What is the maximum length of $\frac{103}{4}"$ L$-80,51$# casing which can be supported by its own strength

a$.$ in air.

b$.$ In $14$ ppg mud?

For the casing above if we were running in casing closed at the bottom $("$floating it in$")$ and took a kick resulting in $3500g$ surface pressure when we closed the annular preventer around the casing, and had $2000$ feet of casing in the hole. What force must the preventer be capable of exerting to keep the casing fixed in place in the hole. $($Just do a force balance$)$