--> --> Sandstone Diagenesis and Source Rock Maturation Interactions During Laramide Basin Evolution, by R. C. Surdam; #90986 (1994).
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Abstract: Sandstone Diagenesis and Source Rock Previous HitMaturationNext Hit Interactions During Laramide Basin Evolution

Ronald C. Surdam

Many of the most productive Cretaceous hydrocarbon reservoir rocks in Rocky Mountain Laramide basins are in close stratigraphic proximity to organic-rich source rocks (e.g. Muddy Sandstone/Mowry Shale). The spatial attributes of mass transfer processes characterizing the diagenesis/Previous HitmaturationTop of these reservoir/source rock systems during basin evolution are interrelated.

Typically, that portion of the Cretaceous shale section in a Laramide basin below a present-day depth of 9,000 feet is anomously pressured, a gas saturated, basin-wide, dynamic fluid-flow compartment. The driving mechanism for the compartmentalization is the generation, storage, and subsequent reaction of hydrocarbons. As these processes proceed in the shales, the fluid-flow system is converted to a multiphase regime, low-permeability rocks are converted to capillary seals, and closure of the seals creates the compartment. Above the anomously pressured, gas saturated shales the fluid-flow system remains single phase and typically under water drive (influenced by the meteoric water regime).

The vertical compartmentalization of the fluid flow system has a pronounced effect on mass transfer characteristics in the sandstones within and above the pressure compartment. Mass transfer in the sandstones, as reflected in alteration of framework grains and cementation/decementation reactions, in those portions of the basin characterized by a single-phase fluid-flow system is large scale and regionally significant. In contrast, in those portions of the basin characterized by a multiphase fluid-flow system, mass transfer in the sandstones, while commonly intense, is on a much smaller scale and typically confined to relatively small, isolated fluid-flow compartments.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994