Geol 404 1st EditionFinal Exam Study GuideLecture 15 Formation of PetroleumWhat 3 things are essential to the formation of petroleum?Organic matter, sediment supply and rich source rock. What are the 3 types of processes and explain each.Diagenesis - the transformation of suitable types of organic matter to the complex polymers we call kerogenCatagenesis - is the cooking or maturation process which kerogen yieldsMetagenesis - is the stage of over cooking or transforming of kerogen to carbonWhere is Type 1 Kerogen found?It’s found in Marine environments.What is the equation for kerogen? ki=A*EXP(-Ei/RT)What is the API Gravity of Light, Medium and Heavy oil?Light- 30+, Medium- 20-30, Heavy- 10-20Lecture 16Reservoir SystemsWhat is the grain size of sand, silt and clay?Sand- .05-2mm feels grittySilt- .002-.05 feels smoothClay- Less than .002 feels silkyWhat type of rock is shale composed of?It’s composed of like clay, and also organic matter and pore water, where Pore water is the free water plus the bounded water.What are Clay Minerals?Are silicate layer sheets and can be either silicate tetrahedral sheet or an aluminum octahedral sheet. These also have Constitutive water within the octahedral layers. Boundedwater is found in the structured water plus the mobile water in the interlayer sheets.What is isomorphous Substitution?Is essentially replacing an ion for another of similar size within a crystalline structure of clay. By doing this the charge and location of charge will change. Basically chemistry. Name the types of Ionic Radii.Tetrahedral Sheets -Si, Al, Fe -.042-.064 radiusOctahedral Sheets -Al,Fe,Mg,Zn -.051-.07 radiusExchange Sites -Al,Fe,Mg,Zn,Fe2,Na,Ca,K,O-2 -.052-.14 radiusWhat do Clay Minerals depend on?The numbers and combinations of structural unitsThe number of cationsThe size and location of layer chargeThe absence or presence of interlayer cationsState the main types of Clay Minerals and give a description for each. Smectite-Usually when temperature is around 75-110 degrees celsius, the water will be extracted, and it's considered your oil window. After losing the water, it will change to Illite. Composed of two sheets of silicon tetrahedral and one sheet of aluminum octahedral linked by oxygen atoms.Illite-Water can still be lost by increasing the temperature to 110-140 degrees Celsius. Kalinite-Is formed when the temperature is increased to anything greater than 600 degrees Celsius. There is no water between these structural layers. With the Increase in burial depth, what are some effects?Some effects are an increase in pore fluid pressure, an increase in temperature, a decreasein porosity, a decrease in pore size and a decrease in the size of organic molecules. Lecture 17HydrocarbonsT/F: Primary migration is natural migration and has been studied by geologists for ages?TrueT/F: Natural Fractures is a driving force for migration?TrueT/F: Permeability will get better the deeper you are?FalseAre natural fractures better for a reservoir or not? Explain why or why not.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 it is for oil to flow. These natural micro fractures are caused when the capillary pressure is so high that the rock will crack if it’s brittle enough. Brittle rock is favored over soft rock.Describe the Oil and Gas Phase in relation to hydrocarbon migration. Gas Phase-Gas density is low and very buoyant.-Gas may dissolve and transport liquid HydroCarbons and the amount of heavier Hydrocarbons dissolved is temperature and pressure dependent.-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. Oil Phase-Organic material may form a continuous bitumen and oil network in shale and result in oil wet rock or mixed wetting.-Discussion - Relevant for only small soluble hydrocarbons. Migration from high to low concentration areas. -Where Methane, takes 1740million to 140 million years.-Solution - Relevant for large soluble hydrocarbonsDescribe the pore diameters of shale in nanometers. Macropores >50 nanometersMesopores = 2-50 nanometersMicropores = .8 - 2 nanometersUltramicropores <.8 nanometers Oil is mainly found in the MesoporesLecture 18 Secondary MigrationWhat is the key element for Secondary Migration to occur?For this to occur there needs to be some kind of source rock. T/F: Microfractures help set up a reservoir system?TrueT/F: Buoyancy is the density contrast between petroleum and the subsurface brines?TrueT/F: When the petroleum migrates upwards there should not be a seal to arrest migration?FalseT/F: Buoyancy effect dictates the rising petroleum?TrueT/F: 3 primary migration basinal areas have been identified capable of generating oil?TrueDescribe in detail what Shadow Problems are.Ortho Contour flow vectors have been sketched in, to show possible secondary migration routes. Finally, three prospects and two or more leads have been identified. Prospects are defined on something seismic or very big. Whereas leads are more theoretical. What is the effect of Migration Distances?The distance from the petroleum source rock to the trap may be as large as many hundreds of kilometers. The outermost field defines the he limit of the Petroleum System for that particular source pod. U.K. North Sea Fields 20-30km from source rocks whereas Western Cadadian Basin Field is 400-500km from it's source. What’s the definition of a Pore Scale?The hydrocarbon molecule size and pore throat diameters are dealing in nanometers, a billionth of a meter. Pore Throats act as molecular sieves allowing particles smaller than the orifice to pass and retaining larger particles. As an oil molecule travels up through a water wet carrier bed in the subsurface environment, it needs to pass through what?Pore throats. Capillary pressure opposes the buoyant force until the radius of the curvature inside the distorted oil globule is equal at its lower and what?Upper ends. What are water wet and oil wet reservoirs?Pore spaces on most reservoir rocks, are presumed to be initially filled with water from the moment of their deposition. When oil invades the rock, a film of water is left on the surface of the grain or pore opening. This film has a high surface adhesion and consequently makes the bound water very difficult to move. The larger grains