Regional Aspects of Stratal Architecture of the Subsurface Mississippian in Kansas Based on Wireline log Cross-Sections and Seismic
Brian Willhite and Sal Mazzullo
The lithostratigraphic architecture of the Mississippian in subsurface Kansas is inherently complex, and to complicate it further, it was then overprinted by syndepositional as well as pre-Cherokee tectonics. Yet, the component lithostratigraphic units within the section, and most importantly the petroleum reservoirs therein, can in fact be identified on log cross-sections, and resolved seismically, with detailed subsurface mapping and core-well cuttings sample analyses. Because different Mississippian lithologic units behave differently in terms of their reservoir production and completion attributes, it is critical to identify the specific exploration objective in an area. The Kinderhookian to basal Osagean part of the section is readily identified based on its generally non-cherty character, local presence of reefs, and mostly aggradational ramp-like, 3-D depositional geometry. These rocks are present throughout Kansas, except for where they have been eroded from positive areas. Overlying Osagean strata dramatically contrast the older rocks, and they are recognized by their siliceous character (spiculite, tripolite, and chert) and dominant progradational geometry, with some internal erosional truncations, that are identifiable seismically. These rocks are present only in southern Kansas, and extend into Oklahoma. Major transgression ensued early in Meramecian time, and the resulting geometries of these units include initially onlapping wedges replaced by later aggradational to progradational, carbonate-dominated systems, both of which locally are truncated by major unconformities.
AAPG Search and Discovery Article #90176©AAPG Mid-Continent Meeting, Wichita, Kansas, October 12-15, 2013