Cores sampling techniques

In 2002, IUPAC initiated work in the development of terminology of a standard for analytical data. The standard format, XML, is intended to be universal for all types of analytical instrumentation, without permutations for different techniques. The XML format is designed to have information content of data defined in several layers. The most generic information is in the first layer, or core. More specific information about the instrumentation, sample details and experimental settings are stored in subsequent layers. The layers are defined as core, sample, technique, vendor, enterprise and user.29 The existence of a universal format will aid in the analysis of data from multiple sources, as well as in the archival and retrieval of data from historical processes. 

By far the most widespread use of NMR in an on-line production environment is the utilization of downhole exploration tools by petroleum service companies such as Schlumberger, Halliburton, and Baker Hughes. Articles on these unilateral NMR systems are found in the patent databases, " academic literature, and on-line resources provided by the exploration companies. The references provided here are just a few examples in a very prolific field. The technique is applied in high-temperature and pressure situations and currently is used down to a depth of about 10 km (6 miles) to produce a picture of water/oil content in the adjacent rock formations as well as to derive permeability, diffusivity, and hydrocarbon chemistry information. Mobile unilateral NMR systems such as the NMR-MOUSE are also being developed in order to take benchtop NMR systems into the field to perform analysis of geological core samples at the drill site. NMR analyzers are also being developed to determine the bitumen content and properties in tar sand production and processing. " " ... 

Any measurement on a real-world sample is always a combination of the free and bound gas sample types. This is because the process of taking the gas sample generally requires that the sediment or rock system is disturbed by some mechanical means which creates the mixing of these sample types. Because of this unavoidable interaction, we have recognised the need to consider an intermediate sample-collection technique that measures the more loosely-bound gases liberated into a container containing the core sample. 

Figure 1. Box model for the calculation of Mn redox cycling near the sediment-water interface. Sedimentation rates are measured with sediment traps. The burial rate Sh is estimated from dated sediment cores. In situ sampling techniques (flux chambers and peepers) are used to quantify the diffusive flux across the sediment-water interface FS6. The resuspension rate R is estimated from the increase in the mass flux of settling material between the 81- and 86-m horizons.

The wavelength and angle dependences of the depth of penetration, d, were given earlier (Equation (3.22)), and this principle is used in the MIR for the sampling technique of ATR spectroscopy. Figure 3.13(c) illustrated this, and, for typical refractive indices of fibre core and sample of 2.5 and 1.5, respectively, and an angle of incidence of 45°, the depth of penetration of the evanescent wave is about 0.152. The effect of the evanescent wave on fibre-optic spectroscopy may be illustrated by the example of plastic-clad silica (PCS) fibre optics for remote spectroscopy in the NIR spectral region, as discussed below. 

When a study of the vertical migration of organics in soil is needed, samples will have to be obtained from various known depths. Sampling techniques to accomplish this include manual excavation of a pit or trench, various types of hand or motor driven core sampling devices, or sampling thieves. In a study of this type, the sampling technique should provide an accurate measurement of the depth of the sample below the original surface. It should also minimize any contamination of the sample with soil from either above or below the layer sampled. 

When using a core sampler the depth to which the sampler penetrates should be compared with the core sample length. Soils which exhibit a compression of greater then 25 % should be sampled by another technique or a differently designed core sampler. 

If the interest in radionuclide distribution extends beneath the soil surface, coring is the preferred sampling technique. Cores are taken to a known depth at the sampling site. Depth profiles are separated at selected vertical intervals to provide information on area deposition and downward movement of a radionuclide. Numerous cores may have to be taken because radionuclide retention can vary with changes in soil constituents in a relatively small area. Samples at greater depths can be obtained from well-drilling cores. 

Shuter, E. and Teasdale, W. E. 1989. Application of drilling coring, and sampling techniques to test holes and wells in Techniques of Water-Resources Investigations. Chapter FI. Book 2. Reston, VA US Geological Survey. 

M. Fiege, T. Davies, T. Frohlich, and P. Lampen, The AnIML core, sample, and technique shells Proposal for an AnlML schema, http //animl.sourcefoige.net/CLC Waters AnIML Proposal.pdf (2(X)4). 

Nuclear logging using gamma radiation, to measure the bulk density, and neutron radiation, to measure water content, are techniques used both at sea and ashore. Preiss (1968) and Richards and Chaney (1997) describe how these techniques may be used for marine sediments both on core samples and in situ. These in-situ methods are particularly apph-cable to near-surface sediments which can be extremely porous and tend to suffer the greatest amount of disturbance when sampled. It is difficult using these techniques to obtain accuracies better than 1%, due to the problems of cahbrating the instruments with specimens of different chemical and mineralogical compositions. 

The amount of chloride ion in the concrete can be measured by sampling the concrete and carrying out chemical analysis (titration) on a liquid extracted from the sample. This is usually done by mixing acid with drillings or crushed core samples. An alternative is pore extraction by squeezing samples of concrete or, more usually mortar. This technique is frequently used in laboratory experimental work as it is often difficult to extract useful pore water samples from field concrete. The soxhlet extraction techniques for free chlorides was discussed earlier. 

Air bubbles were extraeted using the cheese grater technique. Ice core samples weighing 500-1500 g were prepared by selecting crack-free iee and trimming away the outer 5-20 mm. Eaeh sample was sealed in a polyethylene bag and cooled to... 

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