Diagenetic Aspects of Lower Morrowan, Pennsylvanian, Sandstones, Northwestern Oklahoma

摘要: Diagenesis has profoundly altered the reservoir capacity of some lower Morrowan sandstones in Anadarko basin. Definitions sandstone geometry, depositional environment, etc., comprise only part information necessary to explore intelligently for hydrocarbons these rocks. Most Morrow were deposited a broadly transgressive system. Two basic types are recognized: (1) Type A is very nearshore, clean, well sorted, non-glauconitic, non-calcareous high energy environment; (2) B seaward facies A, under conditions and normally poorly "glauconitic," calcareous, here there shaly. Petrographic analyses indicate have either extreme pressure solution no permeability, or moderate minor with secondary quartz overgrowth cement. These rocks generally permeable when medium- coarse-grained impermeable if fine-grained. Upper edges sand bodies tightly cemented CaCO3 possibly through ionic impedance at sand-shale boundary. been diagenetically by solution, extensive carbonate cementation, authigenic clay. Commercial permeability associated removal cements. Such reservoirs random shapes difficult predict evaluate. qualitative petrographic rock fabric classification based on relative degree type grain outlines contacts, amount cement porosity useful mapping their geographic distributions. Integration this data into normal subsurface exploration methods helpful understanding area studied.