TOPOGRAPHIC AND GEOLOGIC CONTROLS ON THE
DISTRIBUTION AND MOVEMENT OF PRODUCED WATER
AND HYDROCARBONS AT THE OSAGE SKIATOOK PETROLEUM
ENVIRONMENTAL RESEARCH SITE "A"
James K. Otton*
U.S. Geological Survey
MS 939 Box 25046
Lakewood, CO 80225
Voice: 303-236-8020
Fax: 303-236-0459
E-mail: jkotton@usgs.gov
Topography, surficial geology, and bedrock geology exert critical control on the distribution and movement of released produced water and hydrocarbons on the landscape at the research site "A". Major point sources for NaCl-bearing produced water and for hydrocarbons at the site appear to be two adjacent pits in which these fluids were stored separately. The two pits sit near the crest of a northwest-trending drainage divide. The northeast sector drains northward into the Cedar Creek arm of Skiatook Lake and the southwest sector drains northwest, west, and then south into the main trunk of the lake. Although it was a primary source for contaminants within the site, a small tank battery upslope and a manmade channel between it and the pits were minor sources of releases to the sector southwest of the drainage divide. Colluvium and bedrock contaminated by produced water salt (NaCl) are remarkably widespread on the site in positions that are topographically below the level of the two pits. The outlet of the produced water pit drained to the north; thus, most salt water was apparently released in that direction. Seepage through pit walls and overflow from the pit probably transported some lesser amounts of salt into the drainage southwest of the divide. Surficial sediments composed of a permeable eolian sand surface layer (20 to 120 cm thick), permeable sandstone-clast-rich slopewash, and clayey to conglomeratic colluvial deposits overlie weathered bedrock (sandstone, clayey sandstone, sandy claystone, and shale). Pathways for produced water movement include 1) topographic lows on the contact between the permeable surficial deposits and the underlying less permeable bedrock units; 2) permeable conglomeratic facies in the colluvial deposits; 3) laterally discontinuous, clean sandstone units in the bedrock; and 4) fractures in bedrock. Shale and dolomite-cemented sandstone might have acted as aquitards. On the outcrop scale, produced waters and hydrocarbons followed permeable zones caused by vertical burrows in bioturbated sandstone. The burrows commonly have a bleached halo around them caused by the dissolution and movement of iron. At one site beneath a pit, hydrocarbon fills an individual vertical burrow.