Lower reducing zone

Upper reducing zone (e) Hottest portion of flame (b) Lower oxidizing zone (c) Lower reducing zone (f)... 

Oil recovery can also be affected by extreme variations in rock permeability, such as when high-permeability thief zones between injectors and producers allow most of the injected drive fluid to channel quickly to producers, leaving oil in other zones relatively unrecovered. A need exists for a low-cost fluid that can be injected into such thief zones (from either injectors or producers) to reduce fluid mobility, thus diverting pressure energy into displacing oil from adjacent lower-permeability zones. 

In some scaled up fluidized bed combustors, the lower combustion zone has been divided into two separate subsections, sometimes referred to as a pant leg design, to provide better mixing of fuel and sorbent in a smaller effective cross section and reduce the potential maldistribution problems in the scaled up plant. 

The nature of the lower vesicular zone is not particularly dependent on flow thickness beyond size compression due to lava overburden. As bubbles rise to escape the rising lower crystallization front, the size of the largest bubble caught depends on the velocity of the front, and once the velocity (slowing with the square-root of time like a cooling half space) is reduced below the Stokes velocity of the smallest bubbles in the distribution, all can escape and the lower boundary of the massive zone (Sahagian et al. 1989) is defined at that point. This is true of any flow thickness, so that the only factor that controls the nature of the lower vesicular zone (relative to that of the upper vesicular zone, which is much more complex) is the overlying pressure of the lava. A thicker flow would result in proportionally smaller size mode, which is the basis of the entire analysis for paleoelevation. 

These processes are illustrated in Fig. 8.16. Sulfate that penetrates down into the sediment from the overlying sea water is reduced to H S by sulfate reducing bacteria that use the deposited organic material as their energy source. Also methane diffusing up from below feeds sulfate reduction in the lower sulfate zone. At depth in... 

To reduce the risk of inappropriate withholding of therapy, programmable features such as sudden onset, rate stability, and electrogram width are usually only available for lower rate zones. In addition, manufacturers have developed another programmed feature called sustained rate duration (19). If tachycardia persists for a programmable amount of time, the ICD will deliver therapy even if stability or sudden onset criteria have not been met. Sustained rate duration can act as a safety net, reducing the likelihood of untreated sustained ventricular arrhythmias. 

HPTLC layers are smaller, contain sorbent with a smaller, more uniform particle size, are thinner, and are developed for a shorter distance compared to TLC layers. These factors lead to faster separations, reduced zone diffusion, better separation efficiency, lower detection limits, less solvent consumption, and the ability to spot more samples per plate. However, smaller samples, more exact spotting techniques, and more reproducible development techniques are required. 

The objective of an in-situ permeability-modification process is to treat the reservoir in such a way that the effective permeability of the high-permeability zones is significantly reduced. Conceptually, it would be desirable to reduce permeability across the entire reservoir—i.e., from injection wells to production wells. Practically, treatment tends to be limited to the region relatively near the wellbore. Also, provisions must be made to prevent the gelling agents from entering and damaging the lower-permeability zones. 

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