Selective plugging agents

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]. 

They were then cut with a diamond saw to form 8-mm-long cylindrical plugs and evaluated for diametral tensile strength using an Instron tester. Testing results of selected experimental agents are provided in Table 2. 

The formation of CVD-W plug was studied by a nonselective or blanket CVD-W and a selective CVD-W. Blanket CVD-W is deposited by the hydrogen or monosilane reduction of tungsten hexafluoride as shown in Eqns. (27), (35) and (36). At present, monosilane is mainly used as a reducing agent because of its high rates even at a low temperature. 

Results. To study the effect of various parameters—such as Dp, Cpo, or Kra—on the effectiveness of an agent, a hypothetical minimum effective concentration was selected (Ceff = 0.1 mg/mL). Low concentrations of agent were required to attain the effective concentration with bolus delivery (Table 10.4). However, the effective dose persists for a short time, leaving half the reproductive tract unprotected within 4-16 h. Plug flow assumes no... 

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