Kansas Geological Survey, Open-file Report 88-39
Great Plains and Cedar Hills Aquifers--Page 25 of 25
(1) Stratigraphic Framework. A review of the literature shows that a usable stratigraphic framework correlated with surface exposures of the Lower Cretaceous rocks in central Kansas does not exist. Work completed during the course of this investigation suggests that by using a diverse combination of lithodensity and natural gamma-ray logs, it is possible to perform a paleoenvironmental analysis of the lithofacies and establish a consistent rock-stratigraphic framework. This information is important in order to predict the distribution of major sandstone-bearing zones in the subsurface and to facilitate regulation of oil-industry activities by physically establishing the requirements for surface casing. In order to accomplish this goal, a combination of geologic and log-analysis techniques will need to be applied.
The next phase of analysis of the logs from the KGS #1 Braun will be focused on porosity estimations and permeability predictions within the Lower Cretaceous formations and Cedar Hills Sandstone, as well as neutron log studies of the bound-water and compactional character of the shale units. In these investigations, research work will be closely coordinated with hydrologic studies, so that results may be integrated effectively into ground-water models.
(2) Description of the Flow System. In order to develop a more quantitative description of the flow system in the Great Plains and Cedar Hills aquifers, water level information, materials properties, and additional water chemistry data need to be developed. This includes hydrologic testing of the monitoring sites to determine the horizontal and vertical hydraulic conductivities and storage properties, use of additional environmental isotopes to determine the ages and geochemical evolution of ground waters in the system, and more recent surveys of water levels and water quality in the Cedar Hills aquifer. Estimates of the materials properties will be useful for developing mathematical simulations of the ground-water flow system. This information can be used to determine rates of interchange between the Cedar Hills and Great Plains aquifers and to test hypotheses. An estimate of the age of ground waters in the Great Plains aquifer will be useful for assessing the potential of recharge to the aquifer from the surface. Much of the Cedar Hills data used in this report was developed in the 1970's from information supplied by well operators. As a result, it is difficult to assess the quality of this early survey data.
(3) Mechanics of Injection. Monitoring of the oil-field brine injection wells needs to be carried out in the subcrop area and at a site west of the subcrop in order to determine the effects of injection on the disposal horizon and overlying aquifers in both areas. In order to do this, carefully-controlled testing and precise observations of the quantities of fluids injected and fluid pressures in the overlying aquifers must be carried out at specific sites. This would probably entail the installation and monitoring of a multiple-completion monitoring well over time to observe the increase of fluid pressures in the Cedar Hills from injection and the effects in the overlying aquifers near the brine disposal well.
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