Geol 404 1st Edition Lecture 12 Outline of Last Lecture I. Well LogsII. WaterIII. Natural GassesIV. Fluid PhasesV. Tectonic Subsidence HistoriesVI. Evolution of BasinsVII. BurialOutline of Current Lecture VIII. ResistivityIX. Natural GassesX. PorosityXI. CompactionXII. PermeabilityXIII. Over PressureCurrent LectureSummary of Lecture 9 and 10VIII. Resistivitya. The closer to a hydrocarbon reservoir, the higher the salinity of connate waterb. Resistivity logs will have displacement if they pick up values that are different than the resistivity of fresh water. c. Salinity is higher in sands than in shalei. Salinity increases with depth IX. Natural Gassesa. The main categories that we care about are:i. Inert Gassesii. Hydrocarbonsiii. Inorganiciv. Organicb. Biggest focus on Hydrocarbons and the Organic gasses when a reservoir engineerc. Hydrocarbon Gassesi. Dry, Wet – the amount of liquid vapor contained in the gas.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.ii. Sweet or Sour – presence of hydrogen sulfided. Hydrocarbons consisting of only carbon and hydrogeni. Paraffins, Naphthenes, Aromaticse.X. Porositya. The total pore space within a rockb. Also described as the void space in a rockc. Equation of pore volume divided by the bulk volumed. Void Ratio Equation of pore volume divided by the solid rock volumee. The bulk volume is the volume of solid rock plus volume of pore volumef. Porosity vs Depth is a exponential decay, meaning the farther down you dig, the worse the porosity or void space in a rock. XI. Compactiona. Porosity depth relationships are used for reconstructing original thickness of sediments and to trace the thickness change and porosity change through timeb. Solid rock thickness Hs can be calculated using the Hs equation, an integralXII. Permeabilitya. The ability of a rock to transmit fluid b. The ability of a fluid to flowc. Fractures and vugs impact permeability a loti. Because if they are present, the SP log will detect really good pore space, but the fluid won’t flow if there is no path for it to follow.ii. This is why we have Apparent Flow and Actual Flowd. Actual Permeability is the permeability of only the effective porosity. e. Apparent Permeability is a less accurate representation of permeability because it includes the total porosity. XIII. Over Pressurea. Compaction and porosity directly impacted by the amount of pressure in a reservoir. b. Over Pressure can be described as Hard, Intermediate, Soft and Normalc. Effective Pressure is a measure of the Lithostatic pressure minus the Pore pressured. Pressure gradients are usually measured using psi/fte. Sediment compaction results in the release of pore fluidsf. Over Pressure occurs if the Capillary Pressure is so high, and keeps increasing. Test is next