Clay-bound water

Studies of rock cores from oilfields are used in the petroleum industry to assess the hydrocarbon content of rock strata and the ease with which the oil can be recovered. The GeoSpecT NMR Rock Core Analyser, a 2 MHz TD-NMR from Oxford Instruments, can provide information on the fluids in oil- and water-saturated rock including oil viscosity and clay-bound water, porosity, fluid distribution, and permeability. Rock cores can be studied at high temperatures and pressures and the instrument can provide diffusion and imaging information. 

Holtzinger, G. Marie, G. Pigments based on clay-bound water-soluble dyes. Fr. Demande FR 2879097, 2006 Chem. Abstr. 2006,145, 69332. 

Total void volume. Clay-bound water is included in pore volume... 

FIGURE 2.11 Volumetric description of a hydrocarbon-bearing clastic and carbonate reservoir. CBW, clay-bound water BVI, bulk volume irreducible/non-movable water BVM, bulk volume... 

NMR is not the end all to petrophysics. It is a new tool for understanding describing the subsurface both reservoir non-reservoir rocks which expands the petrophysical content of our logging data, providing direct estimates of irreducible water, clay bound water the permeability. 

Rook matrix Clay-bound water Capillary-bound water Movabie fiuids OBM filtrate Oil G a s... 

Clay-bound water creates the shortest relaxation time. This clay mineral-bound water effect is controlled by clay mineral properties. Therefore, relaxation time correlates with other interface properties of clay minerals such as specific internal surface and cation exchange capacity (CEC Table 3.3). Thus, T2 could be used as a CEC indicator (see, for example, Martin and Dacy, 2004). 

FIGURES./ NMR data processing—principle. Measured data are in a time domain. The inversion process results in a partitioning of the individual relaxation contributions (bulk volumes) with the three regions clay-bound water (CBW), capillary-bound or immovable water (BVl), and free movable water (BVW). Regions are separated by cut-offs. 

Archie s equations are based on the condition that the electrolytic conductivity of the pore water is the only conductivity component in the rock. This rock type is called clean rock . Natural rocks frequently have some additional conductive components. Most important are clay minerals with clay-bound water-forming shaly rocks or shaly sands. 

Prammer, M.G., Drack, D.E., Bouton, J.C., Gardner, J.S., 1996. Measurement of clay-bound water and total porosity by magnetic resonance logging. Log Anal. 37, 61-69. November-December. 

Little direct, quantitative measurement has been done on bound water existing in equilibrium with clay mineral substances in... 

This study suggests a method for sample preparation to increase the concentration of bound water. By compressing the clay-water... 

Clay minerals behave like Bronsted acids, donating protons, or as Lewis acids (Sect. 6.3), accepting electron pairs. Catalytic reactions on clay surfaces involve surface Bronsted and Lewis acidity and the hydrolysis of organic molecules, which is affected by the type of clay and the clay-saturating cation involved in the reaction. Dissociation of water molecules coordinated to surface, clay-bound cations contributes to the formation active protons, which is expressed as a Bronsted acidity. This process is affected by the clay hydration status, the polarizing power of the surface bond, and structural cations on mineral colloids (Mortland 1970, 1986). On the other hand, ions such as A1 and Fe, which are exposed at the edge of mineral clay coUoids, induce the formation of Lewis acidity (McBride 1994). 

Clay Minerals. The clay minerals in coal all contain water bound within their lattices. Kaolinite contains 13.96%, illite 4.5%, and mont-morillonite 5% bound water. In addition, the montmorillonite in the mixed-layer clays also contains interlayer or adsorbed water. All of the water is lost during the high-temperature ashing. 

Sepiolite clay (<100 mesh) was heated in air at 120°C in order to remove the zeolitic and surface bound water molecules. The partially dehydrated clay mineral was subsequently exposed to acetone vapor at room temperature for a period of four days. H and 29Si CP MAS-NMR experiments revealed that the acetone molecules penetrated into the microporous channels of the sepiolite structure. Broad line 2H NMR studies using acetone-d6 revealed that, in addition to fast methyl group rotations, the guest acetone-d6 molecules were also undergoing 2-fold re-orientations about the carbonyl bond. The presence of acetone-d6 molecules adsorbed on the exterior surfaces of the sepiolite crystals was also detected at room temperature. 

In addition to the above suite of well logs, the newest type of log was obtained via NMR (here called CMR) as shown in Figure 7.37. In this new method, the capillary, clay-bound, and free water (on the right) as determined by the NMR log, are subtracted from the total porosity as determined by the density tool (not shown) to obtain the hydrate saturation in the middle column. 

Figure 7.37 (See color insert following page 390.) 5L-38 CMR logs showing hydrate extent at depths between 900 and 930 m. Note that hydrates are obtained by the difference (middle column) between the total porosity as determined by density (not shown), and the capillary, clay-bound and free water determined by NMR.

Quite often fireclay is burnt to chamotte at the place where it is found. The most common clay mineral in fireclay is kaolinite with the ideal formula Al4[(OH)8/Si4O10], or in the notation applied in world of ceramics Al203.2Si0r2 H20. Kaolinite contains chemically and physically bound water. When you heat it to about 1500 °C, the physically bound form is first released and subsequently the chemically bound one. In the last phase chamotte is formed ... 

The physically bound water in the raw material clay is determined by drying the sample at 105 °C until it has a constant mass. In order to determine the chemically bound water it is necessary to heat the sample to 1100 °C. Remember that between the clay sheets water molecules are bound to the ions of the sheets an ionic dipole bond. In addition some molecules are interconnected by means of H-bridges,... 

The hydrophobic colloids do not have affinity for water thus, they do not contain any bound water. In general, inorganic colloids are hydrophobic, while organic colloids are hydrophilic. An example of an inorganic colloid is the clay particles that cause turbidity in natural water, and an example of an organic colloid is the colloidal particles in domestic sewage. 

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