Formation penetration distance

Importantly, in sandstone acidizing, more acid is not necessarily better. In fact, in most cases, the opposite is true. The formation penetration distance of live acid is usually much less than one foot. However, near-wellbore... 

Formation con osition. The chemical and physical compositions of the formation are very important in defining the acid spending time, and, subsequently, the acid penetration distance. Acid spends very rapidly in highly reactive (>95%) carbonates. Acid spending time can be much slower in formations with lower HCl reactivity (65%-85%). As mentioned previously, the reaction rate of acid in limestone is about twice that in dolomites (at lower temperatures). Therefore, live acid penetration can be deep in low-solubility, lower-temperature dolomites. 

Live acid penetration distance is enhanced by reducing the mass transfer or diffusion of acid in the fracture to the reactive fracture wall surfaces. This slows or partially blocks the acid reaction itself, reducing fluid loss (leak-off) from the fracture to the matrix. Fluid-loss reduction has the greatest effect. Fluid loss is controlled by several factors, including formation permeability and porosity, viscosity of the lost fluid, compressibiHty of the reservoir fluids, and the difference in pressure between the fracture and the matrix. 

It is possible to pump plain acid in such a treatment. When plain acid is used, acid reaction is very fast. The acid will dissolve large amounts of rock near the wellbore but will create a short penetration distance. If a treatment is designed simply to bypass fairly shallow formation damage, plain add may be sufficient. If plain add is used, a large overflush is not needed, because it cannot increase penetration distance. If the intent of the treatment is to stimulate the formation, viscous acid must be used. 

The oxygen in the blast penetrates but a short distance above the tuyere level. It is all consumed in burning the carbon of the coke to CO. Most of the carbon in the coke descends through the shaft of the furnace until it reaches the tuyere zone, where it is met by the blast and burned to carbon monoxide. The high temperature precludes the formation of carbon dioxide. Some of the carbon, however, through actual contact with iron oxide, is oxidized (either to CO or C02) in the upper part of the furnace. This oxidation, of course, liberates heat above, instead of in, the smelting zone where it is most needed and likewise tends to decrease the proportion of carbon fully oxidized to C02 in the furnace and thereby the quantity of heat developed in the furnace. 

For ideal solutions, the partial pressure of a component is directly proportional to the mole fraction of that component in solution and depends on the temperature and the vapor pressure of the pure component. The situation with group III-V systems is somewhat more complicated because of polymerization reactions in the gas phase (e.g., the formation of P2 or P4). Maximum evaporation rates can become comparable with deposition rates (0.01-0.1 xm/min) when the partial pressure is in the order of 0.01-1.0 Pa, a situation sometimes encountered in LPE. This problem is analogous to the problem of solute loss during bakeout, and the concentration variation in the melt is given by equation 1, with l replaced by the distance below the gas-liquid interface and z taken from equation 19. The concentration variation will penetrate the liquid solution from the top surface to a depth that is nearly independent of zlDx and comparable with the penetration depth produced by film growth. As result of solute loss at each boundary, the variation in solute concentration will show a maximum located in the melt. The density will show an extremum, and the system could be unstable with respect to natural convection. 

The formation and stoichiometry of the polymer complex between nucleic acid analogs are affected by two important factors. The first is the base-base distance in the polymer chain, represented as xA and yA in Fig. 17. This distance is one factor in intramolecular base-base interactions in the polymer chain, which also influences what can be called the penetration ability of the polymer. 

The stability and stoichiometry of the complex between polymers containing nucleic add bases are affected by the compatibility of the different base-base distances in the polymers, and also by the mutual penetration ability between the main chains. In the polyMAOA-polyMAOT system, for example, intramolecular base-base distances in each polymer are compatible and these polymers are able to penetrate each other38, Poly-L-lysine derivatives and vinyl polymers are apparently incompatible. This situation alone would lead to unstable complex formation where the overall stoichiometry would not be simple and thus could not reflect the stoichiometry on the binding site. 

It can thus be concluded that both the mutual penetration ability and the compatibility of base-base distances of the polymers are substantial for the formation of the stable polymer complexes by specific base pairing. 

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