Texas Gulf Coast sandstones have been subjected to several stages of burial diagenesis: mechanical compaction, silica and carbonate cementation, and cement and grain dissolution. Each stage is well-developed before the sandstone aquifer is geopressured; only iron-rich carbonate cement continues to be precipitated in the geopressured zone.

Fluids must pass through an aquifer for cementation to occur. Ideally there is minimal fluid movement in the geopressured zone because overpressuring requires the fluids to be trapped. However, if faults are periodically opened and fluids escape, a drop in pressure of the aquifer would result. Lower pressure would allow carbon dioxide gas to evolve and the carbonate equilibrium would then favor precipitation of carbonate minerals.

Evidence of the above process is scale precipitated in wells producing geopressured fluids. As the fluid pressure is lowered by production of the well, iron-rich carbonate minerals are formed. These carbonate minerals are precipitated because of a pressure drop which may be analogous to pressure drops along opened fault zones.

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