Geol 404 1st Edition Lecture 10 Outline of Last Lecture I. Earths WaterII. Natural GassesIII. PetroleumIV. Chemical CompoundsV. Fluid PhasesVI. HydrocarbonsOutline of Current Lecture VII. Petroleum Resource AssessmentVIII. BurialIX. Porosity X. PermeabilityXI. Compaction Pressure and Fluid FlowCurrent LectureVII. Petroleum Resource Assessmenta. First step in assessment is to identify and interpret correctly the basin architecture, and the geometry and sedimentary facies within the basin-fillb. geographic and stratigraphic extents, i.e., basin-scale structure and petroleum system elementsc. The second step is to identify and interpret the fundamental tectonic, thermal and petroleum system processes.d. Propertiesi. Every sediment will have primary properties such as porosity and permeabilityii. The secondary properties include thermal conductivity and densityVIII. Buriala. When a sediment is buried, they start off with an initial porosity and permeabilityb. All properties can change from weight and compaction and temperaturei. Porosity decreases with weight added, when porosity decreases so does permeability.ii. If permeability is too low to allow the water to escape at the rate of added overburden the fluid pressure increases and creates over pressure. iii. Pressure has a direct impact on fluid flow, porosity, thermal conductivity, subsurface temperature distribution and geothermal gradient.iv. Temperature and Time impact the maturation of organic matter most.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.v. Temperature1. Depends on thermal conductivity2. Internal heat generation3. Water flow4. Surface temperature change5. Temperature gives an estimation of formation temperature from borehole measurements6. Insitu temperature is more difficult to estimate thoughvi. Geothermal Gradient1. Depends on Depth and Temperature2. Has a linear curve that gained a higher slope when depth or temperature increases.vii. Internal Heat 1. Depends on Depth and Temperature2. Has a linear line which decreases slope as temperature or depth increaseIX. Porositya. Represents the void space in a rocki. Primary Porosity 1. Inherent, original characteristic of the rockii. Secondary Porosity1. The result of geologic processes most commonly due to solution, recrystallization and dolomitization, and fractures and joints.b. Porosity change with burial can be modeled using an exponential relationshipc. Porosity depth relationships are used for reconstructing original thickness of sediments and trace the thickness change and porosity change with timeX. Permeabilitya. A measure of the ability of a rock to transmit fluidsb. Reservoirs can be very porous but contain fractures and vugs, which directly impact the permeability. c. Darcy’s law can be used to evaluate permeability, along with the porosity permeability equation. d. There are 3 equations in total: Dary’s Law, Kozeny-Carman, and LercheXI. Compaction Pressure and Fluid Flowa. Sediment compaction is the reduction of pore space and subsequent release of pore fluidsb. Over pressure occurs when there is compaction and fluid does not escape the rock (conventional shale has water)c. Over Pressurei. Compaction and porosity development is related to the development of pressureii. The total vertical component of overburden pressure (s) is equal to the effective stress transmitted through the rock plus the fluid pressure. d. Porosity and Permeability Pressurei. Related by the void ratio e being equal to the initial void ratio multiplied by the frame pressure divided by the initial frame pressure all raised to anexponent A. e. Effective Pressurei. Described as Pressure effective = Pressure lithology – Pressure of poreii. Hydrostatic Gradient, Lithostatic Gradient and Geopressured zone all depend on depth and