Abstract: Evaluation of Subsurface Temperature in Eugene Island Block 330 and Vicinity

T. E. McKenna, W. G. Powell

To test the hypothesis that elevated temperatures in the Eugene Island 330 area result from fluid flow in a large growth-fault system, we investigate the temperature structure in the vicinity of this fault system using a set of reliable subsurface temperature data. The data compilation includes over 1000 temperature measurements from pressure recovery tests and well logs; of these, only 5% are reliable measures of formation temperature. We cannot resolve spatially-restricted thermal anomalies along the faults because of the limited distribution of reliable measurements.

A temperature difference of approximately 10°F (6°C) is observed at reservoir depths (6,000-9,000 ft; 1,800-2700 m) across the fault in Eugene Island Block 330 and vicinity. A one-dimensional model of transient heat conduction indicates that up to 80% of this temperature difference is due to the increased sedimentation rate on the downthrown side of the fault. Mobile salt below the sediments on the footwall side of the fault may also contribute

to higher temperatures there because it is a good heat conductor. The temperature difference that we observe (1) is similar in magnitude to previous interpretations, (2) can be explained by sedimentation differences and thermal conductivity contrasts, and (3) does not reflect heat transport by fluid flow in the faults.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994