Surface Volume

As the conditions of pressure and temperature vary, the phases in which hydrocarbons exist, and the composition of the phases may change. It is necessary to understand the initial condition of fluids to be able to calculate surface volumes represented by subsurface hydrocarbons. It is also necessary to be able to predict phase changes as the temperature and pressure vary both in the reservoir and as the fluids pass through the surface facilities, so that the appropriate subsurface and surface development plans can be made. 

This section will firstly consider the properties of oils in the reservoir (compressibility, viscosity and density), and secondly the relationship of subsurface to surface volume of oil during the production process (formation volume factor and gas oil ratio). 

STOIIP" s a term which normalises volumes of oil contained under high pressure and temperature in the subsurface to surface conditions (e.g. 1 bar, 15°C). In the early days of the industry this surface volume was referred to as stock tank oit and since measured prior to any production having taken place it was the volume initially in placd. ... 

The polymer concentration profile has been measured by small-angle neutron scattering from polymers adsorbed onto colloidal particles [70,71] or porous media [72] and from flat surfaces with neutron reflectivity [73] and optical reflectometry [74]. The fraction of segments bound to the solid surface is nicely revealed in NMR studies [75], infrared spectroscopy [76], and electron spin resonance [77]. An example of the concentration profile obtained by inverting neutron scattering measurements appears in Fig. XI-7, showing a typical surface volume fraction of 0.25 and layer thickness of 10-15 nm. The profile decays rapidly and monotonically but does not exhibit power-law scaling [70]. 

Name Type of surface Area of surface Volume... 

In the early days of the commercial development of PVC, emulsion polymers were preferred for general purpose applications. This was because these materials exist in the form of the fine primary particles of diameter of the order of 0.1-1.0 p,m, which in the case of some commercial grades aggregate into hollow secondary particles or cenospheres with diameters of 30-100 p,m. These emulsion polymer particles have a high surface/volume ratio and fluxing and gelation with plasticisers is rapid. The use of such polymers was, however, restricted because of the presence of large quantities of soaps and other additives necessary to emulsion polymerisation which adversely affect clarity and electrical insulation properties. 

Early suspension polymers, although less contaminated, were supplied as more or less spherical particles with a diameter in the range 50-100 p,m. Such materials had a much lower surface/volume ratio than the emulsion polymers and, being of low porosity, the materials were much slower in their gelation with plasticisers. The obvious requirement was to produce more porous particles and these became available about 1950 as easy-processing resins. 

If PVC polymer particles are mixed, at room temperature, with plasticisers the immediate product may take one of two forms. If there is insufficient plasticiser to fill all the gaps between the particle a mush will be produced. If all the voids are filled then the particles will become suspended in the plasticiser and a paste will be formed. In the case of conventional granular polymer, or with emulsion polymer cenospheres, the particles are too large to remain in suspension and will settle out. Therefore compounds used in paste-processes must use polymers with a small particle size. On the other hand there is a lower limit to this, since small particles will have a very high surface/volume ratio and measurable plasticiser absorption will occur at room temperature to give a paste whose viscosity will increase unduly with time. As a consequence paste polymers have an average particle size of about 0.2-1.5 ptm. 

This is the mean abscissa of a graph of cumulative area fraction versus size. Otherwise known as the Surface Volume Mean (or Sauter Mean)... 

ZnO nanoparticles possess greater surface/volume ratio. When used in carboxylated nitrile rubber as curative, ZnO nanoparticles show excellent mechanical and dynamic mechanical properties [41]. The ultimate tensile strength increases from 6.8 MPa in ordinary rabber grade ZnO-carboxylated nitrile rubber system to 14.9 MPa in nanosized ZnO-carboxylated nitrile mbber without sacrificing the elongation at failure values. Table 4.1 compares these mechanical properties of ordinary and nano-ZnO-carboxylated nitrile rubbers, where the latter system is superior due to more rubber-ZnO interaction at the nanolevel. 

The adherence and proliferation of human umbilical vein endothelial cells (HUVECs) were evaluated on the fabricated PCLA scaffold. Results showed that the HUVECs were adhered and proliferated well on the small-diameter-fiber fabrics (0.3 and 1.2 mm in diameter), whereas markedly reduced cell adhesion, restricted cell spreading, and no signs of proliferation were observed on the large-diameter-fiber fabric (7 mm in diameter). That may be due to the high-surface-density fibers provide an extremely high surface/volume ratio, which favors cell attachment and proliferation. 

Exposure time of the wall layer Exposure time of the pool surface Volume of the compound... 

Effect of bead diameter on lactic acid yield is clearly revealed in Fig.6. The optimum bead diameter for the fermentation of lactic acid for cell entrapped in Ca-alginate is 1.0mm with a yield of 30.27 gL and 96.7%. Increasing bead diameter beyond this value did not improve lactic acid production. Smaller bead diameter yields more lactic acid production, due to an increase in the surface volume ratio [9]. A further increase in bead diameter to 5.0mm results in a decrease of lactic acid production to 17.65 gL or 50.7%. 

Dark Decay of UDMH in Air, UDMH was observed to undergo a gradual dark decay in the 30,000-liter Teflon chamber at a rate which depended on humidity. Specifically, at 41 C and 4% RH the observed UDMH half-life was " 9 hours (initial UDMH 4.4 ppm) and at 40 C and 15% RH, the half-life was -6 hours (initial UDMH 2.5 ppm). The only observed product of the UDMH dark decay was NH3, which accounted for only -5-10% of the UDMH lost. In particular, no nitrosamine, nitramine, or hydrazone were observed. Formaldehyde dimethyIhydrazone was observed in previous studies which employed higher UDMH concentrations and reaction vessels with relatively high surface/volume ratios (, ) ... 

Equation (li ) can be used to calculate uncorrected diameter averages. For the number, surface, volume, specific surface, weight and turbidity diameter averages (their definitions have been stated elsewhere (11,12), the following relations can be derived ... 

The relaxation time for each pore will still be expressed by Eq. (3.6.3) where each pore has a different surface/volume ratio. Calibration to estimate the surface relaxivity is more challenging because now a measurement is needed for a rock sample with a distribution of pore sizes or a distribution of surface/volume ratios. The mercury-air or water-air capillary pressure curve is usually used as an estimator of the cumulative pore size distribution. Assuming that all pores have the same surface relaxivity and ratio of pore body/pore throat radius, the surface relaxivity is estimated by overlaying the normalized cumulative relaxation time distribution on the capillary pressure curve [18, 25], An example of this process is illustrated in Figure 3.6.5. The relationship between the capillary pressure curve and the relaxation time distribution with the pore radii, assuming cylindrical pores is expressed by Eq. (3.6.5). 

---