Slug injection mixing

Campos and Guedes de Carvalho also performed experiments on mixing of liquid with a pulsated gas feed [5]. They observed that an increased frequency of slug injection leads to decreased mixing of liquid, and they related this behavior to the detachment of the wakes of slugs in the pulsating liquid. 

J.R.F. Guedes de Carvalho, S.S.S. Cardoso, and J.A.S. Teixeira, Axial Mixing in Slug Flow. The Use of Injected Air to Reduce Taylor Dispersion in a Flowing Liquid, Trans. Inst. Chem. Eng. 77(A) 28 (1993). 

As the surfactant slug is injected into the reservoir, the mixing of injected slug with reservoir components takes place. The mixing of surfactant with reservoir oil and brine often produces emulsions. Moreover, the reservoir parameters such as porosity, pressure, temperature, composition of connate water and crude oil as well as gas-oil ratio affect the formation of oil field emulsions. 

Air Sparging Gas sparging or injection of air bubbles has been effectively used to reduce concentration polarization and enhance mass transfer. " The secondary flows around bubbles promote mixing and reduce the thickness of the concentration polarization boundary layer. When the bubble diameter exceeds that of the membrane (tubular or hollow fiber), slugs are then formed further increase in bubble diameter has no effect on flux improvement. Large slugs can displace most of the boundary layer and cause the pressure to pulsate. This results in enhancing the flux. 

Polymer can be placed in a mixed SP slug or in a polymer-only slug for mobility control. Table 9.1 compares the results from different schemes. In SIM 1, 0.25 PV 0.07 wt.% polymer is injected after the surfactant slug (0.1 PV 2% S). In SIM 2, 0.1 PV X 0.07% polymer is moved to the surfactant slug. In SIM 3, all the polymer in 0.25 PV, 0.07 % polymer slug (0.25 x 0.0007 = 0.000175 PV) is placed in the 0.1 PV surfactant slug. Then the polymer concentration in the 0.1 PV surfactant slug is 0.175%. The recovery factors and incremental recovery factors are almost the same in these three simulation cases. From these simulation cases, it seems that it does not matter where polymer is placed. 

Effect of molecular interactions and additives In the reservoirs the pol3nner solutions mix with different chemicals injected before and after the polymer slug. In this way the interaction between surface active agents and polymers or between caustic materials and polymers is unavoidable at the disintegrated fronts if combined flooding technology is used in practice. These chemicals, which can also be in the polymer solutions, have an influence on the wettability and the solution structure. 

Surfactant slugs are frequently used in EOR processes to mobilize residual oil by changing rock wettability or by reducing oil/water interfacial tension. To increase the efficiency of such processes, polymers can be either co-injected with the surfactant slug or as a chase. In both cases, surfactant and polymer mixing is to be expected. The effects of Triton X-100 (a nonionic surfactant) and Neodol 25-3S (an anionic surfactant) on the viscosity of HPAM solutions were examined by Nasr-El-Din et al. [41]. 

Behavior of Gel Systems in Porous Media. The erosslinked polymer systems mixed at the surface are injected into a formation, where reaction occurs to form a gel. Ideally, once formed, the gel has sufficient strength or viscosity to be immobile. The effective permeability of the rock matrix or fractures in which the gel resides is reduced or, in some cases, essentially eliminated. For processes based on injection of slugs in which the different reactants reside, mixing followed by reaction occurs within the rock. The objective here also is to form a gel that is not mobile. 

Costs prohibit continuous injection of the mobility buffer. At some point in the displacement process, sufficient polymer has been injected to prevent the drive water from fingering through the mobility buffer into the chemical slug. A region of variable concentration forms owing to mixing between the drive water and the polymer. If the polymer concentration in the mobility buffer remains constant, the size of the mobility buffer needed to protect the chemical slug can be estimated from experimental displacement runs or from mathematical models. 

Technician s autoanalyzer, so-called continuous-flow analyzer (Thiers et al, 1971), uses multiphase flow concept for high-throughput analysis. In these machines, the samples to be analyzed are injected to a capillary separated by bubbles. The liquid slug sample is practically sealed between two bubbles. Long capillary tubes with multiple analysis section can be used with minimal mixing of consecutive samples as the bubbles prevent mixing between the samples. 

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