlong; Bao, Cao; Liu, Yu; Lu, Xiaofeng

doi:10.1021/acsomega.0c01888

Cited by 21 publications

(11 citation statements)

References 21 publications

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“…Chemically enhanced oil recovery (CEOR) is one of the most effective EOR methods in beneficially altering reservoir rock and fluid properties, enabling increased crude oil production. One of the most commonly adopted CEOR processes is surfactant flooding, which has been shown to improve oil recovery significantly. − Oil recovery extent is a function of rock and fluid properties, such as pore structure, capillary pressure, interfacial tension (IFT), rock wettability, mobility ratio, and reservoir heterogeneity. Thus, during surfactant flooding, IFT reduction, micro-emulsion formation, and wettability alteration are mechanisms that result in greater oil recovery extent compared to conventional water flooding. − …”

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation of LSW/Surfactant/Alkali Synergism for Enhanced Oil Recovery: Fluid–Fluid Interactions

et al. 2020

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The combination of chemical enhanced oil recovery (CEOR) and low salinity water (LSW) flooding is one of the most attractive enhanced oil recovery (EOR) methods. While several studies on CEOR have been performed to date, there still exists a lack of mechanistic understanding on the synergism between surfactant, alkali and LSW. This synergism, in terms of fluid–fluid interactions, is experimentally investigated in this study, and mechanistic understanding is gained through fluid analysis techniques. Two surfactants, one cationic and one anionic, namely an alkyltrimethylammonium bromide (C19TAB) and sodium dodecylbenzenesulfonate (SDBS), were tested, together with NaOH used as the alkali, diluted formation brine used as the LSW, and the crude oil was collected from an Iranian carbonate oil reservoir. Fluids were analyzed using pendant drop method for interfacial tension (IFT) measurement, and Fourier transform infrared spectroscopy for determination of aqueous and oleic phase chemical interaction. The optimum concentration of LSW for IFT reduction was investigated to be 1000 ppm. Additionally, both surfactants reduced IFT significantly, from 28.86 mN/m to well below 0.80 mN/m, but in the presence of optimal alkali concentration the IFT dropped further to below 0.30 mN/m. IFT reduction by alkali was linked to the production of three different types of in situ anionic surfactants, while in the case of anionic and cationic surfactants, saponification reactions and the formation of the C19TAOH alcohol, respectively, were linked to IFT reduction. The critical micelle concentration and optimal alkali concentration when using cationic C19TAB were significantly lower than with the anionic surfactant; respectively: 335 vs 5000 ppm, and 500 vs 5000 ppm. However, it was found that SDBS was more compatible with NaOH than C19TAB, due to occurrence of alkali deposition with the latter beyond the optimal point.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation of LSW/Surfactant/Alkali Synergism for Enhanced Oil Recovery: Fluid–Fluid Interactions

et al. 2020

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“…The water-wet experimental cores were made of quartz sand, curing agent phenolic, ordinary epoxy resin, as well as modified water-wet epoxy resin with modifier polyethylene glycol, propylene glycol methyl ether, and ammonium persulfate which was similar to the wettability of extralowpermeability reservoir in Dagang Oilfield [31][32][33][34]. Cylindrical cores and plate-fractured models were used in experiments.…”

Section: Methodsmentioning

confidence: 99%

Experimental Investigation on Cyclic Huff-n-Puff with Surfactants Based on Complex Fracture Networks in Water-Wet Oil Reservoirs with Extralow Permeability

Bao

Tian

et al. 2021

Geofluids

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The injection from a well to other wells can be difficult in extralow-permeability oil reservoirs. In order to address this issue, a method of cyclic huff-n-puff with surfactants based on complex fracture networks for a single horizontal well was proposed and then investigated in terms of the effects of injection and fracture parameters on the oil recovery in water-wet extralow-permeability models. Firstly, the interfacial tension (IFT) and contact angle with different surfactant concentrations were measured to determine the basic properties of the surfactants. Then, the experiments of huff-n-puff with surfactants at different threshold injection pressures and soaking time were carried out to determine the oil increasing effects and analyze the pore-scale (micropores, mesopores, and macropores) mechanisms by combining the technology of nuclear magnetic resonance (NMR), which showed that the recovery increased with threshold injection pressure mostly in mesopores and macropores, while that increased with soaking time mostly in micropores. Eventually, the experiments of cyclic huff-n-puff based on different fracture distributions were conducted in six plate-fractured models to investigate the effects of surfactants, primary fracture, and secondary fracture on each cycle of huff-n-puff. Cyclic huff-n-puff with surfactants assisted by complex fracture networks including both primary and secondary fractures would bring to a higher oil recovery. However, other methods should be taken after several cycles of huff-n-puff due to the rapid reduction of oil recovery of each cycle. The findings for the proposed method should provide a meaningful guide to the development of extralow-permeability oil reservoirs.

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“…The experimental apparatus mainly consists of the displacement system, core holder, and metering system [23][24][25][26]. The experimental steps mainly include the following: (1) The core was vacuumed and saturated with simulated water.…”

Section: Dynamic Imbibition Experiments Using Fractured Corementioning

confidence: 99%

“…Besides, the addition of a surfactant can improve the final recovery of water huff-n-puff to some degree [21][22][23]. Compared with the simulated water, on the one hand, surfactant solution can strengthen the water wettability of the core, which is good for decreasing the oil thickness on the pore surface and expanding the contacting area of imbibition.…”

Section: Dynamic Imbibition Experiments Using Fractured Corementioning

confidence: 99%

Study on the Key Influential Factors on Water Huff-n-Puff in Ultralow-Permeability Reservoir

Wang

Xie

Zhang³

et al. 2021

Geofluids

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Ultralow-permeability reservoirs are difficult to effectively develop using conventional technologies, so it generally produces using horizontal wells’ volume fracturing. Besides, oil wells also face the problems of short stable or no production period, rapid decline rate, and extremely low development degree. Water huff-n-puff of oil recovery technology is a quality and efficiency technology to improve the development effect of an ultralow-permeability reservoir. A systematic study on the related key influential factors of water huff-n-puff is done for improving the development effect of ultralow-permeability reservoirs. This manuscript studied the key influential factors of water huff-n-puff and related improving recovery methods using physical simulation experiments to put forward a beneficial condition for water huff-n-puff, combining with the field practice. The results show that imbibition and energy supplement are main mechanisms of water huff-n-puff; imbibition oil recovery is influenced by rock wettability, permeability, boundary condition, fracture length, water injection speed, and imbibition solution type; the stronger the water-wet reservoir rock is, the bigger the core permeability is, the longer the fracture length is, the larger the contacting area between imbibition solution and rock is, the stronger the ability of imbibition solution to change wettability, and to reduce the interfacial tension force between oil and water is, the better effect of water huff-n-puff is. So far, the field practice of water huff-n-puff has been conducted in 38 wells; the success rate can reach 92.1%, cycle oil increment of single well can reach 972 t, and accumulated oil in evaluation period can reach 36936 t, which further proves that water huff-n-puff can achieve a good effect. The effective methods to improve the development effect of an ultralow-permeability reservoir are changing reservoir physical property and supplying reservoir energy. Higher reservoir energy is good for oil flow, and better physical property can improve the displacement effect and imbibition function of injection solution. Artificial fracturing, higher injection-production ratio, and pretreatment of temporary stoppage fracturing are good methods to improve the development effect of water huff-puff.

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Analysis of the Static and Dynamic Imbibition Effect of Surfactants and the Relative Mechanism in Low-Permeability Reservoirs

Cited by 21 publications

References 21 publications

Mechanistic Investigation of LSW/Surfactant/Alkali Synergism for Enhanced Oil Recovery: Fluid–Fluid Interactions

Mechanistic Investigation of LSW/Surfactant/Alkali Synergism for Enhanced Oil Recovery: Fluid–Fluid Interactions

Experimental Investigation on Cyclic Huff-n-Puff with Surfactants Based on Complex Fracture Networks in Water-Wet Oil Reservoirs with Extralow Permeability

Study on the Key Influential Factors on Water Huff-n-Puff in Ultralow-Permeability Reservoir

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