Obviously, the two main elements of hydrocarbons are hydrogen and carbon. Therefore, once we know the amount of [[total organic carbon (TOC)]] present in a rock, we then need to know the amount of hydrogen present in order to assess overall source rock quality. The amount of oxygen and hydrogen present in the kerogen defines the [[Kerogen types|kerogen]] as type [[Type I kerogen|I]], [[Type II kerogen|II]], or [[Type III kerogen|III]] and if the rock will be oil or gas prone.
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Obviously, the two main elements of hydrocarbons are hydrogen and carbon. Therefore, once we know the amount of [[total organic carbon (TOC)]] present in a rock, we then need to know the amount of hydrogen present in order to assess overall source rock quality. The amount of oxygen and hydrogen present in the [[kerogen]] defines the kerogen as type [[Type I kerogen|I]], [[Type II kerogen|II]], or [[Type III kerogen|III]] and if the rock will be oil or gas prone.
==Hydrogen index==
==Hydrogen index==
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The [[hydrogen index (HI)]] represents the amount of hydrogen relative to the amount of organic carbon present in a sample. The [[Rock-Eval_pyrolysis#Rock-eval_pyrolysis|S2 curve]] of a Rock-Eval analysis can help us determine the total amount of hydrogen in milligrams of hydrogen to grams of sample according to the following formula:
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The [[hydrogen index]] (HI) represents the amount of hydrogen relative to the amount of organic carbon present in a sample. The [[Rock-Eval_pyrolysis#Rock-eval_pyrolysis|S2 curve]] of a Rock-Eval analysis can help us determine the total amount of hydrogen in milligrams of hydrogen to grams of sample according to the following formula: