Which log uses a gamma ray source?
The Gamma log is used to record the naturally occurring radiation found in the surrounding borehole rocks from three primary isotopes: Potassium-40 (K), Thorium (Th), and Uranium (U) . Clays have the highest concentration of these radioactive isotopes; hence the Gamma log is also known as the clay log, or shale log.
What is relationship between gamma ray and grain size?
The obvious relationship being suggested when gamma-ray log shapes are used in facies analysis, is that gamma-ray changes, besides indicating clay content, mirror grain size- changes. Low log values indicate a coarse grain size while high values indicate fine grain size (Fig. 2).
What is GR in oil and gas?
An abbreviation for gamma ray, usually with reference to the gamma ray log.
What is natural gamma logging?
Gamma ray logging is a method of measuring naturally occurring gamma radiation to characterize the rock or sediment in a borehole or drill hole. It is a wireline logging method used in mining, mineral exploration, water-well drilling, for formation evaluation in oil and gas well drilling and for other related purposes.
Which of the following from gamma ray log is best indicator of clay content of rock?
Spectral gamma ray logs are most useful in identifying the following: Clay minerals. Illite clays are rich in potassium, whereas smectite and kaolinite contain thorium. The thorium to potassium ratio can distinguish illitic from smectitic shales and so provide a correlation tool.
What is CRP in oil and gas?
CRP – common/central reference point (subsea survey)
What is TDS oil and gas?
“TDS” means total dissolved solids. Source: Oil and Gas, New Mexico Administrative Code Title 19, Chapter 15, January 2013.
What does a well log tell you?
Well logs present a concise, detailed plot of formation parameters versus depth. From these plots, interpreters can identify lithologies, differentiate between porous and nonporous rock and quickly recognize pay zones in subsurface formations.
Why is gamma ray log used as a shale indicator?
Identifying shale volumes. The most common use of gamma ray logs is to estimate the shale “volume” in rocks. It is important to remember that the tool measures radioactivity, and the correlation to shale content is empirical. Shales are presumed to be composed of clay minerals.
What is density log and its purpose?
Density logs are useful for determining hydrocarbon density and for detecting hydrocarbon gas with low density compared to rock matrix or liquid densities. A low density implies high hydrocarbon gas content, while a high density suggests low hydrocarbon gas content.