Sample surface

Fluid samples may be collected downhole at near-reservoir conditions, or at surface. Subsurface samples are more expensive to collect, since they require downhole sampling tools, but are more likely to capture a representative sample, since they are targeted at collecting a single phase fluid. A surface sample is inevitably a two phase sample which requires recombining to recreate the reservoir fluid. Both sampling techniques face the same problem of trying to capture a representative sample (i.e. the correct proportion of gas to oil) when the pressure falls below the bubble point. 

Surface sampling involves taking samples of the two phases (gas and liquid) flowing through the surface separators, and recombining the two fluids in an appropriate ratio such that the recombined sample is representative of the reservoir fluid. 

IlyperChem provides three types ofpotential energy surface sampling algorithms. These are found m the IlyperChem Compute menu Single Point, Ceometry Optimization, and Molecular Dynamics. 

Atr—ftir can be readily performed on most commercial ftir spectrometers through the use of an attachment for atr spectroscopy. These devices provide ir-transparent internal reflection elements that are typically made of Ge, KRS-5, ZnSe, or ZnS. These internal reflection elements are made of materials that are of extremely high purity to avoid losses from absorption by impurities in these devices. Coupling of a thin film or surface sample to one of these reflection elements is accompHshed by pressing the sample against the element while acquiring the spectmm. 

Demonstrated reserve quantities are estabUshed by measurements including drillings surface sampling, etc. Inferred reserves are those derived from geological survey information, not by measurement of the extent of the particular reserve. Not included herein are identified marginal and speculative resources, such as the oil-field and geothermal brines and lithium-hearing clays. These latter reserves are speculative as to extent, not existence. Total undiscovered clays in the western United States are speculatively estimated at 15 x 10 t lithium (16). More detailed Hsts of reserves are also available (15,17). 

Correctly loading the sample into the matrix is one of the most critical steps in f.a.b. analyses. Poor data are inevitable if the sample has been loaded in such a way that it cannot readily be present in high concentration at the surface. Samples should not, therefore, be dried on the target prior to addition of the matrix. 

Vertical Migration. Historically, surface samples at other TCDD sites have been taken to depths of 0 to 6 inches using picks and... 

Surface sampling should be augmented with 12-15 sequential samples taken down to 1.5 meters In order to determine If the pollutant has moved downward. These 12-15 additional samples should be located In the area of major contamination. 

In most cases, if soil samples are needed, only surface samples are collected. An exception would be harvesting root crops where all residues in the top 6 in of soil would be sampled. A typical surface soil sampler is shown in Figure 2. It is the residue adsorbed on small particles (<150 o.m), which could cling to moist skin, which causes the most exposure to workers. After sampling, place a flag in the center of each sampled location to mark the area against future sampling. After the surface layer has been collected, the soil is sieved to collect the fraction <150 lam and the remainder of the soil is discarded. Maintain separate sieves and collectors for treated and control plots to prevent contamination of the control samples. 

Two of the zinc surface samples show results that might intuitively be expected for metal coated surfaces. The polycarbonate and RIM-polyurethane substrates show much lower Fs values with the zinc coating as expected, but Q values are very similar to that of the uncoated substrates. For modified-polyphenylene oxide, however, a very low Q value is obtained suggesting flame... 

Surface samples were collected in snow pits under ultra-clean conditions described elsewhere [13] with the exception that samples for anion analysis were collected in polystyrene cups precleaned without the use of acids. Ice core samples were cleaned to remove surface contamination using the "dry-core" procedure involving rinsing and melting of exterior surfaces with ultra-pure water [13]. Shallow-depth firn cores are permeable and the dry-core rinsing is unsuitable. Therefore an inner core of 2.5 cm diameter was taken from intervals of the 7.6 cm diameter South Pole firn core using a specially-built precleaned stainless steel corer within a -15 °C cold room. Prior to this coring, exposed ends of core sections were shaved away with precleaned stainless steel chisels. 

Table 1 except the Allan Hills surface sample from stake 12,... 

Soini, H.A., Bruce, K.E., Klouckova, I., Brereton, R.G., Penn, D.J. and Novotny, M.V. (2006) In-situ surface sampling of biological objects and preconcentration of their volatiles for chromatographic analysis. Anal. Chem. 78, 7161-2168. 

Table 10.3 Methoxy and organic carbon contents of surface samples (0-15cm) of 22 soils from Eastern Australia...

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