The basis of oil and gas is created small oil and gas molecules form At 120

The basis of oil and gas is created small oil and gas

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° -The basis of oil and gas is created (small oil and gas molecules form) ° -At 120, lots of oil starts to rise. ° -As we rise in temperature We are maturing the organic matter. ° -Complex reactions in organic matter to break into simpler molecules. The heating break the complex molecules into simple ones. ° -St high temperature: the shale releases oil and gas. ° -Oil and gas rise (when the oil shale reaches a certain temperatures). (the liquid is a lot less dense than the rock, so it will rise). Water density: 1g/ml; oil is less dense than water. Oil: 0.85 ° ° The Oil Window ° ° ° ° - At around 100 degrees, we see oil ° - Above 165 degrees, we lose oil, and get mostly NG. ° - Most of NG tends to come from reservoirs that are at greater depths ° - It’s about TIME and temperature. At the oil window, things have been buried for 100M years. ° - Crude oil can be heated up to 300 degrees (it won’t break down if you heat it up rapidy). But with enough time, at a high temperature, things will happen. ° - Oil window: 4-6 km ° - Anything further down (9+) is turned into graphite. °
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° Oil Migration and Entrapment
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° ° ° ° - The source bed gets folded, a fault gets formed (reverse) ° - Faulting causes fracturing, a migration pathway develops, oil migrates upwards. ° - A trap forms and oil accumulates beneath the seal/cap rock. (The oil rises until it is resting on the reservoir rock. ° - Oil moves up the fault, collects in reservoir rock. The oil is trapped there. ° ° Types of Oil and Gas Traps: ° 1) Anticline trap: oil and gas rise to the crest of the fold (up to the seal rock) ° ° 2) Reverse fault trap: oil rises to where it’s sealed in
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° ° ° 3) Unconformity ° ° The Origin of Coal ° -Peak of coal: hot planet (300M)- lots of forest, lots of coal) ° -Don’t see any coal older that 440M years. No plants, no coal. ° ° The Formation of Coal ° -The vegetation of swamps must fall and be buried in an oxygen-poor environment. ° -Compaction and partial decay of the vegetation transforms it into peat. (Is a form of energy in other parts of the world) ° -To transform peat into coal, the peat must be buried deeply (4-10km) by overlying sediment. ° -At a certain depth, the weight of overlying sediment compact the peat and squeezes out any remaining water. ° -Temperature increases with depth, deeply buried peat gradually heats up. ° -Heat accelerates chemical reactions that gradually destroy plant fibers and release elements in the form of gas. ° -The gases seep out of the peat layer, leaving behind a residue concentrated with carbon. Once the carbon proportion of the residue exceeds 50%, the deposits become coal. ° -Process continues, highest grade coal: anthracite. ° ° Phanerozoic Ice Ages and CO 2 ° ° -Impact of burning fossil fuels °
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° ° ° Graph: ° - Temperature are in relative terms to present day ° - Left side: deltao18: Measure of the isotopic composition of oxygen. (2 isotopes: o16 and o18) Ocean water has a consistent o16 o18 ratio Ratio changes as temperature of ocean changes With water vapour, o16 goes with it. The heavier isotope stays behind.
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