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Impact of rock morphology on the dominating enhanced oil recovery mechanisms by low salinity water flooding in carbonate rocks

Farhadi, H ; Sharif University of Technology | 2022

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  1. Type of Document: Article
  2. DOI: 10.1016/j.fuel.2022.124769
  3. Publisher: Elsevier Ltd , 2022
  4. Abstract:
  5. Because of the complex nature of carbonate reservoirs, the required conditions for effective Low Salinity Water Flooding (LSWF) in these reservoirs need further and in depth investigation. In the present study, three calcite cores, i.e. Cal-1, Cal-2, and IL, with the same chemical composition are subjected to tertiary low salinity water flooding (LSWF), while the crude oil and composition of flooding brine kept the same. The experimental results show significant difference in the amount of enhanced oil recovery, as IL had the most additional oil recovery (20.8 % of IOIP), followed by Cal-2 (10.5 % of IOIP) and Cal-1 (3.9 % of IOIP). The results of contact angle, zeta potential, and effluent pH showed that the same geochemical reaction occurred for all three cores. High-resolution FE-SEM images demonstrate that the only difference in these three cases is the rock morphology. Dynamic contact angle measurements indicate that wettability alteration depends on the dominating mechanisms (diffusion/advection) that controls the replacement of high salinity thin water film (which is flanked by crude oil and rock) with the surrounding low salinity brine. The wide pore size distribution of Cal-1 compared to Cal-2 and IL results in a more diffusion-controlled oil recovery mechanisms, which is confirmed by the late-time and the gradual response of Cal-1 to tertiary LSWF. Also, a direct relation between effluent pH and the tertiary oil recovery of Cal-1 highlighted the role of the thickness of the water film in the diffusion rate. More homogenous Cal-2 has a high early oil recovery; however, the angular shape of its particles leads to a partial diffusion-controlled regime that causes a late-time recovery. Finally, the uniform and the rounded particles of IL drift the impact of diffusion away. The results of the present is study emphasizes the role of heterogeneity and angularity on the performance of tertiary LSWF. © 2022 Elsevier Ltd
  6. Keywords:
  7. Low salinity water flooding ; Pore morphology ; Surface chemistry ; Calcite ; Contact angle ; Crude oil ; Diffusion ; Effluents ; Enhanced recovery ; Morphology ; Oil well flooding ; Petroleum reservoir engineering ; Petroleum reservoirs ; Pore size ; Reservoirs (water) ; Rocks ; Wetting ; Enhanced-oil recoveries ; Floodings ; Low-salinity water ; Oil recovery mechanisms ; Pores morphology ; Rock morphology ; Surface electric charge ; Wettability alteration ; Wettability alteration, surface electric charge ; Floods
  8. Source: Fuel ; Volume 324 , 2022 ; 00162361 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/abs/pii/S0016236122016143