On the hydrodynamics of off-bottom plug placement: A 2D model problem
Autor: | A.M. Ghazal, Ida Karimfazli |
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Rok vydání: | 2021 |
Předmět: |
Materials science
Viscoplasticity Advection Flow (psychology) 02 engineering and technology Injector Mechanics 010502 geochemistry & geophysics Geotechnical Engineering and Engineering Geology 01 natural sciences law.invention Fuel Technology 020401 chemical engineering law Newtonian fluid 0204 chemical engineering Diffusion (business) Spark plug Displacement (fluid) 0105 earth and related environmental sciences |
Zdroj: | Journal of Petroleum Science and Engineering. 203:108613 |
ISSN: | 0920-4105 |
DOI: | 10.1016/j.petrol.2021.108613 |
Popis: | Economic and environmental costs have renewed public and industrial interest in safe and long-term well abandonment. Balanced plug is a commonly used plug placement technique that relies on the injection of cement slurry in a well otherwise filled with lower density liquids. In the absence of a mechanical bridge, buoyancy-driven displacement flows may lead to the contamination of the plug or the failure of the process. To develop a mechanistic perspective of the processes that may prevent the buoyancy-driven failure of the placement process, we investigate the injection of a viscoplastic fluid, through a concentric injector, into a vertical channel filled with a lower density Newtonian fluid. The fluids are considered to be miscible and the effect of diffusion on flow development is characterized through exploring a wide range of Peclet numbers, 28 ≤ P e ∞ . We identify two representative flow regimes dominated by either diffusive or advective transport. In the diffusive regime, once the injection starts, a layer of mixed fluids develops below the injector that slowly expands by diffusion. In the advective regime, a finger of the injected fluid invades the channel at the onset of injection. This viscoplastic finger breaks up subsequently, leading to the formation of a layer of mixed fluids below the injector. We provide a mechanistic description of the observed dynamics and show that the formation of a density-stratified layer of mixed fluids is essential for the accumulation of the injected fluid. |
Databáze: | OpenAIRE |
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