Gamma Ray Log
Is the measurment of the natural radioactivity of formation in general shales tend to have high radioactivity while sandstone-limestone-salt-anhydrite have low radioactivity
Its tools used to determine shae content in ashaly sand and used for stratigraphic correlations
Gamma ray is aradioactivity log which measured natural radio activity in the rock
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Properties Of Gamma Ray
Gamma rays burst of high energy electro magnetic waves that are emitted by radioactive elements
All gamma ray encountered in the earth is emmitted by uranium
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? The similarty between Gamma Ray and SP
The gamma ray is similar to sp and gamma ray is replace the sp in salt muds and in air filled holes and when Rmf=Rw
becous sp are used only in fresh mud and dont use in salt mud
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Theory
Gamma ray are high energy electromagnetic waves produced by the decay of radioactivity isotopes such as
k40-th-u
The rays pass from the formation and enter the bore hole .the gamma ray detector registers incomming gamma rays as an electronic pulses
The pulse are sent to the uphole computer where they are counted and timed
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Interpretation
The interpretation of gamma ray curve is based on the assumption that
shale have abundent potassium 40 in their composition the open lattice structure and waves bonds in clays encourage incorporation of impurities the most common of these impurities are uranium-thorium
thus
shales have high radioactivity
sandstone,quartz,carbonates have strong bonds and generally dont allow impurities occupy the composition
thus
sand stone and carbonates have low radioactivity
limestone undergo rearrangement of crystal structure and addition magnesium to become dolomite
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Advantage of Gamma Ray
Good shale indicator
Good correlations
Gamma ray can be run in open and cased hole
Used to determine the top and the bottom of layer
Discribe of radioactive and nonradioactive minerals
The rays pass from the formation and enter the bore hole .the gamma ray detector registers incomming gamma rays as an electronic pulses
The pulse are sent to the uphole computer where they are counted and timed
******************************************************
Interpretation
The interpretation of gamma ray curve is based on the assumption that
shale have abundent potassium 40 in their composition the open lattice structure and waves bonds in clays encourage incorporation of impurities the most common of these impurities are uranium-thorium
thus
shales have high radioactivity
sandstone,quartz,carbonates have strong bonds and generally dont allow impurities occupy the composition
thus
sand stone and carbonates have low radioactivity
limestone undergo rearrangement of crystal structure and addition magnesium to become dolomite
******************************************************
Advantage of Gamma Ray
Good shale indicator
Good correlations
Gamma ray can be run in open and cased hole
Used to determine the top and the bottom of layer
Discribe of radioactive and nonradioactive minerals