Definite "hot spots" or positive geothermal anomalies are associated with 15 of 22 Rocky Mountain oil and gas fields examined in Montana, North Dakota, Wyoming, Utah, Colorado, and New Mexico. Of the remaining 7 fields, 5 have poor to sparse data, and the other 2 show no anomaly or are inconclusive. Stratigraphically as well as structurally controlled fields, and both oil and gas accumulations, show positive geothermal anomalies.

The principal cause for temperature gradient anomalies over oil and gas fields is lateral and upward movement of fluids (primarily water) through the earth's rocks into trapping situations. Such movements not only carry the fluids themselves, but also transport heat from depth.

1. Many Rocky Mountain oil and gas fields are accompanied by positive geothermal anomalies. Similar situations exist in numerous fields in other parts of the world.

2. Anomalies may be induced in several different ways, but upward fluid movement is most important to oil and gas exploration surveys.

3. Accurate temperature measurements are vital to valid interpretations of subsurface geothermics; therefore, temperature measurements must be taken and reported with care and detail in the field.

4. The use of geothermics to locate "hot" anomalies should improve industry success in searching for new oil and gas fields.