HGS Petroleum Exploration Methods What Geologists and Geophysicists

HGS Petroleum Exploration Methods What Geologists and Geophysicists do to find oil and gas Cerro Azul #4 blow-out, Veracruz, Mexico February 1916 Houston Geological Society Academic Liaison Committee 1

HGS Petroleum Exploration Methods Part II: Petroleum System: Source Houston Geological Society Academic Liaison Committee 2

Houston Geological Society Academic Liaison Committee 3

Source: Oil is produced from “source rock” Oil is formed in sedimentary rocks that contain large quantities of organic material. Most of the world’s oil is generated from rocks containing algae, an aquatic plant Houston Geological Society Academic Liaison Committee 4

Source: Oil is produced from “source rock” Oil forms from organic matter that is "cooked" deep within the earth for long periods of time at low temperatures. Fossil organic matter is called kerogen Houston Geological Society Academic Liaison Committee 5

Source: Oil is produced from “source rock” Houston Geological Society Academic Liaison Committee 6

Petroleum System A Dynamic Entity 1) Early Generation Spill Point Migration from ‘Kitchen’ Spill Point Seal Rock Reservoir Rock (Mudstone) (Sandstone) Gas beginning to displace oil 2) Late Generation Displaced oil accumulates Gas displaces all oil Houston Geological Society Academic Liaison Committee 7

Petroleum System: Timing is Critical Trap Must Be Available Before/During Migration Processes: Elements: Generation Source Rock Migration Avenue Houston Geological Society Academic Liaison Committee Trap Accumulation and Preservation Reservoir and Seal 8

HGS Petroleum Exploration Methods Part II: Petroleum System: Reservoir Houston Geological Society Academic Liaison Committee 9

Reservoir: Oil is stored in “reservoir rock” Oil fills the pore-space between grains Houston Geological Society Academic Liaison Committee 10

Reservoir: Oil is stored in “reservoir rock” Sand grains are white, pore space is blue Porosity = 26%, permeability = 2434 md Houston Geological Society Academic Liaison Committee 11

Reservoir Sandstone Pore-Filling Cement Reduces Quality Cement (pink) = Less Space for Petroleum Houston Geological Society Academic Liaison Committee 12