Arbuckle Reservoirs in Central Kansas: Relative Importance of Depositional Facies, Early Diagenesis and Unconformity Karst Processes on Reservoir Properties
Kansas Geological Survey
Open-file Report 98-55
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Arbuckle Reservoirs in Central Kansas: Relative Importance of Depositional Facies, Early Diagenesis and Unconformity Karst Processes on Reservoir Properties |
Kansas Geological Survey Open-file Report 98-55 |
We present a preliminary, 11 part paragenetic sequence based on petrographic observations presented in the preceding section. Listed from oldest to youngest this sequence includes (1) deposition of original facies; (2) intra-Arbuckle subaerial exposure and erosion events as indicated by autobrecciation, mudcracks, fenestrae, and rip-up conglomerates; (3) compaction; (4) early dolomitization evidenced by silicified dolomite rhombs in chert clasts that occur in later fractures. The small crystal size of some dolomite (<0.01 mm), evidence of silica replaced evaporite minerals (anhydrite/gypsum ?), and local occurrence of spheroidal or polyhedral dolomite are supportive of early reflux or mixing zone dolomitization; (5) stylolitization; (6) development of secondary porosity; (7) silicification as indicated by displacive growth textures of silica areas in dolomite, differential compaction between silica (brittle fracturing) and surrounding dolomite matrix (soft sediment deformation), silicified carbonate grains and facies occurring as clasts (with truncated grains at clast boundaries) occurring in later fractured and brecciated areas; (8) later dolomitization evidenced by crystals (>0.03 mm) that cross cut phases associated with events 4 through 7; (9) ferroan and non-ferroan dolomite rims; (10) subaerial exposure and karstification producing the post-Arbuckle (post-Sauk) unconformity as indicated by open, partially occluded, or fully occluded fractures and breccia fabrics, calcite cementation, replacement and dedolomite dissolution, and pore-filling silica cement that cuts across all previous events; and (11) burial producing hematite, pyrite, other opaque minerals, bitumen and oil, later dolomite (some baroque dolomite), and compaction and fracturing that cuts across all previous features.
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