Geol 404 1st Edition Lecture 17 Outline of Last Lecture I. Source RocksII. Clay MineralogyIII. Clay Mineral TypesIV. Physical Changes With BurialOutline of Current Lecture V. HydrocarbonsVI. Gas PhaseVII. Oil PhaseVIII. Shale Pore Diameters and Oil ExpulsionIX. Driving Forces for MigrationCurrent LectureV. Hydrocarbonsa. Primary migration is natural migration and has been studied by geologists for ages.i. What has been found is that there needs to be micro fractures in the rock for migration. And with the addition of more fractures, the easier itis for oil to flow.ii. These natural micro fractures are caused when the capillary pressure is so high that the rock will crack if it’s brittle enough.iii. Brittle rock is favored over soft rockVI. Gas Phasei. Gas density is low and very buoyant.ii. Gas may dissolve and transport liquid HydroCarbons and the amount of heavier Hydrocarbons dissolved is temperature and pressure dependent.iii. This can account for oil deposits because the more amount of hydrocarbons that’s present, the most gas that’s dissolved and the more increase in pressure that is used towards the micro fractures. VII. Oil Phasea. Organic material may form a continuous bitumen and oil network in shale andresult in oil wet rock or mixed wetting.b. Discussion - Relevant for only small soluble hydrocarbons. Migration from high to low concentration areas. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.i. Where Methane, takes 1740million to 140 million years.ii. Solution - Relevant for large soluble hydrocarbonsVIII. Shale Pore Diameters and Oil Expulsiona. Macropores >50 nanometersb. Mesopores = 2-50 nanometersc. Micropores = .8 - 2 nanometersd. Ultramicropores <.8 nanometers i. Oil is mainly found in the Mesoporese. Water .3 nmf. Methane .38 nmg. n-Alkanes .47 nmh. Cyclohexane .48 nmi. Complex Ring Structures 1-3 nmj. Alphaltenic Molecules 5-10 nmi. Expulsion efficiency decreases with increasing hydrocarbon number, but ill increase with less hydrocarbon numbers.IX. Driving Force for Migrationa. Natural Fracturesi. Kerogen will convert to liquid gas, and the pore volume will increase, and create pressure to squeeze the rock, which will generate micro fractures. ii. Then the hydrocarbons will migrate till they hit a fault.iii. Kerogen will be expelled first, then at a higher temperature Kerogen oiland gas condensate will be expelled and then later Kerogen and gas will be expelled b. Permeability vs Depthi. Permeability will obviously get smaller (worse) the deeper you are, but if hydrocarbons are present, then the permeability will eventually hit a breaking point and start to get better with increasing depth. ii. This is because of the micro fractures. X. Hydrocarbon Generation Mir fracturing a. (Mathematical calculations wont be on the final)i. Not required to memorize the equation, however, you should be able to understand