Thermal Regime of the Midcontinent El Dorado Oil Field (Kansas) Interpreted from High Resolution Temperature Logs
by Jason R. McKenna, Southern Methodist University; Daniel F. Merriam, Kansas Geological Survey; and David D. Blackwell, Southern Methodist University
The giant, multizone-producing El Dorado oil field (Butler County in south central Kansas) was discovered on the Nemaha Anticline in 1915. Early indications from bottomhole (BHTs) and drillstem (DSTs) temperature measurements indicated a close relationship between the anticlinal structure and higher subsurface temperatures. Recently, a suite of high resolution temperature logs was made from shut-in wells on the East and West Shumway domes in the field to confirm the three dimensional thermal modeling. The temperature logs generally are conductive, equilibrium profiles demonstrating that these types of logs can provide reliable, equilibrium temperature measurements in an active petroleum setting. Lower temperatures measured in several of the wells on the East Shumway Dome seem to be the result of a significant change in thermal gradient from mass transport of hydrocarbons and in situ thermal conductivity changes related to the presence of hydrocarbons and not to interwell lithologic variability. An analysis of the high resolution temperature logs and log header BHTs taken near the top of the Kansas City Group (Upper Pennsylvanian) and Arbuckle Group (Lower Ordovician) productive zones on the West Shumway Dome indicate that the anomalously high BHT data are close to the actual formation temperature substantiating that the higher temperatures encompass a broader region on the dome than previously assumed.