Rock type

Reservoir rocks are either of clastic or carbonate composition. The former are composed of silicates, usually sandstone, the latter of biogenetically derived detritus, such as coral or shell fragments. There are some important differences between the two rock types which affect the quality of the reservoir and its interaction with fluids which flow through them. 

There is only one method available that allows the study of the vertical and lateral relationship of the different rock types of a reservoir on a scale of 1 1. This is the study of outcrops. These are areas like quarries, readouts, cliffs, mines, etc., which consist of a sequence known to be a reservoir in the vicinity or the lateral equivalent thereof. Detailed investigation of a suitable outcrop can often be used as a predictive tool to model ... 

Field analogues should be based on reservoir rock type (e.g. tight sandstone, fractured carbonate), fluid type, and environment of deposition. This technique should not be overlooked, especially where little information is available, such as at the exploration stage. Summary charts such as the one shown in Figure 8.19 may be used in conjunction with estimates of macroscopic sweep efficiency (which will depend upon well density and positioning, reservoir homogeneity, offtake rate and fluid type) and microscopic displacement efficiency (which may be estimated if core measurements of residual oil saturation are available). 

Rock type Calcium phosphate content, % Work index, kw.-hr./ton... 

Taken from W. S. Fyfe, Geochemistry, Oxford University Press, 1974, with some modifications and additions to incorporate later data. The detailed numbers are subject to various assumptions in the models of the global distribution of the various rock types within the crust, but they are broadly acceptable as an indication of elemental abundances. See also Table 1 in C. K. J0RGENSEN, Comments Astrophys. 17, 49-101 (1993). 

General Rock Types 240. Historical Geology 24 1. Petroleum Geology 242. Source Rocks 243. 

The earth is composed of three general rock types igneous, sedimentary, and metamorphic [24]. 

Inclusion of one rock type (usually igneous) into surrounding rocks is invariably younger than the rocks it intrudes. Inclusions are useful in determining relative geologic ages. 

Underreamer Specifications. Table 4-105 [58] shows example specifications for nine models of Servco roller cone rock-type underreamers. Table 4-106 contains example data for four models of Servco drag-type underreamers [58]. 

Rock Type Type Drag-Type 2-Stage... 

Figure 4-175. Rock-type underreamer nomenclature. (Courtesy Smith International, Inc.)...

Bit Wear and Rock Type. Using downhole weight-on-bit and torque the roller cone bit wear can be estimated while drilling. The well site computer can be used to compute in real-time a dimensionless torque (T ) and a dimensionless rate of penetration (R ) using the following equation ... 

Based on concentrations of trace elements in rock types found in Oregon 38). 

Elements Crustal Abundance Mean in Oregon Rock Types Western Surface Soils Total Recoverable uses Mean DEO Max ... 

In transport-limited conditions, however, susceptibility is not so important due to the isolating effect of thick soils. In the extreme situation of a flat landscape lowering at a uniform rate, the erosional contribution by a particular rock type should be related only to the area exposed. Solids would be cation-deficient. 

Alteration is always a cause for concern in geochemical investigations and the best approach will always be to avoid samples with visual or chemical evidence for alteration. The differential fluid mobility of U, Th, Pa and Ra undoubtedly provides the potential for weathering or hydrothermal circulation to disturb the U-series signatures of arc lavas. In a study of lavas from Mt. Pelee on Martinique, Villemant et al. (1996) found that domeforming lavas were in U-Th equilibrium whereas plinian deposits from the same eruptions had small U-excesses which they interpreted to reflect hydrothermal alteration. However, whilst the addition of U could be due to hydrothermal alteration, the plinian deposits were also displaced to lower °Th/ Th ratios which cannot. Instead, the two rock types may just be from separate magma batches. 

NriaguJO. 1978. Lead in soils, sediments and major rock types. In Nriagu JO, ed. The biogeochemistry of lead in the environment. Part A. Ecological cycles. New York, NY Elsevier/North-Holland Biomedical Press, 15-72. 

COMMON ROCK TYPES Shale, limestone, sandstone, basalt ... 

The results from VIRS analyses are amenable to several methods of interpretation. In the simplest sense, the spectra can be used as empirical measurements on given rock types or formations, without specific reference to the causative minerals. We have found that superficially identical rock types with different geological contexts can in some cases be effectively characterized and discriminated. The comparison of measured spectra with reference spectra from minerals is the main tool used for identification, and is very effective in cases where samples are monomineralic or dominated by a single infrared active species. The size of the area analyzed is 1 cm in diameter. Computer programs with variable levels of automation can speed the process of identification, but... 

Diavik Diamond Mine Inc. is located on an island in Lac de Gras, 300 km northeast of Yellowknife, NT (Fig. 1).). Open pit mining will lead to the eventual development of two 200 Mt permanent stockpiles of waste rock. The country rock consists of granite averaging <0.04 wt.% S and biotite schist averaging >0.08 wt.% S. Both rock types contain low concentrations of carbonate minerals. 

Zaccarini, F. Garuti, G. 2008. Mineralogy and chemical composition of VMS deposits of northern Apennine ophiolites, Italy evidence for the influence of country rock type on ore composition. Mineralogy and Petrology, 84, 61-83. 

Two objects with different spectral properties, i.e., variation in the slope of spectral reflectance curve of two bands, can be separable with the help of ratio images (Lillesand et al. 2007). In this study standard reflectance data of USGS Spectral Library and John Hopkins University spectral library (Available in ENVI) have been used. To enhance the dissimilarity between different rock types in the scene, plots with a higher reflectance were kept in the numerator and plots with low reflectance were kept in the denominator, while taking the band ratios. Using this approach, a ratio of 5/3 was taken for basalt, 7/3 for peridotite, and 4/2 for vegetation. 

As displayed in Figure 4, basalt, gabbro, and peridotite has distinctly different spectral signature and shows texture variations between different rock types. 

The shape and structure of the carbonates and surrounding rock types suggest the carbonates are an intrusive structure rather than representing a sedimentary sequence. 

With calceous rock types, the oxide mineralization extends beyond the veins forming concretion and small masses. The lead content of these mineralization types range from 1.5% to 2.5%, of which 50% is oxidized. The zinc content ranges from 5% to 12%, of which 70% is oxide zinc. 

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