Tour

A working shift for drilling crew or other oilfield workers. Some tours are 8 hours; the three daily tours are called daylight, evening (or afternoon), and graveyard (or morning). 12-hour tours may also be used; they are called simply day tour and night tour.

Tomography

A technique used by geophysicists to measure and display the three-dimensional distribution of velocity or reflectivity of a volume of the Earth by using numerous sources and receivers. Variations in velocity can be attributed to changes in properties of rocks. Tomographic techniques have been used to construct maps of the Earth’s interior, deep in the …