Selective plugging

Selective plugging/addition of air distributor jets to match the spent catalyst distribution... 

Selective plugging of highly permeable zones by injecting slime-forming bacteria followed by sucrose solution that turns on the production of extracellular slimes... 

Bacillus licheniformis produces a water-insoluble levan that has potential application as a selective plugging agent in MEOR. The microorganisms grow on sucrose, glucose, and fructose but produce levan only on sucrose. Thus plugging may be selectively controlled in the reservoir by substrate manipulation. Oil reservoirs that have a temperature of less than 55° C, a pH between 6 and 9, a pressure less than 500 atm, and a salt concentration of 4% or less are potentially suitable [1480]. 

Other experiments are planned to study the location, distribution and resuscitation of ultramicrobacteria in large three-dimensional sandpacks. Such studies will allow a more realistic approximation of reservoir conditions than the unidirectional core studies. We do not consider that the ultramicrobacteria will reach or grow in areas where residual oil is located. Selective plugging involves blocking the high permeability zones already drained of oil. We consider that the injection of ultramicrobacteria will be carried, like waterflood operations, to the areas of the strata already drained of oil and permit them to disperse through pore spaces and resuscitate in these areas. 

Precipitation o-f sur-factant can be use-ful in applications, such as in selective plugging o-f oil reservoirs to improve mobility control (84) or to recover sur-factant from surf actant—based separation processes (85). 

Figure 10 below illustrates a mock up of the initial target structures we will build with the assembly tank. By selectively plugging some of the holes in the structures we can pre-valve them (while the smart cubes are being developed) and assembly multi-cube structures like the C U structures shown in the figure. We note that the latches on the structures are sufficiently strong that they can support the weight of the structure after the assembly fluid is drained. 

Naruse et al.l measured a decrease in surface area and an increase in the mean pore dimensions with an iron oxide employed as NOx reduction catalyst. However, the decrease in activity with surface area was not proportional, and some change in the "pore characteristics was cited as possibly explaining the discrepancy. An increase in average pore dimensions was attributed to selective plugging of the miciopores. 

D. 0. Falk, Process for Selectively Plugging Permeable Zones in a Subterranean Formation, United States Patent 4,485,875, Dec. 4 (1984). 

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