1. n. [Formation Evaluation]

Measurements made by measurements-while-drilling (MWD) tools subsequent to the initial bit run. MWD logs are recorded while drilling the well. However, these tools can also record logs at later times when the drillstring is in the hole. This may be while pulling out after drilling, or on a subsequent bit run or circulating trip. The latter is also known as logging while tripping.

See related terms: formation exposure time