Well-head foams

Undesirable foams Producing oil well and well-head foams Oil flotation process froth Distillation and fractionation tower foams Fuel oil and jet fuel tank (truck) foams... 

Foams can also be used to treat zones near bottom holes to remove solid impurities and for oil and gas well drilling. Stable foams are used in all of the above cases. In other cases, defoaming is necessary to provide a normal course of the processes. First of all, these are foaming in distillation and fractionation towers, producing oil well and well-head foams, fuel oil tank foams. 

Reservoir-foam applications may involve slug injection, in which foaming surfactant solution is injected into the gas stream at the well-head over a period of a few hours, semi-continuous injection, in which surfactant solution is injected at intervals over a period of a day or so, and continuous injection, in which surfactant solution is injected continuously for months or even years. Recently, much attention has been paid to near-well applications of foams [345,726-728],... 

Any kind of dispersion that was useful in the reservoir may be, or may become, an undesirable dispersion when produced at a well-head. This could include used drilling fluid that has returned to the surface, conventional oil production that occurs in the form of a W/O emulsion, or foam from an enhanced oil-recovery process. These can present some immediate handling, process control, and storage problems. In addition, pipeline and refinery specifications place severe limitations on the water, solids, and salt contents of oil they will accept in order to avoid corrosion, catalyst poisoning, and process-upset problems. For pipeline transportation, an oil must usually contain less than 0.5% basic sediment and water (BS W). 

Inclined tube evaporators sometimes perform well in foaming services because of the sharp change in flow direction at the vapor head. It sometimes offers advantages when treating heat sensitive materials. Inclined tube evaporators require low headroom and permit ready accessibility to the tubes. 

Extremely viscous so-called heavy oils are often produced from wells in Canada, Venezuela, and China. These oils often have reported viscosities in the range of (3-30) x 10 mPa s [38 0] and are often produced at the well head as a gas-in-oil emulsion with a gas volume fractions of from 0.05 to 0.40 [41], which has the appearance of chocolate mousse [38]. The foams formed from such gas-in-oil emulsions upon standing can be extremely stable, persisting for several hours in open vessels [38]. 

Place 84 g. of iron filings and 340 ml. of water in a 1 - 5 or 2-litre bolt-head flask equipped with a mechanical stirrer. Heat the mixture to boiling, stir mechanically, and add the sodium m-nitrobenzenesulphonate in small portions during 1 hour. After each addition the mixture foams extensively a wet cloth should be applied to the neck of the flask if the mixture tends to froth over the sides. Replace from time to time the water which has evaporated so that the volume is approximately constant. When all the sodium salt has been introduced, boU the mixture for 20 minutes. Place a small drop of the suspension upon filter paper and observe the colour of the spot it should be a pale brown but not deep brown or deep yellow. If it is not appreciably coloured, add anhydrous sodium carbonate cautiously, stirring the mixture, until red litmus paper is turned blue and a test drop upon filter paper is not blackened by sodium sulphide solution. Filter at the pump and wash well with hot water. Concentrate the filtrate to about 200 ml., acidify with concentrated hydrochloric acid to Congo red, and allow to cool. Filter off the metanilic acid and dry upon filter paper. A further small quantity may be obtained by concentrating the mother liquid. The yield is 55 g. 

Semiflexible molded polyurethane foams are used in other automotive appHcations, such as instmment panels, dashboards, arm rests, head rests, door liners, and vibrational control devices. An important property of semiflexible foam is low resiHency and low elasticity, which results in a slow rate of recovery after deflection. The isocyanate used in the manufacture of semiflexible foams is PMDI, sometimes used in combination with TDI or TDI prepolymers. Both polyester as well as polyether polyols are used in the production of these water-blown foams. Sometimes integral skin molded foams are produced. 

The inlet tube for steam should reach to the bottom of the distillation flask. A i6-mm. bulb on the end of this tube with four 0.8-mm. openings helps to insure thorough mixmg of the heavy residue. If this is not well stirred the aldehyde distils very slowly. It is well to connect the flask to the condenser through a large Hopkins still head in order to prevent the entrainment of foam during the distillation. 

High Viscosity and Surface Tension Bravo (Paper presented at the AIChE Spring National Meeting, Houston, Tex., 1995) studied a system that had 425-cP viscosity, 350 mN/m surface tension, and a high foaming tendency. He found that efficiencies were liquid-phase-controlled and could be estimated from theoretical HTU models. Capacity was less than predicted by conventional methods which do not account for the high viscosity. Design equations for orifice distributors extended well to the system once the orifice coefficient was calculated as a function of the low Reynolds number and the surface tension head was taken into account. 

Non-ionic surfactants are neither positively nor negatively charged but instead they have several oxygen atoms at the head end of the molecule, generally in the form of a series of ->ethoxy groups.711 They produce less foam than anionic surfactants and are used in low temperature laundry detergents because they work well even at 30 °C. 

Odor first comes into play during the shopping trip. The consumer has presumably decided beforehand that he or she needs some shower foam. If he (let us, for the sake of readability, take the proviso "or she" as given) has not yet firmly made up his mind which particular brand or variant to buy, opening a bottle that catches his attention and sniffing at the contents may well be the leading factor in this decision. The perfume must, at this stage, mask the odor of the plastic bottle and the fatty odor of the product base that have collected in the head space. It should in addition please the shopper both as an immediate sensation and as an indication of the odor to expect when he uses the product under the shower. 

The hydrostatic head calculation can be completed in a similar manner, as in Example 1. If proppant is added to the foam, the hydrostatic pressure can be determined for each interval by knowing the proportion of gas, liquid, and proppant for each interval. The fractions of each component can be determined in a similar manner to Example 2. The hydrostatic pressure can be calculated by the summation of the hydrostatic pressure for each increment over the entire depth of the well. 

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