You are here:
SUBSURFACE WELL-LOG CORRELATION OF ARSENIC-BEARING LITHOFACIES IN THE PERMIAN GARBER SANDSTONE AND WELLINGTON FORMATION, CENTRAL OKLAHOMA AQUIFER (COA), CLEVELAND COUNTY, OKLAHOMA
Citation:
Abbott, B. N., S. T. Paxton, S. J. Smith, S. Christenson, AND R W. Puls*. SUBSURFACE WELL-LOG CORRELATION OF ARSENIC-BEARING LITHOFACIES IN THE PERMIAN GARBER SANDSTONE AND WELLINGTON FORMATION, CENTRAL OKLAHOMA AQUIFER (COA), CLEVELAND COUNTY, OKLAHOMA. Presented at American Assn. of Petroleum Geologists Annual Mtg, Dallas, TX, April 18 - 21, 2004.
Impact/Purpose:
To inform the public.
Description:
The fluvial Garber Sandstone and the underlying Wellington Formation are important sources of drinking water in central Oklahoma. These formations, which make up much of the COA, consist of amalgamated sandstones with some interbedded mudstones, siltstones, and local mudstone- and carbonate-clast conglomerates (Breit et al., 1990). Outcrop descriptions of these formations reveal that the sandstones are lenticular and thicknesses vary substantially over short lateral distances. Water from some wells drilled into the Garber-Wellington exceeds federal drinking water standards for arsenic (EPA, 2001). Arsenic, naturally occurring in much of the COA, appears to be concentrated in water that is produced from the finer-grained rocks. This is because the low permeability of the finer-grained intervals inhibits the flushing-out of naturally occurring trace substances (Schlottman et al., 1998). Therefore, in order to decrease the production of water from wells containing elevated arsenic levels, the lateral and vertical distribution of the finer-grained rocks in the subsurface must be better defined. To accomplish this, geophysical logs from oil and water wells, subsurface core, and outcrops are being used to produce cross-sections and maps of the aquifer interval (structure contour, isopach, net-to-gross, and sandstone-shale ratio maps). To date, our work suggests that sand-prone packages within the Garber Sandstone can be correlated but that correlation of individual sandstone bodies is problematic. Through the integration of on-going companion studies, the projection of outcrop gamma-ray profiles and paleodepositional environment to the subsurface should help to further constrain the habitat of arsenic and better define regional permeability fairways.