U.S. Geological Survey
Energy Resource Surveys Program

Schematic diagram showing compaction of mud into shale and resulting expulsion of water and silica cement

Schematic diagram showing compaction of mud into shale and resulting expulsion of water and silica cement. Petroleum that has been generated in the shale prior to fluid expulsion migrates along with the fluids into the adjacent reservoir rock. Accumulation may occur if a trap is present.

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