Salinity and Temperature Anomalies over Structural Oil Fields, Carter County, Oklahoma

Abstract

The relationship between high ground-water salinity and high bottom-hole temperature anomalies and deep-seated structures was investigated in Carter County, Oklahoma. A modified spontaneous potential method was used to compute salinity from 700 well logs at a depth of 300 ft (90 m). This depth was chosen because it was within reach of truck-mounted rigs, yet below brine-polluted ground water. The hydraulics of the shallow aquifers were also investigated to determine the origin of the anomalies. Detailed mapping of the high-salinity anomalies gave good definition of the major structures at 300 ft (90 m) as did detailed mapping of geothermal gradients at 1,200 ft (370 m) over the Healdton oil field (T4S, R3W). Other structures had poorly defined temperature anomalies. Spontaneous potential data indicate that, in general, upward cross-formational flow is not occurring; hence, the high-salinity anomalies are related to partially flushed, tectonically raised structures. In the absence of upward flow, the temperature anomalies are caused by proximity to radioactive basement rocks.