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Example gamma ray log. Blue and black lines indicate the measured gamma rays. Sand section of interest is located at bottom of log where the log moves to the left. Gamma ray logging is a method of measuring naturally occurring gamma radiation to characterize the rock or sediment in a borehole or drill hole.
The lithology in Figure 1 & 2 is represented by the cyan, gray/black and yellow blocks of color. Cyan = lime, gray/black = shale and yellow = sand. More yellow represents more sand identified at that depth. The lithology is measured as a percentage of the total sample as visually inspected under a microscope, normally at 10× magnification ...
Lithology is the basis of subdividing rock sequences into individual lithostratigraphic units for the purposes of mapping and correlation between areas. In certain applications, such as site investigations , lithology is described using a standard terminology such as in the European geotechnical standard Eurocode 7 .
Lithology: A description of the rock's physical characteristics, such as grain size, composition and texture. [4] By studying the lithology of local geological outcrops and core samples, geoscientists can use a combination of log measurements, such as natural gamma, neutron, density and resistivity, [2] to determine the lithology down the well.
In the petroleum industry, lithology, or more specifically mud logging, is the graphic representation of geological formations being drilled through and drawn on a log called a mud log. As the cuttings are circulated out of the borehole , they are sampled, examined (typically under a 10× microscope) and tested chemically when needed.
The shrinkage limit is also a part of the Atterberg limits. The results of this test can be used to help predict other engineering properties. [7] California bearing ratio ASTM D 1883. A test to determine the aptitude of a soil or aggregate sample as a road subgrade. A plunger is pushed into a compacted sample, and its resistance is measured.
Units of formation or higher rank are usually named for the unit's type location, and the formal name usually also states the unit's rank or lithology. A lithostratigraphic unit may have a change in rank over a some distance; a group may thin to a formation in another region and a formation may reduce in rank for member or bed as it "pinches out".
Many relationships between travel time and porosity have been proposed, the most commonly accepted is the Wyllie time-average equation. The equation basically holds that the total travel time recorded on the log is the sum of the time the sonic wave spends travelling the solid part of the rock, called the rock matrix and the time spent travelling through the fluids in the pores.