Refining: From Crude to Usable Products. Structural traps occur when oil is caught by folds, faults, or salt domes that deform the rock layers, creating a sealed enclosure.
How Pressure and Heat Transform Matter Deep Underground
For stubborn reserves, tertiary recovery techniques such as steam injection or chemical flooding reduce the viscosity of the oil, allowing it to flow more easily to the wellhead. Buoyant and less dense than the surrounding rock and water, it begins to migrate upward through porous and permeable geological formations.
This buoyancy drives a slow but relentless migration upward through permeable rock layers. This cap rock prevents further upward movement, causing the oil to accumulate in the porous reservoir rock beneath, forming a concentrated pool of hydrocarbons.
How Pressure and Heat Transform Matter Deep Underground
The movement continues until the oil encounters a non-porous cap rock, such as shale or salt, which acts as a seal. The oil moves until it encounters an impermeable barrier, typically a layer of rock like shale or salt, which traps it beneath and prevents further upward movement.
More About How is oil made in the earth
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