Primary and Secondary Porosity Development in Valley Fill, Marine Sandstone Reservoirs--Misener Formation, North-Central Oklahoma: ABSTRACT

The Devonian Misener formation in north-central Oklahoma consists of a series of discontinuous sand and shale bodies deposited in erosional topographic lows on the post-Hunton unconformity surface. Paleontological, mineralogical, and sedimentological evidence supports a marine depositional setting. Rapid changes in sandstone thickness and reservoir properties are characteristic of Misener sands. These sands were episodically deposited, fine upward, and commonly interfinger with an equivalent shale facies. The basal contact of the Misener sandstone bodies is erosional with the inclusion of shale, phosphate, and sandstone clasts in a medium-grained, dolomitic quartzarenite sandstone. Reservoir porosity is best developed in the poorer sorted, medium-grained, dolomitic quartzarenites of the channel facies. A mixed mineralogy sandstone is critical to the preservation of primary porosity and the development of secondary porosity. Well-sorted, fine-grained quartzarenite sandstones (nonchannel) have been extensively quartz cemented. Early dolomitization in the mixed mineralogy sandstones prevented quartz cementation and preserved primary porosity. Sandstones containing preserved primary porosity served as pathways for the movement of subsurface fluids. These fluids generated secondary porosity by the selective dissolution of glauconite, phosphate, and lithic grains. Significant post-hydrocarbon diagenesis in the form of bitumen precipitation, dedolomitization, and calcite cementation has occurred in the water zone of several Misener sandstone more » reservoirs. The occurrence of these diagenetic products in the oil column suggests post entrapment tilting of some reservoirs. « less