Yes, WELL is a Scrabble word!

Letter values in Scrabble US: W 4, E 1, L 1, L 1.

Is it a valid word?

WELL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

a deep hole or shaft dug or drilled to obtain water or oil or gas or brine
a cavity or vessel used to contain liquid
an abundant source
an open shaft through the floors of a building (as for a stairway)
an enclosed compartment in a ship or plane for holding something as e.g. fish or a plane's landing gear or for protecting something as e.g. a ship's pumps

in good health especially after having suffered illness or injury; at least I feel well"
resulting favorably
wise or advantageous and hence advisable

(often used as a combining form) in a good or proper or satisfactory manner or to a high standard (`good' is a nonstandard dialectal variant for `well')
thoroughly or completely; fully; often used as a combining form
indicating high probability; in all likelihood
(used for emphasis or as an intensifier) entirely or fully
to a suitable or appropriate extent or degree
favorably; with approval
to a great extent or degree
with great or especially intimate knowledge
with prudence or propriety
with skill or in a pleasing manner
in a manner affording benefit or advantage
in financial comfort
without unusual distress or resentment; with good humor