Organic deposition

Paraffin. Paraffin deposition is a function of reservoir or wellbore temperature. If the temperature is above the doud point (the point at which the paraffin present in the oil begins to deposit), deposition will not take place. However, a slight reduction in temperature can cause the paraffin to crystalhze (douding the oil) and deposit in perforations or in the wellbore. Such a temperature change may occur during any well operation in which fluid is introduced from the surface to the wellbore or formation. 

Downhole temperature will be temporarily reduced when foreign fluids contact the formation oil. Once solid paraffin has begun to form (e.g., see fig. 3-4), to resolubihze, an increase in the oil temperature above the well temperature is usually required. Unfortimately, this is often difficult, if not impossible, to accomplish. Repeated treatment with solvent may be necessary. Removal treatment that includes a wax crystal modifier is most effective. 

Asphaltenes. Asphaltenes are high-carbon-number, primarily cyclic hydrocarbons present in crude oil in colloidal suspension. Asphaltenes may drop out of solution as a very nasty, persistent, damaging deposit downhole. 

Identification of organic deposits is especially important in an acid treatment candidate well, because this damage is not acid removable. In fact, contact of organic deposits with add can create more severe (perhaps irreversible) damage. In addition, assessment and identification of organic 

If at all possible, downhole samples should be collected for analysis of paraffin and asphaltene and their potential for deposition. Acid/crude oil fluid-compatibility tests should be conducted by the service company to design a compatible add system. Removal of organic deposits is discussed in chapter 15. 

---

Plugging due to ice, although causing power loss oj even m or seizing, was reversible however the development of recycled crankcase gas resulted in iri ii sibfe solid organic deposits on the walls of the system, especially in the carburetor. 

Electrodialysis Reversal. Electro dialysis reversal processes operate on the same principles as ED however, EDR operation reverses system polarity (typically three to four times per hour). This reversal stops the buildup of concentrated solutions on the membrane and thereby reduces the accumulation of inorganic and organic deposition on the membrane surface. EDR systems are similar to ED systems, designed with adequate chamber area to collect both product water and brine. EDR produces water of the same purity as ED. 

NOTE All-polymer programs employ various types of organic deposit control agents (DCA) such as phosphinocarboxylic acid (PCA) products, which tend to be high temperature-stable sludge dispersants, crystal modifiers, and hardness transporters. 

Clean-in-place (CIP) units for periodic membrane washing and removal of organic deposits, inorganic scales, and biofouling... 

Dried organic deposits m inhibit penetration of the chemical agent. Where possible, objects to be disinfected should be thoroughly cleaned. The presence of ions in water can also affect activity of antimicrobial agents, thus water for testing biocidal activity can be made artifieially hard by addition of ions. 

Organisms are more resistant to ethylene oxide treatment in a dried state, as are those protected from the gas by inclusion in crystalline or dried organic deposits. Thus, a further condition to be satisfied in ethylene oxide sterilization is attainment of a minimum level of moisture in the immediate product environment. This requires a sterilizer humidity of 30-70% and frequently a preconditioning of the load at relative humidities of greater than 50%. 

Regeneration of the catalyst is accomplished in place using air at 250- 350 C to bum off organic deposits. Regeneration takes 24 hours, including purging periods. 

Ousi-Benomar, W. Xue, S. S. I. cssard, R. A. Singh, A. Wu, Z. L. Kuo, P. K. 1994. Structural and optical characterization of BaTi03 thin films prepared by metal-organic deposition from barium 2-ethylhexanoate and titanium dimethoxy dineodecanoate. J. Mat. Res. 9 970-979. 

The organic deposition sources are made of a variety of materials including ceramics (e.g., boron nitride, aluminum oxide, and quartz) or metallic boats (e.g., tantalum or molybdenum). Deposition is carried out in high vacuum at a base pressure of around 10-7 torr. The vacuum conditions under which OLEDs are fabricated are extremely important [41] and evaporation rates, monitored using quartz oscillators, are typically in the range 0.01 0.5 nm/s in research and development tools. In manufacturing, higher rates or multiple sources may be used to reduce tact times. 

Many of the characterization techniques described in this chapter require ambient or vacuum conditions, which may or may not be translatable to operational conditions. In situ or in opemndo characterization avoids such issues and can provide insight and information under more realistic conditions. Such approaches are becoming more common in X-ray adsorption spectroscopy (XAS) methods ofXANES and EXAFS, in NMR and in transmission electron microscopy where environmental instruments and cells are becoming common. In situ MAS NMR has been used to characterize reaction intermediates, organic deposits, surface complexes and the nature of transition state and reaction pathways. The formation of alkoxy species on zeolites upon adsorption of olefins or alcohols have been observed by C in situ and ex situ NMR [253]. Sensitivity enhancement techniques play an important role in the progress of this area. In operando infrared and RAMAN is becoming more widely used. In situ RAMAN spectroscopy has been used to online monitor synthesis of zeolites in pressurized reactors [254]. Such techniques will become commonplace. 

Direct measurement of oxygen uptake can be performed with O2 sensors in the headspace of a closed system and organic deposition by measuring the weight changes with a quartz microbalance. This method was applied to investigate the dependence of jet fuel autoxidation on temperature and the presence of antioxidants . 

High-pressure diesel fuel pumps are not tolerant of dirt, debris, and organic deposits and can be seriously damaged by fuel contaminants. The barrel and plunger clearance is within a 1 to 2 micron tolerance. This tolerance is necessary to ensure that fuel injection pressures are maintained with minimal leakage past the plunger shaft. For this reason, thorough and complete filtration of fuel is required before the fuel reaches the injection pump. 

Hunger and Wang provide an account of advances in the characterization of solid catalysts in the functioning state by nuclear magnetic resonance spectroscopy. Examples include investigations of zeolite-catalyzed reactions with isotopic labels that allow characterization of transition states and reaction pathways as well as characterization of organic deposits, surface complexes, and reaction intermediates formed in catalyst pores. 

Ilium, L., Davis, S. S., Wilson, C. G., Thomas, N. W., and Frier, M. (1982) Blood clearance and organ deposition of intravenously administered colloidal particles. Effects of particle size, nature and shape, Int. J. Pharm., 12 135-146. 

Bader KF. 1966. Organ deposition of silver following silver nitrate therapy of burns. Plast Reconstr Surg 37 550-551. 

Kelly, 3.R. and Nixon, S.W., 1984. Experimental studies of the effect of organic deposition on the metabolism of a coastal marine bottom community. Mar. Ecol. Prog. Ser., 17 (2) 157-169. 

Pacification—Treatment of a column-bridged HPLC system with 20% (6 N) nitric acid to remove buffer and organic deposits and protect metal surfaces from corrosion. The column must be removed before acid treatment. Overnight water wash is needed to remove the last traces of acid. 

Table IV however, shows that the sapwood is filled to a much greater extent than the heartwood for six of the eight species. This is contrary to what would be assumed from the measured void volume. The sugar maple and the basswood are the two exceptions there is essentially the same retention of polymer in the sapwood and heartwood. The heartwood probably has less of the voids filled with polymer, because of organic deposits and tyloses, which block the penetration of the monomer into the capillaries.

If the adsorption results in an organized deposit layer and a certain arrangement similar to the crystalline lattice we speak of epitaxy. A prerequisite of epitaxy is not only a two-dimensional lattice analogy of foreign lattice layers but also the mode of nucleus formation, fusing the nuclei, purity of crystal surface, and binding energy between lattice... 

---