The ornamental design for a well casingcap, as shown and described.
FIG. 1 is a top plan view of a well casing cap embodying my invention.
FIG. 2 is a bottom plan view of the well casing cap shown in FIG. 1 and
embodying my invention; and,
FIG. 3 is a side elevation of the right side of the well casing cap shown
in FIG. 1 and embodying my invention; the left side is a mirror image of
the right.