1. n. [Formation Evaluation]

A formation layer above or below the layer being measured by a logging tool. The term "surrounding bed" is used in particular to describe the adjacent layers above or below a horizontal well. In a vertical well, the term "shoulder bed" is more common, and is used in particular in resistivity logging to describe the layers above and below a reservoir. The term "adjacent bed" is used in both cases.

Synonyms: shoulder bed,  surrounding bed

See: deconvolution,  depth of investigation,  iterative forward modeling,  radial resolution,  vertical resolution