There is no need to include the variables in square brackets. Replace:
an so on.
These line will write something to the commabnd window (square brackets removed already):
CRS = 'n/a'
TimeZone = 'UTC'
Description = 'Lacq field: bottomhole pressure'
If this is not wanted, insert semicolons:
Then running your code creates the MAT file in the current folder. Perhaps you should set this accordingly by: